Tissue degradation,amino acid liberation and bacterial decomposition of bulk stored capelin

Bulk stored capelin with high contents of feed in the gut is easily solubilised because of high proteolytic activity. The amino acids most quickly liberated are arginine, serine, histidine, leucine, lysine and tyrosine; glycine, aspartic acid and glutamic acid are liberated at a slower rate. Bacterial activity results in a rapid and considerable decrease in total amounts of tyrosine, lysine, serine, arginine and histidine. The main products formed by bacterial decomposition of lysine, histidine and arginine are cadaverine, histamine and putrescine, respectively. Storage of capelin in the presence of antibiotics increased the amounts of free amino acids and total amino acids. After 10 days' storage at 6°C, about 30% of the total amino acid content in fish treated with antibiotics were fee amino acids.     

Effects of cooking on content of amino acids and antinutrients in three Chinese indigenous legume seeds

The effects of domestic cooking on the content of amino acids and antinutrients of Phaseolus angularis, Phaseolus calcaratus and Dolichos lablab seeds were evaluated. Heat treatment (30 min) caused significant declines (P<0·05) in the apparent recovery of most of the essential amino acids except leucine and phenylalanine for P angularis, and except phenylalanine for P calcaratus. Cooking D lablab seeds (60 min) also resulted in a significant reduction (P<0·05) in the apparent recovery of all the essential amino acids except leucine, histidine, lysine and threonine. Increased cooking time for P angularis (60 min), P calcaratus (60 min) and D lablab (120 min) led to a lower apparent recovery of methionine (28·9–31·6%) and cystine (17·1–19·3%). Even with increased cooking times, the total essential amino acid levels in all three cooked seeds remained higher than that of the FAO/WHO requirement, except for methionine and cystine. Cooking (60 min) was found to be effective in reducing the tannin contents of P angularis, P calcaratus and D lablab seeds by 70·6, 64·6 and 74·6%, respectively. Upon cooking, phytate and trypsin inhibitory activity in different seeds were also reduced to different extents depending on the cooking times. ©1997 SCI     

Nutritive value of a mixture of tigernut tubers (Cyperus esculentus L.) and baobab seeds (Adansonia digitata L.)

The seeds of baobab (Adansonia digitata L.) and the tubers of tigernut (Cyperus esculentus L.) were analysed chemically for their proximate composition and amino acids. The tubers contained 47.9% digestible carbohydrates, 32.8% oil and 3.8% crude protein. The baobab seeds contained 24.1% digestible carbohydrate, 29.7% oil and 28.4% crude protein. A mixture of the vegetables was prepared from three parts of the tigernuts and one part of baobab seeds, by weight, such that a 10% crude protein meal was obtained. The chemical score of the mixed vegetable was 51%, based on limiting amino acids, i.e. those which contain sulphur. The level of antinutritive substances, such as tannin and tryptic inhibitors, in the raw vegetables were reduced by soaking or boiling.     

Amino Acid Patterns of Different Brands of Corn Steep Liquor

The free amino acids as well as the total amino acid content of Russian corn steep liquor (CSL), French CSL, British CSL, Italian CSL, German dried version of CSL, and Egyptian CSL were identified. The free amino acids and those obtained after the acid hydrolysis in each sample were almost the same. Alanine was the predominant free amino acid found. The major amino acids were arginine, aspartic acid, histidine, glutamic acid, glycine, leucine, lysine, serine and valine with the exception of Italian CSL and German dried CSL, while phenylalanine, methionine, tyrosine, proline as well as cystine were present in lesser amounts. The relation between the amino acid constituents of the different brands of CSL and their penicillin activity were discussed.     

Proteolytic activity,amino acid composition and protein quality of germinating fenugreek seeds (Trigonella foenum graecum L.)

This study determined the changes in proteolytic activity and trypsin inhibitor, due to germination for 120 h, and their relationships to amino acid content and protein quality. The activities of cas-ase, Hb-ase, and BAPA-ase, as well as the trypsin inhibitor of the fenugreek, increased as germination proceeded. Glutamic and aspartic acids were the richest amino acids in fenugreek seeds, followed by leucine, arginine, lysine and proline. After germination, the contents of aspartic acid, phenylalanine, tyrosine, threonine, tryptophan and valine increased, while those of glutamic acid, proline and four of the essential amino acids decreased. All the free amino acids increased after germination, while glycine decreased. Cystine, tryptophan and proline originated in a free form after germination. The chemical score, based on the essential amino acid pattern of whole egg protein, for fenugreek seeds, showed a marked decrease (21%) after germination. The in vitro pepsin, followed by pancreatin digestion, showed a slight increase for the germinated seeds. Germination of seeds lowered the C-PER, a result which indicates that the protein quality decreased.     

