# How does feeding strategy affect the aromatic volatile compounds profile and sensory properties of organic fresh pork?

Chloé Van Baelen, Lucile Montagne, Mohammed Gagaoua, Armelle Prunier, Stefaan de Smet, Els Vossen, Bénédicte Lebret

► To cite this version:

Chloé Van Baelen, Lucile Montagne, Mohammed Gagaoua, Armelle Prunier, Stefaan de Smet, et al.. How does feeding strategy affect the aromatic volatile compounds profile and sensory properties of organic fresh pork?. Meat Science, 2025, 228, pp.109869. 10.1016/j.meatsci.2025.109869. hal-05100159

HAL Id: hal-05100159

https://hal.inrae.fr/hal-05100159v1

Submitted on 5 Jun 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

# How does feeding strategy affect the aromatic volatile compounds profile and sensory properties of organic fresh pork?

Chloé Van Baelen<sup>a</sup>, Lucile Montagne<sup>a</sup>, Mohammed Gagaoua<sup>a</sup>, Armelle Prunier<sup>a</sup>, Stefaan De Smet<sup>b</sup>, Els Vossen<sup>b</sup>, Bénédicte Lebret<sup>a,*</sup>

## ARTICLE INFO

Keywords:

Non-castrated pigs

Sensory analysis

Volatile compounds

GC-MS SPME

Meat quality

Feed composition

## ABSTRACT

This study aimed to evaluate two feeding strategies on pork quality in organic farming using 77 non-castrated male pigs (Piétrain × Large White) reared in two batches, each including two groups. Male littermates were allocated to either a Control group (C, n = 37), fed following the organic specifications, or to a group receiving an organic test feed mainly based on French raw materials and containing more fibre and omega-3 fatty acids (Bio+, n = 40). Within batch, each group was reared in one pen from the same building on deep straw bedding with free outdoor access, with *ad libitum* feeding from around 33 kg until slaughter at around 128 kg of live weight. Loin meat samples were analysed by a trained sensory panel and by SPME-GC-MS to identify the main volatile compounds. Meat from Bio+ pigs showed a significantly more intense red colour (*P* < 0.01), but lower aromatic persistency (*P* < 0.05) and tended to be less tender (*P* = 0.08) than meat from C pigs. None of the samples were qualified as boar tainted. A total of 27 volatile compounds were quantified, with more compounds present in Bio+ pigs, probably due to the greater diversity of raw ingredients in the feeds. The multi-dimensional analyses enabled to observe relationships between volatile compounds and sensory traits but did not differentiate the two feeding strategies. Bio+ feeding strategy compared to C influenced some organoleptic characteristics (red colour of raw meat, aromatic persistency) without modifying the texture, odour and flavour of organic cooked pork.

## 1. Introduction

Meat quality can be defined as a combination of properties that gather the characteristics that the consumer values at the time of purchase and consumption. Meat quality should answer to concerns like: is it good to eat, good for my health, for the animals and the planet (Font-i-Furnols & Guerrero, 2022). Expectations are specific to each of us and evolves over time (Gagaoua et al., 2025). A recent study aimed to comprehensively define the quality of animal-source foods and characterized it in seven properties. These are commercial, safety, technological, organoleptic, nutritional, convenience, and societal image covering ethical, cultural and environmental dimensions associated with the origin of the food product and the way it is produced and processed (Prache, Adamiec, et al., 2022).

Consumers are directly concerned about societal image, organoleptic and nutritional properties of pork. Organic farming aims to improve some quality attributes associated to the societal image. Indeed, the

organic specifications aim to reinforce animal welfare and health, to respect the environment, and to limit chemical inputs [Regulation EU 2018/848]. Organoleptic property means all the sensory attributes perceived by the consumers through the appearance (colour, marbling, drip loss...), the odour, the texture and the flavour of the meat. These are crucial for (re-)purchase and can be affected by many factors during production, transformation and storage (Prache, Adamiec, et al., 2022). In organic pig systems, the farmer's choices (genotype, feeding, housing conditions) to meet the specifications set by organic production standards can also influence other dimensions of pork quality (Prache, Lebret, et al., 2022). Feeding practices, for instance, can modulate numerous pork properties, such as the carcass leanness and therefore its commercial value, the meat technological, sensory, and nutritional properties and some image attributes associated with the origin of feed ingredients (Lebret & Čandek-Potokar, 2022). In organic systems, the consequences of feeding practices have been shown to affect growth performance, carcass composition (lean/fat ratio) and its commercial

<footnote><sup>a</sup> PEGASE, INRAE, Institut Agro, 35590 Saint-Gilles, France</footnote>

<footnote><sup>b</sup> Lanupro, Ghent University, Ghent, Belgium</footnote>

<footnote>* Corresponding author.
E-mail address: benedicte.lebret@inrae.fr (B. Lebret).</footnote>
value, as well as meat nutritional quality through fatty acid composition (Argemi-Armengol et al., 2022; Quander-Stoll et al., 2022; Van Baelen et al., 2024), or the sensory quality (Hansen et al., 2006; Jonsäll et al., 2002). However, the effects vary between studies due to different experimental conditions and interactive effects of feeding with other factors (genotype, housing conditions...; Prache, Lebret, et al., 2022).

The European regulation states that if male piglets are castrated, it must be performed until seven days of age and with anaesthesia and analgesia [Regulation EU, 2018/848]. However, considering animal welfare, it makes more sense not to perform this mutilation, especially as anaesthesia and analgesia only partially relieve the pain (Prunier et al., 2020). Moreover, there is also a risk of post-operative pain, and a higher risk of infections due to open wound. However, meat from non-castrated males (entire males) can present unpleasant odours or flavours known as boar taint, mainly due to androstenone and skatole deposition in adipose tissues (Lundström et al., 2009). Recently, another component: 2-amino-acetophenone has been shown to contribute also to boar taint and consumer rejection of pork products (Mörlein et al., 2024). While androstenone is mainly related to sexual development which is largely under genetic influence, skatole is metabolized from tryptophan by gut bacteria and its backfat concentration largely depends on pig's farming conditions, including feeding (Zamaratskaia & Squires, 2009). In fact, the synthesis and/or tissue accumulation of skatole depends on the tryptophan availability in the gut, the orientation of bacterial fermentation which can be controlled by the diet in particular the fibre content, and the faecal excretion of skatole produced (Wesoly & Weiler, 2012). As an example, adding chicory that contains fermentable fibres to the diet of non-castrated males was effective to reduce backfat skatole concentrations (Zammerini et al., 2012).

The aim of this study was to assess the effects of two feeding strategies on the organoleptic properties of pork from non-castrated males reared in organic farming. Pigs were fed with organic diets, that either strictly met the organic specifications (Control), or were based on local (mainly French) raw ingredients rich in omega-3 fatty acids and with provision of organic forages (Bio+ feeding strategy). Organoleptic properties included the evaluation of sensory attributes by a trained panel. We further analysed and determined the aromatic volatile compounds' profile (volatile organic compounds or volatile compounds) separated by Solid Phase Micro Extraction (SPME) and identified by GC-MS (gas chromatography-mass spectrometry). The hypothesis was that the Bio+ feeding strategy may improve sensory quality by decreasing the risk of boar taint and may modify the aromatic compounds profile of pork. This study was based on the animal experiment described in detail by Van Baelen et al. (2024), aiming to test the effects of these two feeding strategies on several quality properties of organic pork. We previously showed that in comparison with the control, the Bio+ feeding strategy did not affect commercial properties (animal growth and carcass traits), but improved some technological (pHu) and nutritional indicators (n-6:n-3 fatty acid ratio) of pork, and decreased backfat skatole concentration (Van Baelen et al., 2024). The second aim of the present work was to integrate, using multivariate statistical analyses, the effects of these feeding strategies on the multiple properties of quality of organic pork from non-castrated males.

# 2. Material and methods

## 2.1. Ethics approval

The experiment was performed in the INRAE experimental facilities (GenESI Porganic, 86,480 Rouillé, France; DOI: https://www.doi.org/1.0.15454/1.5572415481185847E12) in compliance with EU directive 2010/63/ EU for animal experiments, French legislation and organic specifications. This facility is certified organic by "Certipaq Bio". The technical and scientific staff had individual accreditation from the French Minister to experiment on living animals. The methods were approved by the local Committee on Ethics in animal experimentation

and the present animal experimentation was authorized by the French Ministry of Higher Education, Research and Innovation (APAFiS #34201-2,021,113,014,545,668 v6).

## 2.2. Animals, experimental design and feeding strategy

The experimental design of this study has been described in detail in Van Baelen et al. (2024). Key elements are briefly reported here. Seventy-seven organic non-castrated male pigs (Piétrain NN (non-carrier of the n allele at the RYR1 gene) × Large White) were produced in two batches ($n = 49$ and $n = 28$ pigs in batches 1 and 2, respectively). Within each batch, at weaning (49 days old), male littermates were allocated to one of two collective pens where they stayed during the post-weaning and growing-finishing periods until slaughter at about 128 kg live weight. Each pen included a resting area on deep straw bedding (1.3 $m^2$/pig) with fresh straw added weekly, a feeding zone on concrete floor (0.20 $m^2$/pig) and a covered outdoor area on concrete floor (1.0 $m^2$/pig). Within batch, at around 33 kg of live weight (LW; 11 weeks old, beginning of the experiment), each pen was randomly allocated to one feeding strategy: Control (C; batch 1: $n = 25$ and batch 2: $n = 12$ pigs) and Bio+ (batch 1: $n = 24$ and batch 2: $n = 16$ pigs). Within a batch, the two pens dedicated to the experiment were adjacent and strictly identical. The four experimental pens (2 pens per batch) were in the same building. As the second batch had fewer pigs, the pen size was reduced using bales of hay to maintain the same available surface per pig in the resting area (1.3 $m^2$/pig). A diagram of the animal building and experimental pens is shown in Supplementary file (Fig. S1). The C diets corresponded to the minimum organic specifications. The Bio+ diets were mainly based on French raw ingredients, contained faba bean and were rich in omega-3 FA (linseed, camelina). Two diets were formulated for each strategy, one for the growing (5 weeks) and the second for the finishing phase (around 8 weeks). Within each phase, the diets were isoenergetic and isoproteic and contained similar lysine concentrations, i.e. 1.2 g lysine /MJ NE (van Milgen & Noblet, 2003; Table S1). In addition, the Bio+ pigs had permanent access to organic forage (grassland hay during growing and clover wrapping during the finishing phase) distributed in a rack. All animals had free access to feed and water throughout the experiment. The distributed quantities of each diet determined by pen were on average 2.47 and 2.29 kg/d per pig during the growing phase and 3.00 and 3.06 kg/d per pig during the finishing phases, respectively for the C and Bio+ pigs (Van Baelen et al., 2024). The Bio+ pigs ate on average 65 g/d per pig of grassland hay during the growing phase, and 117 g/d per pig of clover wrapping during the finishing phase. Pigs were weighed individually at the start of the experiment, at the end of the growing period and the day before slaughter.

## 2.3. Slaughter, carcass and meat quality measurements and loin sampling

Animals were slaughtered in a commercial slaughterhouse (Cooperl, 79,800 Sainte-Eanne, France) at an average of 128 kg LW, in two series per batch, each series including the same number of pigs from each experimental group (i.e., pen). The heaviest half of the pigs from each pen were slaughtered in the first series. The other half, which remained in their original pen, were slaughtered in the second series that occurred two weeks (batch 1) or three weeks (batch 2) after the first series to reach the targeted LW at slaughter. The day before slaughter, feed (and forage in Bio+ pigs) was removed at 10:00 am. In the morning, pigs were individually weighed and transferred on a roofed platform where they remained in two pens, one for each feeding strategy (C and Bio+) without feed but with free access to water. Pigs from the same series were mixed all together at loading into a truck, transported to the slaughterhouse (maximum duration of 30 min) and kept in lairage in a single pen (still without mixing with non-experimental pigs). They were slaughtered in the early morning, by electrical stunning at high voltage and exsanguination. Boar odour detection (odorous or non-odorous carcasses) was carried out on each carcass using the human nose
method (Mathur et al., 2012), by trained and experienced abattoir staff. The hot carcass was weighed, and carcass lean meat content was determined using the CSB-Image-Meater device (CSB, Geilenkirchen, Germany) and prediction equations (Commission Regulation, 2017a; Commission Regulation, 2017b) based on four automatic measurements of muscle thickness (minimal muscle thickness at the *Gluteus medius* muscle level; average muscle thickness over four lumbar vertebrae) and backfat thickness (minimal fat thickness over the *Gluteus medius*; average backfat thickness over four lumbar vertebrae) (Blum et al., 2014).

