Chemical and nutritional changes in soybean during germination

Germination of soybeans for 6 days depressed the trypsin inhibitor activity by 32%. Oil content, acid value, iodine value and total unsaturated fatty acids of soybean oil decreased while peroxide value and total saturated fatty acids pronouncedly increased. Percentage of palmitic and linoleic fatty acids were highly affected during germination. Analysis of the hydrocarbon and sterol classes revealed n-tricosane and β-sitosterol to be, respectively, the major components. Marked changes in both hydrocarbon and sterol constituents occurred upon germination. Different periods of soybean germination increased non-protein nitrogen and decreased reducing sugars. However, total ash content decreased due to soaking; thereafter it was constant for the rest of the germination period. Different amino acid components increased due to germination when compared with their content in dry seeds. The protein solubility of germinated soybean was higher in H₂O, 5% NaCl and 0·02m NaOH than it was in ungerminated seeds. Water and oil absorption, emulsification and foaming capacities of soybean were increased after germination. A marked improvement in digestibility by pepsin was noticed while tryptic digestibility was still low (38%). PAGE patterns showed drastic changes in both low and high molecular weight protein fractions due to germination.     

Some changes in cottonseed oil during frying of flafel and eggplant

The changes in the characteristics, composition and technological properties of cottonseed oil during heating for 50 h at 200°C in the presence of air were studied. The effects of the heated oil in frying two types of Egyptian vegetable—flafel and eggplant—were also examined. The results showed that as the heating time of the oil increased: (a) the free fatty acids increased and both iodine value and peroxide number decreased; (b) the triglycerides hydrolysed and (c) the loss of oil weight, the tendency of oil to foam and the time necessary to fry the vegetable increased.     

Physicochemical changes of oat seeds during germination

The physicochemical properties of native and germinated oat seeds cultivated in China and their correlations were investigated. The growth curve during germination of oat seeds was described. The malt yield was 84% at the end of malting. The losses by removing of shoots and rootlets were the major cause of the total dry matter losses in the last 24 h of germination. With total starch enzymes activities increasing continuously, the starch content decreased considerably from 60% to 20%, and the reducing and soluble sugars contents increased. Oat seed kernel protein increased slightly, but the lysine content increased almost 30% at the end of germination. The phytic acid content declined from 0.35% to 0.11% during germination. There is a significant correlation among compositions including starch, protein, free and reducing sugars, free amino acid, and phytic acid. A close correlation also was found between the colour of malt flour dried at 50 °C and the length of shoots and rootlets. The results suggest that oats grown in China are a good food material and that germination can improve their nutritional properties.     

发酵香肠成熟过程中的生化变化

本文综合概述了有关发酵香肠在成熟过程中的一系列复杂生物化学变化及其影响因素,并提出今后有关发酵香肠的主要研究方向.     

Biochemical and nutritional changes in fish proteins during drying

Biochemical and nutritional changes in the muscle proteins of a lean marine fish Nempiterus japonicus during drying at 50, 60 and 70°C were investigated. Solubility of proteins in water, 0.6 M NaCl, 1.5 M urea, 8 M urea and 10 g litre^?1 sodium dodecyl sulphate (SDS) decreased as drying progressed at all three temperatures; most of the decrease occurring in the initial 4 h of drying SDS-polyacrylamide gel electrophoresis of 1.5 M urea, 8 M urea and SDS extracts showed that higher molecular weight (MW) protein fractions were more sensitive to drying and disappeared much earlier from electropherograms than the lower MW protein fractions. Residual solubility of proteins near the pH range of 4–6 was found to increase during drying, but solubility at acid and alkaline pH was adversely affected. Decrease of solubility by drying was more affected at acid pH, especially at higher temperatures than at alkaline pH. Sulphydryl groups registered a regular and sharp decrease with drying except at 50°C, where initially an increase was observed. Apart from disulphide and hydrophobic bonds, free amino groups also appear to be involved in denaturation reactions during drying. Pepsin digestibility of fish muscle decreased slightly during drying but a clear relationship with drying temperature was not evident. Highly significant differences in proteins between protein efficiency ratio (PER), net protein utilisation (NPU) and biological value were observed between the drying temperatures. The PER and NPU of fish dried at 60°C were significantly higher than those dried at 50 or 70°C.     