Free Amino Acids in Ham Muscle During Successive Aging Periods and Their Relation to Flavor

SUMMARY— The free amino acids and total ninhydrin positive material (NPM) in a 1% picric acid extract from dry-cured hams were measured after six different periods of aging. Correlation coefficients were calculated between amino acid values and taste panel scores. Significant (P < .051 increases were observed for NPM, serine, glutamic acid, threonine, leucine and isoleucine (not separated), valine, phenylalanine, proline, tyrosine, alanine, glycine and histidine during successive aging periods. Correlation coefficients between NPM and the organoleptic measurements of aged flavor, acidity, elasticity, crumbliness and softness were all highly significant. It k postulated that the increase in free amino acids can be attributed to action of the naturally occurring cathepsins. The free amino acids and their changes in concentration in relationship to flavor are discussed.     

THE AMINO ACIDS CONTENT OF SOME IRAQI DATES

SUMMARY –Amino acid content and nutritive value of three varieties of Iraqi dates was studied. Protein of the date was acid hydrolyzed for 24 hr and the amino acid content determined in a Phoenix automatic analyzer. The protein content on a fresh weight basis was 1.96% for Zahdi, 1.89% for Hillawi and 2.38% for Sayer. The following amino acids were present in these varieties: lysine, histidine, arginine, aspartic acid, threonine, glutamic acid, serine, prolin, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine and phenylalanine. Glutamic acid was present in highest concentration and Sayer variety contained more amino acids than Hillawi and Zahdi. Tryptophan and half-cystine may have been destroyed during acid hydrolysis.     

The contents of the neuro-excitatory amino acid β-ODAP (β-N-oxalyl-l-α,β-diaminopropionic acid), and other free and protein amino acids in the seeds of different genotypes of grass pea (Lathyrus sativus L.)

The free and protein amino acids of nine different genotypes of grass pea (Lathyrus sativus L.) seeds were analysed by HPLC with pre-column PITC (phenyl isothiocyanate) derivatisation. Among the free amino acids, homoarginine was quantitatively the most important (up to 0.8% seed weight) and stable while the neuro-excitatory amino acid β-ODAP (β-N-oxalyl-l-α,β-diaminopropionic acid) showed highest variation (0.02–0.54%) in the nine genotypes examined. Among protein amino acids, glutamic acid was quantitatively most significant, followed by aspartic acid, arginine, leucine, lysine and proline. The sulphur amino acid, methionine, showed the lowest concentration in all the L. sativus genotypes, and also in lentil (Lens culinaris) and in soybean (Glycine max) seeds analysed at the same time.     

Chemical,amino acid and fatty acid composition of Sterculia urens L. seed

The chemical, amino acid and fatty acid compositions of Sterculia urens seeds are reported. The cotyledons were found to be rich in protein (30.88%) and lipids (39.2%). The major amino acids in defatted Sterculia urens cotyledon flour (DSCF) were determined as glutamic acid, arginine and aspartic acid. Cysteine, methionine, tyrosine and histidine were observed in minor quantities. The ratio of essential to non-essential amino acids was observed to be 0.45. Among the essential amino acids, isoleucine was found to be higher than the reported FAO/WHO requirements. The GC-FID and GC–MS analysis revealed that the major fatty acids of the total lipid were stearic acid (31.72%), linoleic acid (28.83%) and palmitic acid (26.79%). Eicosadienoic acid (4.98%) and eicosatrienoic acid (2.96%) were also found in the total lipid.     