After 24 h of carcass chilling at +4 °C, the ultimate pH (pHu) of the *Longissimus thoracis et lumborum* (LTL) muscle was determined directly on the carcass, using and Ingold Xeroltyl electrode (Mettler Toledo) and Syleps pH meter (Lorient, France) calibrated with pH buffers 4.0 and 7.0, and with temperature compensation. A transversal slice of LTL (last and second to last rib level) was taken and bloomed for 15 min at +4 °C under artificial light before determination of colour coordinates (CIE colour coordinates L\* (lightness), a\* (redness), b\* (yellowness), C\* (saturation (chroma) and h\* (hue angle); average value of three different measurements per slice) using a chromameter Minolta CR400 (Osaka, Japan), with a D65 illuminant, a 1-cm diameter aperture and a 2° observer angle, after calibration against a white tile. This same transversal slice of LTL was used for drip loss (EZ method) determination. A core sub-section was removed, cut into small pieces, frozen in liquid nitrogen and stored at -80 °C prior to analysis for thiobarbituric acid reactive substances (TBARS; Van Baelen et al., 2024). The TBARS concentration was determined in duplicate after forced chemical oxidation induced by iron trichloride and sodium ascorbate for 0, 120, 240, 360 or 480 min, and expressed as µg of malondialdehyde (MDA) produced per g of tissue. Another transversal slice of LTL muscle (first lumbar vertebra) was taken and stored under vacuum at -20 °C before determination of lipid concentration from chloroform-methanol extraction and fatty acid profile analysis by gas chromatography, as detailed by Van Baelen et al. (2024).

A third transversal slice of LTL muscle was taken at the 12th dorsal vertebra level cut into two parts in thickness direction, vacuum packaged, kept for ageing at +4 °C for 7 days after slaughter, and then stored at -20 °C until the analyses of aromatic compounds and the analysis of dipeptides (carnosine and anserine) and vitamin E (Van Baelen et al., 2024). The same day after slaughter, another piece of deboned loin (LTL muscle) was taken between the 5th and 11th dorsal vertebrae (18 cm long and around 800 g), trimmed of external fat, vacuum packaged, kept at +4 °C and shipped to the IDELE laboratory (14,310, Villers-Bocage, France) for sensory analyses.

## 2.4. Sensory analyses

The sensory analyses were carried out in accordance with standard NF EN ISO 13299 in a sensory analysis room complying with standard NF EN ISO 8589. Consent has been obtained from each panellist for the sensory analysis which was managed by IDELE laboratory. The sensory panel included 13 (male or female) selected, qualified and trained panellists for pork assessment (NF ISO 8586-1 and 8586-2). From 10 to 13 of these panellists participated at each sensory session and each of them evaluated all the samples during the session. On the week before the first session, every panellist participated in two training sessions using commercial pork. Then, the 77 experimental loin samples aged under vacuum at +4 °C for 7 to 8 days were assessed over 11 sessions. Each session included between six and eight meat samples, balanced between experimental treatments (Bio+ or Control). At each session, on all meat samples tested, a transversal slice of LTL muscle was taken at the level of the 11th dorsal vertebra for the evaluation of raw meat. On the remaining cranial part of the loin samples, cubic pieces (25 ± 1 g) were prepared and cooked in an oven for 5 min 30 s at +250 °C to a core temperature of +73 °C. The samples were served one by one (monadic) following a random distribution between the experimental treatments

(C or Bio+ pigs). The panellists assessed the appearance of raw meat (red colour, marbling, homogeneity of marbling, odour) and the eating traits of cooked meat (odour, flavour, tenderness, juiciness, aromatic persistency), on a continuous scoring scale from 0 (absence) to 10 (high intensity). Panellists also mentioned the presence or absence (binary response) of typical odours (animal, grilled, sweaty, urine, faecal, boar, fatty, rancid, hay, milky and hazelnut) or flavours (animal, acid, grilled, sweet, urine, faecal, boar, floury, milky, salty, undergrowth, fatty, rancid and umami). A total of 458 and 430 individual responses (= number of panellists x number of samples) were obtained in the Bio+ and Control treatments, respectively. For statistical analyses, the average of individual panellist scores for each sensory trait was calculated per pig whereas individual binary scores were used for the presence of typical odours or flavours.

## 2.5. Aromatic compounds analysis

Aromatic compounds were analysed by SPME-GC-MS following the method described by Vossen et al. (2020). From the 77 meat samples, 76 were analysed (one removed due to technical issues) over seven sessions (week of analyses). Each analysis session included randomized samples between treatments, and as much as possible the same number of samples from each experimental treatment and each batch. The 7-days aged meat samples were minced, from which 3 g were weighed and transferred to GC-MS vials with Teflon/silicon septum cap, in duplicate and stored at -20 °C until analysis.

On the day of the analysis, the vials were defrosted at room temperature for one hour and the internal standard was added (1 µL: 2-methyl-3-heptanone dissolved in hexane with a final concentration of 0.408 mg/mL as internal solution). Then, the vials were put in the oven and heated for 2 h at +103 °C. The samples were cooled to room temperature for 10 min. SPME was used to extract volatile compounds by inserting a divinylbenzene/carboxen/polydimethylsiloxane fibre (Supelco, Inc., Bellefonte, PA, USA) into the vials. Headspace absorption was performed at +37 °C in a heating block for 40 min. Volatile compounds were analysed using a gas chromatograph coupled to a mass spectrometer (Trace DSQ II, Thermo, Finnigan). The volatiles compounds were separated on HP-5 capillary column (30 m × 0.320 mm i. d., 0.25 µm film thickness; flow rate = 1.5 mL/min). The initial temperature was +37 °C for 10 min, ramped to +170 °C at a rate of +4 °C/min, held for 1 min, then ramped to +250 °C at a rate of +30 °C/min, held for 2 min. The scan range was 33–250 m/z and the electro-impact mass spectra were generated at 70 eV. Chromatograms were analysed with Qual browser on Xcalibur software (Thermo Scientific Xcalibur, version 4.2.47). For each sample, the compounds were considered as present if they were found in both analytical replicates with a probability of minimum 50 % to match with NIST library standards (National Institute of Standards and Technology, USA); if one of the two was below 50 %, then the compound was not considered. Odour descriptions of the identified compounds were obtained from the records in two online databases (https://www.flavornet.org/, https://www.odour.org.uk/), in the non-polar (DB-5) column. Volatile compounds in pork samples were quantified based on the chromatographic peak area (Vossen et al., 2017). The limit of detection was set at 1 × 10⁵ peak area (arbitrary unit). Peak areas of volatile compounds were used to calculate the relative abundance to the internal standard (IS) area using the following formula, and the result was expressed as µg volatile compounds per kg of pork.

$$ \text{Relative abundance (µg/kg)} = \frac{\text{peak area ratio} \left( \frac{\text{volatile}}{\text{IS}} \right) \times 0.408 \ \mu\text{g (IS)}}{m(\text{meat})(\text{g})} \times 1000 $$

The Odour Active Value (OAV) which is an indicator of the odour intensity of each volatile compound detected, was calculated using the
following formula, according to Han et al. (2020):

$$OAV = \frac{\text{Relative abundance of the volatile compound}}{\text{Odour threshold}}$$

The odour threshold represents the compounds' threshold for the aqueous phase, whose values were obtained from van Gemert (2011). Aroma compounds with an OAV ≥ 1 were considered to contribute to the overall aroma and were referred to as odour active compounds (Beldarrain et al., 2022).

## 2.6. Statistical analyses

The statistical analyses were processed and performed with R studio software (version 4.3.0; The R Core Team, 2023), XLSTAT 2018.2 software (AddinSoft, Paris, France) and the web-service MetaboAnalyst 6.0 platform (https://www.metaboanalyst.ca/).

Typical odours or flavours, that were binary variables (rated either present or absent) were analysed by a mixed generalized linear model using a binomial transformation (procedure glmer of the lmerTest package) followed by the Anova procedure of the car package. The model included the feeding strategy (n = 2) and the batch (n = 2) as fixed effects, the panellist (n = 13), the sensory session (n = 11) and the pig (n = 77) within session as random effects. Thereafter, odds ratios (OR) as well as their 95 % confidence intervals (CI) were calculated for each binary variable for the feeding strategy and for the batch effects.

Other data (except backfat androstenone and skatole concentrations) were analysed using a mixed general linear model (procedure lme of the nlme package) followed by the Anova procedure of the car package. Pig was considered as the statistical unit. The model included the feeding strategy (n = 2), the batch (n = 2) and the slaughter day within batch (n = 2 per batch) as fixed effects for data of growth performance, carcass and meat quality traits and fatty acid composition (already published by Van Baelen et al., 2024). The model included the feeding strategy (n = 2) and the batch (n = 2) as fixed effects, and the sensory session (n = 11) as a random effect for the sensory data, or the week of SPME-GC-MS analysis (n = 7) as random effect for the analysis of volatile compounds' data. The distribution of residuals of the models were checked for normality (with histogram), and Ls-means (Least-square means) were calculated per feeding strategy (emmeans package; Lenth et al., 2024). For backfat skatole concentration, because the distribution of residuals could not reach a normal distribution even after a log or square root transformation, a non-parametric method (Kruskal-Wallis test with kruskal.test function, R software version 4.3.0) was used to determine the effects of feeding strategy. The same analysis was undertaken to determine the effect of batch. For harmonization, the same non-parametric method was conducted for backfat androstenone concentration.

Within the objective of having an overview of the effect of feeding strategy along with an in-depth profiling of the control and Bio+ groups, data were further analysed using principal component analysis (PCA) on XLSTAT 2018.2. The selected variables (Table 1) were first log-transformed to correct for heteroscedasticity and then standardized using Pareto scaling, which employs the square root of the standard deviation as the scaling factor, thereby preserving the original units of the data. Subsequently, PCA was applied to the normalized data of meat quality variables to explore any clustering and/or separation of the pigs depending on the feeding strategy (two treatments). The suitability of the factorial model was checked with the Kaiser Meyer-Olkin (KMO) test for sampling adequacy. The overall KMO values were reported for each PCA. We performed two PCAs: the first one is based on the sensory traits and volatile compounds data (PCA1) and the second one, used the same data to which we added data related to animal growth performance, meat technological and nutritional quality traits including fatty acid composition (PCA2). The added data were from the same individuals and published in a former paper (Van Baelen et al., 2024). Variables used for PCA are listed in Table S2.

