# Biochemical, Oxidative, and Lipolytic Changes during Vacuum-Packed Storage of Dry-Cured Loin: Effect of Chestnuts Intake by Celta Pigs

Authors: María Gómez; Aida Cachaldora; Sonia Fonseca; Rubén Domínguez; Javier Carballo; Inmaculada Franco
Journal: Journal of Food Quality
 (2018)

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## Abstract

The effect of the inclusion of chestnuts in the finishing diet of Celta pig breed on the characteristics of dry-cured loin, a traditional Spanish dry-cured meat product, after the manufacturing process and the vacuum-packed storage was studied. In general, no significant differences between the diets (chestnut, mixed, and concentrate diet) were obtained for physicochemical (moisture, intramuscular fat, and titratable acidity) and lipolytic parameters. Lower pH and higher values for oxidation parameters (peroxide and TBA values) were obtained in loins from pigs fed with chestnuts. However, no differences were found for fatty acids from the different lipid fractions when diets were compared, with the exception of some minor fatty acids. Free fatty acids represented over 2.7% of the fat in the final product. The distinction between diets was procured when a discriminant canonical analysis was performed for fatty acid contents. After vacuum-packed storage, only a slight evolution of the studied parameters was obtained.


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## Body

## 1. Introduction

Dry-cured pork loin is a typical Spanish meat product, which represents an important market [1]. During dry-curing process of meat products, lipids degradation occurs, mainly due to lipolytic and oxidative phenomena [2]. Lipolysis leads to the release of free fatty acids (FFA) from both neutral (NL) and polar (PL) lipids. Lipid oxidation reactions produced also changes in the fatty acid composition of the different lipid fractions, giving rise to a number of compounds, which are essential in the development of the typical aroma in these products [3]. Among factors affecting fatty acid composition of pig lipids (genetic factors, rearing system, sex and castration, age at slaughtering, or location in the carcass), feeding appears to be the most important factor [4].Celta pig, a traditional breed from Galicia (northwest of Spain), was very important until the 1950s but then it was substituted for commercial crossbreeds, being near to disappear in the 80s. High value-added meat products are obtained from Celta pig due to the great fat infiltration in the lean meat [4, 5].In Galicia, chestnuts (Castanea sativa Mill.) have been traditionally used in pig feeding. This fruit is composed of carbohydrates, proteins, lipids, and acceptable content of minerals and vitamins [5]. Also, the content of linoleic acid in its fat is notable [6]. Chestnuts in Spain are insufficiently exploited; this, combined to its adequate composition, makes them suitable for pig feeding.The novelty of this work lies in the use ofLongissimus dorsi from Celta pig breed for manufacturing dry-cured loin, as products from this breed were not subjected to many studies so far. Chestnuts can be used on Celta pig feeding in an extensive regime with the consequent reduction of the production cost and obtaining products with a differential quality and added value. Therefore, the aim of this study was to determine the influence of including chestnut in the finishing diet of Celta pig breed on lipolytic and oxidative parameters and fatty acid composition of the manufactured dry-cured loin. For this purpose, three batches of dry-cured loins were manufactured from pigs fed with three different finishing diets (only with concentrate, only with chestnuts, and a mixed diet of chestnuts and concentrate) and chemical composition, physicochemical, lipolytic, and oxidative parameters and fatty acid composition were studied in the final product and during 6 months of vacuum-storage.


## 2. Material and Methods

### 2.1. Animals, Diets, and Dry-Cured Loin Manufacture

Thirty-six pigs from Celta breed were reared by the INORDE (Instituto Ourensano de Desarrollo, Ourense, Spain) in a semiextensive system with a density of 12 pigs per hectare. The animals were weaned at the age of 40 days and castrated at 60 days for the males and at 90 days for the females. Pigs were fed with a commercial concentrate until the month 12 and then they were divided into three groups of 12 pigs each. In the first group (chestnut diet), the pigs, after a month of adaptation in which the pigs were fed with a mixed diet of chestnuts and concentrate, received during the rest of the fattening period (3 months) a diet constituted only by chestnuts (5 kg of chestnuts per day and pig). On the second group (mixed diet), the pigs received during the fattening period (last 4 months) a mixed diet of concentrate and chestnuts (1.5 kg of concentrate and 2.5 kg of chestnuts per day and pig). Finally, in the last group (concentrate diet), the pigs were fed the entire fattening period with the commercial concentrate (3 kg of concentrate per day and pig). The chemical composition of the three diets is shown in a previous work using these pigs [5] and it is shown in Table 1.Table 1
General composition and fatty acids of the experimental diets: chestnut, mixed, and concentrate.
Chestnuta Chestnuts-concentrateb Concentratec Energy (kcal/100 g) 275.5 343.1 456.6 Composition (g/100 g) Dry matter 51.9 66.0 89.5 Crude protein 4.20 8.40 15.3 Ethereal extract 3.30 3.90 4.90 Crude fibre 2.00 3.00 4.60 Starch 32.0 34.9 39.7 Ash 1.30 3.20 6.30 Fatty acids (mg/100 g) C12 1.23 ± 0.04 3.18 ± 0.05 6.99 ± 0.06 C14 3.63 ± 0.11 20.0 ± 0.14 52.4 ± 0.19 C14:1n-5 0.04 ± 0.01 0.10 ± 0.01 0.21 ± 0.02 C15 2.35 ± 0.02 3.68 ± 0.02 6.12 ± 0.00 C15:1 1.00 ± 0.01 1.10 ± 0.01 1.22 ± 0.03 C16 501 ± 1.25 714 ± 0.92 1097 ± 0.37 C16:1n-7 12.0 ± 0.03 32.2 ± 0.12 71.8 ± 0.26 C17 3.20 ± 0.01 7.66 ± 0.09 16.3 ± 0.24 C17:1 1.86 ± 0.02 4.30 ± 0.05 9.03 ± 0.08 C18 32.5 ± 0.31 174 ± 0.22 454 ± 0.08 C18:1n-9 911 ± 3.37 1073 ± 2.32 1317 ± 0.57 C18:2n-6 1510 ± 0.61 1475 ± 1.65 1272 ± 3.37 C18:3n-6 2.50 ± 0.04 2.62 ± 0.06 2.66 ± 0.08 C18:3n-3 190 ± 5.58 173 ± 3.58 122 ± 0.24 C20 7.54 ± 0.09 7.33 ± 0.07 6.26 ± 0.04 C20:1n-9 12.9 ± 0.24 15.3 ± 0.19 19.0 ± 0.09 C20:2n-6 1.59 ± 0.15 3.24 ± 0.22 6.41 ± 0.34 C20:3n-6 1.28 ± 0.01 1.52 ± 0.03 1.88 ± 0.06 C20:4n-6 0.37 ± 0.10 1.82 ± 0.13 4.69 ± 0.20 C20:3n-3 0.53 ± 0.51 1.08 ± 0.44 2.15 ± 0.31 C20:5n-3 0.43 ± 0.10 0.99 ± 0.08 2.09 ± 0.05 C22 7.43 ± 0.08 7.63 ± 0.07 7.40 ± 0.07 C22:1n-9 2.40 ± 0.25 3.28 ± 0.57 4.82 ± 1.09 C22:2n-6 85.6 ± 3.31 188 ± 3.81 385 ± 4.63 C23 1.61 ± 0.07 9.75 ± 0.14 25.9 ± 0.27 C24 4.90 ± 0.22 4.18 ± 0.73 2.29 ± 1.57 C24:1n-9 0.32 ± 0.09 0.65 ± 0.19 1.27 ± 0.36 ∑SFA 566 ± 1.23 951 ± 0.89 1675 ± 0.33 ∑UFA 2734 ± 1.23 2977 ± 0.89 3225 ± 0.33 ∑MUFA 941 ± 3.31 1129 ± 2.67 1425 ± 1.60 ∑PUFA 1793 ± 2.08 1847 ± 2.03 1800 ± 1.93 ∑SFA: sum of saturated fatty acids; ∑UFA: sum of unsaturated fatty acids; ∑MUFA: sum of monounsaturated fatty acids; ∑PUFA: sum of polyunsaturated fatty acids;a5 kg of chestnuts/animal and day. b(1.5 kg of commercial compound feed + 2.5 kg of chestnuts)/animal and day. c3 kg of commercial compound feed/animal and day.At 16 months, the pigs were transported to a commercial slaughterhouse (Frigolouro, Porriño, Pontevedra, Spain). After slaughtering, and after 24 hours of refrigeration, the Longissimus dorsi muscles were removed from the carcasses and after removing the surface fat and connective tissue, the muscles were seasoned with a commercial mixture (Doscamix LM30 Salamanca, Doscadesa, Murcia, Spain) containing between other ingredients salt, nitrites, sucrose, and paprika. The dry-cured loin manufacture was carried out in the industry “Cárnicas Pérez Guerra” (Taboadela, Ourense, Spain). For each of the three diets, 18 units of dry-cured loin were manufactured. Loins were kept for 8 days at 4°C and at a relative humidity (RH) of 85–90% to allow the seasoning mixture to penetrate. After that, loins were stuffed into collagen casings and held for 30 days at 4°C at 65–70% RH. Finally, loins were ripened in a natural drying room for 60 additional days where the mean conditions were 8–16°C and at 70–75% RH.To study the product characteristics, six units of dry-cured loin of each diet group were taken (final product). To study the product stability, after manufacturing, 12 units of dry-cured loin from each batch (diet group) were vacuum-packed and then stored at 20–23°C and 45–55% RH. Samples from each batch were taken after 3 and 6 months of vacuum-packed storage. To prepare samples for analysis, after removing and discarding the outer casing of each loin, the edible part was ground until a homogeneous mass was obtained. After determining the pH and the moisture content, the samples were vacuum-packed and frozen at −80°C for no longer than a month before further analysis.


### 2.2. Analytical Methods

Dry matter, pH, titratable acidity, acidity value, peroxide value, and TBARS were determined as described by Franco et al. [7]. Fat was extracted according to Folch et al. [8] procedure. Fat extract was weighted and the fat content was expressed as percentage of fat per 100 g of dry matter.The different lipid fractions (neutral and polar lipids and free fatty acids) were separated using NH2-aminopropyl columns (500 mg) (SUPELCO, Bellefonte, USA) as described by Kaluzny et al. [9] with some modifications. Two hundred milligrams of the extracted lipids in chloroform was applied to the column. NL were eluted with 3 ml of a mixture of chloroform : 2-propanol (2 : 1), free fatty acids were eluted with 3 ml of 2% of acetic acid in diethyl ether, and finally PL were eluted with 3 ml of methanol. Fatty acids from each lipid fraction and five hundred milligrams of fat (total fatty acids) were transesterified following the method of Shehata et al. [10]. The identification and quantification of the fatty acids methyl esters were carried out by Gas Chromatography using a Thermo Finnigan Trace GC (Thermo Finnigan, Austin, TX, USA) chromatograph, equipped with a Split/Splitless AI 3000 Autoinjector and a flame ionization detector (FID). The separation of the different fatty acids was carried out in an HP-INNOWAX column (30 m; 25 mm ID; 0.25 mm film thickness) (Agilent Technologies, Santa Clara, CA, USA). The temperatures of the detector and injector were 250°C and 230°C, respectively. The gasses used were air (350 mL/min), hydrogen (35 mL/min), and helium (carrier gas) (30 mL/min). Chromatographic conditions were as follows: initial oven temperature of 50°C (held for 1 min) and a ramp at 5°C/min to 248°C (held for 15 min). Identification of fatty acids was performed by comparison of the retention times obtained with a pattern of fatty acid methyl esters (SUPELCO, Bellefonte, USA) and the results were expressed for fatty acids from total NL and PL as percentage of chromatographic total area. Free fatty acids were quantified using tridecanoic acid at 500 mg/L, as internal standard, which was added to samples prior to methylation and the results were expressed as mg/100 g of fat [5].Means were compared by the least squares difference (LSD) test at a significance level of 0.05, using the software Statistica© 8.0 for Windows (Statsoft Inc., Tulsa, OK, USA). Canonical discriminant analysis (CDA) was applied to different lipid fraction in order to classify the three diets used in Celta pig fed. The selection of variables for CDA was achieved with the extraction of principal components through a factor analysis, selecting the variables with a major discriminant capacity.


## 2.1. Animals, Diets, and Dry-Cured Loin Manufacture

Thirty-six pigs from Celta breed were reared by the INORDE (Instituto Ourensano de Desarrollo, Ourense, Spain) in a semiextensive system with a density of 12 pigs per hectare. The animals were weaned at the age of 40 days and castrated at 60 days for the males and at 90 days for the females. Pigs were fed with a commercial concentrate until the month 12 and then they were divided into three groups of 12 pigs each. In the first group (chestnut diet), the pigs, after a month of adaptation in which the pigs were fed with a mixed diet of chestnuts and concentrate, received during the rest of the fattening period (3 months) a diet constituted only by chestnuts (5 kg of chestnuts per day and pig). On the second group (mixed diet), the pigs received during the fattening period (last 4 months) a mixed diet of concentrate and chestnuts (1.5 kg of concentrate and 2.5 kg of chestnuts per day and pig). Finally, in the last group (concentrate diet), the pigs were fed the entire fattening period with the commercial concentrate (3 kg of concentrate per day and pig). The chemical composition of the three diets is shown in a previous work using these pigs [5] and it is shown in Table 1.Table 1
General composition and fatty acids of the experimental diets: chestnut, mixed, and concentrate.
Chestnuta Chestnuts-concentrateb Concentratec Energy (kcal/100 g) 275.5 343.1 456.6 Composition (g/100 g) Dry matter 51.9 66.0 89.5 Crude protein 4.20 8.40 15.3 Ethereal extract 3.30 3.90 4.90 Crude fibre 2.00 3.00 4.60 Starch 32.0 34.9 39.7 Ash 1.30 3.20 6.30 Fatty acids (mg/100 g) C12 1.23 ± 0.04 3.18 ± 0.05 6.99 ± 0.06 C14 3.63 ± 0.11 20.0 ± 0.14 52.4 ± 0.19 C14:1n-5 0.04 ± 0.01 0.10 ± 0.01 0.21 ± 0.02 C15 2.35 ± 0.02 3.68 ± 0.02 6.12 ± 0.00 C15:1 1.00 ± 0.01 1.10 ± 0.01 1.22 ± 0.03 C16 501 ± 1.25 714 ± 0.92 1097 ± 0.37 C16:1n-7 12.0 ± 0.03 32.2 ± 0.12 71.8 ± 0.26 C17 3.20 ± 0.01 7.66 ± 0.09 16.3 ± 0.24 C17:1 1.86 ± 0.02 4.30 ± 0.05 9.03 ± 0.08 C18 32.5 ± 0.31 174 ± 0.22 454 ± 0.08 C18:1n-9 911 ± 3.37 1073 ± 2.32 1317 ± 0.57 C18:2n-6 1510 ± 0.61 1475 ± 1.65 1272 ± 3.37 C18:3n-6 2.50 ± 0.04 2.62 ± 0.06 2.66 ± 0.08 C18:3n-3 190 ± 5.58 173 ± 3.58 122 ± 0.24 C20 7.54 ± 0.09 7.33 ± 0.07 6.26 ± 0.04 C20:1n-9 12.9 ± 0.24 15.3 ± 0.19 19.0 ± 0.09 C20:2n-6 1.59 ± 0.15 3.24 ± 0.22 6.41 ± 0.34 C20:3n-6 1.28 ± 0.01 1.52 ± 0.03 1.88 ± 0.06 C20:4n-6 0.37 ± 0.10 1.82 ± 0.13 4.69 ± 0.20 C20:3n-3 0.53 ± 0.51 1.08 ± 0.44 2.15 ± 0.31 C20:5n-3 0.43 ± 0.10 0.99 ± 0.08 2.09 ± 0.05 C22 7.43 ± 0.08 7.63 ± 0.07 7.40 ± 0.07 C22:1n-9 2.40 ± 0.25 3.28 ± 0.57 4.82 ± 1.09 C22:2n-6 85.6 ± 3.31 188 ± 3.81 385 ± 4.63 C23 1.61 ± 0.07 9.75 ± 0.14 25.9 ± 0.27 C24 4.90 ± 0.22 4.18 ± 0.73 2.29 ± 1.57 C24:1n-9 0.32 ± 0.09 0.65 ± 0.19 1.27 ± 0.36 ∑SFA 566 ± 1.23 951 ± 0.89 1675 ± 0.33 ∑UFA 2734 ± 1.23 2977 ± 0.89 3225 ± 0.33 ∑MUFA 941 ± 3.31 1129 ± 2.67 1425 ± 1.60 ∑PUFA 1793 ± 2.08 1847 ± 2.03 1800 ± 1.93 ∑SFA: sum of saturated fatty acids; ∑UFA: sum of unsaturated fatty acids; ∑MUFA: sum of monounsaturated fatty acids; ∑PUFA: sum of polyunsaturated fatty acids;a5 kg of chestnuts/animal and day. b(1.5 kg of commercial compound feed + 2.5 kg of chestnuts)/animal and day. c3 kg of commercial compound feed/animal and day.At 16 months, the pigs were transported to a commercial slaughterhouse (Frigolouro, Porriño, Pontevedra, Spain). After slaughtering, and after 24 hours of refrigeration, the Longissimus dorsi muscles were removed from the carcasses and after removing the surface fat and connective tissue, the muscles were seasoned with a commercial mixture (Doscamix LM30 Salamanca, Doscadesa, Murcia, Spain) containing between other ingredients salt, nitrites, sucrose, and paprika. The dry-cured loin manufacture was carried out in the industry “Cárnicas Pérez Guerra” (Taboadela, Ourense, Spain). For each of the three diets, 18 units of dry-cured loin were manufactured. Loins were kept for 8 days at 4°C and at a relative humidity (RH) of 85–90% to allow the seasoning mixture to penetrate. After that, loins were stuffed into collagen casings and held for 30 days at 4°C at 65–70% RH. Finally, loins were ripened in a natural drying room for 60 additional days where the mean conditions were 8–16°C and at 70–75% RH.To study the product characteristics, six units of dry-cured loin of each diet group were taken (final product). To study the product stability, after manufacturing, 12 units of dry-cured loin from each batch (diet group) were vacuum-packed and then stored at 20–23°C and 45–55% RH. Samples from each batch were taken after 3 and 6 months of vacuum-packed storage. To prepare samples for analysis, after removing and discarding the outer casing of each loin, the edible part was ground until a homogeneous mass was obtained. After determining the pH and the moisture content, the samples were vacuum-packed and frozen at −80°C for no longer than a month before further analysis.


