bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and composition of mesophyll, epidermis and fibre cell walls from leaves of perennial ryegrass (lolium perenne) and italian ryegrass (lolium multiflorum)
Authors: Gordon Alex H. , Lomax James A. , Dalgarno Karen , Chesson Andrew
Published: October 2006

Cells of mesophyll, epidermis and residual fibrous material were obtained from leaves of Italian and perennial ryegrass harvested at different stages of maturity by mechanical disruption of leaf tissue. Mesophyll cells were selectively removed by filtration through 0.045 mm nylon mesh and remaining non‐mesophyll cells centrifuged in metrizamide solutions (56–58% wt to vol.) of known density (1.308–1.329 g cm3 at 5°C) to obtain a pure epidermis cell fraction and a residual fibre fraction. Whole mesophyll cells contributed 63–72%, epidermis 12–15% and the fibre fraction 15–24% to the total leaf dry matter. Fibre values were higher in late‐cut samples. Cell walls were prepared from mesophyll and epidermis cells by disruption and washing to remove cell contents. Fibre cells were judged free of cell contents and received no further treatment. Examination of cell wall preparations by light and electron microscopy showed that both mesophyll and epidermis preparations were essentially free from contaminating material. Mesophyll cell walls were uniformly thin (200 nm) while those of epidermis ranged from 2000–3000 nm at the outer face, thinning to 300 nm or less at the inner surface. An electron‐light layer (cuticle) of approximately 200 nm thickness was present covering the outer face of the epidermis. The fibre fraction largely consisted of sclerenchyma, but contained, in addition, other vascular cells, detached annular rings and heavily silicified leaf hairs. Analysis of cell walls accounted for 85–90% of dry matter. Cellulose was the major component of all cell walls examined (approximately 40% of dry matter) with xylose residues accounting for a further 11% of mesophyll, 13.5–17.5% of epidermis and 21–25% of fibre cell walls. Arabinose was low in fibre cells but was present in much higher proportions in mesophyll and epidermis walls. The ratio of arabinose to xylose was approximately 1:1.5 for mesophyll, 1:2.5 for epidermis and 1:7.0 for the fibre fraction. The molar ratio acetyl to xylose remained fairly constant at 1:4 regardless of the grass, cell type or maturity of the sample. The uronic acid content of epidermis was higher than that in other cell types and showed an increase with increasing maturity of the grass, reaching over 9% in late‐cut samples. Total phenolic material represented 2–3% of mesophyll and epidermis cell walls and 6% of fibre walls. Ferulic acid alone was released from the primary cell walls by saponification and p‐coumaric and ferulic acids from the secondary‐thickened fibre walls. Crude protein values (NX6.25) were high in mesophyll cell wall preparations and low in epidermis and fibre cell walls. Amino acid patterns were similar for both grasses and cell types but hydroxyproline was found in greater amounts in fibre cell walls than in either epidermis or mesophyll.
Synthesis of aroma compounds by apples supplied with alcohols and methyl esters of fatty acids
Authors: Bartley Ian M. , Stoker Paul G. , Martin Andrew D. E. , Hatfield Stephen G. S. , Knee Michael
Published: October 2006

Ester synthesis by apples supplied with alcohols (C2–C8) and methyl esters of short chain fatty acids (C4–C8) was studied using gas chromatographic analysis of the products. The substrates were supplied as vapours to whole fruits stored in 2% O2 at 3°C. The alcohols were converted to the corresponding acetate ester; butanol, pentanol and hexanol were converted most rapidly. The methyl esters of short chain fatty acids (Cn) were converted to esters with an alkyl group (Cn‐2, Cn‐4) confirming the presence in whole fruits of an active β‐oxidation pathway for fatty acids. Ester synthesis was stimulated when apples were supplied with methyl octanoate at different periods during long term storage in 2% O2. Treatment of the fruit immediately postharvest did not enhance ethylene synthesis.
Acidification, proteolysis and flavour potential in fermenting cocoa beans
Authors: Biehl Böle , Brunner Ernst , Passern Detlef , Quesnel Victor C. , Adomako Daniel
Published: October 2006

Cocoa fermentations in Ghana and Trinidad as well as anaerobic fermentation‐like incubations of fresh cocoa beans in Germany were carried out under controlled conditions. Samples of beans were taken during the course of these treatments and determinations were made as to acidification (pH, acetic acid content), proteolysis (free α‐amino nitrogen, peptide nitrogen and SDS electrophoresis of the protein peptides) and flavour potential (gas chromatography of the highly volatile compounds, in particular isopentanal and organoleptic analysis after thin layer roasting). A positive correlation between acidification, proteolysis and the development of flavour potential during anaerobic fermentation can be demonstrated in principle. However, the flavour potential is increased if the temperature rise is comparatively slow in both normal fermentation and laboratory incubation. Strong acidification and high accumulation of amino acids and peptides were not essential for a good flavour potential. The isopentanal content proved to be a useful indicator of the progress of normal fermentation in the tropics. These findings can be interpreted on the basis of earlier results about germination‐like processes in the protein vacuoles, pre‐ and post‐mortem subcellular structures and the special characteristics of acetic acid diffusion. Conclusions which are relevant to the practice of cocoa fermentation are discussed in more detail.
Rates of starch hydrolysis and changes in viscosity in a range of common foods subjected to simulated digestion in vitro
Authors: Gee Jennifer M. , Johnson Ian T.
Published: October 2006

