Protein classification of beach pea (Lathyrus maritimus L.)

Protein fractionation of whole seed, cotyledons and hulls of beach pea (Lathyrus maritimus L.) was carried out. Surface topography of pea protein isolates and protein fractions, as well as their polyacrylamide gel electrophoresis (PAGE), was studied. The nitrogen solubility of beach pea seed meal was minimum at pH 4.5. Globulin was the major protein fraction present and its content in whole seeds (57%), cotyledons (62%) and hulls (24%) of beach pea was lower than those of other common pea cultivars; the same was true for its albumin content. However, glutelin content in beach pea seed and its parts (cotyledons and hulls) was higher than those of other pea cultivars. The albumin fraction contained the highest amount of total sulphur-containing amino acids followed by glutelin, globulin and prolamine. The amount of sulphur-containing amino acids in beach pea protein fractions was higher than in other peas. Predicted biological value of albumin and glutelin fractions of beach pea was also higher than green pea and grass pea. Beach pea seed protein fractions showed different UV spectra from other pea cultivars. Protein isolate and protein fractions of beach pea seeds showed similar topographical characteristics to those of other peas. Major polypeptide bands in the range of 35–47 kDa in the protein isolate, as well as protein fractions for beach pea, were detected by PAGE.     

Physicochemical,Morphological, Thermal and Pasting Properties of Starches Isolated from Rice Cultivars Grown in India

Physicochemical, morphological, thermal, and pasting properties of starches, isolated from basmati (HBC-19 and Bas-370) and non-basmati (Jaya, a coarse cultivar; P-44 and HKR-120, the medium cultivars and Sharbati, fine cultivar) rice cultivars grown in India were studied. The amylose content of starches from different cultivars ranged from 2.25 (Jaya) to 22.21 g/100 g of starch (HBC-19). Jaya, HKR-120, and P-44 cultivars showed soft gel consistency as 84, 73, and 69 mm, respectively, whereas Sharbati, Bas-370 and HBC-19 cultivars showed medium gel consistency as 54, 53, and 58 mm, respectively. Swelling power (at 95°C) indicated a significant positive correlation with amylopectin content (r = 0.828, p < 0.05) and gel consistency (r = 0.983, p < 0.01). Turbidity had a highly significant positive correlation with solubility (r = 0.919, p < 0.01) and amylose content (r = 0.945, p < 0.01). Starch form Jaya cultivar showed the presence of smallest size granules (2.4–5.7 μm) with an average size of 3.96 μm, whereas Bas-370 showed the presence of largest size granules (3.3–6.7 μm) with an average size of 5.0 μm. The transition temperatures, enthalpy of gelatinization (ΔH_gel), peak height index (PHI) and gelatinization range were determined using differential scanning calorimetry (DSC). The starch from Sharbati cultivar showed highest onset temperature (T_o), peak temperature (T_p), conclusion temperature (T_c), enthalpy of gelatinization and peak height index (PHI) of 68.8°C, 73.2°C, 79.0°C, 11.56 J/g and 2.63 respectively. Pasting temperature of rice starches varied from 68.9°C (Jaya) to 74.5°C (Sharbati). The peak viscosities observed were in the range of 2223 to 3297 cP, lowest for HBC-19 starch and highest for Jaya starch.     

燕麦麸蛋白的组成及功能性质研究

以燕麦麸为原料制备了燕麦麸浓缩蛋白（OBPC）。同时，也按照Osborne蛋白分级提取方法对燕麦麸蛋白进行了精细的分类，分别得到了燕麦麸清蛋白、球蛋白、醇溶蛋白和谷蛋白。球蛋白和谷蛋白是燕麦麸蛋白的主要组分。清蛋白提取液中含有高含量的可溶性碳水化合物，可以通过（NH4）2S04分级沉淀的方法将其纯度由6．5％提高到67．2％。SDS-PAGE的结果表明OBPC及各蛋白组分有不同的分子组成。OBPC及各蛋白组分的功能性质，包括溶解性、持水持油性、乳化活性、泡沫性质也分别进行了测定，以评价燕麦蛋白作为一种潜在的配料在食品中的应用价值。     

大米谷蛋白储藏过程中结构与功能性质变化的研究

为了研究大米储藏过程中谷蛋白结构与功能性质变化及其相关性,将大米在40℃、相对湿度80%的环境中模拟储藏11周,提取不同储藏时间下的谷蛋白,测定二级结构、内源荧光和功能性质的变化。结果表明,储藏的前5周谷蛋白结构展开,表现为α-螺旋含量从17.04%±3.89%降低至13.02%±0.94%,无规则蜷曲从19.40%±3.02%增加至29.04%±0.55%,同时谷蛋白的溶解性、持油性也相应增强;表面疏水性提升了325.73%,从而谷蛋白的乳化性和乳化稳定性、起泡性和起泡稳定性也随之增强,但持水性降低。而随着储藏时间的延长,在6~11周,谷蛋白α-螺旋含量升高,无规则蜷曲降低,内源荧光强度下降,同时蛋白的功能性质也随之下降,但乳化性有所增强。α-螺旋结构与功能性质变化存在显著相关性（P<0.01）。大米储藏过程中谷蛋白的结构变化与功能性质紧密相关。     