萌芽过程中芝麻主要成分的动态变化

为研究芝麻萌芽过程中主要成分的变化规律,采用气相色谱,氨基酸分析仪和液相色谱分别测定芝麻脂肪酸、氨基酸和木脂素的组成和含量变化,并分析了芝麻脂肪品质变化。结果表明:随着萌芽时间延长,粗蛋白含量先减少后增加再减少;粗脂肪含量从萌芽初期的58. 5%下降到96 h时的27. 2%;亚油酸和亚麻酸的相对含量先增加后降低,在萌芽6 h时达到最高,分别为45. 30%和0. 79%;必需氨基酸含量和酸性氨基酸含量增加,非必需氨基酸含量和碱性氨基酸含量减少;芝麻林素含量一直呈下降趋势,而芝麻素含量在萌芽初期缓慢上升后逐渐下降;萌芽过程中,芝麻脂肪的酸价、过氧化值持续升高。上述变化规律可以为萌芽芝麻食品的开发提供理论依据与数据支撑。     

Biochemical changes during processing of traditional Jinhua ham

Jinhua ham is the most famous traditional meat product of China and one of the most famed dry-cured hams in the world. Its processing consists of six stages: green ham preparation, salting, washing and sun-drying and shaping, ripening, and post-ripening. Intense proteolysis and lipolysis occur during processing period. As a result, the content of free amino acids in final ham products is 14-16 times that of green ham, and 191 volatile compounds have been identified during processing, which make a major contribution to the flavor of Jinhua ham.     

Biochemical changes occurring during the manufacture of budu

The changes that occur during the commercial production of budu, a Malaysian fish sauce were examined. It was shown that the maximum volume of liquid was produced after 140 days and that proteolysis continued to occur until 200 days when 56% of the insoluble fish protein had been hydrolysed into soluble form. The colour was produced early during the fermentation. The aroma constituents, ammonia and trimethylamine, were produced early in the fermentation process, but the volatile fatty acids did not appear when fresh fish (Stolephorus) was used for the fermentation. In the commercial production, n-butanoic acid concentration remained constant during the fermentation but ethanoic acid did increase during the period. The salt concentration and the pH were approximately constant throughout, at 26% and 5.65, respectively.     

Biochemical changes during moulding of self-heated hay in Dewar flasks

Moulding of hay was studied on samples moistened to 40% water content and allowed to heat aerobically in Dewar flasks. Reducing sugar, particularly glucose, decreased and there were increases in pH and in soluble and volatile N. Smaller increases in soluble and volatile N, as well as the conversion of nonreducing sugar to reducing sugar occurred in moistened, sterile hay incubated at 40°; these are analogous to changes during moist wilting of grass. Invertase activity in the hay was confirmed by incubation with sucrose and water.     

Biochemical changes in an intermediate moisture cecina-like meat during storage

Biochemical and microbiological changes in two cecina-like products were evaluated during storage. Two products were prepared, one by salting and the other by infusion in a salt-glycerol solution. The samples were vacuum packed and tested monthly for pH, colour, haematin complex, soluble nitrogen and microbiological spoilage. Proteolysis and increase in pH showed a high correlation for both samples. Temperature-dependent changes in colour and concentration of haematin complex during storage were also found in both samples. The activation energy for haematin transformation was found to be around 1 kcal/mol. Based on the low activation energy for haematin complex degradation (around 1 kcal/mol) for both samples, this process may be regarded as a low energy biochemical process.     

白肋烟种子萌发的生理生化动态研究

以TN86种子为材料,分析了白肋烟种子萌发特征及有关活性酶与相关物质的变化动态。结果表明,呼吸强度、淀粉酶与可溶性总糖和还原糖、蛋白酶与总游离氨基酸、脂肪酶与脂肪酸,以及过氧化物酶(POD)、多酚氧化酶(PPO)、可溶性蛋白质、脯氨酸(pro)、丙二醛(MDA)等的活性或含量都随萌发进程呈上升趋势,其间虽有所波动,但最高峰值期大都在第84-168h之间,仅POD与PPO活性和MDA含量在萌发中期才开始明显上升,直至萌发结束时达高峰值。淀粉酶、蛋白酶、脂肪酶活性与各自催化水解的产物含量呈极显著正相关;而粗脂肪含量随萌发进程而下降,与脂肪酸呈极显著负相关。萌发集中在48-72h,发芽势90%,同步指数0.92。萌发动态符合Logistic生长曲线方程。     

粟米发芽过程中成分含量变化研究

研究发芽对粟米化学成分含量变化影响,包括灰分、粗脂肪、粗蛋白、植酸、γ–氨基丁酸、总黄酮;结果表明,随着发芽时间增加,粗蛋白、γ–氨基丁酸和总黄酮含量显著增加(ρ<0.05);粗脂肪、植酸含量显著降低(ρ<0.05),整个发芽过程灰分含量稍有减少。通过发芽改善粟米营养及功能特性,开发发芽粟米产品具有广阔前景。     

Immunochemical study of changes in the soluble proteins of wheat during germination

During germination and early growth the general immuno-electrophoretic pattern of soluble proteins of two wheat species showed similar changes. Several of the antigenie proteins detected, including the esterase and peroxidase, did not appear to be modified up to 13 days from the start of germination. Others decreased in quantity or disappeared altogether. In contrast to the esterase and peroxidase, the amylolytic enzymes exhibited marked changes. The antigenic β-amylases existing in electrophoretically different forms in the mature wheat seeds appeared to change to an electrophoretically more homogeneous form in germinated seeds. The (β-amylase in germinated wheat seeds retained its antigenic resemblance to the forms of the mature seeds but differed in other aspects from these isozymes. The antigenic α-amylase of germinated seeds was shown to be absent from the mature seeds, even as an inactive-form. Its increase in activity during germination was ascribed to a synthesis rather than activation of a precursor or proenzyme.     