A range of common starch‐rich foods and pure starches was analysed for available carbohydrates and dietary fibre content, and subjected to a simulated digestion procedure in vitro. The initial rates of free sugar release differed markedly between foods; the time required for the release of 50% of the starch content of some legumes was up to 100 fold longer than that for foods such as potatoes and rice. A significant correlation (r=0.806; P<0.01) between the time required for hydrolysis and the total dietary fibre content of the foods was observed. The viscosity of the food samples declined during the course of digestion, but always remained markedly higher than that of pure starch. The rate of hydrolysis of starch appears to be the most important factor governing the human glycaemic response to foods described by other authors, but the final viscosity of partially digested foods may be of some significance.
The nutritive values of feed proteins and feed protein residues resistant to degradation by rumen microorganisms
Authors: Rooke John A.
Published: October 2006

Fishmeal (FM), meat and bone meal (MBM) and rapeseed meal (RSM) were incubated for 8h (RSM) or 24 h (FM, MBM) in nylon bags in the rumens of cattle, in order to prepare from each meal sufficient residues resistant to rumen degradation for evaluation of their nutritive value. The nitrogen (N) and organic matter (OM) contents of FM and MBM were significantly (P<0.05) reduced by rumen incubation. The modified acid detergent fibre content of RSM was increased, and only traces of glucosinolates remained after rumen incubation. The amino acid profiles of FM and RSM were observed to change as a result of rumen incubation, whereas that of MBM was unchanged. The true N digestibilities of all three protein meals when fed to rats as the sole protein source were significantly (P<0.05) reduced by prior rumen incubation (FM, 0.90 to 0.86; MBM, 0.81 to 0.55 and RSM, 0.76 to 0.67). When measured using a rat bioassay, the biological values of FM (65.0 to 79.2) and RSM (53.3 to 83.1) protein were significantly (P<0.05) increased as a result of rumen incubation but that of MBM was unchanged (47.7 vs 41.1). The N digestibility of the protein meals and of their residues resistant to rumen degradation were also estimated in cattle. Samples of the feedstuffs were placed in small polyester bags, inserted into the proximal duodenum of cattle, recovered in faeces and N disappearance from the bags measured. This technique ranked the N digestibilities of the feedstuffs in the same order as in the rat.
The linamarase of Leuconostoc mesenteroides: Production, isolation and some properties
Authors: Okafor Nduka , Ejiofor Michael A. N.
Published: October 2006

Leuconostoc mesenteroides was found to produce highly active linamarase when linamarin was incorporated in its growth medium. The enzyme was isolated from the bacterium and partially purified using diethylaminoethyl (DEAE) cellulose. Its activity was measured spectrophotometrically using linamarin extract. This yielded 62.2 mg CN− g−1 of linamarin. A study of some of its properties showed it was active in the temperature range of ‐10 to +45°C, with an optimum at 29°2°C. Activity was observed over a wide pH range, 4.0–8.0, with optimum at 6.0–6.5. Its pH of stability was 5.5–7.5, while above pH 8.0 there was a rapid loss of activity. Incubating the enzyme at 50°C led to loss of over 90% of its activity within 18 min. The optimal substrate concentration was 0.15–0.20 ml−1. Whereas above 0.25 mg ml−1 there was no observable increase in activity, loss of activity became more pronounced below 0.10 mg ml−1 of substrate.
The composition of orange roughy (Hoplostethus atlanticus) roe lipids
Authors: Body Denis R.
Published: October 2006

Lipid analysis was carried out on orange roughy (Hoplostethus atlanticus) roe oil. Various chromatographic analytical techniques were compared and it was shown, although total orange roughy oil was rich in wax esters, that roe oil contained triacylglycerol and phospholipids as the principal components. The fatty acid content of the individual lipids (except wax esters) had 16:0, 18:1, 20:1, 20:5 and 22:6 as their major constituents.
The bread baking quality of six wheat starches differing in composition and physical properties
Authors: Soulaka Amjad B. , Morrison William R.
Published: October 2006

Starch was isolated from six types of wheat and separated into large A‐granule and small B‐granule fractions which exhibited a suitable range of properties. Respective amylose contents were 28.6–31.0% and 25.1–31.5%, lysophospholipids 707–1014mg 100 g−1, and 1058–1398 mg 100 g−1, and gelatinisation temperatures (GT) by differential scanning calorimetry (DSC) 58.4–62.7°C and 60.5–64.5°C. The A‐ and B‐granule fractions were remixed in various proportions and reconstituted with freeze‐dried gluten and freeze‐dried water‐solubles from flour to test the effects of changes in the properties of the total starch, A‐granule or B‐granule fractions, and the effects of various proportions of B‐granules on the quality of bread. The specific volumes of the loaves were not affected by starch amylose or lipid content, but were significantly correlated with either the GT of the total starches or their A‐granules. The optimum proportion of B‐granules was 25–35% by weight, but their GT had no effect on loaf specific volume. Staling changes were quantified from crumb compressibility measurements and the enthalpy of the endotherm for gelatinisation of retrograded amylopectin in stored breadcrumb, measured by DSC. Initial and limiting moduli of crumb firmness were correlated with loaf specific volume and starch GT, but rate and time constants calculated from the Avrami equation were independent. Rate and time constants and limiting enthalpy values calculated from the DSC results were independent of all other measured parameters.
Processing, suitability and nutritive value of field bean seeds after germination
Authors: Bednarski Wlodzimierz , Tomasik Jan , Piatkowska Barbara
Published: October 2006