<table><caption>**Table 1**
Variables used in multi-dimensional analyses based on quality dimensions.</caption><thead><tr><th>Quality dimension</th><th>Variable</th><th>Variable description</th></tr></thead><tbody><tr><td rowspan="2">Commercial</td><td>ADG</td><td>Average daily gain (g)</td></tr><tr><td>pH LTL</td><td>pH of Longissimus thoracis et lumborum (LTL)</td></tr><tr><td rowspan="10">Technological</td><td>DripLoss</td><td>Drip (24-48 h post mortem) of LTL (%)</td></tr><tr><td>Lipids</td><td>Lipids (intramuscular fat; %) in LTL</td></tr><tr><td>SFA</td><td>Saturated fatty acids (mg/100 g)</td></tr><tr><td>MUFA</td><td>Mono-unsaturated fatty acids (mg/100 g)</td></tr><tr><td>PUFA</td><td>Poly-unsaturated fatty acids (mg/100 g)</td></tr><tr><td>LA:ALA</td><td>Linoleic acid: α-linolenic acid</td></tr><tr><td>Carnosine</td><td>Carnosine concentration in LTL (mg/100 g)</td></tr><tr><td>Anserine</td><td>Anserine concentration in LTL (mg/100 g)</td></tr><tr><td>VitED7</td><td>Vitamin E content (µg α-tocopherol/g) in meat (LTL) aged 7 days</td></tr><tr><td rowspan="10">Nutritional</td><td>MDAµgT0</td><td>Malondialdehyde content (µg/g) of LTL aged 7 days just before (i.e. 0 min) forced chemical oxidation</td></tr><tr><td>MDAµgT480</td><td>Malondialdehyde content (µg/g of LTL) aged 7 days after 480 min of forced chemical oxidation</td></tr><tr><td>L LTL</td><td>Lightness of LTL</td></tr><tr><td>C LTL</td><td>Chroma of LTL</td></tr><tr><td>h LTL</td><td>Hue angle of LTL</td></tr><tr><td>Androstenone<sup>1</sup></td><td>Androstenone concentration in backfat (µg/g liquid fat)</td></tr><tr><td>Red colour Raw meat<sup>1</sup></td><td>Red colour score on raw meat<sup>2</sup></td></tr><tr><td>Marbling Raw meat<sup>1</sup></td><td>Marbling score on raw meat<sup>2</sup></td></tr><tr><td>Homogeneity marbling Raw meat<sup>1</sup></td><td>Homogeneity of marbling score on raw meat<sup>2</sup></td></tr><tr><td rowspan="10">Organoleptic</td><td>Odour Raw meat<sup>1</sup></td><td>Odour score on raw meat<sup>2</sup></td></tr><tr><td>Odour<sup>1</sup></td><td>Odour score on cooked meat<sup>2</sup></td></tr><tr><td>Flavour<sup>1</sup></td><td>Flavour score on cooked meat<sup>2</sup></td></tr><tr><td>Tenderness<sup>1</sup></td><td>Tenderness score on cooked meat<sup>2</sup></td></tr><tr><td>Juiciness<sup>1</sup></td><td>Juiciness score on cooked meat<sup>2</sup></td></tr><tr><td>Aromatic persistency<sup>1</sup></td><td>Aromatic persistency score on cooked meat (assessed on a continuous scale from 0: absence to 10: persistence of the odour for more than 10 s)</td></tr><tr><td>Benzaldehyde<sup>1</sup></td><td rowspan="7">Relative abundance in meat aged 7 days, (µg/kg)</td></tr><tr><td>Heptanal<sup>1</sup></td></tr><tr><td>Hexanal<sup>1</sup></td></tr><tr><td>Nonanal<sup>1</sup></td></tr><tr><td>Octanal<sup>1</sup></td></tr><tr><td>Dimethyl disulfide<sup>1</sup></td></tr><tr><td>2-n-heptyl-furan<sup>1</sup></td></tr><tr><td>2-pentyl-furan<sup>1</sup></td><td></td></tr><tr><td>1-octen-3-ol<sup>1</sup></td><td></td></tr></tbody></table>

Then, a chemometrics analysis based on partial least square discriminant analysis (PLS-DA) using the MetaboAnalyst 6.0 was performed on the same dataset used for PCA2. The PLS-DA aimed to explore the discrimination of the two feeding strategies based on the sensory traits and aromatic compounds. The variables with >60 % missing values were excluded and the remaining missing values were imputed using the k-nearest neighbor feature-wise (KNN) algorithm (Tutz & Ramzan, 2015). Scores plot with confidence ellipses were obtained to show the projection of each individual, and variables were ranked using the variable importance in projection (VIP). Those with VIP scores >0.8 were considered.

## 3. Results

The present study evaluated the sensory properties and aromatic volatile compounds of meat from organic pigs receiving either a Bio+ or a control organic feeding. This is a companion paper of a recent work

<footnote n="1">¹ Variables used only in PCA1.</footnote>

<footnote n="2">² Assessed on a continuous scale from 0: absence to 10: high intensity.</footnote>
that aimed at assessing these two feeding strategies on growth performance, carcass and meat quality traits (Van Baelen et al., 2024). This previous work showed that average daily gain, final live weight and age at slaughter, as well as hot carcass weight, carcass dressing and lean meat content did not differ between the Bio+ and C pigs ($P \ge 0.10$; Table 2). The loin meat from Bio+ pigs had higher pHu ($P < 0.05$) and lower lightness ($P < 0.05$) than meat from C pigs. Backfat concentration of androstenone was higher in Bio+ (0.25, 0.65, 1.75 µg/g liquid fat for 1st, 5th and 9th deciles, respectively) than in C pigs (0.21, 0.40, 1.12 µg/g liquid fat for 1st, 5th and 9th deciles, respectively, $P < 0.05$) whereas backfat skatole concentration was lower in Bio+ (0.02, 0.02, 0.061 µg/g liquid fat for 1st, 5th and 9th deciles, respectively) compared to C pigs (0.02, 0.02, 0.11 µg/g liquid fat for 1st, 5th and 9th deciles, respectively, $P < 0.05$) (Van Baelen et al., 2024). Pigs of batch 1 were on average 4 days older ($P < 0.05$) and +2.0 kg heavier ($P < 0.10$) than pigs of batch 2. The significant effect of slaughter day within batch was related to the time difference between the two slaughtering series. Significant effects of batch and slaughter day within batch were found for colour parameters, with higher $a^*$, $b^*$ and $C^*$ values in batch 2, and in the first slaughtering series compared to the second one within batch 2 (+0.4 for $a^*$ and +0.8 for $b^*$; $P < 0.05$). Backfat concentration of androstenone was significantly higher in the first (0.32, 0.72, 1.62 µg/g liquid fat for 1st, 5th and 9th deciles, respectively) than in the second batch (0.14,

<caption>**Table 2**</caption>

Effect of the pig feeding strategy on growth performance, carcass and meat quality traits (Van Baelen et al., 2024).

<table><thead><tr><th rowspan="2"></th><th colspan="3">Feeding strategy <sup>1</sup></th><th colspan="3">P-value <sup>2</sup></th></tr><tr><th>Control</th><th>Bio+</th><th>Pooled SEM</th><th>Feeding strategy</th><th>Batch</th><th>Slaughter day within batch</th></tr></thead><tbody><tr><td colspan="7">Growing performance (growing and finishing phases)</td></tr><tr><td>Slaughter age (days)</td><td>166</td><td>168</td><td>1.6</td><td>0.116</td><td>0.013</td><td>&lt;0.001</td></tr><tr><td>Final live weight (kg)</td><td>124</td><td>125</td><td>2.2</td><td>0.478</td><td>0.051</td><td>0.168</td></tr><tr><td>Average daily gain (g)</td><td>969</td><td>984</td><td>24.0</td><td>0.442</td><td>0.062</td><td>0.037</td></tr><tr><td>Carcass traits</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Hot carcass weight (kg)</td><td>95.6</td><td>97.9</td><td>1.71</td><td>0.105</td><td>0.122</td><td>0.347</td></tr><tr><td>Carcass dressing (%)</td><td>76.7</td><td>77.0</td><td>0.58</td><td>0.679</td><td>0.262</td><td>0.208</td></tr><tr><td>Lean meat content (%)</td><td>59.5</td><td>60.1</td><td>0.47</td><td>0.117</td><td>0.239</td><td>0.222</td></tr><tr><td colspan="7">Quality traits of Longissimus thoracis et lumborum muscle</td></tr><tr><td>pH 24 h (ultimate pH) <sup>3</sup></td><td>5.48</td><td>5.53</td><td>0.023</td><td>0.011</td><td>0.318</td><td>0.205</td></tr><tr><td>Drip loss (%)</td><td>4.72</td><td>4.30</td><td>0.545</td><td>0.357</td><td>0.523</td><td>0.186</td></tr><tr><td>Colour</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Lightness, L<sup>*</sup></td><td>51.0</td><td>49.8</td><td>0.65</td><td>0.022</td><td>0.128</td><td>0.206</td></tr><tr><td>Redness, a<sup>*</sup></td><td>7.32</td><td>7.35</td><td>0.256</td><td>0.904</td><td>0.002</td><td>0.011</td></tr><tr><td>Yellowness, b<sup>*</sup></td><td>5.27</td><td>5.12</td><td>0.242</td><td>0.487</td><td>0.006</td><td>0.036</td></tr><tr><td>Chroma, C<sup>*</sup></td><td>9.07</td><td>9.01</td><td>0.319</td><td>0.808</td><td>0.001</td><td>0.009</td></tr><tr><td>Hue angle, h<sup>°</sup></td><td>35.7</td><td>34.5</td><td>0.94</td><td>0.151</td><td>0.694</td><td>0.853</td></tr><tr><td>Lipids, %</td><td>2.38</td><td>2.22</td><td>0.208</td><td>0.478</td><td>0.386</td><td>0.756</td></tr><tr><td>C18:2 linoleic acid: C18:3 α-linolenic acid</td><td>18.84</td><td>5.17</td><td>1.575</td><td>&lt;0.001</td><td>0.126</td><td>0.355</td></tr></tbody></table>

0.31, 0.95 µg/g liquid fat for 1st, 5th and 9th deciles, respectively, $P < 0.05$) whereas skatole concentration was lower in the first (0.02, 0.02, 0.06 µg/g liquid fat for 1st, 5th and 9th deciles, respectively) than in the second batch (0.02, 0.02, 0.15 µg/g liquid fat for 1st, 5th and 9th deciles, respectively, $P < 0.05$).

### 3.1. Sensory quality

The feeding strategy affected the red colour intensity assessed on raw meat (Table 3). The meat from Bio+ pigs was judged redder than from C pigs ($P < 0.01$), but the other indicators, these being odour, marbling and homogeneity of marbling, did not differ between the two pig feeding strategies ($P > 0.58$) (Table 3).

The cooked meat from Bio+ pigs was judged slightly less tender ($-0.22$ point on a 10-point scale; $P = 0.075$) and with lower aromatic persistency ($-0.09$ point; $P < 0.05$) compared with meat from C pigs. The other sensory traits, i.e. odour, flavour and juiciness did not differ between the two feeding strategies.

Overall, the feeding strategy did not affect the average intensity scores of odours and flavours of the cooked meat. For the whole set of data, the percentage of samples in which a specific odour or flavour was detected by a panellist is indicated in Table 4, and their number is detailed in Table S3. Briefly, only a minority of samples were rated positive for characteristics associated with boar taint (urine, faecal, boar), and more of them were rated positive for odour descriptors than for flavour descriptors. Odds ratios show that the feeding strategy was not associated with the likelihood of the presence of urine, faecal or boar odours, or flavours in meat ($P > 0.1$, Table 4). However, significant odds ratios indicated a higher likelihood of the presence of faecal odour ($P < 0.001$), boar odour ($P < 0.06$) and boar flavour ($P < 0.005$) in the second batch compared with the first batch. The only significant odds ratios related to the feeding strategy concerned the fatty odour and sweet flavour with a higher likelihood of presence in pork from Control than Bio+ pigs. Significant lower odds ratios were found for milky odour ($P < 0.05$) and animal flavour ($P < 0.01$), indicating a lower likelihood of presence in the second batch than in first batch.

### 3.2. Aromatic compounds in *longissimus thoracis et lumborum* muscle

Twenty-seven volatile compounds were identified by SPME-GC-MS

<caption>**Table 3**</caption>

Effect of the pig feeding strategy on the sensory quality traits of loin (*Longissimus thoracis et lumborum* muscle).