## 2.2. Analytical Methods

Dry matter, pH, titratable acidity, acidity value, peroxide value, and TBARS were determined as described by Franco et al. [7]. Fat was extracted according to Folch et al. [8] procedure. Fat extract was weighted and the fat content was expressed as percentage of fat per 100 g of dry matter.The different lipid fractions (neutral and polar lipids and free fatty acids) were separated using NH2-aminopropyl columns (500 mg) (SUPELCO, Bellefonte, USA) as described by Kaluzny et al. [9] with some modifications. Two hundred milligrams of the extracted lipids in chloroform was applied to the column. NL were eluted with 3 ml of a mixture of chloroform : 2-propanol (2 : 1), free fatty acids were eluted with 3 ml of 2% of acetic acid in diethyl ether, and finally PL were eluted with 3 ml of methanol. Fatty acids from each lipid fraction and five hundred milligrams of fat (total fatty acids) were transesterified following the method of Shehata et al. [10]. The identification and quantification of the fatty acids methyl esters were carried out by Gas Chromatography using a Thermo Finnigan Trace GC (Thermo Finnigan, Austin, TX, USA) chromatograph, equipped with a Split/Splitless AI 3000 Autoinjector and a flame ionization detector (FID). The separation of the different fatty acids was carried out in an HP-INNOWAX column (30 m; 25 mm ID; 0.25 mm film thickness) (Agilent Technologies, Santa Clara, CA, USA). The temperatures of the detector and injector were 250°C and 230°C, respectively. The gasses used were air (350 mL/min), hydrogen (35 mL/min), and helium (carrier gas) (30 mL/min). Chromatographic conditions were as follows: initial oven temperature of 50°C (held for 1 min) and a ramp at 5°C/min to 248°C (held for 15 min). Identification of fatty acids was performed by comparison of the retention times obtained with a pattern of fatty acid methyl esters (SUPELCO, Bellefonte, USA) and the results were expressed for fatty acids from total NL and PL as percentage of chromatographic total area. Free fatty acids were quantified using tridecanoic acid at 500 mg/L, as internal standard, which was added to samples prior to methylation and the results were expressed as mg/100 g of fat [5].Means were compared by the least squares difference (LSD) test at a significance level of 0.05, using the software Statistica© 8.0 for Windows (Statsoft Inc., Tulsa, OK, USA). Canonical discriminant analysis (CDA) was applied to different lipid fraction in order to classify the three diets used in Celta pig fed. The selection of variables for CDA was achieved with the extraction of principal components through a factor analysis, selecting the variables with a major discriminant capacity.


## 3. Results and Discussion

### 3.1. Biochemical, Lipolytic, and Oxidative Parameters

The evolution of compositional, physicochemical, lipolytic, and oxidative parameters of dry-cured loin, after manufacturing process and after 3 and 6 months of vacuum-packed storage, is shown in Table2.Table 2
Biochemical, lipolytic, and oxidative parameters of dry-cured loin from Celta pig fed with three finishing diets (chestnut, mixed, and concentrate), after manufacturing process and after 3 and 6 months of vacuum-packed storage.
Chestnuts Chestnuts-concentrate Concentrate Final product Storage time (months) Final product Storage time (months) Final product Storage time (months) 3 6 3 6 3 6 Dry matter (%) 65.52 ± 1.52 64.56 ± 1.92 64.93 ± 1.15 65.28 ± 2.51 64.97 ± 1.67 64.51 ± 0.77 65.29 ± 2.35 64.78 ± 2.57 65.24 ± 1.94 Intramuscular fat (%) 13.97 ± 1.32 13.64 ± 1.26 13.52 ± 1.17 13.52 ± 2.29 12.90 ± 2.57 12.88 ± 1.91 13.29 ± 1.36 13.39 ± 1.62 12.33 ± 3.32 pH 5.44 ± 0.12  a 1 5.47 ± 0.07  a 1 5.58 ± 0.15  b 1 5.48 ± 0.15  a 1 5.57 ± 0.09  a b 1 5.62 ± 0.09  b 1 5.66 ± 0.13 2 5.69 ± 0.10 2 5.73 ± 0.15 2 Titratable acidity(% lactic acid) 0.99 ± 0.07 a 1.14 ± 0.08  b 1 1.12 ± 0.10  b 1 0.98 ± 0.17 a 1.11 ± 0.08  b 1 1.13 ± 0.11  b 1 0.94 ± 0.07 0.95 ± 0.07 2 1.01 ± 0.15 2 Acidity value(mg KOH/g sample) 23.12 ± 2.17 a 36.61 ± 3.13 b 44.10 ± 5.34  c 12 24.01 ± 3.59 a 38.10 ± 4.74 b 45.58 ± 5.68  c 1 20.90 ± 2.65 a 36.62 ± 3.84 b 41.03 ± 4.81  c 2 Peroxide value(meq O2/kg fat) 20.35 ± 2.44  a 1 13.30 ± 1.30  b 12 15.72 ± 1.50 c 18.63 ± 3.14  a 2 12.04 ± 2.49  b 1 16.22 ± 2.19 c 16.22 ± 2.09  a 2 13.83 ± 1.34  b 2 15.55 ± 2.05 c TBA value(mg MDA/kg sample) 0.30 ± 0.07  a 1 0.12 ± 0.03 b 0.10 ± 0.03 b 0.25 ± 0.07  a 2 0.10 ± 0.03 b 0.07 ± 0.01 b 0.17 ± 0.05  a 3 0.11 ± 0.03 b 0.09 ± 0.04 b a–cDifferent letters within the same row corresponding to the same diet group indicate significant differences (P<0.05); 1–3different numbers within the same row corresponding to the same sampling point indicate significant differences (P<0.05), when the three finishing diets are compared.Dry matter content of dry-cured loin was similar in the three diet groups. The mean values were about 65%. These contents were similar to those previously found in Iberian dry-cured loin [11–13] and just a little higher than from other breeds [1, 14–16]. These values kept constant after 3 and 6 months of vacuum-packed storage. A similar behaviour was also reported [17, 18] because this method of storage is effective in preventing moisture losses during the storage of the meat products.In our study, the three diets had similar daily energy, although the chestnut diet provides, per day, higher contents of fat, C18:1n-9, C18:2n-6, C18:3n-3, and carbohydrates (Table 1). However, intramuscular fat content of dry-cured loin was similar in the three diet groups with values about 13.5% (of dry matter). As expected, these values remained constant during the vacuum-packed storage. The intramuscular fat content of dry-cured loin from Celta pig is closer to those contents determined in dry-cured loin from Iberian pig [11, 12] and quite higher than manufactured from other commercial breeds [19]. Fat is probably the most variable component when dry-cured meat products elaborated from whole pieces are studied. Celta pig is characterized by a highly developed adipogenic metabolism that leads to the deposit of a great amount of fat in its tissues, obtaining higher percentages of back fat compared to other breeds [20].The pH values (Table2) of dry-cured loin were significantly affected by the use of chestnut in the finishing diet (P<0.05). With the increase of chestnuts in the diet, a lower pH (P<0.05) was obtained in the dry-cured product (5.44, 5.48, and 5.66 in chestnut, mixed, and concentrated diets, resp.). During vacuum-packed storage, pH values significantly increased (P<0.05) in dry-cured loins from chestnut and mixed diets. After 6 months of storage, lower values (P<0.05) were obtained in loins from chestnut and mixed diet than in concentrate one (5.58, 5.62, and 5.73, resp.). These differences among diets were also observed when the pH ofLongissimus dorsi muscles of the pigs of the present study were studied [21]. A greater input of carbohydrates (mainly starch) is obtained by chestnut diet (over 1600 g of starch per day) than by mixed or concentrate diet (1395.5 and 1191.0 g of starch per day, resp.). A reason for the pH differences among diets could be related to the fact that the muscle from pigs fed with chestnuts would present a higher content of carbohydrates, which could cause a more prominent pH drop during the muscle rigor-mortis of these pigs, and in consequence, obtaining a lower pH value in fresh meat and in meat products. The pH values observed in the dry-cured loins were slightly lower than observed in the fresh muscles [21]. This pH decrease could have been produced during the first stages of the manufacturing process, as a result of microbial fermentation of the carbohydrates added to the dry-cured loin in its formulation. The pH increase during storage could be attributed to ammonia production as a consequence of proteolytic phenomena, an increase of buffer substances, and a decrease of electrolytes, and to the growth of microorganisms (especially molds and yeasts) capable of consuming lactic acid [22]. The pH values of the present product are in the range obtained in other dry-cured meat products [23, 24].Dry-cured loins from the three diet groups presented similar values for titratable acidity (Table2) around 0.97 g of lactic acid/100 of dry matter. During vacuum-packed storage, this parameter significantly increased (P<0.05) in the loins from chestnut and mixed diet to values over 1.12 g of lactic acid/100 of dry matter. However, the increase of this parameter was less intense in loins from concentrate diet, reaching at the end of the storage lower values (P<0.05) of 1.01 g of lactic acid/100 of dry matter than in the other diet groups. The formation of organic acids during the manufacture process causes the increase of this parameter and then, during vacuum-storage, it could be related to the microorganisms that may establish in the product in anaerobe conditions and are involved on the metabolism of these acids [25]. Our values are in the range of those reported in other dry-cured meat products [26, 27].Regarding lipolytic parameters, the values for acidity index (Table2), expressed as mg KOH/g of sample, in the dry-cured loins after manufacturing process were around 22 mg KOH/g of sample, finding no effect of chestnut inclusion in the finishing diet. These values progressively increased (P<0.05) during the vacuum-packed storage, reaching after 6 months of storage significantly higher (P<0.05) values in loins from mixed diet than from concentrate diet, while loins from chestnut diet showed intermediate acidity index values, so the differences among samples could not be attributed to the inclusion of chestnuts in the finishing diet. Lipolysis is an enzyme catalyzed process, so the factors that greatly affect the FFA content and lipolytic enzyme activity are the time/temperature cycles of the different stages of the process [2]. The absence of differences among diet groups for lipolysis degree in loin after manufacturing process (final product) is expected because they were manufactured following the same processing conditions and formulation. Our results are lower than those found in dry-cured ham [28, 29] and higher than in dry-cured sausages [18, 30]. These intermediate values are expected since the temperature and time conditions employed in the manufacture of this product are among the conditions used for the manufacture of dry-cured ham (higher temperature and longer time) and dry-cured sausages (lower temperature and shorter time).The peroxide values (Table2), expressed as meq O2/kg of fat, in the final product were significantly higher (P<0.05) in loins from chestnut diet than from mixed and concentrate diets. These values decreased (P<0.05) during the first 3 months of vacuum-packed storage and then increased (P<0.05) until the end of storage to similar values in the three diet groups. Similar peroxide values were found in several types of dry-cured meat products [7]. Nevertheless, the oxidation degree of these products is lower than that obtained in other products manufactured from the whole pieces [31, 32]. This could be due to the higher salt content of these products, which is a well-known prooxidant effect [33], and to the longer time of curing stages. The peroxide values decrease during the first months of vacuum-packed storage is related to the absence of oxygen during these stages, and the subsequent increase could be related to the oxygen permeability of the packaging material throughout the storage time [34, 35].The TBA values (Table2), expressed as mg of malonaldehyde (MDA)/kg of sample, of the dry-cured loins, as occurred for peroxide values, were significantly higher (P<0.05) in loins from chestnut diet than from mixed and concentrated diet. During vacuum-packed storage, these values decreased to similar values in the three diet groups. Our results are in the range of previously published values in dry-cured loin [12–15, 36]. The different behaviour of TBA values throughout the storage process with respect to peroxide values could be related to the MDA instability [37] and/or to the reaction of already formed malonaldehyde with sugars or amino acids and amines obtained like a consequence of proteolytic phenomena [38]. The evolution at the end of vacuum-packed storage is quite different for peroxide and TBARS, a fact that was already verified by other authors [34, 38] that show a low reliability of TBARS analysis for the assay of lipid oxidation in a long period of time.