An attempt was made to obtain hydrolysates from field bean seeds after germination. The activity of native proteolytic enzymes, ascorbic acid and phytate phosphorus contents, as well as the activity of proteolytic enzyme inhibitors were studied, as influenced by seed steeping, water acidity and aerating conditions. Germinated field bean seeds were found to be suitable for hydrolysate production. The enzyme activity, as well as the contents of compounds responsible for the nutritive value of seed was determined and depended on germinating conditions.
Nutritive value of mango seed kernel
Authors: Dhingra Sukhsatej , Kapoor Amin C.
Published: October 2006

Seed kernels of two cultivars (Chausa and Dusheri) of mango (Mangifera indica) were analysed for chemical composition, lipid classes, fatty acid composition, amino acid profile and chemical evaluation of protein quality. The seed kernels constituted about 18% of the total fruit and had 5% protein, 6–7% crude fat, 0.19–0.44% tannins, iodine value of 34–44 and saponification number 202–213. Oleic acid (42%) and stearic acid (39%) were the principal fatty acids in the oil. The in vitro digestibility was low in these cultivars, possibly due to the presence of tannins. Sulphur‐containing amino acids (methionine+cystine) and isoleucine were the limiting amino acids in Chausa and Dusheri, respectively. The essential amino acid index and protein quality index were high, thus indicating the good quality of the protein in mango seed kernel.
A simplified method for the extraction of the metals Fe, Zn, Cu, Ni, Cd, Pb, Cr, Co and Mn from soils and sewage sludges
Authors: McGrath Stephen P. , Cunliffe Caroline H.
Published: October 2006

The method described for digestion of soil samples with aqua regia is simple, flexible and safe to operate with large sample throughout. At least nine metals can be determined in the resulting solutions with errors of <5%. The results compare favourably with those from reflux aqua regia and averaged 88% of the certified total values for reference soils and 88% of those for reference sewage sludges.
The kinetics and mechanism of caffeine infusion from coffee: The effect of roasting
Authors: Spiro Michael , Hunter Julia E.
Published: October 2006

Rates of extraction of caffeine into water at 80°C were measured for green and roasted Kenyan arabica coffee beans. The green beans were roasted to controlled extents in a Moda coffee roaster, ground, and sieved to a size range 0.85–1.18 mm. Certain physical properties (weight loss, colour, bean volume and infusion pH) were determined for each product. The half‐time of caffeine infusion did not change significantly on light roasting but dropped by 40% on more severe treatment and by a further 30% when roasted to scorching. The activation energy also decreased on strong roasting. The kinetic parameters have been correlated with the physical properties of the coffees and with the chemical and physical changes of roasting.
Tryptophan determination of food proteins by h.p.l.c. after alkaline hydrolysis
Authors: Nielsen Henrik K. , Hurrell Richard F.
Published: October 2006

The alkaline hydrolysis of proteins prior to tryptophan analysis has been evaluated, and a method for the measurement of tryptophan by reverse phase h.p.l.c. after alkaline hydrolysis has been proposed and compared with published methods. Hydrolysis with either LiOH or NaOH gave similar results. Tryptophan values and the recovery of added 5‐methyltryptophan were similar when hydrolysis was made under tap‐water vacuum (1500 Pa) or at high vacuum (2 Pa). Partially‐hydrolysed starch reduced the losses of tryptophan during hydrolysis better than thiodiglycol. High levels of indolyl‐3‐propionic acid or 5‐methyltryptophan did not further improve tryptophan recovery. 5‐Methyltryptophan is the preferred internal standard; its recovery after hydrolysis more closely resembled that of protein‐bound tritiated tryptophan from goat casein than did the recoveries of α‐methyltryptophan or free 14C‐tryptophan. Under some conditions, the recovery of protein bound tryptophan was lower than the recovery of free tryptophan. The stability of tryptophan in hydrolysates was improved by using a phosphate buffer pH 7.0 containing 0.02% sodium azide.
Structural changes in wheat straw components during decay by lignin‐degrading white‐rot fungi in relation to improvement of digestibility for ruminants
Authors: Agosin Eduardo , Monties Bernard , Odier Etienne
Published: October 2006

Structural changes and resulting in‐vitro dry matter digestibility (IVDMD) were determined during the course of solid‐state fermentation of wheat straw using the lignin‐degrading white‐rot fungi Sporotrichum pulverulentum, Pycnoporus cinnabarinus and Cyathus stercoreus. The first fungus grew very rapidly on straw but degraded hemicelluloses and cellulose non‐selectively resulting in very low IVDMD increases (50% after 35% weight loss). P. cinnabarinus and C. stercoreus preferentially degraded hemicelluloses achieving high improvements in IVDMD (maximum increase of 63 and 94%, respectively) with limited dry weight losses (12 and 18% after 7 and 13 days, respectively). The three fungi exhibited some selectivity among the individual hemicellulose components: O‐acetyls were removed essentially at the same rate as xylan, while uronic acids accumulated as incubation proceeded. Conversely, the arabinose content decreased rapidly, especially with C. stercoreus and P. cinnabarinus, suggesting that removal of this pentose was partly responsible for digestibility improvement. Esterified phenolic acids were rapidly degraded during the first stages of decay by all three fungi although P. cinnabarinus and C. stercoreus degraded ferulic acid faster than p‐coumaric acid. Lignin was preferentially degraded compared to polysaccharides by all three fungi. The amount of lignin removed, as determined by Klason, correlated well with IVDMD improvement (r=−0.97), while acid detergent lignin (ADL) showed a lower correlation (r=‐0.86). Acidolysis yields of decayed lignin pointed to preferential degradation of β‐O‐4 ether linked units by the fungi. Syringyl units were removed faster than guaiacyl units only after 5 to 10% weight loss was obtained.
A sensitive monoclonal‐antibody‐based test for gluten detection: Studies with cooked or processed foods
Authors: Skerritt John H. , Smith Robyn A.
Published: October 2006