<table><thead><tr><th rowspan="2"></th><th colspan="3">Feeding strategy <sup>1</sup></th><th colspan="2">P-value <sup>2</sup></th></tr><tr><th>Control</th><th>Bio+</th><th>Pooled SEM</th><th>Feeding strategy</th><th>Batch</th></tr></thead><tbody><tr><td>Raw meat <sup>3</sup></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Red colour</td><td>5.09</td><td>5.60</td><td>0.150</td><td>0.007</td><td>0.017</td></tr><tr><td>Odour</td><td>2.10</td><td>2.14</td><td>0.110</td><td>0.578</td><td>0.831</td></tr><tr><td>Marbling</td><td>1.95</td><td>1.83</td><td>0.260</td><td>0.737</td><td>0.449</td></tr><tr><td>Homogeneity of marbling</td><td>1.91</td><td>1.84</td><td>0.170</td><td>0.795</td><td>0.404</td></tr><tr><td>Cooked meat <sup>3</sup></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Odour</td><td>5.77</td><td>5.76</td><td>0.110</td><td>0.940</td><td>0.535</td></tr><tr><td>Flavour</td><td>5.82</td><td>5.76</td><td>0.100</td><td>0.269</td><td>0.158</td></tr><tr><td>Tenderness</td><td>6.34</td><td>6.12</td><td>0.145</td><td>0.075</td><td>0.594</td></tr><tr><td>Juiciness</td><td>5.62</td><td>5.57</td><td>0.085</td><td>0.577</td><td>0.098</td></tr><tr><td>Aromatic persistency</td><td>5.89</td><td>5.80</td><td>0.080</td><td>0.038</td><td>0.551</td></tr></tbody></table>

<footnote n="1">¹ Feeding strategy given to the pigs with: Control feed based on the organic specifications and Bio+ feed based on the organic specifications and mainly based on French raw materials, containing faba bean and omega-3 fatty acids sources (camelina meal or linseed extruded meal). Values are least-square of the means.</footnote>

<footnote n="2">² P-values of effects of feeding strategy, batch and slaughter day within batch.</footnote>

<footnote n="3">³ Ultimate pH: measured 24 h after slaughter.</footnote>

<footnote n="1">¹ Feeding strategy given to the pigs with: Control feed based on the organic specifications and Bio+ feed based on the organic specifications and mainly based on French raw materials, containing faba bean and omega-3 fatty acids sources (camelina meal or linseed extruded meal). Values are least-square means.</footnote>

<footnote n="2">² P-values of effects of feeding strategy and batch.</footnote>

<footnote n="3">³ Traits scored by an expert and trained group of panellists on a continuous scale from 0 (absence) to 10 (high intensity).</footnote>
<caption>**Table 4**</caption>

Odds ratios (OR) and their 95 % confidence intervals of the pig feeding strategy and batch on the perception of specific odours or flavours detected in loin (*Longissimus thoracis et lumborum* muscle) by the sensory panellists<fnref n="1" />.

<table><thead><tr><th rowspan="2"></th><th rowspan="2">Positive tests, %<sup>3</sup></th><th colspan="2">Feeding strategy (Control/Bio+)<sup>2</sup></th><th colspan="2">Batch (Batch 2/Batch 1)</th></tr><tr><th>Adjusted OR and 95 % CI<sup>4</sup></th><th>P-value</th><th>Adjusted OR and 95 % CI<sup>4</sup></th><th>P-value</th></tr></thead><tbody><tr><td colspan="6"><strong>Odour descriptors</strong></td></tr><tr><td>Animal</td><td>49.2</td><td>0.87<br>(0.64-1.20)</td><td>0.404</td><td>0.67<br>(0.42-1.06)</td><td>0.084</td></tr><tr><td>Grilled</td><td>41.6</td><td>1.05<br>(0.76-1.45)</td><td>0.777</td><td>0.71<br>(0.39-1.27)</td><td>0.244</td></tr><tr><td>Urine</td><td>17.3</td><td>0.80<br>(0.54-1.20)</td><td>0.282</td><td>1.72<br>(0.76-3.89)</td><td>0.196</td></tr><tr><td>Faecal</td><td>4.6</td><td>1.97<br>(0.86-4.52)</td><td>0.111</td><td>18.93<br>(5.80-61.86)</td><td>&lt;0.001</td></tr><tr><td>Boar</td><td>6.8</td><td>1.15<br>(0.62-2.15)</td><td>0.654</td><td>1.93<br>(0.97-3.84)</td><td>0.059</td></tr><tr><td>Fatty</td><td>5.3</td><td>3.07<br>(1.33-7.06)</td><td>0.009</td><td>1.43<br>(0.46-4.46)</td><td>0.537</td></tr><tr><td>Rancid</td><td>7.8</td><td>1.00<br>(0.57-1.74)</td><td>0.994</td><td>1.16<br>(0.35-3.91)</td><td>0.809</td></tr><tr><td>Milky</td><td>33.3</td><td>0.50<br>(0.13-1.90)</td><td>0.078</td><td>0.71<br>(0.48-1.04)</td><td>0.02</td></tr><tr><td>Sweaty</td><td>9.7</td><td>1.48<br>(0.89-2.49)</td><td>0.133</td><td>1.85<br>(0.66-5.17)</td><td>0.239</td></tr><tr><td>Hay</td><td>16.1</td><td>0.86<br>(0.53-1.41)</td><td>0.555</td><td>0.66<br>(0.37-1.17)</td><td>0.157</td></tr><tr><td>Hazelnut</td><td>6.5</td><td>0.97<br>(0.48-1.94)</td><td>0.922</td><td>0.19<br>(0.06-0.59)</td><td>0.005</td></tr><tr><td colspan="6"><strong>Flavour descriptors</strong></td></tr><tr><td>Animal</td><td>18.1</td><td>0.96<br>(0.66-1.41)</td><td>0.835</td><td>0.54<br>(0.34-0.86)</td><td>0.009</td></tr><tr><td>Grilled</td><td>30.6</td><td>0.92<br>(0.66-1.29)</td><td>0.632</td><td>0.73<br>(0.41-1.29)</td><td>0.275</td></tr><tr><td>Urine</td><td>7.5</td><td>0.83<br>(0.47-1.46)</td><td>0.514</td><td>1.80<br>(0.84-3.88)</td><td>0.134</td></tr><tr><td>Faecal</td><td>0.7</td><td colspan="4">Statistical analyses were not possible</td></tr><tr><td>Boar</td><td>4.8</td><td>1.10<br>(0.53-2.27)</td><td>0.800</td><td>4.22<br>(1.58-11.25)</td><td>0.005</td></tr><tr><td>Fatty</td><td>4.4</td><td>0.56<br>(0.26-1.21)</td><td>0.138</td><td>1.84<br>(0.63-5.34)</td><td>0.263</td></tr><tr><td>Rancid</td><td>9.3</td><td>1.18<br>(0.72-1.96)</td><td>0.511</td><td>0.79<br>(0.43-1.46)</td><td>0.459</td></tr><tr><td>Milky</td><td>23.2</td><td>1.01<br>(0.66-1.53)</td><td>0.968</td><td>0.48<br>(0.14-1.62)</td><td>0.237</td></tr><tr><td>Sweet</td><td>6.8</td><td>1.94<br>(1.04-3.61)</td><td>0.037</td><td>0.96<br>(0.27-3.36)</td><td>0.944</td></tr><tr><td>Acid</td><td>54.7</td><td>1.31<br>(0.93-1.85)</td><td>0.129</td><td>1.12<br>(0.57-2.20)</td><td>0.748</td></tr><tr><td>Floury</td><td>50.9</td><td>1.07<br>(0.79-1.45)</td><td>0.658</td><td>1.27<br>(0.79-2.06)</td><td>0.321</td></tr><tr><td>Salty</td><td>36.7</td><td>0.83<br>(0.57-1.20)</td><td>0.324</td><td>0.89<br>(0.52-1.51)</td><td>0.657</td></tr><tr><td>Underwood</td><td>1.7</td><td colspan="4">Statistical analyses were not possible</td></tr><tr><td>Umami</td><td>3.7</td><td colspan="4">Statistical analyses were not possible</td></tr></tbody></table>

(Table 5). They were divided into seven groups according to their chemical family: aldehydes, aromatics, S-containing compounds, furans, alcohols, hydrocarbons, and ketones. Most of these compounds have an OAV greater than 1, highlighting an effect on the overall odour, except for benzaldehyde and 2-nonanone. Nonanal had the largest OAV value, followed by octanal, dimethyl trisulfide, 2-pentyl-furan, (E)-2-decenal, and 2-undecenal. The lowest OAV values were found for hexanal, dimethyl disulfide and toluene. Among the 27 volatile compounds: two of them were found in all samples (Bio+ and C), these being benzaldehyde and heptanal. Although some compounds were commonly present, few of them were infrequently found in the meat samples: seven out of the 27 identified compounds were found only in meat from Bio+ pigs ((E)-2-decenal, 2-undecenal, 5-ethylcyclopent-1-enecarboxaldehyde, dimethyl trisulfide, cis-2(2-pentenyl)furan, 4-methyl-octane and 2-nonanone) and one compound was found only in meat from C pigs (2-(3-methylbutyl)-thiophene). There was no significant effect of the feeding strategy on the relative abundance of the volatile compounds identified in the loin meat (*P* > 0.14).

### 3.3. Multi-dimensional analyses of meat quality traits evaluated in *longissimus thoracis et lumborum* muscle

The PCA1 conducted with the sensory traits and volatile compounds included 19 variables (Table 1) and had an overall KMO of 0.84. The two first principal components (PC) explained 52 % of the individual variability (Fig. 1). The volatile compounds were mainly projected on PC1 (38 %) while the sensory traits were either on the positive or the negative sides of PC2 (14 %). Some of the sensory traits contributed also to PC3, 4 and 5 altogether the five PCs with eigenvalues >1.0 explained 79 % of the variability (data not shown). The bi-plot showed superimposed ellipses signifying no difference in the distribution of individuals between the two feeding strategies based on the selected variables (Fig. 1).

The analysis of the same data using PLS-DA led to the same conclusions as the PCA analysis, these being the two experimental treatments overlapped, confirming no discrimination between the two feeding strategies in terms of sensory traits and volatile compounds analysed in this trial (Fig. 2A). However, the PLS-DA allowed identifying nonanal, octanal, androstenone, heptanal and red colour of raw pork as the variables that contributed most to the PLS-DA model (VIP score > 1.0, Fig. 2B). Overall, the variables with VIP > 0.8 had their relative abundance higher in Bio+ than in Control meat. However, the sum of the 4 volatiles (nonanal, octanal, heptanal and hexanal) that had the highest relative abundance in Bio+ (Table 5) did not show any statistical difference between Bio+ and C nor a significant correlation with the flavour of the sensory traits (data not shown).

For PCA2, 33 variables were considered (Table 1). The four first PCs with eigenvalues >1.0 accounted for 58 % of the variability, with the two first PCs explaining 40 % of the variability (KMO = 0.73). The PC1, accounting for 26 % of the variability, was positively characterized by the projection of volatile compounds (Fig. 3A), while the PC2 accounting for 14 % of the variability grouped the nutritional (fatty acids, anserine) and technological quality traits (colour parameters). Certain of the sensory traits were further projected in the second axis positively or negatively. PC2 was the PC that tends to differentiate the individuals according to the feeding strategy (*P* = 0.09). However, the first two PCs did not allow a significant differentiation of the two feeding strategies. The discrimination of Bio+ from C was mainly allowed by the third axis (*P* < 0.001), mostly characterized by the technological traits (pHu and drip loss) while the fourth axis gathered the other sensory traits and seemed to drive the separation by the red colour of raw meat (Fig. 3B).

## 4. Discussion

The purpose of the present study was to compare the effects of two organic feeding strategies on pork quality from non-castrated male pigs.