### 3.2. Fatty Acids

Fatty acid composition of neutral lipids (expressed as %) of the dry-cured loins fat is shown in Table3. The profile is almost coincident with that of the total lipids (data not shown). In the dry-cured loin (final product), the saturated fatty acids (SFA) represented above 37%, with the palmitic (24%) and the stearic acid (11%) being the most abundant. The percentage in monounsaturated fatty acids (MUFA) was higher than SFA and around a 51%, with oleic acid (48%) being the most important of them. The less abundant fatty acids were the polyunsaturated (PUFA) (around 11%), where the linoleic acid was the main fatty acid (around 8%). When the effect of the finishing diet was studied, no significant differences were found among these major fatty acids. However, loins from chestnut group showed significant higher content (P<0.05) in some minor fatty acids (C8, C11, C14, C14:1, C15, C15:1, C20, and C24:1n-9) and lower content (P<0.05) in others (C17, C17:1, C18, C20:2n-6, C20:3n-3, and C22:1n-9). Linoleic acid (18:2n-6) is considered the parent of then-6 family because animals can synthetize othern-6 fatty acids from it. Nevertheless, thesen-6 fatty acids can also be directly incorporated through diet. Our results seem to indicate a direct incorporation of C20:2n-6, so that this fatty acid presented higher contents in the loins from pigs with a higher intake of this fatty acid [5]. This fatty acid profile of total lipids was very similar to that previously reported in dry-cured loin [12, 39, 40]. In some of these studies, the effect of the different diets was also studied, obtaining a higher content inn-3 fatty acids using linseed and olive oils [39]. However, no effect onn-3 fatty acids was obtained using pasture and acorn, though a lower content inn-6 fatty acids was found [40]. Along the vacuum-packed storage the fatty acid profile remained constant and the minor differences obtained could be related to the variability between samples.Table 3
Fatty acid composition of neutral lipids (%) of dry-cured loin from Celta pig fed with three finishing diets (chestnut, mixed, and concentrate), after manufacturing process and after 3 and 6 months of vacuum-packed storage.
Chestnuts Chestnuts-concentrate Concentrate Final product Storage time (months) Final product Storage time (months) Final product Storage time (months) 3 6 3 6 3 6 C8 0.02 ± 0.01a 0.004 ± 0.002b1 0.01 ± 0.003c1 0.01 ± 0.003ab 0.01 ± 0.01a2 0.01 ± 0.004b2 0.01 ± 0.003a 0.02 ± 0.01b3 0.003 ± 0.001a2 C10 0.04 ± 0.02a1 0.05 ± 0.004b 0.05 ± 0.01b 0.05 ± 0.0052 0.05 ± 0.005 0.05 ± 0.01 0.04 ± 0.00512 0.04 ± 0.003 0.05 ± 0.01 C11 0.03 ± 0.02a1 0.005 ± 0.001b1 0.01 ± 0.01c 0.02 ± 0.0112 0.02 ± 0.022 0.01 ± 0.005 0.01 ± 0.01a2 0.04 ± 0.02b3 0.005 ± 0.001a C12 0.04 ± 0.02a 0.05 ± 0.001b 0.05 ± 0.01ab 0.05 ± 0.003 0.05 ± 0.005 0.05 ± 0.003 0.04 ± 0.004 0.05 ± 0.003 0.05 ± 0.004 C14 1.21 ± 0.08a1 1.02 ± 0.05b 0.98 ± 0.10b 1.09 ± 0.08a2 0.95 ± 0.10b 0.93 ± 0.06b 1.09 ± 0.082 1.01 ± 0.06 1.02 ± 0.06 C14:1 0.10 ± 0.09a1 0.02 ± 0.01b 0.03 ± 0.02b 0.04 ± 0.022 0.02 ± 0.03 0.01 ± 0.003 0.02 ± 0.012 0.04 ± 0.03 0.01 ± 0.004 C15 0.05 ± 0.05a1 0.02 ± 0.003b 0.02 ± 0.001b 0.02 ± 0.0022 0.02 ± 0.005 0.02 ± 0.003 0.02 ± 0.012 0.02 ± 0.005 0.02 ± 0.003 C15:1 0.002 ± 0.0021 0.001 ± 0.001 0.001 ± 0.001 0.002 ± 0.00112 0.002 ± 0.001 0.001 ± 0.001 0.001 ± 0.0012 0.001 ± 0.001 0.001 ± 0.001 C16 24.43 ± 0.64a1 24.06 ± 0.46a1 22.85 ± 1.41b 23.39 ± 0.902 22.94 ± 1.072 22.93 ± 0.70 24.11 ± 0.6112 23.40 ± 0.5612 23.65 ± 0.67 C16:1 2.18 ± 0.93a 2.40 ± 0.10ab 2.87 ± 0.50b 2.31 ± 0.29 2.35 ± 0.27 2.48 ± 0.26 2.22 ± 0.27 2.48 ± 0.48 2.66 ± 0.43 C17 0.09 ± 0.05a1 0.14 ± 0.01b 0.13 ± 0.02ab 0.13 ± 0.0612 0.16 ± 0.05 0.15 ± 0.03 0.14 ± 0.042 0.13 ± 0.04 0.14 ± 0.02 C17:1 0.11 ± 0.05a1 0.15 ± 0.01ab 0.16 ± 0.03b 0.17 ± 0.032 0.17 ± 0.05 0.17 ± 0.04 0.15 ± 0.0412 0.14 ± 0.03 0.15 ± 0.02 C18 11.09 ± 1.04a1 12.30 ± 0.21b1 10.33 ± 1.32a1 11.87 ± 0.8012 11.55 ± 0.4512 11.61 ± 0.502 12.21 ± 1.222 11.19 ± 1.202 11.55 ± 1.072 C18:1n-9 48.79 ± 1.75a 49.42 ± 0.86ab 51.29 ± 1.56b1 48.75 ± 1.171 49.26 ± 1.21 48.82 ± 1.632 47.89 ± 2.802 48.93 ± 2.21 47.80 ± 1.642 C18:2n-6 7.97 ± 1.27 7.78 ± 0.77 7.89 ± 1.38 8.30 ± 0.92 9.33 ± 1.54 9.37 ± 1.13 8.68 ± 1.80 9.19 ± 1.86 9.22 ± 1.24 C18:3n-6 0.03 ± 0.002 0.05 ± 0.003 0.05 ± 0.0041 0.03 ± 0.003 0.06 ± 0.01 0.06 ± 0.012 0.03 ± 0.01 0.05 ± 0.02 0.05 ± 0.00412 C18:3n-3 0.32 ± 0.05a 0.36 ± 0.03b 0.35 ± 0.05b 0.34 ± 0.02a 0.39 ± 0.07b 0.37 ± 0.05b 0.31 ± 0.07a 0.34 ± 0.08b 0.33 ± 0.05b C20 0.07 ± 0.051 0.07 ± 0.01 0.10 ± 0.02 0.03 ± 0.003a12 0.07 ± 0.03ab 0.07 ± 0.04b 0.03 ± 0.003a2 0.08 ± 0.02b 0.08 ± 0.04b C20:1n-9 0.05 ± 0.01a 0.02 ± 0.01b 0.03 ± 0.01b 0.05 ± 0.01a 0.03 ± 0.01b 0.03 ± 0.01b 0.05 ± 0.01a 0.03 ± 0.01b 0.02 ± 0.003b C20:2n-6 0.24 ± 0.031 0.27 ± 0.02 0.22 ± 0.101 0.30 ± 0.0212 0.32 ± 0.05 0.33 ± 0.032 0.34 ± 0.092 0.32 ± 0.06 0.33 ± 0.072 C20:3n-6 0.11 ± 0.02a 0.10 ± 0.02b1 0.10 ± 0.02b 0.10 ± 0.03a 0.14 ± 0.05b2 0.13 ± 0.02b 0.10 ± 0.03a 0.11 ± 0.03b12 0.13 ± 0.04b C20:4n-6 0.95 ± 0.21 0.82 ± 0.20 0.99 ± 0.28 0.94 ± 0.43 1.24 ± 0.40 1.27 ± 0.33 0.91 ± 0.32 1.25 ± 0.53 1.35 ± 0.59 C20:3n-3 0.03 ± 0.02a1 0.01 ± 0.002b 0.01 ± 0.003b 0.06 ± 0.004a2 0.01 ± 0.001b 0.01 ± 0.004b 0.06 ± 0.02a2 0.01 ± 0.002b 0.01 ± 0.003b C20:5n-3 0.02 ± 0.01a 0.03 ± 0.01b12 0.03 ± 0.005b 0.01 ± 0.005a 0.04 ± 0.01b1 0.04 ± 0.01b 0.01 ± 0.001a 0.03 ± 0.01b2 0.03 ± 0.01b C22 0.03 ± 0.01a 0.01 ± 0.002b 0.01 ± 0.001b 0.03 ± 0.01a 0.01 ± 0.002b 0.01 ± 0.002b 0.03 ± 0.01a 0.01 ± 0.003b 0.01 ± 0.003b C22:1n-9 0.02 ± 0.021 0.01 ± 0.002 0.01 ± 0.002 0.05 ± 0.02a2 0.01 ± 0.005b 0.01 ± 0.001b 0.03 ± 0.01a1 0.01 ± 0.01b 0.01 ± 0.002b C22:2n-6 1.44 ± 0.31a 0.58 ± 0.09b 1.08 ± 0.50ab 1.37 ± 0.47a 0.52 ± 0.16b 0.70 ± 0.35b 1.09 ± 0.17 0.73 ± 0.28 0.89 ± 1.13 C23 0.15 ± 0.03a 0.07 ± 0.01b 0.16 ± 0.06a 0.12 ± 0.05 0.07 ± 0.02 0.09 ± 0.04 0.10 ± 0.02ab 0.09 ± 0.04a 0.17 ± 0.16b C24 0.29 ± 0.12 0.14 ± 0.11 0.13 ± 0.11 0.27 ± 0.22 0.14 ± 0.07 0.20 ± 0.12 0.23 ± 0.09 0.19 ± 0.13 0.19 ± 0.21 C24:1n-9 0.11 ± 0.05a1 0.05 ± 0.04b 0.06 ± 0.04b 0.11 ± 0.071 0.07 ± 0.03 0.08 ± 0.04 0.05 ± 0.022 0.07 ± 0.04 0.06 ± 0.03   ∑SFA 37.53 ± 0.94a 37.94 ± 0.34a1 34.82 ± 2.03b1 37.07 ± 1.38 36.04 ± 1.412 36.13 ± 1.1212 38.05 ± 1.74a 36.28 ± 1.48b2 36.93 ± 1.07ab2 ∑UFA 62.48 ± 0.92a 62.06 ± 0.34a1 65.18 ± 2.03b1 62.92 ± 1.37 63.96 ± 1.412 63.87 ± 1.1212 61.95 ± 1.74a 63.72 ± 1.48b2 63.07 ± 1.07ab2 ∑MUFA 51.37 ± 1.94a 52.07 ± 0.86a 54.45 ± 1.79b1 51.46 ± 0.94 51.91 ± 1.18 51.60 ± 1.632 50.42 ± 2.95 51.70 ± 2.19 50.72 ± 1.522 ∑PUFA 11.12 ± 1.58 10.00 ± 0.97 10.73 ± 2.09 11.46 ± 1.57 12.05 ± 2.10 12.28 ± 1.61 11.53 ± 2.22 12.03 ± 2.46 12.35 ± 2.40 ∑SFA: sum of saturated fatty acids; ∑UFA: sum of unsaturated fatty acids; ∑MUFA: sum of monounsaturated fatty acids; ∑PUFA: sum of polyunsaturated fatty acids.a–cDifferent letters within the same row corresponding to the same diet group indicate significant differences (P<0.05). 1–3Different numbers within the same row corresponding to the same sampling point indicate significant differences (P<0.05), when the three finishing diets are compared.In the neutral lipids (NL), only slight differences are presented, which affects PUFA, showing a lower percentage than in total lipids. This is due to the high proportion of NL in the fat [5]. SFA represented above 36%, with the most abundant being the palmitic (24%) and the stearic acid (11%). MUFA represented over a 53%, with oleic acid (50%) being the most abundant. Finally, PUFA represented a 9% and linoleic acid was the most important of them (7%). This profile coincides with that found by Domínguez et al. [5] in the fat of different intramuscular locations of Celta pig. When the effect of the finishing diet was studied, no significant differences were found for these major fatty acids. However, loins from chestnut group showed significant higher content (P<0.05) in some minor fatty acids (C8, C20:1n-9, and C24:1n-9) and lower content (P<0.05) in others (C20:2n-6). Some of these differences were already found for total fatty acids. The fatty acid composition of NL remained constant during the vacuum-packed storage, with this profile being very similar for the three diet groups. The lack of changes in this profile may be due to PL being the most affected by the lipolysis phenomena [2].The limited effect of the different diets in this fraction of lipids and a little more pronounced in the PL (as can be seen later) could be because PL have a shorter turnover rate than triglycerides [41] and their fatty acid composition is directly more influenced by the diet. On the other hand, average triacylglycerol life has been estimated to be over 180 days [4], longer than the fattening phase of Celta pigs in this study (90 days). A similar trend was previously found in Iberian pigs [42, 43]. Nevertheless, other authors [6] reported an increment in C18:2n-6, C18:3n-3, and C20:4n-6 in fresh meat when chestnut was included in pig’s diet.Fatty acid composition of polar lipids (expressed as %) of the dry-cured loins fat is shown in Table4. The fatty acid profile observed in the dry-cured loins after the manufacturing process (final product) was different to that found in total and NL. The main difference is the high content in PUFA, which supposed over 43%, with the most abundant being the linoleic acid (C18:2n-6) (33%). Nevertheless, MUFA only represented over 14%, while SFA supposed 43%. The major fatty acids of these two groups were oleic and palmitic acid, respectively. Like in the last lipid fractions studied, no differences were found for major fatty acids when the three diet groups of loins were compared, but they were found in some minor fatty acids, which were higher (P<0.05) (C11, C15, C18:3n-6, C18:3n-3, C20:3n-3, and C22) or lower (P<0.05) (C15:1 and C20:2n-6) when chestnut was introduced in the finishing diet. Because C18:2n-6 and C18:3n-3 are essential fatty acids in animal tissues, their content is directly related to their concentration in the diet. Chestnut diet provides a high quantity of these fatty acids than concentrate diet. In the dry-cured muscles, this higher intake was only evident for C18:3n-3. Thus, C18:2n-6 intake could be used to synthesise other fatty acids fromn-6 series, like C18:3n-6, also in significantly higher content in loins from chestnut diet, despite being equally provided in the diets. Also, as occurred in total lipids, a direct incorporation of C20:2n-6 was obtained in loins from concentrate diet [5].Table 4
Fatty acid composition of polar lipids (%) of dry-cured loin from Celta pig feed with three finishing diets (chestnut, mixed, and concentrate), after manufacturing process and after 3 and 6 months of vacuum-packed storage.