A method for detection of wheat, rye, barley and oat proteins in a wide range of foods, including baked goods and processed meats has been developed. The procedure requires immobilisation of food extracts upon nitrocellulose paper followed by treatment with an enzyme‐conjugated monoclonal antibody. Upon addition of the appropriate enzyme substrate, gluten‐containing foods yield purple spots; a wide range of non‐gluten common food proteins did not react. The method has several advantages over other means of detecting cereal protein, such as electrophoresis. It is rapid, requiring little sample preparation, and does not require sophisticated equipment or prior knowledge of electrophoretic patterns of common non‐cereal food proteins. Since the method may be used with cooked or baked foods, it should be suitable for food‐monitoring applications.
The nutritional quality of two types of fish silage for broiler chickens
Authors: Johnson Ray J. , Brown Nick , Eason Paul , Sumner John
Published: October 2006

Fish waste was ensiled either by acidification with formic acid or by fermentation with a bacterial starter culture and molasses. The resulting liquids were mixed with wheat bran (85:15 w/w liquid: bran) and dried (70°C) to produce acid silage meal (ASM) and fermented silage meal (FSM). ASM and FSM were incorporated into wheat‐based diets at 25, 50 and 100 g kg−1 at the expense of soya bean meal. There were two control diets, one which contained soya bean meal as the predominant protein supplement and a second in which fish meal (50 g kg−1) was added at the expense of some of the soya bean meal. Starter diets (13.25 MJ ME kg−1, 12 g kg−1 lysine) were fed from 1‐day‐old to 21‐days‐old and finisher diets (13.25 MJ ME kg−1, 9.5 g kg−1 lysine) were fed from 22 to 42‐days‐old to six replicates each of five birds. Birds were reared in raised‐wire cages, and feed intake, liveweight and mortality were recorded. There were no significant effects of dietary inclusion of either ASM and FSM on the performance of broiler chickens relative to those fed on control diets. FSM contained less crude protein and amino acids than ASM. The recovery of amino acids relative to the total crude protein content from FSM was only 78.7%, presumably as a result of formation of Maillard reaction products during drying.
The effects of increasing yields on the macro‐ and microelement concentrations and offtakes in the grain of winter wheat
Authors: McGrath Stephen P.
Published: October 2006

The variations in major and minor element concentrations in winter wheat grain from a UK survey and from three experiments on farms with high yields (>10tha−1) are given. In the survey, the concentrations of P, K, S, Ca and Mg varied twofold, the elements Fe, Zn and Cu varied threefold, whilst Mn varied by a factor of five. Small varietal differences in grain composition were detected. In the field experiments only the concentrations of Fe, Zn, Cu, Mn and S changed significantly as yields increased, and most of the changes were positive, except for Mn, which did not increase with yield. Foliar fungicidal sprays containing Mn increased grain Mn in 1981 and 1982, but S‐containing sprays did not alter grain S in 1983. The offtakes of all the elements studied are given both nationally and for high and low yields on the three farms. These offtakes are compared with the inputs of P, K and Mg in fertilisers and the likely inputs of S from the atmosphere.
The production of naturally fermented fish silage using various lactobacilli and different carbohydrate sources
Authors: Van Wyk Hercules J. , Heydenrych Christine M. S.
Published: October 2006

The suitability for fish silage‐making of eight different Lactobacillus cultures was investigated. The industrial by‐products whey powder and molasses, as well as refined sugar, were tested as fermentation substrates. Using the information obtained two batches of fish silage were made at local white fish processing plants on a semi‐commercial basis and subsequently successfully used on local cattle and pig farms.
Nutritional evaluation of ethanol extracted Madhuca (Madhuca butyraceae) seed flour
Authors: Shanmugasundaram T. , Venkataraman L. V.
Published: October 2006

Defatted Madhuca flour is toxic due to the presence of saponins. Alcohol, 20–95%, was used to remove the saponins and it was found that two stage 60% ethanol extraction removed 90% of the saponins present in the flour. Rat feeding trials using the ethanol extracted flour at 10 and 15% protein levels yielded PER of 0.8 and 1.5 respectively and did not show any ill effects other than minor cytoplasmic vacuolation in liver and kidney in histological studies.
The effect of varying autoclaving conditions and added sodium hydroxide on amino acid content and nitrogen characteristics of feather meal
Authors: Papadopoulos Manthos C. , El‐Boushy Adel R. , Roodbeen Albertus E.
Published: October 2006

The effects upon amino acid content and nitrogen characteristics of feather meal subjected to varying lengths of processing time (30 to 70 min) moisture content (50 to 70%) and added NaOH (0.2 to 0.6%) were studied by multiple regression techniques. All test products were autoclaved at constant pressure of 345 kPa. The results obtained showed that prolonged processing periods and increased concentrations of NaOH had a substantial effect on the amino acid contents and in particular on the essential ones. There was a marked degradation of cystine, and smaller losses of lysine and methionine. Most of the amino acid contents were lower in the meals with a higher moisture content. In vitro protein digestibility and solubility in alkali and acid, were generally increased by prolonged processing conditions.