<footnote n="1">¹ Each of the 13 panellists scored a total of 34 to 77 loins during 5 to 11 sessions (6 to 8 different pigs per panellist and per session), leading to a total of individual responses of *n* = 430 for Control, and *n* = 458 for Bio+).</footnote>

<footnote n="2">² Feeding strategy given to the pigs with: Control feed based on the organic specifications and Bio+ feed based on the organic specifications and mainly based on French raw materials, containing faba bean and omega-3 fatty acids sources (camelina meal or linseed extruded meal).</footnote>

<footnote n="3">³ A test was positive when the panellist indicated that the specific odour or flavour was present.</footnote>

<footnote n="4">⁴ Adjusted odd ratios (OR) and their 95 % confidence intervals (CI) were calculated for the feeding strategy (*n* = 2) and the batch effects (*n* = 2) after a mixed generalized linear model using a binomial transformation followed by Anova.</footnote>
<caption>**Table 5**</caption>

Effect of the pig feeding strategy on the relative abundance and estimated odour active volatile, odour thresholds and odour description of volatile compounds of loin (Longissimus thoracis et lumborum muscle) aged 8 days.

<table><thead><tr><th rowspan="2"></th><th rowspan="2">LRI <sup>1</sup></th><th rowspan="2">Formula</th><th rowspan="2">Odour thresholds (µg/kg) <sup>2</sup></th><th colspan="2">Relative abundance (µg/kg)</th><th colspan="2">OAV <sup>4</sup></th><th rowspan="2">P-value <sup>5</sup></th><th rowspan="2">Odour description <sup>6</sup></th></tr><tr><th>Control <sup>3</sup></th><th>Bio+ <sup>3</sup></th><th>Control</th><th>Bio+</th></tr></thead><tbody><tr><td><strong>Aldehydes</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>(E)-2-decenal</td><td>1212</td><td>C<sub>10</sub>H<sub>18</sub>O</td><td>1.4</td><td>ø</td><td>23.95</td><td>ø</td><td>17.11</td><td>ø</td><td>Tallow, orange</td></tr><tr><td>2-undecenal</td><td>1311</td><td>C<sub>11</sub>H<sub>20</sub>O</td><td>1</td><td>ø</td><td>15.62</td><td>ø</td><td>15.62</td><td>ø</td><td>Sweet, soap, fat, green</td></tr><tr><td>5-ethylcyclopent-1-enecarboxaldehyde</td><td>1020</td><td>C<sub>8</sub>H<sub>12</sub>O</td><td>–</td><td>ø</td><td>12.35</td><td>ø</td><td>ø</td><td>ø</td><td>–</td></tr><tr><td>Benzaldehyde</td><td>982</td><td>C<sub>7</sub>H<sub>6</sub>O</td><td>750</td><td>46.8</td><td>40.0</td><td>0.06</td><td>0.05</td><td>0.221</td><td>Almond, burnt, sugar</td></tr><tr><td>Heptanal</td><td>905</td><td>C<sub>7</sub>H<sub>14</sub>O</td><td>2.8</td><td>14.3</td><td>16.6</td><td>4.67</td><td>5.87</td><td>0.378</td><td>Fat, citrus, rancid</td></tr><tr><td>Hexanal</td><td>806</td><td>C<sub>6</sub>H<sub>12</sub>O</td><td>5</td><td>36.6</td><td>35.2</td><td>7.04</td><td>7.16</td><td>0.830</td><td>Grass, tallow, fat</td></tr><tr><td>Nonanal</td><td>1104</td><td>C<sub>9</sub>H<sub>18</sub>O</td><td>1.1</td><td>121</td><td>148</td><td>102.1</td><td>135.0</td><td>0.139</td><td>Fat, citrus, green</td></tr><tr><td>Octanal</td><td>1005</td><td>C<sub>8</sub>H<sub>16</sub>O</td><td>0.6</td><td>54.4</td><td>64.9</td><td>83.7</td><td>106.1</td><td>0.265</td><td>Fat, soap, lemon, green</td></tr><tr><td><strong>Aromatics</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ethylbenzene</td><td>893</td><td>C<sub>8</sub>H<sub>10</sub></td><td>–</td><td>0.99</td><td>0.98</td><td>ø</td><td>ø</td><td>ø</td><td>floral</td></tr><tr><td>Toluene</td><td>794</td><td>C<sub>7</sub>H<sub>8</sub></td><td>527</td><td>524</td><td>527</td><td>7.04</td><td>7.16</td><td>0.936</td><td>paint</td></tr><tr><td>1,3-bis(1,1-dimethylethyl)-benzene</td><td>1334</td><td>C<sub>14</sub>H<sub>22</sub></td><td>–</td><td>3.03</td><td>2.50</td><td>ø</td><td>ø</td><td>0.442</td><td>–</td></tr><tr><td>1-chloro-4-(1-chloroethenyl)-cyclohexene</td><td>1172</td><td>C<sub>8</sub>H<sub>10</sub>Cl<sub>2</sub></td><td>–</td><td>1.43</td><td>1.45</td><td>ø</td><td>ø</td><td>0.896</td><td>–</td></tr><tr><td>1-chloro-5-(1-chloroethenyl)-cyclohexene</td><td>1172</td><td>C<sub>8</sub>H<sub>10</sub>Cl<sub>2</sub></td><td>–</td><td>1.96</td><td>1.35</td><td>ø</td><td>ø</td><td>0.290</td><td>–</td></tr><tr><td><strong>Sulphurous-containing compounds</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>2-(3-methylbutyl)-thiophene</td><td>1128</td><td>C<sub>9</sub>H<sub>14</sub>S</td><td>–</td><td>1.57</td><td>ø</td><td>ø</td><td>ø</td><td>ø</td><td>Sulfur</td></tr><tr><td>2-pentyl-thiophene</td><td>1192</td><td>C<sub>9</sub>H<sub>14</sub>S</td><td>–</td><td>2.92</td><td>2.12</td><td>ø</td><td>ø</td><td>0.572</td><td>Sweet, fruit</td></tr><tr><td>Dimethyl disulfide</td><td>722</td><td>C<sub>2</sub>H<sub>6</sub>S<sub>2</sub></td><td>1.1</td><td>9.69</td><td>6.34</td><td>7.72</td><td>5.86</td><td>0.306</td><td>Onion, cabbage, putrid</td></tr><tr><td>Dimethyl trisulfide</td><td>972</td><td>C<sub>2</sub>H<sub>6</sub>S<sub>3</sub></td><td>0.1</td><td>ø</td><td>3.19</td><td>ø</td><td>31.9</td><td>ø</td><td>Sulfur, fish, cabbage sulfur</td></tr><tr><td>Sulfur</td><td>–</td><td>S<sub>6</sub></td><td>–</td><td>0.54</td><td>1.38</td><td>ø</td><td>ø</td><td>ø</td><td>–</td></tr><tr><td><strong>Furans</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>2-hexyl-furan</td><td>1139</td><td>C<sub>10</sub>H<sub>16</sub>O</td><td>–</td><td>9.08</td><td>7.54</td><td>ø</td><td>ø</td><td>ø</td><td>Mushroom, earthy</td></tr><tr><td>2-n-heptylfuran</td><td>1239</td><td>C<sub>11</sub>H<sub>18</sub>O</td><td>–</td><td>5.81</td><td>6.19</td><td>ø</td><td>ø</td><td>0.729</td><td>–</td></tr><tr><td>2-pentyl-furan</td><td>1040</td><td>C<sub>9</sub>H<sub>14</sub>O</td><td>5.8</td><td>152</td><td>136</td><td>24.1</td><td>23.3</td><td>0.489</td><td>Green bean, butter</td></tr><tr><td>cis-2-(2-pentenyl)furan</td><td>1048</td><td>C<sub>9</sub>H<sub>12</sub>O</td><td>–</td><td>ø</td><td>14.83</td><td>ø</td><td>ø</td><td>ø</td><td>–</td></tr><tr><td><strong>Alcohols</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>1-adamantanol</td><td>1031</td><td>C<sub>10</sub>H<sub>16</sub>O</td><td>–</td><td>4.58</td><td>6.13</td><td>ø</td><td>ø</td><td>ø</td><td>–</td></tr><tr><td>1-octen-3-ol</td><td>969</td><td>C<sub>8</sub>H<sub>16</sub>O</td><td>1.5</td><td>5.87</td><td>5.44</td><td>3.71</td><td>3.49</td><td>0.694</td><td>Mushroom, soap</td></tr><tr><td><strong>Hydrocarbons</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>2,2,4,4,5,5,7,7-octamethyl-3,6-dioxa-2,4,5,7-tetrasilaoctane</td><td>807</td><td>C<sub>10</sub>H<sub>30</sub>O<sub>2</sub>Si<sub>4</sub></td><td>–</td><td>3.93</td><td>3.55</td><td>ø</td><td>ø</td><td>ø</td><td>–</td></tr><tr><td>4-methyl-octane</td><td>852</td><td>C<sub>9</sub>H<sub>20</sub></td><td>–</td><td>ø</td><td>0.64</td><td>ø</td><td>ø</td><td>ø</td><td>–</td></tr><tr><td><strong>Ketones</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>2-nonanone</td><td>1052</td><td>C<sub>9</sub>H<sub>18</sub>O</td><td>41</td><td>ø</td><td>5.89</td><td>ø</td><td>0.14</td><td>ø</td><td>Hot milk, soap, green</td></tr></tbody></table>

"-" no data found.

ø below limit of quantification.

Prevalence = number of samples in which the aroma compound was observed/total amount of samples per feeding strategy × 100 %.

100 % 74–99 % 50–73 % 25–49 % 0–24 %.

1 LRI: estimated non polar retention index (n-alkane scale) from Xcalibur software.

2 Odour threshold values (the latest ones in terms of dates compared to 2024) are obtained from (van Gemert, 2011).

3 Feeding strategy given to the pigs with: Control feed based on the organic specifications and Bio+ feed based on the organic specifications and mainly based on French raw materials, containing faba bean and omega-3 fatty acids sources (camelina meal or linseed extruded meal).

4 OAV (odour active value) = relative abundance / odour threshold, calculated from (Han et al., 2020).

5 P-value of effect of the feeding strategy on the relative abundance of volatile compounds of loin obtained with a mixed model, on R studio software, with the feeding strategy and the batch as fixed effects and the day of analysis as a random effect. Statistical analysis was performed for compounds found in a minimum of 10 individuals over 76.

6 Odour descriptions were obtained from the records in two online databases (https://www.flavornet.org/, https://www.odour.org.uk/), in the non-polar (DB-5) column.

The originality of the work was not only to combine sensory traits and aromatic volatile compounds evaluated by SPME-GC-MS data in order to describe the organoleptic quality, but also to relate the organoleptic quality dimension with the other quality dimensions with the aim of revealing synergies and/or antagonisms among organic pork dimensions. Few studies compared sensory traits of meat according to pig breeding (Jonsäll et al., 2002; Kongsted et al., 2011) or farming practices in organic system (Hansen et al., 2006). To the best of our knowledge, except one study on meat quality from pigs fed for few days with organic diets differing in fermentable fibre content (Hansen et al., 2008), no other studies were published on non-castrated male pigs in

organic farming. The profile of volatile compounds in meat has been successfully studied in several species including pork (Elmore et al., 2001; Lopez-Moreno et al., 2023), lamb (Vasta et al., 2010), goat (Madruga et al., 2009) and beef (Acevedo et al., 2012). Our work thus provided novel insights on this specific topic in organic pork from non-castrated males and integrated them with the sensory analyses data.