Chestnuts Chestnuts-concentrate Concentrate Final product Storage time (months) Final product Storage time (months) Final product Storage time (months) 3 6 3 6 3 6 C8 0.01 ± 0.003a 0.01 ± 0.003a 0.02 ± 0.003b12 0.004 ± 0.004a 0.01 ± 0.003b 0.02 ± 0.01c1 0.004 ± 0.002a 0.01 ± 0.004b 0.01 ± 0.01b2 C10 N.D. N.D. N.D. N.D. N.D. N.D. 0.001 ± 0.001 N.D. N.D. C11 0.02 ± 0.01ab 0.01 ± 0.01a 0.03 ± 0.02b1 0.02 ± 0.01 0.02 ± 0.01 0.01 ± 0.012 0.01 ± 0.01a 0.02 ± 0.02a 0.03 ± 0.02b1 C12 0.02 ± 0.01a 0.06 ± 0.05ab 0.09 ± 0.08b 0.01 ± 0.01a 0.08 ± 0.06b 0.06 ± 0.04ab 0.02 ± 0.02a 0.04 ± 0.02a 0.10 ± 0.06b C14 5.22 ± 2.04a 4.42 ± 0.57a 5.53 ± 2.70a12 4.17 ± 2.16a 5.03 ± 1.41ab 6.46 ± 1.51b1 5.28 ± 1.09 4.35 ± 2.22 3.67 ± 0.682 C14:1 0.04 ± 0.05 0.02 ± 0.011 0.06 ± 0.08 0.01 ± 0.01a 0.14 ± 0.18b2 0.08 ± 0.03ab 0.02 ± 0.01a 0.20 ± 0.15b2 0.13 ± 0.07b C15 0.14 ± 0.06a 0.03 ± 0.01b 0.05 ± 0.04b12 0.11 ± 0.06a 0.05 ± 0.01b 0.10 ± 0.05ab1 0.09 ± 0.06a 0.04 ± 0.01ab 0.04 ± 0.01b2 C15:1 0.09 ± 0.07 0.08 ± 0.011 0.08 ± 0.0612 0.10 ± 0.06a 0.15 ± 0.04b2 0.10 ± 0.03a1 0.10 ± 0.03a 0.06 ± 0.04ab1 0.05 ± 0.02b2 C16 25.51 ± 1.37a 25.85 ± 3.68a 25.69 ± 1.84a12 27.74 ± 1.72 27.07 ± 2.51 27.78 ± 0.931 27.31 ± 1.62 27.32 ± 2.40 27.12 ± 1.672 C16:1 1.36 ± 0.55a 0.57 ± 0.20b 0.54 ± 0.08b 1.49 ± 0.80a 0.52 ± 0.12b 0.35 ± 0.07b 1.69 ± 0.47a 0.73 ± 0.37b 0.57 ± 0.33b C17 3.24 ± 1.21 3.29 ± 1.55 3.88 ± 1.431 3.19 ± 2.14a 2.73 ± 1.31a 2.09 ± 1.56b2 2.50 ± 0.83 2.95 ± 1.19 3.53 ± 1.081 C17:1 1.62 ± 0.61 1.71 ± 0.74 1.87 ± 1.21 1.50 ± 1.06ab 1.36 ± 0.88a 2.41 ± 0.58b 1.30 ± 0.42 1.71 ± 0.75 1.70 ± 0.60 C18 6.90 ± 0.36a 7.35 ± 1.38ab 8.72 ± 2.74b1 7.65 ± 0.81a 8.30 ± 1.12a 8.25 ± 1.75a12 6.80 ± 0.89 7.86 ± 1.32 6.89 ± 1.122 C18:1n-9 11.35 ± 2.39a 14.85 ± 2.37b1 13.92 ± 1.21b 10.90 ± 1.39a 12.09 ± 1.42b2 12.65 ± 0.77b 10.67 ± 1.91a 13.86 ± 4.03b12 12.83 ± 2.92ab C18:2n-6 34.36 ± 2.50a 25.84 ± 2.19b 24.42 ± 2.94b 32.23 ± 1.74a 26.83 ± 2.92b 24.83 ± 2.13b 31.92 ± 4.15a 26.03 ± 4.23b 24.55 ± 3.80b C18:3n-6 0.13 ± 0.02a1 0.12 ± 0.02a1 0.09 ± 0.02b12 0.11 ± 0.02a2 0.13 ± 0.02a1 0.10 ± 0.01b1 0.09 ± 0.012 0.09 ± 0.012 0.08 ± 0.022 C18:3n-3 0.37 ± 0.08a1 0.36 ± 0.04a1 0.31 ± 0.02b1 0.32 ± 0.03a12 0.28 ± 0.05b2 0.17 ± 0.06a2 0.26 ± 0.052 0.25 ± 0.042 0.22 ± 0.032 C20 0.03 ± 0.01a 0.08 ± 0.02b1 0.05 ± 0.01c12 0.03 ± 0.01a 0.06 ± 0.03b2 0.07 ± 0.02b1 0.02 ± 0.01a 0.04 ± 0.01ab2 0.04 ± 0.01b2 C20:1n-9 0.18 ± 0.04a 0.28 ± 0.04b1 0.28 ± 0.06b1 0.22 ± 0.05a 0.37 ± 0.04b2 0.41 ± 0.02b2 0.22 ± 0.06a 0.28 ± 0.03b1 0.30 ± 0.07b1 C20:2n-6 0.43 ± 0.04a1 0.57 ± 0.05b1 0.68 ± 0.04b1 0.57 ± 0.07a2 0.79 ± 0.07b2 0.94 ± 0.04c2 0.61 ± 0.05a2 0.71 ± 0.16b2 0.77 ± 0.25b1 C20:3n-6 0.98 ± 0.13 1.03 ± 0.17 1.06 ± 0.1312 0.93 ± 0.11a 1.03 ± 0.07a 1.26 ± 0.07b1 0.88 ± 0.07 0.86 ± 0.23 0.88 ± 0.342 C20:4n-6 6.77 ± 1.71a 8.49 ± 3.36a 9.39 ± 2.20b 7.27 ± 2.97a 9.48 ± 1.31ab 9.06 ± 1.63b 8.16 ± 2.78 9.48 ± 1.80 8.80 ± 3.34 C20:3n-3 0.06 ± 0.03 0.08 ± 0.01 0.06 ± 0.031 0.07 ± 0.01a 0.09 ± 0.01ab 0.11 ± 0.01b2 0.04 ± 0.03a 0.08 ± 0.01b 0.09 ± 0.03b2 C20:5n-3 0.01 ± 0.01a 0.01 ± 0.004a 0.05 ± 0.03b1 0.01 ± 0.002a 0.03 ± 0.002a 0.07 ± 0.01b1 0.01 ± 0.005a 0.02 ± 0.02a 0.11 ± 0.05b2 C22 0.48 ± 0.04a1 0.63 ± 0.15b1 0.64 ± 0.08b1 0.46 ± 0.12a1 0.54 ± 0.06ab1 0.59 ± 0.07b1 0.35 ± 0.032 0.40 ± 0.052 0.40 ± 0.072 C22:1n-9 0.02 ± 0.005a 0.04 ± 0.01a 0.10 ± 0.02b1 0.02 ± 0.005a 0.04 ± 0.004a 0.24 ± 0.15b2 0.02 ± 0.01 0.05 ± 0.05 0.05 ± 0.0041 C22:2n-6 0.33 ± 0.27a 0.77 ± 0.19b12 0.90 ± 0.33b12 0.46 ± 0.23a 0.52 ± 0.38a1 0.64 ± 0.12a1 0.64 ± 0.41a 1.13 ± 0.54b2 1.32 ± 0.55b2 C23 0.03 ± 0.01a 0.04 ± 0.01a 0.09 ± 0.07a1 0.03 ± 0.02a 0.07 ± 0.005a 0.28 ± 0.22b2 0.04 ± 0.01 0.04 ± 0.02 0.10 ± 0.061 C24 0.24 ± 0.30a 2.80 ± 0.73b 1.14 ± 1.31ab1 0.21 ± 0.25a 1.82 ± 0.69a 0.68 ± 0.22a1 0.77 ± 0.89a 1.18 ± 1.31a 4.61 ± 3.75b2 C24:1n-9 0.09 ± 0.13a 0.60 ± 0.19b1 0.25 ± 0.25a1 0.18 ± 0.19a 0.37 ± 0.14a12 0.19 ± 0.06a1 0.15 ± 0.16a 0.20 ± 0.16a2 0.99 ± 0.75b2   ∑SFA 41.82 ± 1.89a 44.58 ± 3.29ab 45.93 ± 4.15b 43.62 ± 2.33 45.77 ± 4.01 46.40 ± 0.49 43.19 ± 2.02 44.26 ± 2.66 46.56 ± 3.54 ∑UFA 58.18 ± 1.89a 55.42 ± 3.29ab 54.07 ± 4.15b 56.38 ± 2.33 54.23 ± 4.01 53.60 ± 0.49 56.81 ± 2.02 55.74 ± 2.66 53.44 ± 3.54 ∑MUFA 14.75 ± 2.14a 18.16 ± 1.77b1 17.10 ± 0.80a 14.42 ± 1.37 15.05 ± 1.202 16.43 ± 0.891 14.18 ± 1.88a 17.09 ± 4.38b12 16.61 ± 3.21ab2 ∑PUFA 43.43 ± 2.74a 37.27 ± 5.03b 36.97 ± 4.57ab 41.97 ± 3.19a 39.18 ± 3.88ab 37.17 ± 0.86b 42.63 ± 3.57a 38.65 ± 4.01ab 36.83 ± 6.17b ∑SFA: sum of saturated fatty acids; ∑UFA: sum of unsaturated fatty acids; ∑MUFA: sum of monounsaturated fatty acids; ∑PUFA: sum of polyunsaturated fatty acids.a–cDifferent letters within the same row corresponding to the same diet group indicate significant differences (P<0.05). 1–3Different numbers within the same row corresponding to the same sampling point indicate significant differences (P<0.05), when the three finishing diets are compared.After vacuum-packed storage, changes in the fatty acids profile of this fraction were observed. After 3 months of storage, PUFA percentage significantly decreases (P<0.05) to values around 38% and then they remained constant to the end of storage. Among these fatty acids, the most affected were the C18:2n-6 (descending over 10%), C18:3n-6, and C18:3n-3. The differences among diet groups were the same than those found in the final product. As mentioned above, PL are considered the main source of free fatty acids [5] and also they are highly susceptible to oxidation.Fatty acid profile obtained for PL was similar to those reported in other studies in dry-cured loin [16, 44], although contents in PUFA were higher than those in other works [3], which could be related to the higher oxidation indexes obtained in those products.The content in free fatty acids (FFA) (expressed as mg/100 g of fat) of the dry-cured loins fat is shown in Table5. The mean content of FFA represented over 2700 mg/100 g of fat and no significant differences were found for this total content when the three diet groups were compared. The major fatty acids, expressed as percentage (data not shown), were around 38% for SFA, 33% for MUFA, and 27% for PUFA, and as in the last fractions studied, the most representatives in each groups were palmitic and stearic, oleic, and linoleic acid, respectively. In the final product, significant differences (P<0.05) were found in some minor fatty acids, with higher (C12, C18:3n-3, and C22:1n-9) and lower (C20:2n-6 and C20:3n-3) content in loins from chestnut diet. The values and the profile obtained in the present study for FFA are similar to those previously reported in the scientific literature for dry-cured loin [3, 16]. The similarity of the profile with the beforehand studied about PL, especially with regard to high PUFA percentage, confirms that FFA comes mainly from polar fraction but also is perceived as an influence of NL.Table 5
Free fatty acids content (mg/100 g of fat) of dry-cured loin from Celta pig fed with three finishing diets (chestnut, mixed, and concentrate), after manufacturing process and after 3 and 6 months of vacuum-packed storage.
Chestnuts Chestnuts-concentrate Concentrate Final product Storage time (months) Final product Storage time (months) Final product Storage time (months) 3 6 3 6 3 6 C8 0.08 ± 0.03a 0.44 ± 0.28b1 0.18 ± 0.23a 0.11 ± 0.07 0.07 ± 0.032 0.21 ± 0.19 0.15 ± 0.18 0.05 ± 0.012 0.09 ± 0.02 C10 0.78 ± 0.17a 2.66 ± 0.20b 4.00 ± 0.80c1 0.88 ± 0.10a 2.21 ± 0.21b 4.32 ± 0.56c1 0.78 ± 0.17a 2.38 ± 0.47b 3.08 ± 0.47c2 C11 0.05 ± 0.04a1 0.18 ± 0.05b 0.27 ± 0.04c 0.07 ± 0.03a1 0.15 ± 0.05a 0.30 ± 0.04b 0.19 ± 0.192 0.15 ± 0.04 0.22 ± 0.02 C12 1.43 ± 0.51a1 2.34 ± 0.25b1 3.59 ± 0.77c1 1.38 ± 0.31a2 2.08 ± 0.39b2 2.95 ± 0.25c12 1.07 ± 0.15a2 2.01 ± 0.17b3 2.83 ± 0.57c2 C14 19.85 ± 5.01a 46.33 ± 5.04b1 65.74 ± 8.14c1 19.11 ± 3.05a 37.74 ± 5.52b2 54.93 ± 7.46c2 17.54 ± 3.88a 45.45 ± 9.93b1 55.85 ± 7.28c2 C14:1 0.24 ± 0.07a 0.45 ± 0.03b1 0.71 ± 0.05c1 0.24 ± 0.05a 0.37 ± 0.07b2 0.58 ± 0.12c2 0.22 ± 0.04a 0.46 ± 0.06b1 0.60 ± 0.05c2 C15 1.38 ± 0.05a12 1.99 ± 0.13b 2.04 ± 0.21b 1.65 ± 0.46a1 2.06 ± 0.35b 2.06 ± 0.36b 1.23 ± 0.29a2 1.77 ± 0.45b 1.96 ± 0.30b C15:1 0.02 ± 0.01ab1 0.01 ± 0.01a1 0.03 ± 0.02b12 0.05 ± 0.03a2 0.03 ± 0.02b12 0.02 ± 0.01b1 0.01 ± 0.01a1 0.03 ± 0.01b2 0.04 ± 0.004b2 C16 680.86 ± 114.75a 1118.17 ± 136.99b 1449.04 ± 254.88c1 783.47 ± 189.31a 1019.24 ± 157.95b 1262.90 ± 88.46c2 637.12 ± 119.71a 938.43 ± 73.09b 1177.97 ± 180.22c2 C16:1 42.05 ± 6.42a 62.73 ± 9.30b 95.11 ± 11.13c1 40.53 ± 5.26a 53.05 ± 8.77b 76.93 ± 20.79c2 36.25 ± 7.71a 53.56 ± 3.39b 69.95 ± 12.11c2 C17 8.57 ± 0.78a12 14.66 ± 2.85b1 15.23 ± 1.13b 10.32 ± 2.32a1 14.99 ± 4.40b1 15.21 ± 2.56b 7.20 ± 1.71a2 10.64 ± 1.08b2 12.83 ± 1.92b C17:1 3.78 ± 0.40a 6.31 ± 1.46b 6.82 ± 0.76b1 5.25 ± 0.92a 5.71 ± 1.27a 8.70 ± 3.34b2 4.34 ± 0.87 4.65 ± 0.45 4.60 ± 2.173 C18 257.30 ± 40.29a 480.31 ± 10.81b 651.41 ± 113.57c1 280.81 ± 57.27a 482.94 ± 44.34b 585.87 ± 46.80c12 266.44 ± 43.73a 418.36 ± 47.45b 539.71 ± 72.84c2 C18:1n-9 842.50 ± 112.84a 1180.02 ± 139.06b 1574.24 ± 88.62c1 910.03 ± 94.12a 1057.36 ± 88.18a 1304.07 ± 193.82b2 828.82 ± 183.70a 1109.08 ± 82.26b 1213.99 ± 256.72b2 C18:2n-6 557.27 ± 28.20a12 446.58 ± 27.16b 471.71 ± 36.01b 626.10 ± 103.47a1 522.66 ± 68.00b 522.30 ± 48.00b 524.67 ± 128.772 465.49 ± 72.48 525.69 ± 59.27 C18:3n-6 3.41 ± 0.40 2.98 ± 0.4212 3.00 ± 0.16 3.60 ± 0.77 3.37 ± 0.781 3.35 ± 0.38 3.07 ± 0.69 2.60 ± 0.392 3.09 ± 0.42 C18:3n-3 17.77 ± 2.60a1 14.04 ± 0.53b12 16.93 ± 1.47a1 17.00 ± 2.361 15.10 ± 2.941 14.69 ± 2.3812 12.68 ± 3.392 11.76 ± 0.852 13.52 ± 2.352 C20 2.24 ± 0.51a 3.61 ± 0.44b 4.67 ± 0.88c 2.50 ± 0.48a 3.31 ± 0.52b 4.11 ± 0.37c 2.06 ± 0.45a 3.33 ± 0.18b 4.18 ± 0.72c C20:1n-9 12.76 ± 1.43a 19.22 ± 2.50b 24.89 ± 2.58c 14.36 ± 2.60a 17.40 ± 0.81a 23.21 ± 5.33b 14.89 ± 3.35a 19.31 ± 2.28b 22.61 ± 3.18b C20:2n-6 6.37 ± 1.06a1 9.26 ± 0.71b 10.82 ± 0.77b1 8.36 ± 1.11a2 10.55 ± 1.59b 13.48 ± 2.47c2 9.02 ± 1.71a2 10.83 ± 1.24b 13.48 ± 1.31c2 C20:3n-6 10.04 ± 2.93a 7.47 ± 0.92b 6.20 ± 0.58b 11.10 ± 1.91a 8.36 ± 2.13b 8.54 ± 1.48b 11.29 ± 3.53a 6.96 ± 2.16b 7.73 ± 1.23b C20:4n-6 119.52 ± 45.79 139.76 ± 44.09 153.46 ± 24.721 91.85 ± 22.48 126.45 ± 34.77 124.02 ± 38.982 85.76 ± 15.61a 119.59 ± 11.76ab 145.95 ± 49.86b2 C20:3n-3 1.61 ± 0.491 1.68 ± 0.20 1.72 ± 0.311 2.24 ± 0.4212 1.98 ± 0.46 2.11 ± 0.382 2.28 ± 0.46a2 0.65 ± 0.82b 0.49 ± 0.35b2 C20:5n-3 0.59 ± 0.16a12 0.43 ± 0.36ab1 0.97 ± 0.39b1 0.99 ± 0.391 0.96 ± 0.692 2.10 ± 0.22b2 0.18 ± 0.25a2 0.77 ± 0.48b12 2.03 ± 0.54c2 C22 4.02 ± 0.95a1 4.05 ± 0.50a1 2.96 ± 0.31b 4.25 ± 0.941 3.31 ± 0.6212 3.59 ± 0.11 2.07 ± 1.772 2.60 ± 0.912 2.87 ± 0.34 C22:1n-9 0.65 ± 0.10 0.77 ± 0.431 0.80 ± 0.371 0.74 ± 0.19ab 0.96 ± 0.39a12 0.41 ± 0.17b2 0.61 ± 0.30a 1.15 ± 0.25b2 0.80 ± 0.25a1 C22:2n-6 74.29 ± 7.39a 122.36 ± 15.63b1 179.02 ± 26.91c 64.75 ± 13.45a 201.88 ± 95.53b2 141.02 ± 25.56c 63.81 ± 19.62a 150.02 ± 26.25b1 160.56 ± 24.46c C23 4.80 ± 0.49a 8.42 ± 2.11a1 15.36 ± 3.42b1 4.38 ± 0.54a 13.77 ± 6.82b2 9.95 ± 3.15c2 4.84 ± 2.34a 9.85 ± 2.71b1 10.98 ± 2.31c2 C24 31.56 ± 5.85a 81.80 ± 28.92b 54.12 ± 16.73ab1 52.83 ± 30.72a 73.75 ± 56.84a 136.08 ± 26.69b2 53.05 ± 46.99a 80.29 ± 31.15ab 106.75 ± 34.38b2 C24:1n-9 19.67 ± 5.5212 24.87 ± 6.55 21.91 ± 10.781 29.14 ± 7.53a1 25.60 ± 15.60a 49.21 ± 17.33b2 12.36 ± 8.45a2 28.40 ± 9.85b 46.21 ± 11.21c2   ∑FFA 2725.48 ± 236.95a 3803.91 ± 291.97b 4836.99 ± 480.95c1 2988.07 ± 450.03a 3707.42 ± 464.09b 4377.22 ± 373.63c12 2604.01 ± 434.95a 3500.63 ± 279.32b 4150.65 ± 499.72c2 ∑SFA 1012.93 ± 142.95a 1764.96 ± 145.52b 2268.63 ± 359.49c1 1161.77 ± 273.38a 1655.63 ± 242.04b 2082.48 ± 126.77c12 993.74 ± 161.35a 1515.31 ± 115.42b 1919.30 ± 249.30c2 ∑UFA 1712.55 ± 151.29a 2038.95 ± 172.79b 2568.37 ± 140.48c1 1826.30 ± 184.73a 2051.79 ± 249.55a 2294.74 ± 248.30b12 1610.26 ± 337.28a 1985.32 ± 184.13b 2231.35 ± 295.67b2 ∑MUFA 921.67 ± 112.07a 1294.38 ± 144.86b 1724.51 ± 93.60c1 1000.33 ± 100.30a 1160.48 ± 112.14a 1463.13 ± 214.66b2 897.51 ± 192.32a 1216.65 ± 88.47b 1358.81 ± 264.36b2 ∑PUFA 790.88 ± 58.58 744.56 ± 63.421 843.86 ± 57.84 825.97 ± 118.07 891.31 ± 163.942 831.62 ± 61.94 712.75 ± 154.86a 768.67 ± 95.93ab12 872.53 ± 85.27b ∑FFA: sum of free fatty acids; ∑SFA: sum of saturated fatty acids; ∑UFA: sum of unsaturated fatty acids; ∑MUFA: sum of monounsaturated fatty acids; ∑PUFA: sum of polyunsaturated fatty acids.a–cDifferent letters within the same row corresponding to the same diet group indicate significant differences (P<0.05). 1–3Different numbers within the same row corresponding to the same sampling point indicate significant differences (P<0.05), when the three finishing diets are compared.After vacuum-packed storage, as occurred for acidity index, FFA content significantly increased (P<0.05) to reach after six months of storage higher values in loins from chestnut diet than in concentrate diets. The FFA profile was also modified during storage, decreasing PUFA to 19% and increasing SFA to 46%. This alteration leads us to think that a change in the acting microbial enzymes could have happened. Some authors attributed the higher lipolysis during the vacuum-storage to the action of lactic acid bacteria [45] in addition to endogenous lipases and phospholipases.