Determination of endogenous amino acid flow at the terminal ileum of the rat

In a comparative study endogenous amino acid flow was determined in twenty-four 190-g male rats (protein-replete) given diets containing synthetic amino acids as the sole nitrogen source but devoid of specific amino acids, and six rats fed a protein-free diet. Endogenous flows were not significantly different (P > 0.05) for aspartic acid, glutamic acid, serine and lysine but were significantly higher (P < 0.05) under protein-free alimentation than amino acid alimentation for proline, glycine and alanine. This indicates that the protein-free method did not lead to lowered endogenous amino acid excretions owing to an altered amino acid metabolism in the protein-free state. The loss of some amino acids may be enhanced under protein-free alimentation. The high apparent digestibility of the synthetic amino acids not excluded from the diets (histidine, arginine, threonine, valine, isoleucine, leucine, tyrosine, phenylalanine) indicated that their ileal excretions were mainly of endogenous origin. There were no significant differences (P>0.05) between the latter excretions and those obtained by feeding the rats a protein-free diet.     

In Vitro Digestibility of Thermally Processed Diafiltered Whey as Influenced by Water Activity

Diafiltered whey protein concentrates of varying water activity were heated at 121°C for 83.3 min (5000 s). Nitrogen and amino acid digestibilities were determined by the digestion cell technique. Whey nitrogen digestibility significantly decreased only at a water activity of .97. Although this heat treatment did not affect the amino acid profile of the protein, the relative digestibility of most amino acids was slightly increased at a water activity of .3 but relative digestibility decreased at a water activity of .5 and .97. At a water activity of .7, digestibility slightly increased for aspartic acid, threonine, glutamic acid, proline, cysteine, isoleucine, histidine, and arginine and decreased or remained unchanged for the other amino acids. At a water activity of .97, the relative digestibility of aspartic acid, threonine, serine, glutamic acid, glycine isoleucine, leucine, and phenylalanine, significantly decreased. Water activity plays a role in the structural organization of heated whey, which in turn affects the enzymatic liberation of amino acids.     

烟叶中游离氨基酸与化学成分派生值之间的关系

系统地分析了烤烟烟叶中游离氨基酸与化学成分派生值的关系。参试材料３１份,每个样品鉴定２６项指标。对试验数据分别进行简单相关分析、逐步回归和偏相关分析以及典型相关分析。简单相关分析结果表明,游离氨基酸组分与化学成分派生值之间均存在一定的相关关系。其中丝氨酸、甘氨酸、缬氨酸含量较高,钾／氯比值较高,则烟叶品质较好。逐步回归和偏相关分析系统地分析了游离氨基酸组分对化学成分派生值贡献的大小。其中对施木克值的贡献,以蛋氨酸最大,甘氨酸、丙氨酸和色氨酸次之;对于氧化钾与氯的比值来说,贡献最大的是丝氨酸。典型相关分析结果表明,游离氨基酸与化学成分派生值间的典型相关主要是由组氨酸、酪氨酸、脯氨酸、苯丙氨酸、亮氨酸、丙氨酸、苏氨酸、胱氨酸、天冬氨酸、氨与施木克值、两糖差及糖／碱比值相关显著引起的。     

Effect of industrial processing on amino acid content of broccoli

The levels of amino acids in broccoli stems and florets before and after various blanching times (in the case of freezing) and after bottling have been studied to elucidate to what extent nutrient quality is affected by industrial processing. The following amino acids (mg kg^?1 fresh weight) were identified by ion exchange chromatography in raw broccoli florets: glutamine (1338), proline (732), asparagine (578), valine (310), arginine (296), isoleucine (204), threonine (169), leucine (166), phenylalanine (159), aspartic acid (140), lysine (127), alanine (122), tyrosine (105), S‐methylcysteine (96), histidine (89), ornithine (59), glutamic acid (44), γ‐aminobutyric acid (31), glycine (11) and serine (0.2). Raw stems contained the same amino acids but at lower levels (p < 0.05). The levels of all these amino acids fell during both industrial processes studied (bottling and freezing after blanching for 60, 90, 120 and 150 s), particularly in the frozen samples (losses of 50–70% in the florets and 20–50% in the stems). In summary, losses of broccoli amino acids were lower if blanching times were kept short. The optimal blanching time at 94 °C for florets and stems intended for freezing was 90 s, and this did not result in any great loss of nutritional value related to amino acid content. Bottled florets had greater nutritional value than those frozen after being exposed to the longest blanching times (120 and 150 s). © 2001 Society of Chemical Industry     