The higher intensity of red colour of raw meat from the Bio+ compared with C pigs can be explained by their lower lightness, which can be due to their higher ultimate pH, and may improve the appearance of pork for consumers (Gagaoua et al., 2023). Except a slightly lower aromatic persistency score for the Bio+ compared with C pork, the Bio+
<figure><img src="image_3.png" /><figcaption>**Fig. 1.** First Principal Component Analysis (PCA1) on variables associated to organoleptic properties of loin and volatile organic compounds. Bi-plot highlighting the extent of separation of the feeding strategies is given in the bottom right of the projection of variables within the two first components. The overall Kaiser-Meyer-Olkin (KMO) computed for the PCA is 0.84. The projection of the individuals of control (orange) and Bio+ (green) are encircled in ellipses (x,y-means ± x,y-standard deviation), while the means depicts the barycentre of each ellipse. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)</figcaption></figure>

feeding strategy did not affect the intensities of odours of raw and cooked meat. Most importantly, the occurrence of descriptors of odours and flavour traits show very low problems of pork boar taint, in agreement with the fact that none of the carcasses were detected as boar-tainted by the human nose test undertaken at the slaughterhouse by trained and experienced staff (Van Baelen et al., 2024). Indeed, among the two Bio+ pigs and two C pigs exhibiting high backfat skatole concentrations (i.e. over 0.15 µg/g; Van Baelen et al., 2024), meat from only one Bio+ pig was found to exhibit faecal and boar odours (by only two panellists) and faecal flavour (by only one panellist). The two Bio+ pigs exhibiting high backfat androstenone concentrations (i.e. over 3.0 µg/g; Van Baelen et al., 2024) were found to exhibit meat urine odour by three panellists, whereas none of the panellists detected boar odour, or urine or boar flavour in these meat samples. The low boar taint incidence in our experiment may be explained by the average low concentrations of skatole and androstenone in the backfat samples, regardless of the feeding strategy. This can be also related to the overall low intramuscular fat content in the loin meat samples. The presence of fibre in the Bio+ and the C diets, which has been shown to reduce gut skatole production from tryptophan (Wesoly & Weiler, 2012), as well as the regular addition of fresh straw in the pen to maintain the bedding area clean along the experiment (Prunier et al., 2013), could have contributed to limit the backfat skatole concentration. Besides, in our experiment, the Piétrain boars (Piétrain NN; Nucleus, Le Rheu, France) used to inseminate sows were chosen for their low risk of androstenone-related odours. Analyses of the odds ratios indicated that the likelihood of faecal

and boar odours as well as boar flavour was higher for the pigs from the second than for the first batch. This may be explained by the higher concentration of backfat skatole in pigs from the second than from the first batch (Van Baelen et al., 2024). Indeed, skatole has a strong faecal odour (Lundström et al., 2009; Zamaratskaia & Squires, 2009).

The volatile compounds analyses revealed several chemical families, illustrating the diversity of molecules present in pork, even though no significant effect of the feeding strategy were found on the calculated odour active values of these compounds. The compounds of the aldehyde family result from the oxidation of lipids (oleic acid and linoleic acid autooxidation, or other ones). The relationship between precursor compounds and their oxidation products is well established (Aaslyng & Meinert, 2017; Aquilani et al., 2018; Zang et al., 2020). Specifically, hexanal, which is a typical marker for lipid oxidation (Goethals et al., 2020), is derived from linoleic acid and octanal and nonanal from oleic acid (Cui et al., 2023; Wojtasik-Kalinowska et al., 2018). These compounds contribute to the overall flavour and allows the development of the fatty, grassy, greeny, almond or even sweet odours in the cooked meat, mainly thanks to their low thresholds (Sohail et al., 2022). These aromatic compounds can show a wide range of odours, such as the “painty” odour of toluene and the “floral” odour of ethylbenzene, as highlighted by Giri et al. (2010) and the website www.flavornet.org. The S-containing compounds give sulphurous, cabbage and fishy odour. For example, dimethyl disulphide, which is obtained from methionine metabolism, is an important fraction of aroma in fish paste products (Giri et al., 2010) and with dimethyl trisulfide, they both have a strong
<figure><img src="image_4.png" /><figcaption>**Fig. 2.** Partial least squares-discriminant analysis (PLS-DA). A) Projection of the pigs according to their feeding strategy on the two first components of the PLS-DA. B) The top 15 variables are given and highlighted by the variable importance in projection (minimal VIP score ≥ 0.8 in red and robust VIP ≥ 1 in black). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)</figcaption></figure>

sulphurous odour (Wojtasik-Kalinowska et al., 2018). 2-pentylthio-phene, which is a product from the Maillard reaction, gives a sweet odour of the meat (Sohail et al., 2022). Furans are generally found in low number of compounds in pork (Mottram, 1985) and they give a buttery and earthy odour. Two compounds that are not usually found in pork were detected in our study these being 2-n-heptylfuran reported in chicken with fatty odour and cis-2(2-pentenyl)furan reported in crab with tomato-like odour (Sohail et al., 2022). Alcohols, mainly generated as the reaction products of lipid oxidation, were detected in meat of the two experimental groups (Bio+ and C pigs), but in low abundance. Compared to other volatile compounds, 1-Octen-3-ol was the only alcohol with an established odour threshold. It has been reported to be generated by β-oxidation (Ahamed et al., 2023). Cheng et al. (2023) reported that 1-octen-3-ol was the most abundant alcoholic compound in cooked Tibetan pork, and significantly contributed to pork flavour due to its low odour threshold. In contrast, we found in this trial low relative abundances of this compound. This can be attributed to the presence of vitamin E in our pork samples after 7 days of ageing what-ever the feeding strategy, which may have helped prevent oxidation (Van Baelen et al., 2024). The compound 1-octen-3-ol is also a key compound in pork flavour and other studies detected this compound in pork broth (Chang et al., 2021) and in precooked pork after reheating (O'Sullivan et al., 2003; Zang et al., 2020). It has been proposed as a driver of the overall pork aroma because it imparts a potent mushroom odour with a lower odour threshold (Song et al., 2017). Hydrocarbons are modulated by the content of muscle glycogen and there is a positive correlation between roasty aroma and carbohydrates content (Aaslyng & Meinert, 2017). In our experiment, the glycolytic potential of the LTL muscle was lower in the Bio+ compared to C pigs (Van Baelen et al., 2024), but no differences were found in the concentration of hydro-carbons, which were relatively common (Han et al., 2020). Regarding the roasty aroma, cooked meat contains carbohydrates which increase as the end-point cooking temperature, hence allowing more time to the reaction to occur (Aaslyng & Meinert, 2017). Some compounds like (E)-2-decenal, 2-undecenal, 5-ethylcyclopent-1-enecarboxaldehyde, dimethyl trisulfide, cis-2(2-pentenyl)furan, 4-methyl-octane and 2-non-anone, with high OAV, were found only in the meat from Bio+ pigs.

They can be considered as volatiles signatures of Bio+ meat, as the diet being one of the main source of volatile compounds in meat (Mottram et al., 2004). The presence of the three aldehydes, mainly originating from the oxidation of FA, might be directly linked to the greater concentration of crude fat and of unsaturated FA in Bio+ feeds, compared with the controls (e.g., 83.5 vs 78.2% of unsaturated FA in the Bio+ and C finishing diets, respectively). Oxidation might have occurred in the Bio+ feeds containing camelina meal (growing diet) or extruded linseed (finishing diet) that were not enriched in antioxidant compounds such as vitamin E. Even though it was not established in pork, the use of forages in the Bio+ feeding strategy could also explain the exclusive presence of some aromatic compounds in Bio+ pork, as found in beef from silage-fed compared with concentrate-fed steers (Elmore et al., 2004).

Other flavour compounds such as ketones are derived from lipid oxidation and they are likely to be produced by thermal oxidation or degradation of polyunsaturated fatty acids (Zang et al., 2020). The fact that in our study the meat was minced and cooked at +103 °C before the analysis of volatile compounds, may have allowed the roasty aromas to be released more easily and carried into the vial, thereby detected. Freshly cooked loin may contain fewer compounds than cooked ham or cured pork products. For example, 31 aroma-active compounds were identified in cooked Tibetan fresh pork within two muscles, *Longissimus thoracis et lumborum* and *Semitendinosus*, and across different sampling locations (Zhao et al., 2025). Twenty-nine volatile compounds were found in cooked ham (Benet et al., 2015), and up to 100 or more are usually identified in dry-cured ham (Gandemer, 2002; Marusic et al., 2014; Pugliese et al., 2009) or dry-fermented sausages (Marco et al., 2004). Although some compounds are known to be particularly smelly, it is the balance between compounds that causes the odour and/or flavour. All together, these compounds produce a cocktail of odours and flavours that can vary due to the conditions of storage, cooking or extraction before SPME-GC-MS analysis. As most of the compounds have an OAV above 1, these ones are considered as important for the overall aromatic profile of the meat. Also, not all volatile compounds described in the literature could be detected in our samples, which can be attributed to the specific parameters used for SPME-GC-MS. Indeed, this explorative method allows the identification of certain volatile
<figure><img src="image_5.png" /><figcaption>**Fig. 3.** Second Principal Component Analysis (PCA2) performed to integrate growth performance, technological, nutritional and organoleptic properties of loin, including volatile organic compounds. A) Projection on the PCs 1 and 2 of the variables and related the bi-plot highlighting the extent of separation of the feeding strategies given in the bottom. B) Projection on the PCs 3 and 4 of the variables and the related bi-plot highlighting the extent of separation of the feeding strategies. For each bi-plot, an analysis of variance has been conducted and the results were considered statically different at the level of 5 % using Tukey post-hoc test. The biplots depicting the overall projection of the individuals of control (orange) and Bio+ (green) are encircled in ellipses (x,y-means ± x,y-standard deviation), while the means depicts the barycentre of each ellipse. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)</figcaption></figure>

compounds in meat, but the odour and flavour perceived at eating do not solely depend on volatile compounds, as non-volatiles compounds also contribute (Gorbatov & Lyaskovskaya, 1980). For example, androstenone and skatole could not be detected by the SPME-GC-MS analysis due to their high molecular weight. It is also difficult to make links with the occurrences of meat odour and flavour descriptors, due to the low occurrence of several descriptors such as rancid, boar and fatty.

The feeding strategy had only minor effects on the sensory properties of meat and did not significantly affect the concentration of most of the volatile compounds that were present in the pork from the two strategies, similar to what has been observed by Wojtasik-Kalinowska et al. (2018) using 3 % linseed oil in the diet. The composition of the feed might have an effect on the presence and abundance of volatile compounds, either directly in the feed or via the action of the microflora. The complexity of the Bio+ diets might explain the greater number of volatiles compounds in pork from Bio+. In particular, the finishing diet used for the Bio+ strategy contained soyabean meal, sunflower meal, extruded linseed and faba beans as protein sources whereas the diet used for C was based only on soybean meal. Furthermore, the higher levels of aldehyde in muscle from the Bio+ diet may be due to the use of linseed or sunflower meal in the finishing Bio+ diet (Orlova et al., 2021;

Pointner et al., 2024). A greater complexity of the aromatic profile of dry-fermented sausages, prepared from outdoor pigs supplemented with alfalfa hay was also found compared with conventional indoor pigs, which was explained by more lipid peroxidation, less lipid β-oxidation, less amino acid degradation, less volatiles from spices (Skrlep et al., 2018). Differences in aromatic compounds depending on animal feeding strategy have also been reported in other species and animal-based products, like in cheese depending on the nature of forages and pasture diversity (Martin et al., 2005) or in beef from steers fed with either grass silage and sugar beet pulp or concentrates (Elmore et al., 2004).

The multi-dimensional analyses showed a certain number of relationships among the variables used, most importantly between the volatile compounds and the sensory traits, but did not allow to observe a difference in the overall organoleptic quality between the two feeding strategies. This was in agreement with the observation that the feeding strategy had no impact on most of the sensory and aromatic compound's variables evaluated in Bio+ compared to the control. Despite variability between samples for androstenone and skatole contents, these do not contribute to the main axes, confirming that in our experimental conditions no odour or flavour issues due to "boar tainted" males were
detected. This allows us to conclude that the Bio+ feeding sustainable strategy is not deteriorating the quality of organic pork nor it improves significantly the organoleptic quality. The PCA conducted using the sensory traits and volatile compounds did not allow to separate the two feeding strategies, confirming the lack of differences in the relative abundance of the aromatic compounds identified in meat between the experimental treatments. Although the composition of volatile compounds is greatly variable from one individual to another, the separation could not be driven by the variables used for the analysis. These findings can be explained by several reasons. First, due to the complexity of the aromas from the feeding strategies. Second, the method enables the detection of only part of the aromatic molecules. Third, the narrow range in the sensory traits between the two experimental treatments does not favour observing aroma differences. However, the PCA conducted using other variables, these being growth performance, technological, nutritional and sensory traits, and aromatic profiles, allowed to observe a weak differentiation between feeding strategies, mostly driven by technological and nutritional quality traits and to some extent by the red colour of raw meat. Overall, the multivariate and chemometrics analyses failed to distinguish the two feeding strategies, hence allowing us to conclude that the Bio+ feeding strategy may be a win-win approach to keep the organic pork quality traits high while improving the image quality by feeding the animals with a part of locally produced raw ingredients. The comparison of the environmental footprints of the two feeding strategies warrants further investigation.

