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1.
Hordein, the major storage protein of barley (Hordeum vulgare L.), was hydrolysed by three selected proteases, including alcalase, flavourzyme and pepsin. The effects of protease type and hydrolysis time on hordein molecular weight, surface hydrophobicity, secondary structure and antioxidant activity were investigated. Flavourzyme hydrolysis of hordein was relatively more extensive and rapid, resulting in the formation of medium- and small-sized peptides with a broad distribution within 30 min. Alcalase and pepsin more gradually and less extensively hydrolysed hordein into medium- and larger-sized peptides, respectively. Protein surface hydrophobicity decreased with an increasing degree of hydrolysis. The flavourzyme and alcalase hydrolysates had superior DPPH (1,1-diphenyl-2-picryl hydrazyl) free radical scavenging activity (44-70 and 48-58%, respectively, at 0.5 mg/mL), Fe2+-chelating ability (21-64% and 39-73%, respectively, at 1 mg/mL), and superoxide radical scavenging capacity. It is proposed that the large- and medium-size hydrolysate fractions were most likely responsible for the antioxidant activities of hordein hydrolysates, and could be used as antioxidant peptides in food and nutraceutical applications.  相似文献   

2.
Proteins in unmalted and malted barley and in brewers’ spent grain (BSG) obtained after mashing were fractionated on the basis of their differential extractability in different media and characterised by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and high-performance liquid chromatography (HPLC). Albumins and globulins were first extracted with 5.0% NaCl and hordeins (barley prolamins) were extracted with 55.0% 1-propanol in the presence, or absence, of 1.0% DTT. Glutelins were then extracted with 2.0% SDS/6.0 M urea/1.0% DTT or with 55.0% 1-propanol/6.0 M urea/1.0% DTT/0.036 M Tris-HCl (pH 8.4). Under non-reducing conditions, monomeric C hordeins and some B hordeins were extracted from unmalted barley, whereas most if not all B, C and D hordeins were extracted under reducing conditions. During malting, disulfide bonds are reduced and B and D hordeins are broken down by proteolysis. No D hordeins were extracted from malt and nearly the same levels of malt B hordeins were extracted both under non-reducing and reducing conditions. B hordeins present in BSG proteins were only extractable under reducing conditions. Whereas most of the C hordeins were extracted from BSG under non-reducing conditions, more C hordeins were extracted under reducing conditions. Mashing probably induced disulfide bond formation resulting in aggregation. Although earlier literature suggested the formation of an aggregate composed of B and D hordein (and glutelin) during mashing, the present work suggests the formation of an aggregate composed of B hordeins in which C hordeins are entrapped.  相似文献   

3.
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.  相似文献   

4.
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.  相似文献   

5.
Seed nitrogen content, protein composition and free amino acid content were determined in rice mutant lines with altered storage protein composition and their parental cultivars. The Lgc1 gene, which causes low glutelin content and high content of 13 kDa prolamin and 26 kDa globulin, did not affect grain weight, nitrogen content, or free amino acid content. The glb1 gene, which lacks the 26 kDa globulin, did not affect grain weight or nitrogen content, but in mutant lines with glb1 gene the content of the major free amino acids was significantly (1.3–1.5 times) higher than those of their parental cultivars. These results suggest that absence of 26 kDa globulin is accompanied by an accumulation of a high level of free amino acids in rice grains.  相似文献   

6.
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。  相似文献   

7.
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.  相似文献   

8.
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.  相似文献   

9.
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。  相似文献   

10.
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.  相似文献   

11.
Improvement of rice storage proteins is important in rice breeding for high nutritional quality. Seventy-one recombinant inbred lines (RIL) derived from a cross between japonica variety Asominori and indica variety IR24 were used to study the inheritance of crude protein and protein fraction contents in rice. A total of 16 QTL were identified and mapped on eight chromosomes. Several QTL affecting contents of different protein fractions were mapped in the same chromosomal region. In particular, two QTL with a significant contribution were identified to simultaneously affect prolamin and glutelin contents. One QTL denoted as qCP-12 affecting crude protein content (CP) was located in the same region as QTL qGLT-12 affecting glutelin content, in agreement with the positive correlation between glutelin level and protein content. QTL with larger genetic effects were further confirmed using two sets of chromosome segment substitution lines (CSSL), where Asominori and IR24 were used as the recurrent parents. By QTL comparative analysis, two QTL for CP, three for globulin content and one for prolamin content were located in the vicinity of CP QTL previously identified in polished rice. Application of these results in rice breeding is discussed.  相似文献   

