Changes in nitrogenous and other chemical constituents,protein fractions and in vitro protein digestibility of germinating fluted pumpkin ( Telfairia occidentalis Hook) seed

The effect of 7 days of germination on levels of nitrogenous and other nutrition related parameters, protein fractions and in vitro protein digestibility of fluted pumpkin (Telfairia occidentalis) seed was studied. The non-protein nitrogen gradually increased and the protein nitrogen content decreased during germination. Albumin and globulin fractions were found to be the major seed proteins of fluted pumpkin seeds, constituting about 58.6% of the total protein of the ungerminated (raw) seeds. The protein fractions, albumin and glutelin, were observed to increase by 61.5% and 57.0%, respectively, while a 54.6% decrease was noted in the prolamine fraction. The globulin fraction increased at the beginning of germination but decreased at the end. Germination significantly (p 0.05) increased the crude protein, nitrogen solubility and in vitro protein digestibility but decreased the fat, phytic acid and polyphenol contents of the seeds.     

Transglutaminase polymerisation of buckwheat (Fagopyrum esculentum Moench) proteins

Recently, screening of transglutaminase (TGase) treatment on several gluten-free cereals revealed significant improvements on the baking performances of buckwheat flour by promoting protein networks. In this study, the impact of TGase on the protein fractions of buckwheat flour was investigated in order to better understand the activity and specificity of the enzyme. Albumin, globulin, prolamin and glutelin fractions were extracted from the flour and incubated with TGase. Capillary electrophoresis, two dimensional (2D) gel electrophoresis and size exclusion chromatography (SEC) were performed on each fraction. Capillary electrophoresis and 2D gel electrophoresis revealed that buckwheat main storage proteins, i.e. 2S albumin, 13S and 8S globulin, were cross-linked after TGase treatment. SEC showed the presence of high molecular weight (HMW) protein polymers in the TGase-treated albumin and globulin fraction. Analysis of the amino acid composition of the fractions revealed high amounts of glutamine and lysine residues in all fractions. In conclusion, the increase in the average molecular weight of buckwheat proteins and the formation of HMW protein polymers after TGase treatment are responsible for the improved functionality of buckwheat flour in terms of breadmaking potential. The enzyme was revealed to be not fraction specific as all fractions were TGase-reactive.     

Transglutaminase polymerisation of buckwheat (Fagopyrum esculentum Moench) proteins

Recently, screening of transglutaminase (TGase) treatment on several gluten-free cereals revealed significant improvements on the baking performances of buckwheat flour by promoting protein networks. In this study, the impact of TGase on the protein fractions of buckwheat flour was investigated in order to better understand the activity and specificity of the enzyme. Albumin, globulin, prolamin and glutelin fractions were extracted from the flour and incubated with TGase. Capillary electrophoresis, two dimensional (2D) gel electrophoresis and size exclusion chromatography (SEC) were performed on each fraction. Capillary electrophoresis and 2D gel electrophoresis revealed that buckwheat main storage proteins, i.e. 2S albumin, 13S and 8S globulin, were cross-linked after TGase treatment. SEC showed the presence of high molecular weight (HMW) protein polymers in the TGase-treated albumin and globulin fraction. Analysis of the amino acid composition of the fractions revealed high amounts of glutamine and lysine residues in all fractions. In conclusion, the increase in the average molecular weight of buckwheat proteins and the formation of HMW protein polymers after TGase treatment are responsible for the improved functionality of buckwheat flour in terms of breadmaking potential. The enzyme was revealed to be not fraction specific as all fractions were TGase-reactive.     

Characterisation and functional properties of Australian rice protein isolates

Albumin, globulin, glutelin and prolamin fractions were isolated from an Australian rice variety (cv. Langi) and characterised by yield, protein content and molecular weight profile using both capillary electrophoresis (SDS-CE) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The influence of pre-extraction enzymatic hydrolysis of starch and heating to 70 °C was also investigated, as was the extraction of the glutelin fraction without prior removal of the albumin and globulin fractions. Pre-extraction treatment affected mainly the albumin fraction, increasing dry matter yield but reducing protein content. SDS-CE was able to separate the protein fractions over a wider molecular weight range than SDS-PAGE, and the peaks from SDS-CE showed slightly higher molecular weight compared to equivalent bands from SDS-PAGE. The glutelin fraction extracted without prior removal of albumin and globulin fractions had different characteristics compared to those obtained by conventional extraction methods. Pre-extraction hydrolysis of starch did not significantly affect the emulsifying, foaming and gelling properties of extracted protein. Although rice glutelin had poor solubility, emulsifying and foaming properties in aqueous systems, it had good gelling properties which could be important for food applications.     