### 3.3. Discrimination of the Different Finishing Diets

With the objective of discrimination between diets, multivariate statistical techniques were applied. The variables used for the analysis were the percentage of the fatty acids for total PL and NL and the content in free fatty acids. In the final product and after storage, a factorial analysis was previously performed to obtain the variables which contributed the most to the classification. From these variables, a canonical discriminant analysis was carried out and the coefficients (correlation discriminant functions) obtained are presented in Table6. When canonical discriminant analysis was performed for their selected fatty acids, the percentage of classification was of the 100% for the final product and the product after storage in all the lipids fractions, except for the total lipids in the product after storage, with a classification of the 94.4%, in NL in the final product with a classification of the 94.4% and in FFA in the final product with a classification of the 88.9%.Table 6
Results of canonical discriminant analysis: loadings of correlation matrix between predictor variables (standardized canonical coefficients) and discriminant functions (roots 1 and 2).
Fatty acids Total fatty acids Neutral lipids Polar lipids Free fatty acids Final product After storage Final product After storage Final product After storage Final product After storage Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 C8         1.960 −0.279 C10     2.085 −1.058 C11 −1.073 1.052 2.455 0.523 C12               4.286 1.750 C14     −1.649 0.943   −8.483 1.054 C14:1             −0.011 0.089 C15   1.812 0.364       0.388 0.123 C15:1     0.907 0.585     −0.071 −0.505 C16   −1.087 0.243           −2.547 −3.738 C16:1         7.730 −1.666     4.319 1.446 C17         −2.701 0.835 1.593 −0.449 C17:1 −1.929 1.384 C18     0.848 −0.333 C18:1n-9         0.748 −0.905   0.600 −0.496 1.890 −0.604 C18:2n-6       −3.246 5.010 0.748 −0.905   0.630 1.656 C18:3n-6               −2.581 1.599 C18:3n-3 2.597 −0.059     1.963 −3.369     −1.294 0.210 C20     0.749 −0.972 C20:1n-9     0.784 −0.028         −7.534 0.257 C20:2n-6 −1.725 −0.414 −1.236 0.148       2.069 1.321 C20:3n-6     −0.953 −0.001 −1.424 −0.730 −0.254 0.538 −1.390 −1.441   1.658 0.348 C20:4n-6 0.058 −0.379 −2.083 0.644   0.744 −4.360   −1.727 0.092 C20:3n-3           0.457 −0.036 0.542 −0.104 C20:5n-3 0.898 −0.685     1.258 3.166 C22     0.423 0.409   1.041 −1.872     −0.961 −2.000 C22:1n-9   1.414 0.476         −0.344 0.170 C22:2n-6   1.129 0.527         −0.216 −1.346 C23 1.185 −0.388 C24             −0.016 −0.162 C24:1n-9   −1.274 −1.585   1.273 0.046  Statistics  CanonicalR 0.936 0.544 0.951 0.522 0.911 0.817 0.940 0.656 0.895 0.756 0.942 0.788 0.810 0.665 0.968 0.904 Eigenvalue 7.06 0.42 9.53 0.38 4.88 2.01 7.59 0.76 4.02 1.33 7.86 1.64 1.91 0.79 14.96 4.50 Cumulative proportion 0.944 1.000 0.962 1.000 0.708 1.000 0.909 1.000 0.751 1.000 0.827 1.000 0.707 1.000 0.769 1.000 Probability 0.010 0.649 0.015 0.818 0.007 0.080 0.001 0.217 0.009 0.118 0.001 0.070 0.268 0.458 0.000 0.007The functions with the highest signification (P<0.001) were root 1 for NL and PL and FFA after being vacuum-packed. A larger coefficient corresponds to a greater contribution of the respective variable to the discrimination between groups. The fatty acids with the highest discriminating power (Table 6) were in the final product C18:3n-3 acid for total lipids, C10 acid for NL, C14 acid for PL, and C18:2n-6 acid for FFA. In the product after storage, the fatty acids with the highest discriminating power were C11 acid for total lipids, C18:2n-6 acid for NL, C20:2n-6 acid for PL, and C20:1n-9 acid for free fatty acids.Within the fatty provided in a large quantity by the chestnut diet, C18:2n-6 could be introduced in the classification of the diet groups in NL in the final product and in PL in the product after storage. However, C18:3n-3 could be also used in the classification of the diets for the total lipids and FFA in the final product and in NL in the product after storage. C18:1n-9 could be introduced in the discrimination roots in the final product for PL and FFA and for FFA in the product after storage. Within the fatty acids provided in a small quantity by the chestnut diet, C20:2n-6 could be used in the discriminant roots for total lipids in the final product and in the product after storage and for PL in the product after storage. Finally, C20:4n-6 could be used for the discrimination of the diets for total lipids in the final product and in the product after storage and for NL and PL in the product after storage. The fatty acids that could be introduced in a greater number of roots were the C20:3n-6 and C20:4n-6.These results are in accordance with a previous work, where “chorizo,” a traditional dry-cured Spanish sausage, was manufactured with the meat of these Celta pigs [46]. In this study, also the fatty acids C18:2n-6, C18:3n-3, C18:1n-9, C20:2n-6, and C20:4n-6 could be used in the classification of the diets in the different lipid fractions.


## 3.1. Biochemical, Lipolytic, and Oxidative Parameters

The evolution of compositional, physicochemical, lipolytic, and oxidative parameters of dry-cured loin, after manufacturing process and after 3 and 6 months of vacuum-packed storage, is shown in Table2.Table 2
Biochemical, lipolytic, and oxidative parameters of dry-cured loin from Celta pig fed with three finishing diets (chestnut, mixed, and concentrate), after manufacturing process and after 3 and 6 months of vacuum-packed storage.
Chestnuts Chestnuts-concentrate Concentrate Final product Storage time (months) Final product Storage time (months) Final product Storage time (months) 3 6 3 6 3 6 Dry matter (%) 65.52 ± 1.52 64.56 ± 1.92 64.93 ± 1.15 65.28 ± 2.51 64.97 ± 1.67 64.51 ± 0.77 65.29 ± 2.35 64.78 ± 2.57 65.24 ± 1.94 Intramuscular fat (%) 13.97 ± 1.32 13.64 ± 1.26 13.52 ± 1.17 13.52 ± 2.29 12.90 ± 2.57 12.88 ± 1.91 13.29 ± 1.36 13.39 ± 1.62 12.33 ± 3.32 pH 5.44 ± 0.12  a 1 5.47 ± 0.07  a 1 5.58 ± 0.15  b 1 5.48 ± 0.15  a 1 5.57 ± 0.09  a b 1 5.62 ± 0.09  b 1 5.66 ± 0.13 2 5.69 ± 0.10 2 5.73 ± 0.15 2 Titratable acidity(% lactic acid) 0.99 ± 0.07 a 1.14 ± 0.08  b 1 1.12 ± 0.10  b 1 0.98 ± 0.17 a 1.11 ± 0.08  b 1 1.13 ± 0.11  b 1 0.94 ± 0.07 0.95 ± 0.07 2 1.01 ± 0.15 2 Acidity value(mg KOH/g sample) 23.12 ± 2.17 a 36.61 ± 3.13 b 44.10 ± 5.34  c 12 24.01 ± 3.59 a 38.10 ± 4.74 b 45.58 ± 5.68  c 1 20.90 ± 2.65 a 36.62 ± 3.84 b 41.03 ± 4.81  c 2 Peroxide value(meq O2/kg fat) 20.35 ± 2.44  a 1 13.30 ± 1.30  b 12 15.72 ± 1.50 c 18.63 ± 3.14  a 2 12.04 ± 2.49  b 1 16.22 ± 2.19 c 16.22 ± 2.09  a 2 13.83 ± 1.34  b 2 15.55 ± 2.05 c TBA value(mg MDA/kg sample) 0.30 ± 0.07  a 1 0.12 ± 0.03 b 0.10 ± 0.03 b 0.25 ± 0.07  a 2 0.10 ± 0.03 b 0.07 ± 0.01 b 0.17 ± 0.05  a 3 0.11 ± 0.03 b 0.09 ± 0.04 b a–cDifferent letters within the same row corresponding to the same diet group indicate significant differences (P<0.05); 1–3different numbers within the same row corresponding to the same sampling point indicate significant differences (P<0.05), when the three finishing diets are compared.Dry matter content of dry-cured loin was similar in the three diet groups. The mean values were about 65%. These contents were similar to those previously found in Iberian dry-cured loin [11–13] and just a little higher than from other breeds [1, 14–16]. These values kept constant after 3 and 6 months of vacuum-packed storage. A similar behaviour was also reported [17, 18] because this method of storage is effective in preventing moisture losses during the storage of the meat products.In our study, the three diets had similar daily energy, although the chestnut diet provides, per day, higher contents of fat, C18:1n-9, C18:2n-6, C18:3n-3, and carbohydrates (Table 1). However, intramuscular fat content of dry-cured loin was similar in the three diet groups with values about 13.5% (of dry matter). As expected, these values remained constant during the vacuum-packed storage. The intramuscular fat content of dry-cured loin from Celta pig is closer to those contents determined in dry-cured loin from Iberian pig [11, 12] and quite higher than manufactured from other commercial breeds [19]. Fat is probably the most variable component when dry-cured meat products elaborated from whole pieces are studied. Celta pig is characterized by a highly developed adipogenic metabolism that leads to the deposit of a great amount of fat in its tissues, obtaining higher percentages of back fat compared to other breeds [20].The pH values (Table2) of dry-cured loin were significantly affected by the use of chestnut in the finishing diet (P<0.05). With the increase of chestnuts in the diet, a lower pH (P<0.05) was obtained in the dry-cured product (5.44, 5.48, and 5.66 in chestnut, mixed, and concentrated diets, resp.). During vacuum-packed storage, pH values significantly increased (P<0.05) in dry-cured loins from chestnut and mixed diets. After 6 months of storage, lower values (P<0.05) were obtained in loins from chestnut and mixed diet than in concentrate one (5.58, 5.62, and 5.73, resp.). These differences among diets were also observed when the pH ofLongissimus dorsi muscles of the pigs of the present study were studied [21]. A greater input of carbohydrates (mainly starch) is obtained by chestnut diet (over 1600 g of starch per day) than by mixed or concentrate diet (1395.5 and 1191.0 g of starch per day, resp.). A reason for the pH differences among diets could be related to the fact that the muscle from pigs fed with chestnuts would present a higher content of carbohydrates, which could cause a more prominent pH drop during the muscle rigor-mortis of these pigs, and in consequence, obtaining a lower pH value in fresh meat and in meat products. The pH values observed in the dry-cured loins were slightly lower than observed in the fresh muscles [21]. This pH decrease could have been produced during the first stages of the manufacturing process, as a result of microbial fermentation of the carbohydrates added to the dry-cured loin in its formulation. The pH increase during storage could be attributed to ammonia production as a consequence of proteolytic phenomena, an increase of buffer substances, and a decrease of electrolytes, and to the growth of microorganisms (especially molds and yeasts) capable of consuming lactic acid [22]. The pH values of the present product are in the range obtained in other dry-cured meat products [23, 24].Dry-cured loins from the three diet groups presented similar values for titratable acidity (Table2) around 0.97 g of lactic acid/100 of dry matter. During vacuum-packed storage, this parameter significantly increased (P<0.05) in the loins from chestnut and mixed diet to values over 1.12 g of lactic acid/100 of dry matter. However, the increase of this parameter was less intense in loins from concentrate diet, reaching at the end of the storage lower values (P<0.05) of 1.01 g of lactic acid/100 of dry matter than in the other diet groups. The formation of organic acids during the manufacture process causes the increase of this parameter and then, during vacuum-storage, it could be related to the microorganisms that may establish in the product in anaerobe conditions and are involved on the metabolism of these acids [25]. Our values are in the range of those reported in other dry-cured meat products [26, 27].Regarding lipolytic parameters, the values for acidity index (Table2), expressed as mg KOH/g of sample, in the dry-cured loins after manufacturing process were around 22 mg KOH/g of sample, finding no effect of chestnut inclusion in the finishing diet. These values progressively increased (P<0.05) during the vacuum-packed storage, reaching after 6 months of storage significantly higher (P<0.05) values in loins from mixed diet than from concentrate diet, while loins from chestnut diet showed intermediate acidity index values, so the differences among samples could not be attributed to the inclusion of chestnuts in the finishing diet. Lipolysis is an enzyme catalyzed process, so the factors that greatly affect the FFA content and lipolytic enzyme activity are the time/temperature cycles of the different stages of the process [2]. The absence of differences among diet groups for lipolysis degree in loin after manufacturing process (final product) is expected because they were manufactured following the same processing conditions and formulation. Our results are lower than those found in dry-cured ham [28, 29] and higher than in dry-cured sausages [18, 30]. These intermediate values are expected since the temperature and time conditions employed in the manufacture of this product are among the conditions used for the manufacture of dry-cured ham (higher temperature and longer time) and dry-cured sausages (lower temperature and shorter time).The peroxide values (Table2), expressed as meq O2/kg of fat, in the final product were significantly higher (P<0.05) in loins from chestnut diet than from mixed and concentrate diets. These values decreased (P<0.05) during the first 3 months of vacuum-packed storage and then increased (P<0.05) until the end of storage to similar values in the three diet groups. Similar peroxide values were found in several types of dry-cured meat products [7]. Nevertheless, the oxidation degree of these products is lower than that obtained in other products manufactured from the whole pieces [31, 32]. This could be due to the higher salt content of these products, which is a well-known prooxidant effect [33], and to the longer time of curing stages. The peroxide values decrease during the first months of vacuum-packed storage is related to the absence of oxygen during these stages, and the subsequent increase could be related to the oxygen permeability of the packaging material throughout the storage time [34, 35].The TBA values (Table2), expressed as mg of malonaldehyde (MDA)/kg of sample, of the dry-cured loins, as occurred for peroxide values, were significantly higher (P<0.05) in loins from chestnut diet than from mixed and concentrated diet. During vacuum-packed storage, these values decreased to similar values in the three diet groups. Our results are in the range of previously published values in dry-cured loin [12–15, 36]. The different behaviour of TBA values throughout the storage process with respect to peroxide values could be related to the MDA instability [37] and/or to the reaction of already formed malonaldehyde with sugars or amino acids and amines obtained like a consequence of proteolytic phenomena [38]. The evolution at the end of vacuum-packed storage is quite different for peroxide and TBARS, a fact that was already verified by other authors [34, 38] that show a low reliability of TBARS analysis for the assay of lipid oxidation in a long period of time.