国内外不同品种啤酒大麦萌发过程中蛋白质的变化

采用9种国内外啤酒大麦为材料,以考马斯亮蓝G-250方法榆测其萌发过程中清蛋白、球蛋白、醇溶蛋白和谷蛋白含量的动态变化,并进行SDS-PAGE电泳分析.结果表明:大麦萌发过程中,清蛋白含量逐渐升高,平均增加2.116倍;球蛋白含量先升高后降低,萌发后比萌发前略高;醇溶蛋白和谷蛋白的含量逐渐降低,分别平均减少1.983和2.167倍.国内外不同品种啤酒大麦的清蛋白和球蛋白组成基本相同,醇溶蛋白存在显著的差异,谷蛋白也有一定的差别,因此醇溶蛋白可以作为鉴定大麦不同品种和品质的依据之一,谷蛋白也可以作为一种辅助的鉴别依据.     

Biochemical changes during ripening of some sudanese date varieties

Changes in the chemical composition of three popular Sudanese varieties of date (Jawa, Bentamoda and Mishrig Wad Laggai) during ripening are described and are related to changes in texture and in the activities of various degradative enzymes in the fruit. Total invertase levels were high throughout maturation of the three varieties. Although the proportion of soluble enzyme increased during ripening solubilisation did not appear to influence the relative amounts of sucrose and reducing sugars in the ripening fruit. Both cellulase and polygalacturonase were absent or at low levels in the green fruit but displayed large increases in activity during ripening. This enhancement was reflected in a reduction in fruit firmness although little change in cellulose or pectin levels was apparent analytically until the final stage of ripening. Despite a considerable rise in pectinesterase activity during ripening no significant trend could be discerned in the degree of esterification of pectin suggesting that the enzyme is of minor importance in softening of these fruit.     

Biochemical changes in green sweet peppers during storage at different temperatures

The effect of temperature on the levels of moisture, ascorbic acid, proteins and phenolic compounds in green sweet peppers (cvs. Sumo and Quadrato d'Asti) was investigated after seven days' storage at a relative humidity of 85–90%. Chemical composition did not differ appreciably after storage at 10°C, whereas changes were found after storage at 20°C and 30°C. Therefore, 10°C was the most favourable storage temperature for peppers although, at 20°C, retention of quality was adequate in terms of texture and appearance.     

Proteins in oats; their synthesis and changes during germination: a review

Oats (Avena sativa L.) are distinct among cereals due to their considerably higher protein concentration. At the same time oats possess a protein quality of high nutritional value and a special protein composition. Most cereals like wheat, barley, and rye have a high percentage of prolamins, the alcohol-soluble fraction, which usually contains most of the storage proteins, but oats are an exception. Their major storage proteins belong to the salt-water soluble globulin fraction, whereas oats prolamins are a minor component. During oats groat development, most obvious is the fairly linear increase in the globulin fraction. Oats globulins share structural features with the 11 S globulins of legumes and other dicots. Amino acid composition of oats is superior to that of other cereals due to the higher amount of limiting amino acids like lysine and threonine. During germination, total amino acid analysis revealed an increase in essential amino acids like lysine and tryptophan, which leads to an increased nutritional value of germinated oats. Oats protein products including globulin have been chemically modified by various methods to improve their functional properties.     

Morphological changes of starch granules during grain filling and seed germination in wheat

In this study, the morphological changes of wheat starch granules during grain filling and seed germination were observed under scanning electron microscopy. Until 3 days post anthesis (DPA), the pericarp tissue was the major site of starch deposited. From 6 DPA, the size and the number of granules in endosperm gradually increased. The “double disk structure”, “pin holes”, and “equatorial groove” at the surfaces of the granules were observed during grain filling, these micro‐structural features might aid the enzymatic hydrolysis of starch granules during seed germination. The equatorial groove of granule was more susceptible to enzymatic hydrolysis than the flat surface.     

Biochemical changes during the preservation stage of ripe olive processing

The influences of initial sodium chloride (6% and 0% w/v in tap water) and acetic acid concentrations (0.3%, and 0.6% v/v), use of starter culture, and aerobic versus anaerobic conditions on the biochemical changes that take place throughout the preservation stage of ripe olive processing were investigated. Glucose, fructose and sucrose were completely consumed during preservation. Mannitol and malic acid were metabolized only in the presence of lactic acid bacteria or oxidative yeast (aerobic treatment). The main metabolites produced were lactic and acetic acid in aerobic or anaerobic treatments inoculated with Lactobacillus plantarum. Methanol and ethanol were present in all the brines although in a lower concentration when conditions were aerobic. Thus, induced lactic fermentation led to the most efficient utilization of carbohydrates and yielded the most suitable physicochemical characteristics for ripe olive preservation.