Influence of nitrogen on the biological aging of sherry wine

Nitrogen compounds are essential to the growth and metabolism of yeasts. The uptake and metabolism of nitrogen compounds by Saccharomyces cerevisiae depend not only on the strain and its physiological condition, but also on the chemical and physical properties of its environment. The effect of the addition of different amino acids (L ‐proline, L ‐threonine, L ‐arginine, L ‐glutamic acid, L ‐leucine and L ‐valine) to nitrogen‐depleted natural or nitrogen‐free synthetic wine on the cell growth, flor velum formation and sherry wine compound production was investigated under controlled biological aging by S. cerevisiae var. capensis strain G1 a typical flor yeast. The formation of flor velum was dependent on particular amino acid, oxygen availability and the composition of wine. Consumption of glycerol was related with the cell growth; in contrast, acetaldehyde tended to be released. Amino acid supplementation resulted in the release to wine of amino acids, esters and higher alcohols. The amino acid which was released in nearly all cases was L ‐leucine. Addition of L ‐glutamic acid resulted in the release mainly of ethyl acetate, in the case of L ‐leucine isoamyl alcohols were released, and for L ‐valine isobutanol. In the three cases, 1,1‐diethoxyethane was released in large quantities. The findings might indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential. Copyright © 2006 Society of Chemical Industry     

一种植物乳杆菌对干酪模型成熟中微生物及蛋白质水解的影响

采用无菌条件下生产的新鲜干酪凝块制作干酪模型,以WSN,12%TCASN和氨基酸含量等为指标测定植物乳杆菌SP-3对其的促熟作用。微生物测定表明SP-3在干酪模型的成熟过程中(12d)能保持较高的浓度;WSN结果表明SP-3对干酪中蛋白质的初级水解无显著影响;12%TCASN的结果表明SP-3影响了干酪中小肽的形成;5%PTA-SN和总游离氨基酸浓度测定结果表明植物乳杆菌SP-3促进了体系中游离氨基酸的产生;游离氨基酸的分析显示谷氨酸、亮氨酸、组氨酸的含量明显高于对照组,而丝氨酸、赖氨酸、脯氨酸的含量低于对照组。以上结果表明,植物乳杆菌SP-3能加快干酪体系中蛋白质的水解进程,具有促进干酪成熟的作用。     

Protein and amino acids contents of Libyan dates at three stages of development

The protein and amino acid contents of three Libyan date varieties (Taasfirt, Bikrari and Khadhrai) at different stages of fruit development were determined. The protein concentration in all three varieties was highest at the green stage. Seventeen amino acids were detected and quantified; their concentrations (dry weight basis) were higher in Khadhrai and Bikrari than in Taasfirt. At the green stage the concentrations of glutamic acid, aspartic acid, lysine, leucine, alanine and serine were highest. At the yellow and ripe stages, glutamic acid, aspartic acid, lysine, leucine, proline and glycine were present in high concentrations. For most amino acids the concentrations were higher at the yellow stage than at the ripe stage. Copyright © 2004 Society of Chemical Industry     

ISOLATION AND IN VITRO HYDROLYSIS OF GLOBULIN G1 FROM LENTILS (LENS CULINARIS, MEDIK)

The major globulin fraction from lentil seeds was investigated with respect to in vitro hydrolysis by trypsin and chymotrypsin. Globulin was isolated by a NaCl-ascorbate extraction procedure and purified by DEAE-cellulose chromatography and gel filtration chromatography on Sepharose CL-6B. The purity and identification of the protein were performed by PAGE. The native globulin, with a molecular weight of 375 kD, was resolved by SDS-PAGE into twelve polypeptides with molecular weights ranging from 61 to 14.5 kD. Native and heated globulin G1 was hydrolyzed with trypsin and chymotrypsin. SDS-PAGE indicated that native globulin was more resistant to digestion than heated protein. Amino acid analysis of the major globulin revealed that glutamic acid was present in the largest concentration, followed by aspartic acid, arginine and leucine. As is also the case for other legumin-like globulins, lentil G1 was deficient in sulfur-containing amino acids.     