Nutritional potential ofVigna minima (Roxb.) Ohwi and Ohashi:

Quantitative variation in different fractions of seed proteins and their amino acid levels in populations ofVigna minima (Roxb.) Ohwi and Ohashi and inV. umbellata cv. IC 1568 — the rice bean — were investigated. Globulin I fraction, together with globulin II, constitutes 38 to 54 per cent of the total seed protein. The alkali soluble (glutelin) fraction is the second largest fraction. Both these fractions show broad range of variation, suggesting a broad genetic base. The profiles are population specific; the coastal population, which contains higher seed protein also possesses maximum levels of globulin I and glutelin fraction suggesting its potentiality for breeding lines with high protein content, high nutritive value, and salt tolerance. Protein content is positively correlated with globulin I and glutelin fractions, which are in turn positively correlated with each other. The amino acid profiles are specific not only to the fractions but also to the populations. The range of variation in the levels of all amino acids in different fractions is broad suggesting substantial genetic diversity. The average levels of lysine and sulphur amino acids are high in globulin I and glutelin fractions.     

Fundamental study on protein changes taking place during malting of oats

During the malting process, storage proteins are degraded by proteolytic enzymes into small peptides and amino acids. The activity of these enzymes was measured during malting of oats and was found to be increased. To quantify proteolytic degradation, proteins of unmalted, germinating and malted grains were fractionated. After extracting the oat proteins (Osborne fractionation), protein fractions were analysed using a Lab-on-a-Chip technique, which separates the proteins – based on their molecular weight – by capillary electrophoresis. This new technique for the analysis of proteins was supported by using two-dimensional gel electrophoresis. In addition, amino acid analysis was carried out. In general a degradation of proteins to small peptides and amino acids could be observed in the globulin, prolamin and glutelin fractions. In the albumin fraction a protein increase was observed, which is due to the fact that this fraction contains the majority of the metabolically active proteins. Amino acid analysis supported the observation of increased protein amount in the albumin fraction and decreased protein amounts in the other fractions. Some proteins, which have not been described in the literature, were detected in the albumin and glutelin fraction, since Lab-on-a-Chip technique allows detection of proteins with low molecular weights of 4.5 kDa.     

Antioxidative properties of partially purified barley hordein, rice bran protein fractions and their hydrolysates

Antioxidative properties of proteins from barley and rice bran and their hydrolysates were examined. Three major hordein fractions of barley, B, C and D hordeins, were partially purified by gel filtration. Albumin, globulin, prolamin and glutelin fractions of rice bran were fractioned by the Osborne method. Hydrolysates of these protein fractions were prepared by digesting with pepsin followed by trypsin. Antioxidant properties in terms of antioxidative activity against linoleic acid peroxidation and reducing activity without the lipid adjuvant were investigated. The globulin fraction from rice bran protein revealed the strongest antioxidative activity throughout the incubation time of 7 days (p ≤ 0.05). The albumin fraction of rice bran protein showed the highest reducing activity (6964 μmol of Fe²⁺) followed by globulin, prolamin, glutelin and hordein fractions with activities of 2904, 2017, 1809 and 1333 μmol of Fe²⁺, respectively (p ≤ 0.05). Partially purified C hordein exhibited the highest reducing activity compared with B and D hordeins. Protein hydrolysates obtained after digestion with pepsin and trypsin exhibited much greater antioxidative, as well as reducing, activities than those from before digestion.     

Total protein and protein fractions in tubers of Group Andigena and Phureja-Tuberosum hybrids

Proteins of potato clones with a wide range of total protein content and from two different genetic backgrounds were divided into albumin, globulin, prolamin, glutelin and residual fractions. More soluble protein was recovered from older, more mature tubers than was recovered from younger tubers. Differences in amounts of the protein fractions were detected among the clones. However, the amount of each fraction within a clone was highly correlated with total protein. The percentage of the total protein allocated to each fraction remained relatively constant among the clones which are assumed to be producing mature tubers. Soluble protein (albumin plus globulin) correlated highly with total protein in both Andigena and Phureja-Tuberosum' selections.Scientific Journal Series Article 11, 153 of the Minnesota Agricultural Experiment Station. This research was supported by a grant from the Rockefeller Foundation.     