## 3.2. Fatty Acids

Fatty acid composition of neutral lipids (expressed as %) of the dry-cured loins fat is shown in Table3. The profile is almost coincident with that of the total lipids (data not shown). In the dry-cured loin (final product), the saturated fatty acids (SFA) represented above 37%, with the palmitic (24%) and the stearic acid (11%) being the most abundant. The percentage in monounsaturated fatty acids (MUFA) was higher than SFA and around a 51%, with oleic acid (48%) being the most important of them. The less abundant fatty acids were the polyunsaturated (PUFA) (around 11%), where the linoleic acid was the main fatty acid (around 8%). When the effect of the finishing diet was studied, no significant differences were found among these major fatty acids. However, loins from chestnut group showed significant higher content (P<0.05) in some minor fatty acids (C8, C11, C14, C14:1, C15, C15:1, C20, and C24:1n-9) and lower content (P<0.05) in others (C17, C17:1, C18, C20:2n-6, C20:3n-3, and C22:1n-9). Linoleic acid (18:2n-6) is considered the parent of then-6 family because animals can synthetize othern-6 fatty acids from it. Nevertheless, thesen-6 fatty acids can also be directly incorporated through diet. Our results seem to indicate a direct incorporation of C20:2n-6, so that this fatty acid presented higher contents in the loins from pigs with a higher intake of this fatty acid [5]. This fatty acid profile of total lipids was very similar to that previously reported in dry-cured loin [12, 39, 40]. In some of these studies, the effect of the different diets was also studied, obtaining a higher content inn-3 fatty acids using linseed and olive oils [39]. However, no effect onn-3 fatty acids was obtained using pasture and acorn, though a lower content inn-6 fatty acids was found [40]. Along the vacuum-packed storage the fatty acid profile remained constant and the minor differences obtained could be related to the variability between samples.Table 3
Fatty acid composition of neutral lipids (%) of dry-cured loin from Celta pig fed with three finishing diets (chestnut, mixed, and concentrate), after manufacturing process and after 3 and 6 months of vacuum-packed storage.
Chestnuts Chestnuts-concentrate Concentrate Final product Storage time (months) Final product Storage time (months) Final product Storage time (months) 3 6 3 6 3 6 C8 0.02 ± 0.01a 0.004 ± 0.002b1 0.01 ± 0.003c1 0.01 ± 0.003ab 0.01 ± 0.01a2 0.01 ± 0.004b2 0.01 ± 0.003a 0.02 ± 0.01b3 0.003 ± 0.001a2 C10 0.04 ± 0.02a1 0.05 ± 0.004b 0.05 ± 0.01b 0.05 ± 0.0052 0.05 ± 0.005 0.05 ± 0.01 0.04 ± 0.00512 0.04 ± 0.003 0.05 ± 0.01 C11 0.03 ± 0.02a1 0.005 ± 0.001b1 0.01 ± 0.01c 0.02 ± 0.0112 0.02 ± 0.022 0.01 ± 0.005 0.01 ± 0.01a2 0.04 ± 0.02b3 0.005 ± 0.001a C12 0.04 ± 0.02a 0.05 ± 0.001b 0.05 ± 0.01ab 0.05 ± 0.003 0.05 ± 0.005 0.05 ± 0.003 0.04 ± 0.004 0.05 ± 0.003 0.05 ± 0.004 C14 1.21 ± 0.08a1 1.02 ± 0.05b 0.98 ± 0.10b 1.09 ± 0.08a2 0.95 ± 0.10b 0.93 ± 0.06b 1.09 ± 0.082 1.01 ± 0.06 1.02 ± 0.06 C14:1 0.10 ± 0.09a1 0.02 ± 0.01b 0.03 ± 0.02b 0.04 ± 0.022 0.02 ± 0.03 0.01 ± 0.003 0.02 ± 0.012 0.04 ± 0.03 0.01 ± 0.004 C15 0.05 ± 0.05a1 0.02 ± 0.003b 0.02 ± 0.001b 0.02 ± 0.0022 0.02 ± 0.005 0.02 ± 0.003 0.02 ± 0.012 0.02 ± 0.005 0.02 ± 0.003 C15:1 0.002 ± 0.0021 0.001 ± 0.001 0.001 ± 0.001 0.002 ± 0.00112 0.002 ± 0.001 0.001 ± 0.001 0.001 ± 0.0012 0.001 ± 0.001 0.001 ± 0.001 C16 24.43 ± 0.64a1 24.06 ± 0.46a1 22.85 ± 1.41b 23.39 ± 0.902 22.94 ± 1.072 22.93 ± 0.70 24.11 ± 0.6112 23.40 ± 0.5612 23.65 ± 0.67 C16:1 2.18 ± 0.93a 2.40 ± 0.10ab 2.87 ± 0.50b 2.31 ± 0.29 2.35 ± 0.27 2.48 ± 0.26 2.22 ± 0.27 2.48 ± 0.48 2.66 ± 0.43 C17 0.09 ± 0.05a1 0.14 ± 0.01b 0.13 ± 0.02ab 0.13 ± 0.0612 0.16 ± 0.05 0.15 ± 0.03 0.14 ± 0.042 0.13 ± 0.04 0.14 ± 0.02 C17:1 0.11 ± 0.05a1 0.15 ± 0.01ab 0.16 ± 0.03b 0.17 ± 0.032 0.17 ± 0.05 0.17 ± 0.04 0.15 ± 0.0412 0.14 ± 0.03 0.15 ± 0.02 C18 11.09 ± 1.04a1 12.30 ± 0.21b1 10.33 ± 1.32a1 11.87 ± 0.8012 11.55 ± 0.4512 11.61 ± 0.502 12.21 ± 1.222 11.19 ± 1.202 11.55 ± 1.072 C18:1n-9 48.79 ± 1.75a 49.42 ± 0.86ab 51.29 ± 1.56b1 48.75 ± 1.171 49.26 ± 1.21 48.82 ± 1.632 47.89 ± 2.802 48.93 ± 2.21 47.80 ± 1.642 C18:2n-6 7.97 ± 1.27 7.78 ± 0.77 7.89 ± 1.38 8.30 ± 0.92 9.33 ± 1.54 9.37 ± 1.13 8.68 ± 1.80 9.19 ± 1.86 9.22 ± 1.24 C18:3n-6 0.03 ± 0.002 0.05 ± 0.003 0.05 ± 0.0041 0.03 ± 0.003 0.06 ± 0.01 0.06 ± 0.012 0.03 ± 0.01 0.05 ± 0.02 0.05 ± 0.00412 C18:3n-3 0.32 ± 0.05a 0.36 ± 0.03b 0.35 ± 0.05b 0.34 ± 0.02a 0.39 ± 0.07b 0.37 ± 0.05b 0.31 ± 0.07a 0.34 ± 0.08b 0.33 ± 0.05b C20 0.07 ± 0.051 0.07 ± 0.01 0.10 ± 0.02 0.03 ± 0.003a12 0.07 ± 0.03ab 0.07 ± 0.04b 0.03 ± 0.003a2 0.08 ± 0.02b 0.08 ± 0.04b C20:1n-9 0.05 ± 0.01a 0.02 ± 0.01b 0.03 ± 0.01b 0.05 ± 0.01a 0.03 ± 0.01b 0.03 ± 0.01b 0.05 ± 0.01a 0.03 ± 0.01b 0.02 ± 0.003b C20:2n-6 0.24 ± 0.031 0.27 ± 0.02 0.22 ± 0.101 0.30 ± 0.0212 0.32 ± 0.05 0.33 ± 0.032 0.34 ± 0.092 0.32 ± 0.06 0.33 ± 0.072 C20:3n-6 0.11 ± 0.02a 0.10 ± 0.02b1 0.10 ± 0.02b 0.10 ± 0.03a 0.14 ± 0.05b2 0.13 ± 0.02b 0.10 ± 0.03a 0.11 ± 0.03b12 0.13 ± 0.04b C20:4n-6 0.95 ± 0.21 0.82 ± 0.20 0.99 ± 0.28 0.94 ± 0.43 1.24 ± 0.40 1.27 ± 0.33 0.91 ± 0.32 1.25 ± 0.53 1.35 ± 0.59 C20:3n-3 0.03 ± 0.02a1 0.01 ± 0.002b 0.01 ± 0.003b 0.06 ± 0.004a2 0.01 ± 0.001b 0.01 ± 0.004b 0.06 ± 0.02a2 0.01 ± 0.002b 0.01 ± 0.003b C20:5n-3 0.02 ± 0.01a 0.03 ± 0.01b12 0.03 ± 0.005b 0.01 ± 0.005a 0.04 ± 0.01b1 0.04 ± 0.01b 0.01 ± 0.001a 0.03 ± 0.01b2 0.03 ± 0.01b C22 0.03 ± 0.01a 0.01 ± 0.002b 0.01 ± 0.001b 0.03 ± 0.01a 0.01 ± 0.002b 0.01 ± 0.002b 0.03 ± 0.01a 0.01 ± 0.003b 0.01 ± 0.003b C22:1n-9 0.02 ± 0.021 0.01 ± 0.002 0.01 ± 0.002 0.05 ± 0.02a2 0.01 ± 0.005b 0.01 ± 0.001b 0.03 ± 0.01a1 0.01 ± 0.01b 0.01 ± 0.002b C22:2n-6 1.44 ± 0.31a 0.58 ± 0.09b 1.08 ± 0.50ab 1.37 ± 0.47a 0.52 ± 0.16b 0.70 ± 0.35b 1.09 ± 0.17 0.73 ± 0.28 0.89 ± 1.13 C23 0.15 ± 0.03a 0.07 ± 0.01b 0.16 ± 0.06a 0.12 ± 0.05 0.07 ± 0.02 0.09 ± 0.04 0.10 ± 0.02ab 0.09 ± 0.04a 0.17 ± 0.16b C24 0.29 ± 0.12 0.14 ± 0.11 0.13 ± 0.11 0.27 ± 0.22 0.14 ± 0.07 0.20 ± 0.12 0.23 ± 0.09 0.19 ± 0.13 0.19 ± 0.21 C24:1n-9 0.11 ± 0.05a1 0.05 ± 0.04b 0.06 ± 0.04b 0.11 ± 0.071 0.07 ± 0.03 0.08 ± 0.04 0.05 ± 0.022 0.07 ± 0.04 0.06 ± 0.03   ∑SFA 37.53 ± 0.94a 37.94 ± 0.34a1 34.82 ± 2.03b1 37.07 ± 1.38 36.04 ± 1.412 36.13 ± 1.1212 38.05 ± 1.74a 36.28 ± 1.48b2 36.93 ± 1.07ab2 ∑UFA 62.48 ± 0.92a 62.06 ± 0.34a1 65.18 ± 2.03b1 62.92 ± 1.37 63.96 ± 1.412 63.87 ± 1.1212 61.95 ± 1.74a 63.72 ± 1.48b2 63.07 ± 1.07ab2 ∑MUFA 51.37 ± 1.94a 52.07 ± 0.86a 54.45 ± 1.79b1 51.46 ± 0.94 51.91 ± 1.18 51.60 ± 1.632 50.42 ± 2.95 51.70 ± 2.19 50.72 ± 1.522 ∑PUFA 11.12 ± 1.58 10.00 ± 0.97 10.73 ± 2.09 11.46 ± 1.57 12.05 ± 2.10 12.28 ± 1.61 11.53 ± 2.22 12.03 ± 2.46 12.35 ± 2.40 ∑SFA: sum of saturated fatty acids; ∑UFA: sum of unsaturated fatty acids; ∑MUFA: sum of monounsaturated fatty acids; ∑PUFA: sum of polyunsaturated fatty acids.a–cDifferent letters within the same row corresponding to the same diet group indicate significant differences (P<0.05). 1–3Different numbers within the same row corresponding to the same sampling point indicate significant differences (P<0.05), when the three finishing diets are compared.In the neutral lipids (NL), only slight differences are presented, which affects PUFA, showing a lower percentage than in total lipids. This is due to the high proportion of NL in the fat [5]. SFA represented above 36%, with the most abundant being the palmitic (24%) and the stearic acid (11%). MUFA represented over a 53%, with oleic acid (50%) being the most abundant. Finally, PUFA represented a 9% and linoleic acid was the most important of them (7%). This profile coincides with that found by Domínguez et al. [5] in the fat of different intramuscular locations of Celta pig. When the effect of the finishing diet was studied, no significant differences were found for these major fatty acids. However, loins from chestnut group showed significant higher content (P<0.05) in some minor fatty acids (C8, C20:1n-9, and C24:1n-9) and lower content (P<0.05) in others (C20:2n-6). Some of these differences were already found for total fatty acids. The fatty acid composition of NL remained constant during the vacuum-packed storage, with this profile being very similar for the three diet groups. The lack of changes in this profile may be due to PL being the most affected by the lipolysis phenomena [2].The limited effect of the different diets in this fraction of lipids and a little more pronounced in the PL (as can be seen later) could be because PL have a shorter turnover rate than triglycerides [41] and their fatty acid composition is directly more influenced by the diet. On the other hand, average triacylglycerol life has been estimated to be over 180 days [4], longer than the fattening phase of Celta pigs in this study (90 days). A similar trend was previously found in Iberian pigs [42, 43]. Nevertheless, other authors [6] reported an increment in C18:2n-6, C18:3n-3, and C20:4n-6 in fresh meat when chestnut was included in pig’s diet.Fatty acid composition of polar lipids (expressed as %) of the dry-cured loins fat is shown in Table4. The fatty acid profile observed in the dry-cured loins after the manufacturing process (final product) was different to that found in total and NL. The main difference is the high content in PUFA, which supposed over 43%, with the most abundant being the linoleic acid (C18:2n-6) (33%). Nevertheless, MUFA only represented over 14%, while SFA supposed 43%. The major fatty acids of these two groups were oleic and palmitic acid, respectively. Like in the last lipid fractions studied, no differences were found for major fatty acids when the three diet groups of loins were compared, but they were found in some minor fatty acids, which were higher (P<0.05) (C11, C15, C18:3n-6, C18:3n-3, C20:3n-3, and C22) or lower (P<0.05) (C15:1 and C20:2n-6) when chestnut was introduced in the finishing diet. Because C18:2n-6 and C18:3n-3 are essential fatty acids in animal tissues, their content is directly related to their concentration in the diet. Chestnut diet provides a high quantity of these fatty acids than concentrate diet. In the dry-cured muscles, this higher intake was only evident for C18:3n-3. Thus, C18:2n-6 intake could be used to synthesise other fatty acids fromn-6 series, like C18:3n-6, also in significantly higher content in loins from chestnut diet, despite being equally provided in the diets. Also, as occurred in total lipids, a direct incorporation of C20:2n-6 was obtained in loins from concentrate diet [5].Table 4
Fatty acid composition of polar lipids (%) of dry-cured loin from Celta pig feed with three finishing diets (chestnut, mixed, and concentrate), after manufacturing process and after 3 and 6 months of vacuum-packed storage.