Apparent ileal digestibility of amino acids in feed ingredients determined with broilers and layers

The apparent ileal digestibility of amino acids in eight feed ingredients were determined using broilers and layers. The ingredients included three cereals (wheat, sorghum and maize), one cereal by‐product (wheat middlings), three oilseed meals (canola, cottonseed and soybean meals) and one animal protein meal (meat and bone meal). Dietary protein in the assay diets was supplied solely by the test ingredient. All diets contained 20 g kg^?1 acid‐insoluble ash as an indigestible marker, and each diet was offered ad libitum in mash form to five replicate pens of 42‐day‐old broilers and 60‐week‐old layers. The digestibility coefficients of most amino acids for wheat and sorghum were similar (P > 0.05) in broilers and layers. The digestibility of most amino acids for maize was higher (P < 0.05) in broilers compared to those in layers. The digestibility of individual amino acid for wheat middlings was higher (P < 0.05) in layers than in broilers. In general, the digestibility of amino acids for cottonseed meal, soybean meal, and meat and bone meal were similar (P > 0.05) between broilers and layers. The influence of class of bird on digestibility in canola meal was variable. The digestibility of threonine, valine, isoleucine, leucine, phenylalanine, glutamic acid and alanine were higher (P < 0.05), and those of methionine, histidine and lysine were lower (P < 0.05) in broilers compared to layers. These results suggest that the practice of using amino acid digestibility values generated with broilers for layers may not be appropriate for all feed ingredients. Copyright © 2006 Society of Chemical Industry     

Comparative composition of aerial and subterranean potato tubers (Solanum tuberosum L)

The composition of aerial and subterranean tubers of two potato genotypes cvs Desiree (red skin) and Epicure (white skin) was compared immediately after harvest using a range of analytical methods. Irrespective of genotype, aspartic acid, arginine, glycine, glutamic acid, histidine, leucine, serine, threonine and total amino acid concentrations were significantly higher (P<0·05) in aerial compared with subterranean tuber tissue. Significant increases (P<0·05) in valine in aerial tubers, but no significant differences in alanine, tyrosine and iso-leucine, when compared with subterranean tubers of cv Desiree, were found. In cv Epicure, alanine, tyrosine and iso-leucine were significantly higher in aerial tubers (P<0·05); however, no significant differences in valine were recorded. There was no significant increases in lysine and phenylalanine between tuber types. Regardless of genotype α-solanine, α-chaconine, chlorogenic acid, chlorophyll and crude protein concentrations were significantly higher in aerial tubers compared with subterranean ones (P<0·01). No significant increases in total lipids between tuber types were found. In cv Desiree, ascorbic acid content was not significantly different between aerial and subterranean tuber tissue, but in cv Epicure concentrations were significantly higher (P<0·01) in aerial tubers. Starch concentrations were significantly higher in subterranean tubers of both cultivars (P<0·05). Sugar content was significantly higher in aerial tubers of cv Epicure (P<0·01), but not significantly different between aerial and subterranean tubers of cv Desiree. Regardless of genotype, phosphorus, magnesium, potassium, zinc, manganese and sodium concentrations were significantly higher (P<0·05) in aerial tubers. Iron and copper concentrations were significantly higher in aerial tubers of cv Desiree (P<0·01), but significantly less in cv Epicure compared with subterranean tubers (P<0·01, P<0·05). Calcium concentrations were not significantly different between aerial and subterranean tubers of cv Desiree, but significantly higher in aerial tuber tissue of cv Epicure (P<0·01). Total gross energy (mJ kg⁻¹ FW) was higher in aerial tubers of cv Desiree compared with subterranean tubers (P>0·05), but not significantly different between aerial and subterranean tubers of cv Epicure. The potential applications of aerial tubers for industrial purposes are discussed. © 1997 SCI.     

Changes in the amino acid compounds of the wholecrop wheat during ensiling and after fermentation

Changes in amino acid fractions of chopped low-to-medium protein whole-crop wheat were studied at four stages of maturation and at two stages after a 24 h wilting period. Tests were carried out after an ensiling period of 90 days, and after a further 7-day post-fermentation aerobic exposure. Total amino acids contents in the dry matter during the fermentation period remained stable. Quantities of essential amino acids decreased during maturation and fermentation and remained stable during post fermentation aerobic exposure. The highest amino acid concentrations recorded in the fresh material were those of arginine, lysine, glutamic acid, alanine, leucine, glycine and aspartic acid. Free amino acids varied from a low level in the fresh material < 10% of the total amino acids to ca 65% after the aerobic process. Ammonia-N content increased in the silage and remained relatively stable on post fermentation aerobic exposure. The concentration of all free amino acids increased except arginine and glutamine during the ensiling period and post fermentation aerobic exposure. After wilting, an increase in free amino acids and a decrease in insoluble amino acids was recorded. The changes in concentration of 18 amino acids during ensilage and following post fermentation aerobic exposure are given.