It was concluded that the inverse relationship between amino acid content and nitrogen characteristics should be taken into account for feather meal evaluation. Higher values for in vitro protein digestibility and solubility were considered to be favourable unless other structural modifications to the protein affect its nutritional value.
Polyphenoloxidase from guava (Psidium guajava L.)
Authors: Augustin M. A. , Ghazali Hasanah M. , Hashim Hasimah
Published: October 2006

Polyphenoloxidase (PPO) was isolated from guava (Psidium guajava L., cv. Kampuchea). Purification by acetone precipitation and dialysis of the Amicon concentrate resulted in 4.9‐fold and 17.2‐fold purification of the dialysed crude extract respectively. Polyacrylamide gel electrophoresis indicated that PPO had a molecular weight in the region of 120000–140000. The pH optimum of the enzyme was found to be 7.2. Heat inactivation studies showed that heating for 1.1, 3.5, and 10.1 min at 75, 65 and 55°C respectively caused a 50% loss in enzymic activity. The enzyme‐catalysed browning reaction was significantly inhibited in the presence of sodium metabisulphite, L‐cysteine hydrochloride and ascorbic acid.
Determination of sugars in tropical root crops using 13C N.m.r. spectroscopy: Comparison with the h.p.l.c. method
Authors: Tamate Jerry , Bradbury J. Howard
Published: October 2006

The 13C nuclear magnetic resonance (n.m.r.) spectrum of sugars normally present in foods, viz. glucose, fructose, sucrose, maltose and raffinose contains resonances that are diagnostic of each sugar. The quantity of each sugar is determined by measurement of the ratios of the peak heights of the sugar resonances compared with peak height of an internal standard, present at constant concentration in all solutions. A linear calibration relationship between the peak height ratio and concentration is established for single resonances of glucose and fructose and for two resonances of each of sucrose, maltose and raffinose. Samples of sweet potato and taro flour dried at 40°C, were blended with 80% ethanol, the sugars were extracted and analysed by 13C n.m.r. and h.p.l.c. Both methods gave similar results and have similar degrees of reproducibility. The n.m.r. method is useful for quantitation of sugars and identification of other molecules extracted from the food, but requires more material than does h.p.l.c. Drying at 40°C causes a decrease in sucrose content and increases in glucose, fructose and maltose which partly compensate for the loss in sucrose. There is considerable variability of the sugar content between different sweet potato tubers and between different taro corms of the same cultivar as well as across different cultivars. For sweet potato the total sugar content is 0.6‐3.6% fresh weight, with considerably more sucrose present than glucose, fructose and maltose. With taro total sugar content is 0.2‐0.8% fresh weight. Raffinose is present in one sample only.
Kinetics and equilibria of tea infusion: Rates of extraction of theaflavin, caffeine and theobromine from several whole teas and sieved fractions
Authors: Price William E. , Spiro Michael
Published: October 2006

The rates of infusion of theaflavin and caffeine into water at 80°C have been measured for Kapchorua Pekoe Fannings, Kapchorua Pekoe Dust, Betjan Flowery Broken Orange Pekoe and Rupai Flowery Orange Fannings whole teas and sieved fractions. For Kapchorua PF fractions the rates of theobromine infusion were also determined. Caffeine always infused faster than theobromine, and both infused faster than theaflavin. Rate constants were obtained from the slopes of first order kinetic plots which yielded straight lines with small intercepts. The rate constants for all three constituents increased by a factor of 2.2 as leaf size decreased from 850–1000μm to 500–600μm. The rates of extraction from whole teas varied more than fourfold. Kapchorua PD gave the most rapid rates and Betjan FBOP the slowest. Comparisons of similarly sized fractions of teas showed that leaf size distributions accounted for half these differences and the intrinsic properties of the leaf for the remaining factor of two. The Kenyan CTC teas gave higher rate constants than the Indian orthodox teas. From the rate constants, the effective diffusion coefficients for theaflavin and caffeine in Betjan FBOP leaf were calculated and found to be some 100 times smaller than in water. This shows the diffusion processes within the leaf to be complex ones.
Changes in sterol and phospholipid composition of apples during storage at low temperature and low oxygen concentration
Authors: Bartley Ian M.
Published: October 2006

Free sterol and phospholipid in the cortical tissue of apple were determined during storage of the fruits in air at 12 and 3.5°C and in 2 kPa O2 (98 kPa N2) at 3.5°C. In air at 12°C, the sitosterol content declined slightly (about 4%) during fruit ripening whilst phospholipid increased about 8%. At 3.5°C in air and 2 kPa O2, sitosterol content increased by 16% and phospholipid by 25–31%. The increase in phospholipid in 2 kPa O2 occurred more slowly than in air. Transfer of apples to air after 33 or 64 days in 2 kPa O2 led to rapid accumulation of phospholipid in the fruit (20% and 10%, respectively) compared with apples maintained in 2 kPa O2. An increase in concentration of phosphatidylcholine (PC) accounted for most of the change observed in total phospholipid.
Formation of two types of gels from bovine myosin
Authors: Hermansson Anne‐Marie , Harbitz Ole , Langton Maud
Published: October 2006