## 5. Conclusion

Overall, the feeding strategy affected some sensory traits of organic pork, with a more intense red colour and a slightly lower aromatic persistency of loin meat from Bio+ compared to Control pigs, but without any significant effect on tenderness, juiciness, odour or flavour scores. The aromatic profile revealed a greater diversity of volatile compounds in meat from Bio+ pigs, probably due to the diversity of the ingredients used in this feeding strategy. However, the integration of the sensory and aromatic profiles of pork using multivariate analysis did not allow to discriminate the two feeding strategies. Nevertheless, differences between the two feeding strategies were observed depending on whether axis of the PCA was considered. Finally, our study shows that it is possible to raise non-castrated males in organic farming while limiting the risk of pork boar taint for the consumers.

## Consent form

This study does not involve any experimentation with human subjects. Consent has been obtained from each panellist for the sensory analysis which was managed by IDELE laboratory.

## CRediT authorship contribution statement

**Chloé Van Baelen:** Writing – review & editing, Writing – original draft, Visualization, Methodology, Investigation, Formal analysis, Conceptualization.
**Lucile Montagne:** Writing – review & editing, Validation, Supervision, Resources, Project administration, Methodology, Funding acquisition, Conceptualization.
**Mohammed Gagaoua:** Writing – review & editing, Validation, Methodology.
**Armelle Prunier:** Writing – review & editing, Validation, Methodology, Funding acquisition, Conceptualization.
**Stefaan De Smet:** Writing – review & editing, Validation, Methodology, Conceptualization.
**Els Vossen:** Writing – review & editing, Validation, Methodology, Conceptualization.
**Bénédicte Lebret:** Writing – review & editing, Validation, Supervision, Resources, Project administration, Methodology, Funding acquisition, Conceptualization.

## Declaration of generative AI and AI-assisted technologies in the writing process

The authors did not use any artificial intelligence assisted technologies in the writing process.

## Financial support statement

This work was supported by Institut national de recherche pour l'agriculture, l'alimentation, et l'environnement (INRAE) and national programme Casdar FARINELLI. This project is part of a PhD (C. Van Baelen) co-funded by INRAE (METABIO métaprogramme) and the Brittany region. C. Van Baelen also received a mobility grant (Rennes Metropole and the Brittany region) for carrying out part of the laboratory analyses at Ghent University, Belgium.

## Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

## Acknowledgements

The authors thank S. Ferchaud, S. Moreau, T. Terrasson, and D. Grivault from Porganic, INRAE GenESI, 86480 Rouillé France for animal care and sample collection, and E. Kowalski for her support at Ghent University.

## Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.meatsci.2025.109869.

## Data availability

None of the data were deposited in an official repository.

## References

* Aaslyng, M. D., & Meinert, L. (2017). Meat flavour in pork and beef – From animal to meal. *Meat Science*, **132**, 112–117. https://doi.org/10.1016/j.meatsci.2017.04.012

* Acevedo, C. A., Creixell, W., Pavez-Barra, C., Sánchez, E., Albornoz, F., & Young, M. E. (2012). Modeling volatile organic compounds released by bovine fresh meat using an integration of solid phase microextraction and databases. *Food and Bioprocess Technology*, **5**(6), 2557–2567. https://doi.org/10.1007/s11947-011-0571-1

* Ahamed, Z., Seo, J., Eom, J.-U., & Yang, H.-S. (2023). Optimization of volatile compound extraction on cooked meat using HS-SPME-GC-MS, and evaluation of diagnosis to meat species using volatile compound by multivariate data analysis. *LWT*, **188**, Article 115374. https://doi.org/10.1016/j.lwt.2023.115374

* Aquilani, C., Sirtori, F., Flores, M., Bozzi, R., Lebret, B., & Pugliese, C. (2018). Effect of natural antioxidants from grape seed and chestnut in combination with hydroxytyrosol, as sodium nitrite substitutes in Cinta Senese dry-fermented sausages. *Meat Science*, **145**, 389–398. https://doi.org/10.1016/j.meatsci.2018.07.019

* Argemi-Armengol, I., Villalba, D., Ramon Bertolin, J., Angeles Latorre, M., Panellà-Riera, N., & Alvarez-Rodriguez, J. (2022). Dietary silage supplement modifies fatty acid composition and boar taint in pork fat. *Annals of Animal Science*, **22**(3), 1115–1124. https://doi.org/10.2478/aoas-2021-0086

* Beldarrain, L. R., Morán, L., Sentandreu, M.À., Barron, L. J. R., & Aldai, N. (2022). Effect of ageing time on the volatile compounds from cooked horse meat. *Meat Science*, **184**, Article 108692. https://doi.org/10.1016/j.meatsci.2021.108692

* Benet, I., Guàrdia, M. D., Ibañez, C., Solà, J., Arnau, J., & Roura, E. (2015). Analysis of SPME or SBSE extracted volatile compounds from cooked cured pork ham differing in intramuscular fat profiles. *LWT - Food Science and Technology*, **60**(1), 393–399. https://doi.org/10.1016/j.lwt.2014.08.016

* Blum, Y., Monziols, M., Causeur, D., & Daumas, G. (2014). Recalibrage de la principale méthode de classement des carcasses de porcs en France. *Journées de la Recherche Porcine*, vol. 46. *Journées Recherche Porcine* (pp. 39–44). Paris (France): INRA-IFIP. Retrieved from https://www.journées-recherche-porcine.com/texte/2014/genetiquo/9Q1.pdf. (Accessed 5 April 2025).

* Chang, Y., Wang, S., Chen, H., Zhang, N., & Sun, J. (2021). Characterization of the key aroma compounds in pork broth by sensory-directed flavor analysis. *Journal of Food Science*, **86**(11), 4932–4945. https://doi.org/10.1111/1750-3841.15937
Cheng, L., Li, X., Tian, Y., Wang, Q., Li, X., An, F., Luo, Z., Shang, P., Liu, Z., & Huang, Q. (2023). Mechanisms of cooking methods on flavor formation of Tibetan pork. *Food Chemistry*, *X*, 19, Article 100873. https://doi.org/10.1016/j.fochx.2023.100873

Commission Regulation. (2017a). Commission implementing Regulation (EU) 2017/1184 of 20 April 2017 laying down rules for the application of Regulation (EU) No 1308/2013 of the European Parliament and of the Council as regards the Union scales for the classification of beef, pig and sheep carcasses and as regards the reporting of market prices of certain categories of carcasses and live animals. *Official Journal of the European Union L*, 171, 103–112, 4.7.2017. Retrieved from https://eur-lex.europa.eu/eli/reg_impl/2017/1184/oj/eng Accessed April 5, 2025.

Commission Regulation. (2017b). Commission delegated Regulation (EU) No 2017/1182 of 20 April 2017 supplementing Regulation (EU) No 1308/2013 of the European Parliament and of the Council as regards the Union scales for the classification of beef, pig and sheep carcasses and as regards the reporting of market prices of certain categories of carcasses and live animals. *Official Journal of the European Union L*, 171, 74–99, 4.7.2017. Retrieved from https://eur-lex.europa.eu/eli/reg_del/2017/1182/oj/eng Accessed April 5, 2025.

Cui, H., Wang, Y., Liu, X., Wang, Y., Zhang, L., Chen, Y., Jia, Y., Zhao, G., & Wen, J. (2023). Identification of common aroma contributors and the regulated metabolites of different kinds of meat. *LWT*, 181, Article 114737. https://doi.org/10.1016/j.lwt.2023.114737

Elmore, J. S., Mottram, D. S., & Hierro, E. (2001). Two-fibre solid-phase microextraction combined with gas chromatography-mass spectrometry for the analysis of volatile aroma compounds in cooked pork. *Journal of Chromatography A*, 905(1), 233–240. https://doi.org/10.1016/S0021-9673(00)00990-0

Elmore, J. S., Warren, H. E., Mottram, D. S., Scollan, N. D., Enser, M., Richardson, R. I., & Wood, J. D. (2004). A comparison of the aroma volatiles and fatty acid compositions of grilled beef muscle from Aberdeen Angus and Holstein-Friesian steers fed diets based on silage or concentrates. *Meat Science*, 68(1), 27–33. https://doi.org/10.1016/j.meatsci.2004.01.010

Font-i-Furnols, M., & Guerrero, L. (2022). Understanding the future meat consumers. *Meat Science*, 193, Article 108941. https://doi.org/10.1016/j.meatsci.2022.108941

Gagaoua, M., Gondret, F., & Lebreb, B. (2025). Towards a 'one quality' approach of pork: A perspective on the challenges and opportunities in the context of the farm-to-fork continuum - Invited review. *Meat Science*, 226, Article 109834. https://doi.org/10.1016/j.meatsci.2025.109834

Gagaoua, M., Suman, S. P., Purslow, P. P., & Lebreb, B. (2023). The color of fresh pork: Consumers expectations, underlying farm-to-fork factors, myoglobin chemistry and contribution of proteomics to decipher the biochemical mechanisms. *Meat Science*, 206, Article 109340. https://doi.org/10.1016/j.meatsci.2023.109340

Gandemer, G. (2002). Lipids in muscles and adipose tissues, changes during processing and sensory properties of meat products. *Meat Science*, 62, 309–321. https://doi.org/10.1016/S0309-1740(02)00128-6

van Gemert, L. J. (2011). Odour thresholds: Compositions of odour thresholds values in air, water and other media. *Oliemans Punter*.

Giri, A., Osako, K., & Ohshima, T. (2010). Identification and characterization of headspace volatiles of fish miso, a Japanese fish meat based fermented paste, with special emphasis on effect of fish species and meat washing. *Food Chemistry*, 120(2), 621–631. https://doi.org/10.1016/j.foodchem.2009.10.036

Goethals, S., Van Hecke, T., Vossen, E., Vanhaecke, L., Van Camp, J., & De Smet, S. (2020). Commercial luncheon meat products and their in vitro gastrointestinal digests contain more protein carbonyl compounds but less lipid oxidation products compared to fresh pork. *Food Research International*, 136, Article 109585. https://doi.org/10.1016/j.foodres.2020.109585

Gorbatov, V. M., & Lyaskovskaya, Y. N. (1980). Review of the flavour-contributing volatiles and water-soluble non-volatiles in pork meat and derived products. *Meat Science*, 4(3), 209–225. https://doi.org/10.1016/S0309-1740(80)00509-9

Han, D., Zhang, C. H., Fauconnier, M. L., & Mi, S. (2020). Characterization and differentiation of boiled pork from Tibetina, Sanmenxia and duroc × (Landrac × Yorkshire) pigs by volatiles profiling and chemometrics analysis. *Food Research International*, 130. https://doi.org/10.1016/j.foodres.2019.108910

Hansen, L. L., Claudi-Magnussen, C., Jensen, S. K., & Andersen, H. J. (2006). Effect of organic pig production systems on performance and meat quality. *Meat Science*, 74 (4). https://doi.org/10.1016/j.meatsci.2006.02.014. Article 4.