12.
Microfluidization followed by density-based separation was employed to extract protein from broken rice by disrupting protein-starch agglomerates. Follow-up enzyme treatments (amylase and glucoamylase) were performed to further improve the purity of the protein-rich fraction. High protein recovery (81.87%) and purity (87.89%) were obtained. The protein composition, solubility, structural properties, and in vitro digestibility of rice proteins prepared by enzyme-assisted microfluidization (EM-RP) and alkaline extraction (AE-RP) were compared. EM-RP was mainly composed of glutelin, which had low solubility and native structure. By contrast, large quantities of prolamin and globulin appeared in the AE-RP except glutelin, leading to the richness of glutamic acid/glutamine, leucine, aromatic and charged amino acids in the AE-RP. Compared to AE-RP, EM-RP showed higher digestibility due to the richness of glutelin (an easy-to-digest protein), as evidenced by higher nitrogen release during pepsin-trypsin digestion. The presence of prolamin (an indigestible protein) in AE-RP decreased protein digestibility although alkaline extraction improved its hydrolysis. These results suggest that enzyme-assisted microfluidization could be an effective technique to non-destructively and selectively extract rice glutelin.  相似文献   

13.
氮肥运筹对啤酒大麦籽粒品质及产量的影响   总被引：1，自引：0，他引：1  
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。  相似文献   

14.
Immunological methods based on monoclonal antibodies with varying specifities towards gluten proteins have been used to control the purity of gluten-free products. Commercially available methods have been developed to detect gluten proteins found in wheat. However, difficulties have occurred in quantifying barley proteins with the same accuracy as wheat proteins. Barley is also a common contaminant in oat products. In this study, oat flour samples were deliberately contaminated with known amounts of barley flour and analysed using two commercial enzyme linked immunosorbent assays (ELISA). The methods were based on an ω-gliadin antibody and an R5 antibody. The results obtained with the R5 antibody were overestimates while the ω-gliadin antibody underestimated the higher barley prolamin content. This study showed that inaccuracies in ELISA assays in quantifying barley contaminations can possibly be eliminated by using a hordein standard. However, it is necessary to know the source of contamination. This would prevent overestimation of the hordein content of gluten-free products. Overestimation unnecessarily reduces the variety of gluten-free products and may decrease compliance to a gluten-free diet.  相似文献   

15.
The percent distributions of protein fractions namely albumin + globulin, prolamine and glutelin were studied in developing grains of NP 113 barley and its high lysine mutant Notch-2. During development the percentage of albumin + globulin fraction decreased in NP 113, while those of prolamine and glutelin remained unchanged. The increase in prolamine was substantial from 24 to 31DAA. In Notch-2 the trend followed by albumin + globulin and prolamine was like that in NP 113, while the glutelin fraction showed an increase as compared to 10 DAA. The percent of albumin + globulin was slightly higher in Notch-2 as compared to NP 113. The absolute amount (mg/grain) of all the protein fractions increased during development in both NP 113 and its mutant Notch-2. During the grain development the prolamine content was substantially lower in the mutant than in the parent NP 113. The albumin + globulin content per endosperm was in general also higher in NP 113 than Notch-2. Amino acid analysis of the protein fractions did not reveal significant changes in lysine between NP 113 and Notch-2. Thus, the improvement in lysine in the mutant is primarily due to reduced synthesis of the prolamine fraction and not due to an increase in lysine in the mutant hordein fraction. Part of the improvemenht in lysine may also be due to increase in the percentage of albumin + globulin fractions which is lysine rich.Part of the Ph.D thesis submitted by S. Joshi to P.G. School, IARI, New Delhi.  相似文献   

16.
The endosperm storage proteins of barley (hordeins) can be divided into four groups A, B, C and D. The A hordeins are probably not true storage proteins and their genetics has not been studied. The other three groups are specified by the lociHor-2, Hor-1 andHor-3, respectively. These all appear to map on chromosome 5 withHor-1 andHor-2 being linked both to each other (ca. 12% recombination) and to the mildew-resistance lociMla andMlk. The nature of the loci has been studied further by examining the chemical relationship between the proteins and by isolation of the mRNAs specifying them and the preparation of cDNA clones. N-terminal and C-terminal amino acid sequences of C hordein fractions show a high degree of structural homology. The relative positions of methionine residues in the polypeptide chains have been used to compare the various B hordein polypeptides. Cloning of double-stranded cDNA derived from endosperm poly A+ RNA has given rise to a family of B hordein-related DNAs, some of which have been sequenced. The results of these approaches suggest that the hordein loci are complex multigene families derived from single ancestral genes by cycles of gene duplication and mutation.  相似文献   