我国江浙地区粳稻品种间的植酸与蛋白质组分差异及其相关性

选用我国江浙地区近期育成的晚粳稻品种（系）29个,对它们在浙江杭州相同栽培条件下籽粒中的植酸、蛋白质含量与其组分差异及其相关性进行了分析。供试29个品种(系)植酸含量的平均值为0.868%,变化幅度为0.699%~1034%,其中秀水系列品种的植酸含量一般较低,而武育粳系列和淮字系列品种（系）的植酸含量则相对较高;供试29个品种材料总蛋白质含量的平均值为8.722%,其含量大致呈正态分布。在4种蛋白质组分中,谷蛋白、球蛋白和清蛋白在品种间的变异系数较大,而醇溶蛋白则相对较小,且在分布频率上也表现出品种类型间的差异特征;除谷蛋白与总蛋白质之间存在着极显著的正相关外,供试29个品种(系)的植酸含量与蛋白质含量及4种蛋白质组分含量间并无密切的关系。     

Effects of glutelin and globulin on the physicochemical properties of rice starch and flour

The effect of two rice endosperm proteins, glutelin and globulin, on the physicochemical properties of rice starch and flour was investigated. Albumin, globulin, prolamin and glutelin were sequentially extracted from defatted rice flour with de-ionised water, 1.5 M NaCl, propan-2-ol and 0.1 M NaOH, respectively, followed by dialysis and lyophilisation. Globulin and glutelin were then added to pure rice starch at various concentrations, separately and together, and the pasting and textural properties of mixtures were analysed by the Rapid Visco Analyser (RVA) and TA-XT2 textural analyser, respectively. The presence of glutelin in rice starch caused an increase in pasting temperature but a decrease in the viscosity parameters of the starch paste. The concentration of glutelin was also positively correlated with the hardness and adhesive properties of the starch gel. The presence of globulin, on the other hand, resulted in a decrease in all the pasting and textural parameters except gel hardness and the changes were linearly correlated with the concentration of the protein for most of the physical parameters. When the two proteins were added to rice starch together, the outcomes in pasting and textural properties were generally dependent upon the relative concentrations of the two proteins, but were also influenced by the presence of the other two protein fractions, albumin and prolamin. The presence of globulin initially accelerated the rate of water absorption by starch during cooking while the presence of glutelin slowed it down, but in both cases, the ultimate amount of water absorbed was significantly lower than that by pure starch. The contrasting effects of the different protein fractions mean that it might be possible to manipulate the textural properties of rice starch and flour to achieve desirable sensory outcomes by varying the proportions of the protein fractions in product formulations.     

醋制对黑豆蛋白含量及多肽ACE抑制活性的影响

为考察醋制对黑豆蛋白含量及多肽ACE抑制活性的影响,为对黑豆醋浸过程中蛋白组分及含量变化进行分析,并对相应ACE抑制肽活性进行测定。黑豆经醋浸不同时间后,采用顺序抽提法提取清蛋白、球蛋白、醇溶蛋白和谷蛋白,并采用凯氏定氮法及SDS-PAGE电泳进行定量和定性分析;各蛋白组分经胃蛋白酶水解,经超滤(截留分子量3 k D)后收集滤液,获得多肽组分,RP-HPLC法进行ACE抑制活性评价。结果表明:经醋浸14 d后,黑豆总蛋白含量变化幅度小于±0.5%;清蛋白含量由55.13%(0 d)降低至9.61%(14 d);球蛋白由7.04%(0 d)增加到20.34%(14 d);醇溶蛋白由0.81%(0 d)增加到1.72(14 d);谷蛋白由21.11%(0 d)增加到59.45%(14 d),含量最高。醋浸处理降低了清蛋白源多肽的ACE抑制活性,但提高了球蛋白、醇溶蛋白及谷蛋白多肽的ACE抑制活性,其中,谷蛋白多肽抑制率由18.18%(0 d)增加至37.58%(14 d),抑制活性升高。醋浸可改变黑豆各蛋白组分的含量和对应多肽的ACE抑制活性,其中,谷蛋白含量及其多肽ACE抑制活性均有增加。研究结果表明可进一步采用分离纯化技术从谷蛋白多肽中获得高活性降压肽。     

Processing of maize germ oil cake into edible food grade meal and evaluation of its protein quality