Hansen, L. L., Stolzenbach, S., Jensen, J. A., Henckel, P., Hansen-Moller, J., Syriopoulos, K., & Byrne, D. V. (2008). Effect of feeding fermentable fibre-rich feedstuffs on meat quality with emphasis on chemical and sensory boar taint in entire male and female pigs. *Meat Science*, 80(4), 1165–1173. https://doi.org/10.1016/j.meatsci.2008.05.010

Jonsäll, A., Johansson, L., Lundström, K., Andersson, K., Nilsen, A., & Risvik, E. (2002). Effects of genotype and rearing system on sensory characteristics and preference for pork (*M-Longissimus dorsi*). *Food Quality and Preference*, 13(2), 73–80. https://doi.org/10.1016/S0950-3293(01)00060-X

Kongsted, A. G., Claudi-Magnussen, C., Hermansen, J. E., Horsted, K., & Andersen, B. H. (2011). Effect of breed on performance and meat quality of first parity sows in a seasonal organic rearing system. *Journal of the Science of Food and Agriculture*, 91 (15). https://doi.org/10.1002/jsfa.4539. Article 15.

Lebreb, T., & Cândek-Potokar, M. (2022). Review: Pork quality attributes from farm to fork. Part I. Carcass and fresh meat. *Animal*, 16, Article 100402. https://doi.org/10.1016/j.animal.2021.100402

Lenth, R. V., Bolker, B., Buerkner, P., Giné-Vázquez, I., Herve, M., Jung, M., Love, J., Miguez, F., Riebl, H., & Singmann, H. (2024). Emmeans: Estimated Marginal Means, aka Least-Squares Means [R package emmeans version 1.10.0]. URL https://cran.r-project.org/web/packages/emmeans/index.html.

Lopez-Moreno, C., Campos, S. F.-P., Baena, S. L., Navarrete, J. T. L., & de Molina, J. C. O. F. (2023). Analysis of volatile flavor compounds and

physicochemical properties in conventional and organic pork meats using SPME-GC-MS. *Food Science and Engineering*, 159–181. https://doi.org/10.37256/fse.4220232425

Lundström, K., Matthews, K. R., & Haugen, J.-E. (2009). Pig meat quality from entire males. *Animal: An International Journal of Animal Biochemistry*, 3(11), 1497–1507. https://doi.org/10.1017/S1751731109990693

Madruda, M. S., Stephen Elmore, J., Dodson, A. T., & Mottram, D. S. (2009). Volatile flavour profile of goat meat extracted by three widely used techniques. *Food Chemistry*, 115(3), 1081–1087. https://doi.org/10.1016/j.foodchem.2008.12.065

Marco, A., Navarro, J. L., & Flores, M. (2004). Volatile compounds of dry-fermented sausages as affected by solid-phase microextraction (SPME). *Food Chemistry*, 84(4), 633–641. https://doi.org/10.1016/S0308-8146(03)00288-7

Martin, B., Verdier-Metz, I., Buchin, S., & Hurtaud, C. (2005). How do the nature of forages and pasture diversity influence the sensory quality of dairy livestock products? *Animal Science*, 81(2), 205–212. https://doi.org/10.1079/ASC50800205

Marusic, N., Vidacek, S., Janci, T., Petrak, T., & Medic, H. (2014). Determination of volatile compounds and quality parameters of traditional Istrian dry-cured ham. *Meat Science*, 96(4), 1409–1416. https://doi.org/10.1016/j.meatsci.2013.12.003

Mathur, P. K., ten Napel, J., Bloemhof, S., Heres, L., Knol, E. F., & Mulder, H. A. (2012). A human nose scoring system for boar taint and its relationship with androstenone and skatole. *Meat Science*, 91(4), 414–422. https://doi.org/10.1016/j.meatsci.2012.02.025

van Milgen, J., & Noblet, J. (2003). Partitioning of energy intake to heat, protein, and fat in growing pigs. *Journal of Animal Science*, 81(14_suppl_2), E86–E93. https://doi.org/10.2527/2003.814_suppl_2E86x

Mörlein, D., Mörlein, J., Gerlach, C., Strack, M., Kranz, B., & Brüggemann, D. A. (2024). An overlooked compound contributing to boar taint and consumer rejection of meat products: 2-aminoacetophenone. *Meat Science*, 213, Article 109497. https://doi.org/10.1016/j.meatsci.2024.109497

Mottram, D. S. (1985). The effect of cooking conditions on the formation of volatile heterocyclic compounds in pork. *Journal of the Science of Food and Agriculture*, 36(5), 377–382. https://doi.org/10.1002/jsfa.2740360510

Mottram, D. S., Koutsidis, G., Oruna-Concha, M. J., Ntova, M., & Elmore, J. S. (2004). Analysis of important flavour precursors in meat. In K. D. Deibler, & J. Delwiche (Eds.), *Handbook of flavour characterization* (pp. 463–472). New York: Marcel Dekker.

Orlova, Y., Harmon, R. E., Broadbelt, L. J., & Iedema, P. D. (2021). Review of the kinetics and simulations of linseed oil oxidation. *Progress in Organic Coatings*, 151(106), 041. https://doi.org/10.1016/j.porgcoat.2020.106041

O'Sullivan, M. G., Byrne, D. V., Jensen, M. T., Andersen, H. J., & Vestergaard, J. (2003). A comparison of warmed-over flavour in pork by sensory analysis, GC/MS and the electronic nose. *Meat Science*, 65(3), 1125–1138. https://doi.org/10.1016/S0309-1740(02)00342-X

Pointner, T., Rauh, K., Aunon-Lopez, A., Kostadinović Velickovska, S., Mitrev, S., Arsov, E., & Pignitter, M. (2024). Comprehensive analysis of oxidative stability and nutritional values of germinated linseed and sunflower seed oil. *Food Chemistry*, 454 (139), 790. https://doi.org/10.1016/j.foodchem.2024.139790

Prache, S., Adamiec, C., Astruc, T., Baeza-Campeone, E., Bouillot, P. E., Clinquart, A., ... Sante-Lhoutellier, V. (2022). Review: Quality of animal-source foods. *Animal*, 16 (100), 376. https://doi.org/10.1016/j.animal.2021.100076

Prache, S., Lebreb, T., Baeza, E., Martin, B., Gautron, J., Feidt, C., Medale, F., Corraze, G., Raulet, M., Lefevre, F., Verrez-Bagnis, V., & Sans, P. (2022). Review: Quality and authentication of organic animal products in Europe. *Animal*, 16(100), 405. https://doi.org/10.1016/j.animal.2021.100405

Prunier, A., Brillouët, A., Merlot, E., Meunier-Salaün, M. C., & Tallet, C. (2013). Influence of housing and season on pubertal development, boar taint compounds and skin lesions of male pigs. *Animal*, 7(12), 2035–2043. https://doi.org/10.1017/S151731110031596

Prunier, A., Devillers, N., Herskin, M., Sandercock, D., Sinclair, A., Tallet, C., & von Borell, E. (2020). *Husbandry interventions in suckling piglets, painful consequences and mitigation* (pp. 107–138). https://doi.org/10.3920/978-90-8686-894-04

Pugliese, C., Sirtori, F., Ruiz, J., Martin, D., Parenti, S., & Franci, O. (2009). Effect of pasture on chestnut or acorn on fatty acid composition and aromatic profile of fat of Cinta Senese dry-cured ham. *Grasas y Aceites*, 60(3). https://doi.org/10.3989/gya.130208. Article 3.

Quander-Stoll, N., Bautze, D., Zollitsch, W., Leiber, F., & Fruh, B. (2022). Effects of 100 % organic feeding on performance, carcass composition and fat quality of fattening pigs. *Biological Agriculture & Horticulture*, 38(4), 271–284. https://doi.org/10.1080/01448765.2022.2119889

Sklep, M., Cândek-Potokar, M., Tomazin, U., Lukac, N. B., & Flores, M. (2018). Properties and aromatic profile of dry-fermented sausages produced from Krskopolje pigs reared under organic and conventional rearing regime. *Animal*, 12(6), 1316–1323. https://doi.org/10.1017/S1751731117002713

Sohail, A., Al-Dalali, S., Wang, J., Xie, J., Shakoor, A., Asimi, S., Shah, H., & Patil, P. (2022). Aroma compounds identified in cooked meat: A review. *Food Research International*, 157(111), 385. https://doi.org/10.1016/j.foodres.2022.111385

Song, S., Tang, Q., Fan, L., Xu, X., Song, Z., Hayat, K., Feng, T., & Wang, Y. (2017). Identification of pork flavour precursors from enzyme-treated lard using Maillard model system assessed by GC-MS and partial least squares regression. *Meat Science*, 124, 15–24. https://doi.org/10.1016/j.meatsci.2016.10.009

The R Core Team. (2023). R: A language and environment for statistical computing. https://www.sәmanticscholar.org/paper/R%3A-a-language-and-environment-for-r-statistical-Team/659408b243cec55de8d0a3bc51b81173007aa89b.

Tutz, G., & Ramzan, S. (2015). Improved methods for the imputation of missing data by nearest neighbor methods. *Computational Statistics & Data Analysis*, 90, 84–99. https://doi.org/10.1016/j.csda.2015.04.009
Van Baelen, C., Montagne, L., Ferchaud, S., Prunier, A., & Lebret, B. (2024). Feeding strategy in organic pig farming as a lever to improve various quality dimensions of pork. *Animal, 101*, 190. https://doi.org/10.1016/j.animal.2024.10119

Vasta, V., Jerónimo, E., Brogna, D. M. R., Dentinho, M. T. P., Biondi, L., Santos-Silva, J., ... Bessa, R. J. B. (2010). The effect of grape seed extract or *Cistus ladanifer* L. on muscle volatile compounds of lambs fed dehydrated lucerne supplemented with oil. *Food Chemistry, 119*(4), 1339-1345. https://doi.org/10.1016/j.foodchem.2009.09.010

Vossen, E., Goethals, S., De Vrieze, J., Boon, N., Van Hecke, T., & De Smet, S. (2020). Red and processed meat consumption within two different dietary patterns: Effect on the colon microbial community and volatile metabolites in pigs. *Food Research International, 129*(108), 793. https://doi.org/10.1016/j.foodres.2019.108793

Vossen, E., Raes, K., Van Mullem, D., & De Smet, S. (2017). Production of docosahexaenoic acid (DHA) enriched loin and dry cured ham from pigs fed algae: Nutritional and sensory quality. *European Journal of Lipid Science and Technology, 119*(5), Article 1600144. https://doi.org/10.1002/ejlt.201600144

Wesoly, R., & Weiler, U. (2012). Nutritional influences on skatole formation and skatole metabolism in the pig. *Animals, 2*(2), 221-242. https://doi.org/10.3390/ani2020221

Wojtasik-Kalinowska, I., Guzek, D., Górska-Horczyczak, E., Brodowska, M., Sun, D.-W., & Wierzbicka, A. (2018). Diet with linseed oil and organic selenium yields low n-6/n-3 ratio pork Semimembranosus meat with unchanged volatile compound profiles. *International Journal of Food Science & Technology, 53*(8), 1838-1846. https://doi.org/10.1111/ijfs.13763

Zamaratskaia, G., & Squires, E. J. (2009). Biochemical, nutritional and genetic effects on boar taint in entire male pigs. *Animal, 3*(11), 1508-1521. https://doi.org/10.1017/S1751731108003674

Zammerini, D., Wood, J. D., Whittington, F. M., Nute, G. R., Hughes, S. I., Hazzledine, M., & Matthews, K. (2012). Effect of dietary chicory on boar taint. *Meat Science, 91*, 396-401. https://doi.org/10.1016/j.meatsci.2012.01.020

Zang, M., Wang, L., Zhang, Z., Zhang, K., Li, D., Li, X., Wang, S., & Chen, H. (2020). Changes in flavour compound profiles of precooked pork after reheating (warmed-over flavour) using gas chromatography-olfactometry-mass spectrometry with chromatographic feature extraction. *International Journal of Food Science & Technology, 55*(3), 978-987. https://doi.org/10.1111/ijfs.14306

Zhao, L., Wang, J., Yang, P., Erasmus, S. W., Huang, F., Barbut, S., & Zhang, C. (2025). Exploring relationships between precursor changes and aroma-active compounds formation of cooked Tibetan pork under different cooking methods. *Meat Science, 109*, 819. https://doi.org/10.1016/j.meatsci.2025.109819