17.
Rice bran (RB) is an important by-product from the rice production with a high valorization potential. The aim of the present work was to explore this potential by considering combined protein and phenolic fractions and enzymatic hydrolysis. The influence of different protocols in the recovery/fractioning of protein were evaluated, including defatting procedures, in rice brans from two very different locations: Portugal and Colombia. The different protein fractions achieved were characterized. Proteins were further hydrolyzed using trypsin and their hydrolysates were characterized in terms of degree of hydrolysis and peptide size. Moreover, the total phenolic content (TPC) and phenolic compounds’ profile on extracted fractions and hydrolysates of RB from Portugal and Colombia were determined. The functional potential was assessed in terms of antioxidant and antihypertensive activities. Though the protein concentrates had already significant potential bioactivities, protein hydrolysates showed that the TPC, antioxidant and antihypertensive activities significantly increased with the digestion by trypsin. Hydrolysates of RB from Portugal presented a higher antioxidant and hypertensive activities in comparison with hydrolysates of RB from Colombia, moreover it presented a higher content of TPC. This study indicated that the exploitation potential of rice bran can be increased with simple fractioning procedures, that combined protein/phenolic fractions are important to deliver functionality and that hydrolysis can be a relevant tool to release that functionality. Furthermore, regional differences in rice bran composition are also important factors to consider. Overall, this knowledge can be used to increase the industrial potential of valorization for this by-product.  相似文献   

18.
稻米蛋白质组分及总蛋白质含量与淀粉RVA谱特征值的关系   总被引：5，自引：0，他引：5  
 利用低谷蛋白含量（low glutelin content, LGC）粳稻品种W1721与大面积应用的杂交粳稻恢复系轮回422构建了重组自交系群体。根据种子总蛋白质的SDS PAGE带型,推断各单株LGC位点的基因型。在排除脂肪的影响下,比较了基因型LGCLGC（谷蛋白含量较醇溶蛋白低）与基因型lgclgc（谷蛋白含量较醇溶蛋白高）在RVA谱特征值上的差异,以及同一基因型内总蛋白质含量与淀粉RVA谱特征值的关系。结果表明基因型LGCLGC的崩解值和回复值的平均值分别显著和极显著大于基因型lgclgc;LGC对崩解值和回复值的相对加性效应分别为3.91%和4.45%,贡献率分别为4.81%和12.81%。LGCLGC型的稻米,总蛋白质含量与崩解值和消减值分别存在显著的负线性回归和正线性回归关系,贡献率分别为9.86%和11.48%;lgclgc型的稻米,总蛋白质含量与消减值和回复值都存在极显著的负线性回归关系,贡献率分别为1341%和27.88%。结合前人研究认为,稻米食味品质受谷蛋白相对于醇溶蛋白的含量以及总蛋白质含量的影响;而总蛋白质含量对食味品质的影响因谷蛋白相对于醇溶蛋白的含量的不同而异。因此,育种工作中应当把谷蛋白相对于醇溶蛋白的含量以及总蛋白质含量同时作为选择指标。  相似文献   

19.
Rice (Oryza sativa), an important cereal as a staple food worldwide, can be used in gluten-free diets. This study aimed to isolate and characterize the active rice proteins and assess the anti-leukaemia response via in vitro and ex vivo experiments. Temperature-stable protein-containing extracts augmented this effect. Proteomic analysis identified various protein spots known with functions involving metabolism-related, transport, storage, antioxidation, development, and disease-resistance proteins. Among these, storage proteins were the most abundant. To avoid masking the other relatively scanty rice storage proteins, albumin, globulin, glutelin and prolamin were separated and quantified. The human peripheral blood mononuclear cells-conditioned medium (PBMC-CM) prepared from prolamin treatment showed an increment in production of tumor necrosis factor-α. Human leukaemia U937 cells cultured in the presence of prolamin-prepared PBMC-CM were inhibited in growth capacity and were triggered differentiation toward monocytes. Neutralization of prolamin by polyclonal antibody attenuated its activity. Rice prolamin, undetectable by wheat gliadin-specific antibody, has greater anti-leukaemia activity than wheat proteins glutenin and gliadin. In conclusion, rice prolamin is effective in activating human anti-leukaemia immunity and may not induce unwanted inflammatory diseases.  相似文献   

20.
Cereal based products intended for gluten sensitive individuals, particularly to celiac disease patients, tend to have poor organoleptic qualities and they contain low levels of healthy whole grain compounds. Adding whole grain ingredients, such as malt hydrolysates, could compensate these defects provided that the ingredients are adequately free from toxic prolamin epitopes. Here we demonstrate that the level of toxic prolamin epitopes in the malt autolysates (wheat, barley, rye) were substantially lower than in the native malts but too high to allow “very low in gluten” labelling. To further eliminate the residual levels of toxic prolamin epitopes, a proline-specific endoprotease from Aspergillus niger was added to the malt autolysates. In the resulting malt hydrolysates (of wheat and rye but not barley), the prolamins were indeed greatly reduced and were below the very low gluten limit of 100 mg/kg. Malt hydrolysates with adequately low gluten levels may potentially be used as novel ingredients within gluten-free foods.  相似文献   

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