Chestnuts Chestnuts-concentrate Concentrate Final product Storage time (months) Final product Storage time (months) Final product Storage time (months) 3 6 3 6 3 6 C8 0.01 ± 0.003a 0.01 ± 0.003a 0.02 ± 0.003b12 0.004 ± 0.004a 0.01 ± 0.003b 0.02 ± 0.01c1 0.004 ± 0.002a 0.01 ± 0.004b 0.01 ± 0.01b2 C10 N.D. N.D. N.D. N.D. N.D. N.D. 0.001 ± 0.001 N.D. N.D. C11 0.02 ± 0.01ab 0.01 ± 0.01a 0.03 ± 0.02b1 0.02 ± 0.01 0.02 ± 0.01 0.01 ± 0.012 0.01 ± 0.01a 0.02 ± 0.02a 0.03 ± 0.02b1 C12 0.02 ± 0.01a 0.06 ± 0.05ab 0.09 ± 0.08b 0.01 ± 0.01a 0.08 ± 0.06b 0.06 ± 0.04ab 0.02 ± 0.02a 0.04 ± 0.02a 0.10 ± 0.06b C14 5.22 ± 2.04a 4.42 ± 0.57a 5.53 ± 2.70a12 4.17 ± 2.16a 5.03 ± 1.41ab 6.46 ± 1.51b1 5.28 ± 1.09 4.35 ± 2.22 3.67 ± 0.682 C14:1 0.04 ± 0.05 0.02 ± 0.011 0.06 ± 0.08 0.01 ± 0.01a 0.14 ± 0.18b2 0.08 ± 0.03ab 0.02 ± 0.01a 0.20 ± 0.15b2 0.13 ± 0.07b C15 0.14 ± 0.06a 0.03 ± 0.01b 0.05 ± 0.04b12 0.11 ± 0.06a 0.05 ± 0.01b 0.10 ± 0.05ab1 0.09 ± 0.06a 0.04 ± 0.01ab 0.04 ± 0.01b2 C15:1 0.09 ± 0.07 0.08 ± 0.011 0.08 ± 0.0612 0.10 ± 0.06a 0.15 ± 0.04b2 0.10 ± 0.03a1 0.10 ± 0.03a 0.06 ± 0.04ab1 0.05 ± 0.02b2 C16 25.51 ± 1.37a 25.85 ± 3.68a 25.69 ± 1.84a12 27.74 ± 1.72 27.07 ± 2.51 27.78 ± 0.931 27.31 ± 1.62 27.32 ± 2.40 27.12 ± 1.672 C16:1 1.36 ± 0.55a 0.57 ± 0.20b 0.54 ± 0.08b 1.49 ± 0.80a 0.52 ± 0.12b 0.35 ± 0.07b 1.69 ± 0.47a 0.73 ± 0.37b 0.57 ± 0.33b C17 3.24 ± 1.21 3.29 ± 1.55 3.88 ± 1.431 3.19 ± 2.14a 2.73 ± 1.31a 2.09 ± 1.56b2 2.50 ± 0.83 2.95 ± 1.19 3.53 ± 1.081 C17:1 1.62 ± 0.61 1.71 ± 0.74 1.87 ± 1.21 1.50 ± 1.06ab 1.36 ± 0.88a 2.41 ± 0.58b 1.30 ± 0.42 1.71 ± 0.75 1.70 ± 0.60 C18 6.90 ± 0.36a 7.35 ± 1.38ab 8.72 ± 2.74b1 7.65 ± 0.81a 8.30 ± 1.12a 8.25 ± 1.75a12 6.80 ± 0.89 7.86 ± 1.32 6.89 ± 1.122 C18:1n-9 11.35 ± 2.39a 14.85 ± 2.37b1 13.92 ± 1.21b 10.90 ± 1.39a 12.09 ± 1.42b2 12.65 ± 0.77b 10.67 ± 1.91a 13.86 ± 4.03b12 12.83 ± 2.92ab C18:2n-6 34.36 ± 2.50a 25.84 ± 2.19b 24.42 ± 2.94b 32.23 ± 1.74a 26.83 ± 2.92b 24.83 ± 2.13b 31.92 ± 4.15a 26.03 ± 4.23b 24.55 ± 3.80b C18:3n-6 0.13 ± 0.02a1 0.12 ± 0.02a1 0.09 ± 0.02b12 0.11 ± 0.02a2 0.13 ± 0.02a1 0.10 ± 0.01b1 0.09 ± 0.012 0.09 ± 0.012 0.08 ± 0.022 C18:3n-3 0.37 ± 0.08a1 0.36 ± 0.04a1 0.31 ± 0.02b1 0.32 ± 0.03a12 0.28 ± 0.05b2 0.17 ± 0.06a2 0.26 ± 0.052 0.25 ± 0.042 0.22 ± 0.032 C20 0.03 ± 0.01a 0.08 ± 0.02b1 0.05 ± 0.01c12 0.03 ± 0.01a 0.06 ± 0.03b2 0.07 ± 0.02b1 0.02 ± 0.01a 0.04 ± 0.01ab2 0.04 ± 0.01b2 C20:1n-9 0.18 ± 0.04a 0.28 ± 0.04b1 0.28 ± 0.06b1 0.22 ± 0.05a 0.37 ± 0.04b2 0.41 ± 0.02b2 0.22 ± 0.06a 0.28 ± 0.03b1 0.30 ± 0.07b1 C20:2n-6 0.43 ± 0.04a1 0.57 ± 0.05b1 0.68 ± 0.04b1 0.57 ± 0.07a2 0.79 ± 0.07b2 0.94 ± 0.04c2 0.61 ± 0.05a2 0.71 ± 0.16b2 0.77 ± 0.25b1 C20:3n-6 0.98 ± 0.13 1.03 ± 0.17 1.06 ± 0.1312 0.93 ± 0.11a 1.03 ± 0.07a 1.26 ± 0.07b1 0.88 ± 0.07 0.86 ± 0.23 0.88 ± 0.342 C20:4n-6 6.77 ± 1.71a 8.49 ± 3.36a 9.39 ± 2.20b 7.27 ± 2.97a 9.48 ± 1.31ab 9.06 ± 1.63b 8.16 ± 2.78 9.48 ± 1.80 8.80 ± 3.34 C20:3n-3 0.06 ± 0.03 0.08 ± 0.01 0.06 ± 0.031 0.07 ± 0.01a 0.09 ± 0.01ab 0.11 ± 0.01b2 0.04 ± 0.03a 0.08 ± 0.01b 0.09 ± 0.03b2 C20:5n-3 0.01 ± 0.01a 0.01 ± 0.004a 0.05 ± 0.03b1 0.01 ± 0.002a 0.03 ± 0.002a 0.07 ± 0.01b1 0.01 ± 0.005a 0.02 ± 0.02a 0.11 ± 0.05b2 C22 0.48 ± 0.04a1 0.63 ± 0.15b1 0.64 ± 0.08b1 0.46 ± 0.12a1 0.54 ± 0.06ab1 0.59 ± 0.07b1 0.35 ± 0.032 0.40 ± 0.052 0.40 ± 0.072 C22:1n-9 0.02 ± 0.005a 0.04 ± 0.01a 0.10 ± 0.02b1 0.02 ± 0.005a 0.04 ± 0.004a 0.24 ± 0.15b2 0.02 ± 0.01 0.05 ± 0.05 0.05 ± 0.0041 C22:2n-6 0.33 ± 0.27a 0.77 ± 0.19b12 0.90 ± 0.33b12 0.46 ± 0.23a 0.52 ± 0.38a1 0.64 ± 0.12a1 0.64 ± 0.41a 1.13 ± 0.54b2 1.32 ± 0.55b2 C23 0.03 ± 0.01a 0.04 ± 0.01a 0.09 ± 0.07a1 0.03 ± 0.02a 0.07 ± 0.005a 0.28 ± 0.22b2 0.04 ± 0.01 0.04 ± 0.02 0.10 ± 0.061 C24 0.24 ± 0.30a 2.80 ± 0.73b 1.14 ± 1.31ab1 0.21 ± 0.25a 1.82 ± 0.69a 0.68 ± 0.22a1 0.77 ± 0.89a 1.18 ± 1.31a 4.61 ± 3.75b2 C24:1n-9 0.09 ± 0.13a 0.60 ± 0.19b1 0.25 ± 0.25a1 0.18 ± 0.19a 0.37 ± 0.14a12 0.19 ± 0.06a1 0.15 ± 0.16a 0.20 ± 0.16a2 0.99 ± 0.75b2   ∑SFA 41.82 ± 1.89a 44.58 ± 3.29ab 45.93 ± 4.15b 43.62 ± 2.33 45.77 ± 4.01 46.40 ± 0.49 43.19 ± 2.02 44.26 ± 2.66 46.56 ± 3.54 ∑UFA 58.18 ± 1.89a 55.42 ± 3.29ab 54.07 ± 4.15b 56.38 ± 2.33 54.23 ± 4.01 53.60 ± 0.49 56.81 ± 2.02 55.74 ± 2.66 53.44 ± 3.54 ∑MUFA 14.75 ± 2.14a 18.16 ± 1.77b1 17.10 ± 0.80a 14.42 ± 1.37 15.05 ± 1.202 16.43 ± 0.891 14.18 ± 1.88a 17.09 ± 4.38b12 16.61 ± 3.21ab2 ∑PUFA 43.43 ± 2.74a 37.27 ± 5.03b 36.97 ± 4.57ab 41.97 ± 3.19a 39.18 ± 3.88ab 37.17 ± 0.86b 42.63 ± 3.57a 38.65 ± 4.01ab 36.83 ± 6.17b ∑SFA: sum of saturated fatty acids; ∑UFA: sum of unsaturated fatty acids; ∑MUFA: sum of monounsaturated fatty acids; ∑PUFA: sum of polyunsaturated fatty acids.a–cDifferent letters within the same row corresponding to the same diet group indicate significant differences (P<0.05). 1–3Different numbers within the same row corresponding to the same sampling point indicate significant differences (P<0.05), when the three finishing diets are compared.After vacuum-packed storage, changes in the fatty acids profile of this fraction were observed. After 3 months of storage, PUFA percentage significantly decreases (P<0.05) to values around 38% and then they remained constant to the end of storage. Among these fatty acids, the most affected were the C18:2n-6 (descending over 10%), C18:3n-6, and C18:3n-3. The differences among diet groups were the same than those found in the final product. As mentioned above, PL are considered the main source of free fatty acids [5] and also they are highly susceptible to oxidation.Fatty acid profile obtained for PL was similar to those reported in other studies in dry-cured loin [16, 44], although contents in PUFA were higher than those in other works [3], which could be related to the higher oxidation indexes obtained in those products.The content in free fatty acids (FFA) (expressed as mg/100 g of fat) of the dry-cured loins fat is shown in Table5. The mean content of FFA represented over 2700 mg/100 g of fat and no significant differences were found for this total content when the three diet groups were compared. The major fatty acids, expressed as percentage (data not shown), were around 38% for SFA, 33% for MUFA, and 27% for PUFA, and as in the last fractions studied, the most representatives in each groups were palmitic and stearic, oleic, and linoleic acid, respectively. In the final product, significant differences (P<0.05) were found in some minor fatty acids, with higher (C12, C18:3n-3, and C22:1n-9) and lower (C20:2n-6 and C20:3n-3) content in loins from chestnut diet. The values and the profile obtained in the present study for FFA are similar to those previously reported in the scientific literature for dry-cured loin [3, 16]. The similarity of the profile with the beforehand studied about PL, especially with regard to high PUFA percentage, confirms that FFA comes mainly from polar fraction but also is perceived as an influence of NL.Table 5
Free fatty acids content (mg/100 g of fat) of dry-cured loin from Celta pig fed with three finishing diets (chestnut, mixed, and concentrate), after manufacturing process and after 3 and 6 months of vacuum-packed storage.
Chestnuts Chestnuts-concentrate Concentrate Final product Storage time (months) Final product Storage time (months) Final product Storage time (months) 3 6 3 6 3 6 C8 0.08 ± 0.03a 0.44 ± 0.28b1 0.18 ± 0.23a 0.11 ± 0.07 0.07 ± 0.032 0.21 ± 0.19 0.15 ± 0.18 0.05 ± 0.012 0.09 ± 0.02 C10 0.78 ± 0.17a 2.66 ± 0.20b 4.00 ± 0.80c1 0.88 ± 0.10a 2.21 ± 0.21b 4.32 ± 0.56c1 0.78 ± 0.17a 2.38 ± 0.47b 3.08 ± 0.47c2 C11 0.05 ± 0.04a1 0.18 ± 0.05b 0.27 ± 0.04c 0.07 ± 0.03a1 0.15 ± 0.05a 0.30 ± 0.04b 0.19 ± 0.192 0.15 ± 0.04 0.22 ± 0.02 C12 1.43 ± 0.51a1 2.34 ± 0.25b1 3.59 ± 0.77c1 1.38 ± 0.31a2 2.08 ± 0.39b2 2.95 ± 0.25c12 1.07 ± 0.15a2 2.01 ± 0.17b3 2.83 ± 0.57c2 C14 19.85 ± 5.01a 46.33 ± 5.04b1 65.74 ± 8.14c1 19.11 ± 3.05a 37.74 ± 5.52b2 54.93 ± 7.46c2 17.54 ± 3.88a 45.45 ± 9.93b1 55.85 ± 7.28c2 C14:1 0.24 ± 0.07a 0.45 ± 0.03b1 0.71 ± 0.05c1 0.24 ± 0.05a 0.37 ± 0.07b2 0.58 ± 0.12c2 0.22 ± 0.04a 0.46 ± 0.06b1 0.60 ± 0.05c2 C15 1.38 ± 0.05a12 1.99 ± 0.13b 2.04 ± 0.21b 1.65 ± 0.46a1 2.06 ± 0.35b 2.06 ± 0.36b 1.23 ± 0.29a2 1.77 ± 0.45b 1.96 ± 0.30b C15:1 0.02 ± 0.01ab1 0.01 ± 0.01a1 0.03 ± 0.02b12 0.05 ± 0.03a2 0.03 ± 0.02b12 0.02 ± 0.01b1 0.01 ± 0.01a1 0.03 ± 0.01b2 0.04 ± 0.004b2 C16 680.86 ± 114.75a 1118.17 ± 136.99b 1449.04 ± 254.88c1 783.47 ± 189.31a 1019.24 ± 157.95b 1262.90 ± 88.46c2 637.12 ± 119.71a 938.43 ± 73.09b 1177.97 ± 180.22c2 C16:1 42.05 ± 6.42a 62.73 ± 9.30b 95.11 ± 11.13c1 40.53 ± 5.26a 53.05 ± 8.77b 76.93 ± 20.79c2 36.25 ± 7.71a 53.56 ± 3.39b 69.95 ± 12.11c2 C17 8.57 ± 0.78a12 14.66 ± 2.85b1 15.23 ± 1.13b 10.32 ± 2.32a1 14.99 ± 4.40b1 15.21 ± 2.56b 7.20 ± 1.71a2 10.64 ± 1.08b2 12.83 ± 1.92b C17:1 3.78 ± 0.40a 6.31 ± 1.46b 6.82 ± 0.76b1 5.25 ± 0.92a 5.71 ± 1.27a 8.70 ± 3.34b2 4.34 ± 0.87 4.65 ± 0.45 4.60 ± 2.173 C18 257.30 ± 40.29a 480.31 ± 10.81b 651.41 ± 113.57c1 280.81 ± 57.27a 482.94 ± 44.34b 585.87 ± 46.80c12 266.44 ± 43.73a 418.36 ± 47.45b 539.71 ± 72.84c2 C18:1n-9 842.50 ± 112.84a 1180.02 ± 139.06b 1574.24 ± 88.62c1 910.03 ± 94.12a 1057.36 ± 88.18a 1304.07 ± 193.82b2 828.82 ± 183.70a 1109.08 ± 82.26b 1213.99 ± 256.72b2 C18:2n-6 557.27 ± 28.20a12 446.58 ± 27.16b 471.71 ± 36.01b 626.10 ± 103.47a1 522.66 ± 68.00b 522.30 ± 48.00b 524.67 ± 128.772 465.49 ± 72.48 525.69 ± 59.27 C18:3n-6 3.41 ± 0.40 2.98 ± 0.4212 3.00 ± 0.16 3.60 ± 0.77 3.37 ± 0.781 3.35 ± 0.38 3.07 ± 0.69 2.60 ± 0.392 3.09 ± 0.42 C18:3n-3 17.77 ± 2.60a1 14.04 ± 0.53b12 16.93 ± 1.47a1 17.00 ± 2.361 15.10 ± 2.941 14.69 ± 2.3812 12.68 ± 3.392 11.76 ± 0.852 13.52 ± 2.352 C20 2.24 ± 0.51a 3.61 ± 0.44b 4.67 ± 0.88c 2.50 ± 0.48a 3.31 ± 0.52b 4.11 ± 0.37c 2.06 ± 0.45a 3.33 ± 0.18b 4.18 ± 0.72c C20:1n-9 12.76 ± 1.43a 19.22 ± 2.50b 24.89 ± 2.58c 14.36 ± 2.60a 17.40 ± 0.81a 23.21 ± 5.33b 14.89 ± 3.35a 19.31 ± 2.28b 22.61 ± 3.18b C20:2n-6 6.37 ± 1.06a1 9.26 ± 0.71b 10.82 ± 0.77b1 8.36 ± 1.11a2 10.55 ± 1.59b 13.48 ± 2.47c2 9.02 ± 1.71a2 10.83 ± 1.24b 13.48 ± 1.31c2 C20:3n-6 10.04 ± 2.93a 7.47 ± 0.92b 6.20 ± 0.58b 11.10 ± 1.91a 8.36 ± 2.13b 8.54 ± 1.48b 11.29 ± 3.53a 6.96 ± 2.16b 7.73 ± 1.23b C20:4n-6 119.52 ± 45.79 139.76 ± 44.09 153.46 ± 24.721 91.85 ± 22.48 126.45 ± 34.77 124.02 ± 38.982 85.76 ± 15.61a 119.59 ± 11.76ab 145.95 ± 49.86b2 C20:3n-3 1.61 ± 0.491 1.68 ± 0.20 1.72 ± 0.311 2.24 ± 0.4212 1.98 ± 0.46 2.11 ± 0.382 2.28 ± 0.46a2 0.65 ± 0.82b 0.49 ± 0.35b2 C20:5n-3 0.59 ± 0.16a12 0.43 ± 0.36ab1 0.97 ± 0.39b1 0.99 ± 0.391 0.96 ± 0.692 2.10 ± 0.22b2 0.18 ± 0.25a2 0.77 ± 0.48b12 2.03 ± 0.54c2 C22 4.02 ± 0.95a1 4.05 ± 0.50a1 2.96 ± 0.31b 4.25 ± 0.941 3.31 ± 0.6212 3.59 ± 0.11 2.07 ± 1.772 2.60 ± 0.912 2.87 ± 0.34 C22:1n-9 0.65 ± 0.10 0.77 ± 0.431 0.80 ± 0.371 0.74 ± 0.19ab 0.96 ± 0.39a12 0.41 ± 0.17b2 0.61 ± 0.30a 1.15 ± 0.25b2 0.80 ± 0.25a1 C22:2n-6 74.29 ± 7.39a 122.36 ± 15.63b1 179.02 ± 26.91c 64.75 ± 13.45a 201.88 ± 95.53b2 141.02 ± 25.56c 63.81 ± 19.62a 150.02 ± 26.25b1 160.56 ± 24.46c C23 4.80 ± 0.49a 8.42 ± 2.11a1 15.36 ± 3.42b1 4.38 ± 0.54a 13.77 ± 6.82b2 9.95 ± 3.15c2 4.84 ± 2.34a 9.85 ± 2.71b1 10.98 ± 2.31c2 C24 31.56 ± 5.85a 81.80 ± 28.92b 54.12 ± 16.73ab1 52.83 ± 30.72a 73.75 ± 56.84a 136.08 ± 26.69b2 53.05 ± 46.99a 80.29 ± 31.15ab 106.75 ± 34.38b2 C24:1n-9 19.67 ± 5.5212 24.87 ± 6.55 21.91 ± 10.781 29.14 ± 7.53a1 25.60 ± 15.60a 49.21 ± 17.33b2 12.36 ± 8.45a2 28.40 ± 9.85b 46.21 ± 11.21c2   ∑FFA 2725.48 ± 236.95a 3803.91 ± 291.97b 4836.99 ± 480.95c1 2988.07 ± 450.03a 3707.42 ± 464.09b 4377.22 ± 373.63c12 2604.01 ± 434.95a 3500.63 ± 279.32b 4150.65 ± 499.72c2 ∑SFA 1012.93 ± 142.95a 1764.96 ± 145.52b 2268.63 ± 359.49c1 1161.77 ± 273.38a 1655.63 ± 242.04b 2082.48 ± 126.77c12 993.74 ± 161.35a 1515.31 ± 115.42b 1919.30 ± 249.30c2 ∑UFA 1712.55 ± 151.29a 2038.95 ± 172.79b 2568.37 ± 140.48c1 1826.30 ± 184.73a 2051.79 ± 249.55a 2294.74 ± 248.30b12 1610.26 ± 337.28a 1985.32 ± 184.13b 2231.35 ± 295.67b2 ∑MUFA 921.67 ± 112.07a 1294.38 ± 144.86b 1724.51 ± 93.60c1 1000.33 ± 100.30a 1160.48 ± 112.14a 1463.13 ± 214.66b2 897.51 ± 192.32a 1216.65 ± 88.47b 1358.81 ± 264.36b2 ∑PUFA 790.88 ± 58.58 744.56 ± 63.421 843.86 ± 57.84 825.97 ± 118.07 891.31 ± 163.942 831.62 ± 61.94 712.75 ± 154.86a 768.67 ± 95.93ab12 872.53 ± 85.27b ∑FFA: sum of free fatty acids; ∑SFA: sum of saturated fatty acids; ∑UFA: sum of unsaturated fatty acids; ∑MUFA: sum of monounsaturated fatty acids; ∑PUFA: sum of polyunsaturated fatty acids.a–cDifferent letters within the same row corresponding to the same diet group indicate significant differences (P<0.05). 1–3Different numbers within the same row corresponding to the same sampling point indicate significant differences (P<0.05), when the three finishing diets are compared.After vacuum-packed storage, as occurred for acidity index, FFA content significantly increased (P<0.05) to reach after six months of storage higher values in loins from chestnut diet than in concentrate diets. The FFA profile was also modified during storage, decreasing PUFA to 19% and increasing SFA to 46%. This alteration leads us to think that a change in the acting microbial enzymes could have happened. Some authors attributed the higher lipolysis during the vacuum-storage to the action of lactic acid bacteria [45] in addition to endogenous lipases and phospholipases.