Myosin was isolated from bovine m. semimembranosus and gels were formed by heat treatment at different pH values and ionic strengths. The gels were subjected to rigidity measurements and their microstructure was studied by scanning electron microscopy. This article provides evidence that myosin can form two completely different gel structures in the pH range 5.5–6.0, depending on ionic strength. Fine stranded gel structures were formed at low ionic strength (0.25M KCl), whereas coarsely aggregated gel structures were formed at high ionic strength (0.6M KCl). The fine stranded structure had a higher rigidity than the coarsely aggregated structure. It was found that all fine strand myosin gels were formed from turbid solutions and the aggregate gels from clear solutions. When the pH was lowered to 4 in 0.6M KCl a strand‐type gel structure formed spontaneously on dialysis, even without heat treatment. This structure did not change in character on heating. It was concluded that the conditions required for the formation of strand‐type myosin gels were already present before the heat treatment and that the strands were made up of myosin filaments at certain pH and ionic strength combinations, which produced a turbid solution. The strand‐type structures were considered specific with regard to myosin interactions which was not the case for the aggregated structures. Variation of the heating temperature in the range 55 to 65°C had no major effect on the type of structure formed.
The effect of oat hulls, added to the basal ration for pregnant sows, on reproductive performance, apparent digestibility, rate of passage and plasma parameters
Authors: Mroz Zdzislaw , Partridge Ian G. , Mitchell Gordon , Keal Hugh D.
Published: October 2006

Thirty‐five Large White x Landrace sows were housed in individual stalls during gestation and were fed a standard diet (DE, 13.2 MJ kg−1) supplemented with oat hulls (OH), such that the ratios of basal diet to OH were 1:0, 9:1, 7:3 or 1:1. Digestibility and balance measurements were made during 7‐day periods beginning on days 45 and 90 of gestation. During a 3‐week lactation all sows were fed a standard diet (calculated DE, 12.5 MJ kg−1, CP, 152 g kg−1). Increasing OH intake increased mean net maternal weight gains and P2 fat depths during pregnancy and tended to increase total litter weight at birth. Sow‐milk solids content and litter weight gain during the 3‐week suckling period also tended to increase (nonsignificant), following increasing OH supplementation during gestation. Increasing OH intake tended to increase VFA and reduce cholesterol concentration in blood plasma at 56 days of gestation. The time taken to consume the once‐daily feed allowance increased and gastrointestinal transit time decreased as OH intake increased. The apparent digestibilities of the major nutrients were significantly depressed with increasing levels of OH in the diet but the total amounts of nutrients absorbed increased. The following values were calculated for OH by the difference method: apparent digestibility of DM, 0.31; apparent digestibility of ADF, 0.17; DE, 6.25 MJ kg−1; ME 6.01 MJ kg−1.
Yield and composition of cell wall residues isolated from various feedstuffs used for non‐ruminant farm animals
Authors: Carré Bernard , Brillouet Jean‐Marc
Published: October 2006

The contents of cell wall residue were measured in 14 common feedstuffs used for non‐ruminant farm animals by utilising a technique involving pronase and α‐amylase treatments. Comparison with the contents of neutral detergent fibre (NDF) revealed that the NDF procedure underestimated cell wall contents in the dicotyledonous plant materials. The losses of cell wall material due to the neutral detergent solution were correlated (r=0.931, P<0.01) with the amount of pectic substances present in the cell wall residues of the dicotyledonous plant materials. Cell wall residues were analysed for starch, crude protein, polysaccharides, condensed tannins, sulphuric acid lignin, acetyl bromide lignin, and ash. Condensed tannins in the cell wall residues of sorghum, rapeseed meal and field bean resulted in a large protein contamination (11.3–26.6%) of these residues and to an overestimation of their lignin content. Compositions of polysaccharides are discussed from chemical and nutritonal viewpoints.
Loss of selected water‐insoluble polysaccharides and component neutral sugars from swede (Brassica napus (cv. danestone)) and cereal bran measured during digestion in the pig caecum
Authors: Robertson James A. , Murison Sandra D. , Chesson Andrew
Published: October 2006

Sources of dietary fibre with a high pentose sugar content have been shown to have the greatest effect in promoting faecal bulking, though no underlying reason for this has been found. Pentose‐containing polysaccharides in dietary fibre are, in isolation, as degradable as other polysaccharides, though their known association with lignin could be important in helping to maintain the structural integrity and hence the bulking ability of a fibre source. Using a modified nylon bag technique, the potential digestibility of fibre prepared from a source rich in pentose sugars (cereal bran) and a source poor in pentose sugars (Swede; Brassica napus, cv. Danestone) was estimated in the pig caecum. Swede fibre was effectively completely degraded (within 18 h) but in bran 100% digestion was not achieved even with extended incubation. Rates of fibre component loss, estimated from material recovered from the nylon bags, showed that different fibre components were degraded at different rates and that the rate of degradation was not always linear. In swede xylose was less readily lost than other fibre components and the rate was non‐linear whilst in bran xylose was preferentially lost and at a linear rate. In bran arabinose was less readily lost. The results showed that the bulking effects of fibre sources with a high pentose sugar content were unlikely to be due solely to pentose content. Differences in rates of digestion suggested that different linkage groups contained within a component may be able to modify the degree of fibre digestion, most probably by the linkage of specific pentosans to lignin.
Effect of nitrogen fertiliser on the nitrate contents of field vegetables grown in Britain
Authors: Greenwood Duncan J. , Hunt John
Published: October 2006