The commercial oil cake produced during expeller pressing of maize germ, was extracted with n-hexane and 80 percent ethanol followed by seiving to remove undesirable materials. In defatted maize germ oil cake (DMGOC): protein, starch, fat, crude fiber (CF) and ash were respectively 24.69, 36.55, 5.68, 7.56 and 3.90 percent and they decrease after processing except ash, which increased slightly. It contains better quality protein having only 3 percent zein and 47 percent albumin. Its amino acids like lysine and tryptophan and biological value (BV) were higher than that of whole maize grain, and was comparable with that of the amino acid requirement of preschool children and casein diets both. Its digestible energy (DE) was lower compared with whole maize grain as well as the casein diets. After processing albumin, globulin and zein decreased whereas glutelin and the residual fraction increased. Not much differences were observed in chemical composition and different amino acids, in vitro protein digestibility (IVPD), true digestibility (TD), BV and DE improved after processing.     

氮肥运筹对啤酒大麦籽粒品质及产量的影响

为了揭示氮肥运筹对啤酒大麦籽粒品质和产量的调节效应,以啤酒大麦花30为材料,在施纯氮总量225kg.hm-2条件下,研究了不同氮肥运筹对千粒重、β-淀粉酶活性、蛋白质组分含量动态变化和产量及其构成因子的影响。结果表明:(1)随花后天数的增加,大麦籽粒千粒重、β-淀粉酶活性、醇溶蛋白和谷蛋白含量呈现由低到高的变化,而清蛋白和球蛋白含量先急剧上升,后略微下降;(2)增加拔节肥比例能显著增加β-淀粉酶活性、醇溶蛋白和谷蛋白含量,而对清蛋白和球蛋白含量影响较小;(3)千粒重、β-淀粉酶活性及蛋白质组分含量的相关性均达极显著水平;(4)随着氮肥用量后移,有效穗数、产量呈上升趋势,千粒重呈下降趋势。综合考虑各项指标,建议在类似本试验条件下的啤酒大麦生产区,基肥、苗肥、拔节肥比例以6∶3∶1为宜。     

Distribution of seed protein fractions and amino acids in different anatomical parts of chickpea (Cicer arietinum L.) and pigeonpea (Cajanus cajan L.)

Studies on protein fractionation in seed coat, embryo, cotyledons and whole seed were made to observe the differences, if any, between chickpea and pigeonpea. Results indicated that globulin was the major fraction of embryo and cotyledons of these legumes. Seed-coat nitrogen was observed to be mostly comprised of nonprotein nitrogen and glutelin fractions and thus differed from other components in both chickpea and pigeonpea. The albumin fraction of cotyledons of both crops had the highest concentration of sulphur amino acids, methionine and cystine. Glutelin contained a considerably higher concentration of methionine and cystine than did globulin in chickpea and pigeonpea. This suggests that lines with higher glutelin should be identified to improve their protein quality. The amino acid compositions of different seed components did not show large differences between these two pulse crops.Submitted as JA no. 180 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).     

Extractability and chromatographic separation of rice endosperm proteins

The molecular weight (MW) distribution of proteins extracted with different solvents from defatted rice endosperm was examined by size exclusion-high performance liquid chromatography (SE-HPLC) with 2.0% sodium dodecyl sulfate (SDS) (w/v) as mobile phase. The resulting protein peaks were further characterized by SDS-PAGE. Under the experimental conditions, 2.0% SDS extracted 64% of the proteins. Adding 6.0 M urea resulted in a 15% increase in extractability (up to 79%). With using 20–100 mM NaOH, 70–81% of the proteins were extractable. Maximum extractability was reached with 2.0% SDS, 6.0 M urea and 0.5–1.5% dithiothreitol (DTT). Apparent MW profiles of rice endosperm proteins allowed classification into six fractions of decreasing apparent MW. Fraction VI contained the low MW albumin, globulin, and prolamin protein material. Fractions IV and V originated from α and β glutelin subunits, respectively. The polypeptides of fraction III consisted of an α and a β subunit linked by an intermolecular disulfide bond. The polypeptides of fractions I and II were dimers, trimers or more highly polymerized forms of the (α–β) glutelin subunit dimer in fraction III. While the work confirmed that rice glutelin is composed of polymers of α and β subunits, remarkably, higher MW glutelin aggregates (fractions I–III) only partly dissociated on reduction. Low MW protein material (fraction VI) was entrapped in the aggregated protein network and was released on reduction. The rapid and reproducible SE-HPLC method developed for rice protein separation allows a more quantitative approach than SDS-PAGE.     