## 3.3. Discrimination of the Different Finishing Diets

With the objective of discrimination between diets, multivariate statistical techniques were applied. The variables used for the analysis were the percentage of the fatty acids for total PL and NL and the content in free fatty acids. In the final product and after storage, a factorial analysis was previously performed to obtain the variables which contributed the most to the classification. From these variables, a canonical discriminant analysis was carried out and the coefficients (correlation discriminant functions) obtained are presented in Table6. When canonical discriminant analysis was performed for their selected fatty acids, the percentage of classification was of the 100% for the final product and the product after storage in all the lipids fractions, except for the total lipids in the product after storage, with a classification of the 94.4%, in NL in the final product with a classification of the 94.4% and in FFA in the final product with a classification of the 88.9%.Table 6
Results of canonical discriminant analysis: loadings of correlation matrix between predictor variables (standardized canonical coefficients) and discriminant functions (roots 1 and 2).
Fatty acids Total fatty acids Neutral lipids Polar lipids Free fatty acids Final product After storage Final product After storage Final product After storage Final product After storage Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 Root 1 Root 2 C8         1.960 −0.279 C10     2.085 −1.058 C11 −1.073 1.052 2.455 0.523 C12               4.286 1.750 C14     −1.649 0.943   −8.483 1.054 C14:1             −0.011 0.089 C15   1.812 0.364       0.388 0.123 C15:1     0.907 0.585     −0.071 −0.505 C16   −1.087 0.243           −2.547 −3.738 C16:1         7.730 −1.666     4.319 1.446 C17         −2.701 0.835 1.593 −0.449 C17:1 −1.929 1.384 C18     0.848 −0.333 C18:1n-9         0.748 −0.905   0.600 −0.496 1.890 −0.604 C18:2n-6       −3.246 5.010 0.748 −0.905   0.630 1.656 C18:3n-6               −2.581 1.599 C18:3n-3 2.597 −0.059     1.963 −3.369     −1.294 0.210 C20     0.749 −0.972 C20:1n-9     0.784 −0.028         −7.534 0.257 C20:2n-6 −1.725 −0.414 −1.236 0.148       2.069 1.321 C20:3n-6     −0.953 −0.001 −1.424 −0.730 −0.254 0.538 −1.390 −1.441   1.658 0.348 C20:4n-6 0.058 −0.379 −2.083 0.644   0.744 −4.360   −1.727 0.092 C20:3n-3           0.457 −0.036 0.542 −0.104 C20:5n-3 0.898 −0.685     1.258 3.166 C22     0.423 0.409   1.041 −1.872     −0.961 −2.000 C22:1n-9   1.414 0.476         −0.344 0.170 C22:2n-6   1.129 0.527         −0.216 −1.346 C23 1.185 −0.388 C24             −0.016 −0.162 C24:1n-9   −1.274 −1.585   1.273 0.046  Statistics  CanonicalR 0.936 0.544 0.951 0.522 0.911 0.817 0.940 0.656 0.895 0.756 0.942 0.788 0.810 0.665 0.968 0.904 Eigenvalue 7.06 0.42 9.53 0.38 4.88 2.01 7.59 0.76 4.02 1.33 7.86 1.64 1.91 0.79 14.96 4.50 Cumulative proportion 0.944 1.000 0.962 1.000 0.708 1.000 0.909 1.000 0.751 1.000 0.827 1.000 0.707 1.000 0.769 1.000 Probability 0.010 0.649 0.015 0.818 0.007 0.080 0.001 0.217 0.009 0.118 0.001 0.070 0.268 0.458 0.000 0.007The functions with the highest signification (P<0.001) were root 1 for NL and PL and FFA after being vacuum-packed. A larger coefficient corresponds to a greater contribution of the respective variable to the discrimination between groups. The fatty acids with the highest discriminating power (Table 6) were in the final product C18:3n-3 acid for total lipids, C10 acid for NL, C14 acid for PL, and C18:2n-6 acid for FFA. In the product after storage, the fatty acids with the highest discriminating power were C11 acid for total lipids, C18:2n-6 acid for NL, C20:2n-6 acid for PL, and C20:1n-9 acid for free fatty acids.Within the fatty provided in a large quantity by the chestnut diet, C18:2n-6 could be introduced in the classification of the diet groups in NL in the final product and in PL in the product after storage. However, C18:3n-3 could be also used in the classification of the diets for the total lipids and FFA in the final product and in NL in the product after storage. C18:1n-9 could be introduced in the discrimination roots in the final product for PL and FFA and for FFA in the product after storage. Within the fatty acids provided in a small quantity by the chestnut diet, C20:2n-6 could be used in the discriminant roots for total lipids in the final product and in the product after storage and for PL in the product after storage. Finally, C20:4n-6 could be used for the discrimination of the diets for total lipids in the final product and in the product after storage and for NL and PL in the product after storage. The fatty acids that could be introduced in a greater number of roots were the C20:3n-6 and C20:4n-6.These results are in accordance with a previous work, where “chorizo,” a traditional dry-cured Spanish sausage, was manufactured with the meat of these Celta pigs [46]. In this study, also the fatty acids C18:2n-6, C18:3n-3, C18:1n-9, C20:2n-6, and C20:4n-6 could be used in the classification of the diets in the different lipid fractions.


## 4. Conclusions

A study of the main characteristics of dry-cured loin from Celta pig was performed, including the description of the fatty acid profile of the different lipid fractions. Also, the vacuum storability of the product was checked. Chestnuts inclusion in the finishing diet of Celta pig resulted in a lower pH value and in higher values of oxidation parameters of the dry-cured loin. However, fatty acid profile of the different lipid fractions was generally not affected by finishing diet, although, when a discriminant canonical analysis was performed, the discernment between the three finishing diets was procured. According to these results, including chestnuts on Celta pig feeding in an extensive regime would result in a remarkable impact on the main characteristics of the dry-cured products. Nevertheless, further researches (volatile compounds and sensory analysis) should be carried out in order to determine if the higher fat oxidation in loins from chestnut diet could be decisive in the acceptation of this dry-cured product.



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*Source: 7690501-2018-04-11.xml*