The nitrate and percentage organic nitrogen contents of 14 vegetable and two arable crops were measured after they had been grown with different levels of N‐fertiliser. Foliage crops always contained substantial quantities of nitrate which increased with increase in the rate of N‐fertiliser application. Grain of legumes and cereals, storage roots of carrots, parsnips and sugar beet, and onion bulbs and leeks contained no detectable amounts of nitrate even when N‐fertiliser application rates were very high. Storage roots of red beet, swede and white turnip contained more than 3 mg NON g−1 dry weight when grown with exceptionally high levels of fertiliser‐N but contained very little when grown with the optimum amount of fertiliser‐N or less. An equation was developed that linked NON to percentage organic‐N for those parts of plants that could accumulate nitrate. It gave good fits to the data from seven crop species grown at a range of different levels of N‐nutrition. It is estimated from the foregoing data and a survey of household food consumption that the average British person consumes about 60 mg NON week−1 in field vegetables. If N‐fertilisers were withheld consumption would be about 30 mg and if excess were applied it would be about 120 mg NON week−1.
In Situ De‐esterification of lime pectin
Authors: King Karen , Mitchell John R. , Norton Grenville , Caygill John
Published: October 2006

The in situ de‐esterification of pectin in lime pulp by the action of pectinesterase (PE) has been investigated. It has been shown that the degree of pectin esterification is reduced to about 20% when the pulp is held at pH 8.5 for 90 min. The rate of de‐esterification by the enzyme in situ is highest when the pH is in the range 7.5–9.0 and the NaCl concentration is 0.1–0.3M. At pH values above 9 chemical de‐esterification becomes important. The activity of extracted lime PE was shown to be almost independent of pH in the range pH 6.0–9.0. It is suggested that the difference between the behaviour of the extracted and the in situ enzyme is due to the fact that the latter needs to be solubilised before it can act on some of the pectin in the pulp. In support of this it is found that the proportion of lime PE which can be extracted from the pulp decreases with decreasing pH and ionic strength, reflecting electrostatic binding to the cell wall.
Electrophoretic characterisation of low‐molecular weight wheat protein of variable solubility
Authors: Zawistowska U. , Bushuk W.
Published: October 2006

A low mol. wt protein (S protein) which has a high affinity for endogenous polar lipid was isolated from wheat gluten, partially purified and compared electrophoretically with low mol. wt components of several previously studied wheat protein preparations. Mobilities of S protein components in acidic polyacrylamide gel electrophoresis (PAGE) were very close to those of the chloroform/methanol soluble low mol. wt proteins (CM proteins). A fraction of S protein separated by gel filtration chromatography on Sephadex G‐50 (S‐III protein) was almost identical to CM proteins by two‐dimensional electrophoresis. Bands with mobilities similar to those of S‐III protein were present in PAGE patterns of gliadin, the low mol. wt fractions IV and V obtained from gliadin by gel filtration chromatography on Sephadex G‐200, and the albumin/globulin fraction of flour prepared by the Osborne solubility fractionation. Because of its variable solubility S protein cannot be unambiguously classified according to the Osborne solubility classification of plant proteins.
Quality of rainbow trout chilled‐stored after post‐catch holding
Authors: Dawood Abdul A. , Roy Rajat N. , Williams Clive S.
Published: October 2006

The shelf‐life of headed and gutted rainbow trout (Salmo gairdneri) was evaluated over period of storage at 0°C. There were three groups of samples: (i) fish held at 10°C for 6h and iced, (ii) fish held at 20°C for 6h and iced and (iii) fish held at 30°C for 6h and iced. Quality was assessed over the period of iced storage by measurements of total volatile bases (TVB), hypoxanthine, thiobarbituric acid, pH, water holding capacity (WHC) and tissue compressibility (TC). The results indicated that holding at various time/temperature periods before icing influences quality over the period of iced storage. Deterioration in quality was most pronounced when the fish had been held at high ambient temperatures of 30°C. Hypoxanthine values appeared to give an accurate indication of quality of freshwater fish. There was a linear increase in hypoxanthine values over the period of iced storage for all samples. However, for trout held at 30°C for 6 h before icing the values appeared to be highest. The coefficients of linear regression for fish iced immediately on receipt were lowest per day. It is suggested that hypoxanthine values may be used as chemical indicators of quality of freshwater trout.
Effects of temperature on the ripening of mango fruit (mangifera indica L. var. tommy atkins)
Authors: Medlicott Andrew P. , Reynolds Stephen B. , Thompson Anthony K.
Published: October 2006

The effects of temperature on the ripening of Tommy Atkins mango were studied. Ripening temperature can affect fruit colour, flavour and texture development differently. Fruits at 12°C did not ripen to full eating quality during the 16 days of the experiment. Sugar levels were comparable with those at other temperatures, but acid levels were higher; they retained some green coloration, had lower pulp carotenoids and showed incomplete softening. After 15 days at 17°C, fruits had softened and degreened to an acceptable level but had a poor pulp colour. They were comparatively high in sugars but were also high in acids, resulting in a low sugar:acid ratio. Fruits kept at 22, 27 and 32°C all showed the development of good quality characteristics of high chlorophyll breakdown, high pulp carotenoids, a good texture and a balanced sugar: acid ratio. Similar characteristics were shown at 37°C, although the peel generally appeared mottled and the pulp had slightly lower sugar:acid ratios.
Influence of repeated frying on the digestive utilisation of various fats
Authors: Varela Gregorio , Moreiras‐Varela Olga , Ruiz‐Roso Baltasar , Conde Rafael
Published: October 2006