不同大豆品种豆腐产量的研究

选用２３个辽宁、吉林和山东的春大豆和夏大豆栽培品种为试材。调查百粒重和单株粒重，测定豆腐加工特性、籽粒蛋白质含量和籽粒蛋白质各组分含量。研究表明：筛选到豆腐产量高的品种可能性很大。可把籽粒吸水重和籽粒膨胀体积作为品种豆腐产量的间接选择性状。筛选到豆腐产量与单株粒重均高的品种难度很大，筛选到豆腐产量和籽粒蛋白质含量均高，豆腐产量和籽粒蛋白质质量均高的品种存在着一定难度。不同品种籽粒蛋白质各组分含量差     

水氮互作对小麦籽粒蛋白质组分和品质的影响

为了给强筋小麦高产优质高效栽培提供理论依据,以高产强筋小麦品种济麦20为材料,研究了施氮量和灌溉量对小麦籽粒蛋白质组分和品质的影响.结果表明,施氮量由120 kg*ha-1(N1)增加至240 kg*ha-1(N2),籽粒蛋白质含量、清蛋白和球蛋白含量增加,(醇溶蛋白+麦谷蛋白含量)/(清蛋白+球蛋白含量)比值(谷醇/清球比值)降低,面团稳定时间缩短.同一施氮量条件下,由不灌水(W0)到灌2水(W1),籽粒蛋白质含量增加,谷醇/清球比值降低,面团稳定时间缩短;由灌2水(W1)到灌3水(W2)和5水(W3),籽粒蛋白质含量降低,蛋白质组分中清蛋白和球蛋白含量升高,醇溶蛋白和麦谷蛋白含量降低,谷醇/清球比值降低,面团稳定时间亦缩短.以上结果表明,在本试验条件下,增加施氮量和灌水量导致面团稳定时间缩短,原因是清蛋白和球蛋白占总蛋白含量的比例,即谷醇/清球比值降低.     

Seed protein fractions and amino acid composition in gram (Cicer arietinum)

Six chickpea strains were analysed for their protein content and various protein fractions. The protein content ranged from 20.9–25.27%. Albumin, globulin, prolamin and glutelin contents ranged from 8.39–12.31%; 53.44–60.29%; 3.12–6.89% and 19.38–24.40% respectively. Salt soluble proteins (albumin + globulin) and globulins resolved into 19–23 bands whereas albumin proteins resolved into 30–34 bands. The molecular weights of various polypeptides ranged from 10–91 kD. Amino acid analysis of total proteins revealed that glutamic acid was present in maximum concentration followed by aspartic acid and arginine. Just like other pulse proteins, chick pea proteins were also found deficient in sulphur containing amino acids.     

大豆种子贮存蛋白组成及其相关分析

1988年选用14个,1989年选用15个蛋白质含量差异较大的主要为江淮地区的大豆品种,进行随机区组试验。大豆种子中球蛋白、清蛋白、醇溶谷蛋白以及谷蛋白的品种间平均分别为28.56％、7.50％、1.81％和5.71％,品种间变幅分别为6.08％、10.25％、1.03％和6.51％。清蛋白含量与全蛋白含量。谷蛋白含量与全蛋白含量之间显著正相关,清蛋白含量对种子全蛋白含量品种间差异的相对贡献最大,而球蛋白含量对品种间全蛋白含量差异的相对贡献最小。球蛋白含量与株高、分枝数和单株粒重存在显著的正相关;但株高和清蛋白含量、单株荚数及单株粒数和谷蛋白含量有显著负相关。     

辣木籽渣组分蛋白的理化与功能性质研究

辣木籽渣是辣木籽提取油之后的副产物,为了提高其综合利用价值,本文以辣木籽渣为原料,通过奥斯本（Osborne）四步法提取清蛋白、球蛋白、谷蛋白和醇溶蛋白,分析比较了4种组分蛋白的理化性质及功能特性。结果表明：清蛋白、球蛋白、谷蛋白和醇溶蛋白的提取率分别为10.34%、0.69%、3.40%和3.65%,纯度均在82%以上,清蛋白、球蛋白、谷蛋白的分子量均较低（5~25 kDa）,且清蛋白的蛋白条带浓度最高。此外,清蛋白的溶解性、乳化性、乳化稳定性及起泡性均为最优,但泡沫稳定性最差,在静置120 min后消散。4种组分蛋白的持油性均受温度的影响,球蛋白受温度影响最小。本研究表明辣木籽渣是一种较优质的植物蛋白资源,可为其在食品工业的加工利用提供理论依据