Three types of fat, olive oil, soya bean oil and a solid cooking fat were used to fry potatoes, lean beef or sardines. The heating cycle was carried out once and repeated ten times and the true digestibility (TD) and energy digestibility (ED) determined by feeding trials on rats. The results showed very little change in either measurement compared with the fresh, unheated fats. Discarded olive oil from an industrial fryer was also examined and found to be only slightly lower in TD and ED than after ten cycles in the laboratory.
The tryptophan content of extractable seed proteins from cultivated legumes, sunflower and Acacia
Authors: Sastry M. C. Shamanthaka , Murray David R.
Published: October 2006

The total salt‐extractable protein from seeds of important cultivated legumes and sunflower kernels has a tryptophan content ranging from 0.91% (by wt) for chickpea (Cicer arietinum) to 1.99% (by wt) for green gram (Vigna radiata). In species with substantial albumin fractions, the tryptophan content of the albumin fraction is higher than that of the globulin fraction by factors ranging between 2.3 (pigeon pea, Cajanus cajan) and 20.3‐fold (pea, Pisum sativum, cv. Telephone). Although the protein content of Acacia seeds is relatively low (5–14% of seed weight), the tryptophan content of Acacia seed proteins is usually greater than that of the cultivated legumes (1.50–2.66%, by wt).
Effects of intraperitoneally injected vicine and convicine on the rat: Induction of favism‐like signs
Authors: Arbid Mahmoud S. S. , Marquardt Ronald R.
Published: October 2006

Rats were injected intraperitoneally with single or several successive doses of vicine or convicine. Single injections of these compounds at different concentrations caused increased respiration rates, generalised cyanosis, abdominal convolutions and, after several hours, death which appeared to be caused by asphyxiation. The tissues of the dead animals were engorged with dark brown blood and the large intestine and caecum contained entrapped gases and watery digesta and faecal matter. A second study demonstrated that injected vicine and convicine were cleared from the intraperitoneal cavity over several hours via the kidney and large intestine and that they were cleaved in the digesta of the large intestine and colon to divicine and isouramil. In a third study, rats were injected daily for 10 days with vicine or convicine. There were increases in spleen weight and blood monocytes and neutrophil counts and decreases in liver weight, blood glutathione and glucose concentrations, and lymphocyte counts. Blood from rats pretreated in vivo with convicine was shown to have an altered ultraviolet absorbance pattern. A similar pattern developed in vitro only in the presence of the aglycones of vicine (divicine) or convicine (isouramil) but not in the presence of the compounds themselves. The results of these studies demonstrate that vicine and convicine when injected intraperitoneally into the rat are converted to their aglycones which cause signs similar in many respects to those observed in the human metabolic disease, favism.
Extractability and functional properties of some legume proteins isolated by three different methods
Authors: Abdel‐Aal El‐Sayed M. , Shehata Ahmed A. , El‐Mahdy Ahmed R. , Youssef Mohamed M.
Published: October 2006

The extraction of protein from the flour of three grain legumes (faba beans, chick peas and fenugreek) was investigated using three different methods. Three protein preparations were made: by alkaline extraction and precipitation at isoelectric pH (protein isoelectric precipitate, PIP); extraction with 0.5 M sodium chloride solution and precipitation by ionic strength reduction (protein micellar mass, PMM); extraction in aqueous or saline solution in the presence of pepsin or pancreatin (partially hydrolysed protein preparation, PHP). Two of the protein isolates had higher values of water absorption and fat absorption compared to their corresponding parent flours, with fenugreek being the exception. Oil emulsification of the isolates was in the descending order: PMM, PHP and PIP. The PHP isolate had the highest nitrogen solubility index (NSI) values at pH 2.4 followed by PMM at pH 5.7–6.4 and finally PIP at pH 4.5–5.5.
High‐performance liquid chromatographic determination of oligosaccharides in leguminous seeds
Authors: Knudsen Ida M.
Published: October 2006

A simple and reliable high‐performance liquid chromatographic (h.p.l.c.) method has been developed for the determination of sucrose, raffinose and stachyose in leguminous seeds. A LiChrosorb NH2 column (Merck) and an acetonitrile+water solvent (65:35, by vol) at a flow rate of 1 ml min−1 were used for the separation. An interference type refractive index detector (Tecator) was used for the detection. With this detector the smallest amount of oligosaccharide detectable was 10 ng. With a traditional deflection type refractive index detector the smallest amount of oligosaccharide detectable was 240 μg. The oligosaccharides were extracted by placing the whole, dry seeds in boiling water for 30 min, blending the seeds and water, placing the whole suspension in a shaking bath at 60°C for 60 min, and removing the solid material by centrifuging. The extract was deproteinated by adding 65 parts of acetonitrile to 35 parts of extract (by vol), placing the mixture at 5°C for 60 min, and filtering off the resulting proteinaceous precipitate before injection into the chromatograph. The entire procedure has been successfully applied to soya beans, chick peas, garden peas and red kidney beans with recoveries of added raffinose in the range 97–102%.
Chemical composition and in‐vitro digestibility of thermochemically treated peanut hulls
Authors: Kerr Thomas J. , Windham William R. , Woodward Janet H. , Benner Ronald
Published: October 2006

Changes in chemical composition and digestibility of peanut hulls after a variety of thermochemical treatments were monitored. Mineral acids and base under elevated temperature (121°C) were generally ineffective for decreasing the fibrous, lignocellulosic component of the hulls. Only nitric acid‐treatment effectively decreased the relative lignin content of the hulls. The lignin:nitrogen ratio and carbohydrate content of treated hulls were both highly correlated with in‐vitro digestibility. Overall, thermochemical treatments did not increase the digestibility of peanut hulls.