蛋白质谷氨酰胺酶对米谷蛋白功能性质的影响

研究蛋白质谷氨酰胺酶对米谷蛋白功能性质的影响,测定米谷蛋白及其脱酰胺样品的溶解度、乳化、起泡、黏度、持水持油力等功能性质。结果表明,谷氨酰胺酶法脱酰胺的米谷蛋白其功能性质均有提高,在中性溶液中溶解度显著增加(达到96.99%);酶解时间1～12h 的范围内,改性蛋白在中性条件下的乳化性能最好,酶解时间1～5h 的范围内,强酸性条件下的乳化稳定性得到显著改善,并呈现出最佳的起泡性能,而起泡稳定性和黏度则随着反应时间的增加均逐渐降低;此外,改性蛋白与未改性蛋白比较,持水性提高1.75～2.03 倍,持油性提高1.58～1.94 倍。     

Influence of Pine Nut (Pinus koraiensis) Oil Fractions on Physicochemical Properties of Rice Starch Solutions

The physicochemical properties of rice starch suspensions effected by interactions with pine nut oil fractions were investigated. Oil fractions (crude pine nut oil, glycolipid, nonpolar lipid, gums, and degummed oil) from pine nut (Pinus koraiensis) were prepared by solvent extraction and addition of boiling water. The influence of the fractions on the physicochemical properties of rice amylose solution (5%, w/w) was determined by measuring the complexing index, absorbance ratio (630/520 nm), colour, rheological characteristics, and microscopic structure at various concentrations. Their effect on rice starch swelling power was also determined. The glycolipid fraction had the highest complexing index with rice amylose. Rice amylose solutions containing the glycolipid fraction exhibited greater pseudoplastic fluid (n<0.7) behaviour, higher colour difference values, and lower absorption ratios (1.64‐1.48) than did those containing other fractions. Hydrated oil fraction (gums) complexed with amylose only poorly, if at all, but amylose solutions containing them had rheological properties similar to those containing the glycolipid fraction. The addition of oil fractions increased the swelling power value compared to the control.     

The protein and the amino acid composition of some rice and maize varieties grown in North Vietnam

The protein and amino acid composition of several rice and maize varieties grown in North Vietnam, and their digestibility, was determined. The protein content (N×5.95) of rice cultivars ranged from 7.0 to 10.8% of which 70–80% was in the glutelin fraction. The true digestibility was relatively good (87.6–91.8%). In general, lysine and threonine were found to be the first and second nutritionally limiting amino acids, except for two varieties, which had a low content of sulphur-containing amino acids. The protein content of maize cultivars ranged from 8.4 to 12.9%. Zein and glutelin were the main components occurring in near-equal quantities (except in the opaque-2 mutant). The overall amino acid distribution was similar to that of maize grown in other countries. Lysine levels were relatively low, and it was the first nutritionally limiting amino acid, except in the opaque-2 cultivar, tryptophan being the second one. The digestibility ranged from 87.5 to 91.1%.     

Characterization of protein fractions from chickpea (Cicer arietinum L.) and oat (Avena sativa L.) seeds using proteomic techniques

Albumin, globulin and glutelin fractions were prepared from chickpea and oat seeds using sequential extractions. Molecular characteristics of individual protein fractions were investigated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in combination with proteomic techniques. SDS-PAGE results revealed that chickpea albumin and globulin fractions (C-Ab and C-Gb) showed protein bands with molecular weights (MWs) related to subunits of legumin (11S globulin) and pea vicilin (7S globulin); oat protein fractions (O-Ab, O-Gb and O-Gt) showed most protein bands with MWs related to subunits of oat 12S globulin (avenalin). With proteomic analysis, eighteen tryptic peptides from chickpea globulin fraction showed sequence homology that corresponded to chickpea legumin α- and β-subunit (NCBI accession number: gi|6273402; theoretical mass 56,216 Da) while sixteen tryptic peptides from chickpea albumin fraction (C-Ab) were identified as chickpea provicilin precursor (NCBI accession number: gi|82173888; theoretical mass 51,390 Da); fifteen tryptic peptides from oat protein fractions were identified with origin from oat 12S seed storage globulin 1 (NCBI accession number: gi|134918; theoretical mass 58,508 Da). The identified tryptic peptide, ALIVPQNFAIAAK, was commonly found in chickpea glutelin fraction (C-Gt), rice glutelin fraction (R-Gt), and oat albumin, globulin and glutelin fractions (O-Ab, O-Gb and O-Gt).     

Physicochemical and functional properties of albumin,globulin and glutelin fractions of green lentil seed

Defatted lentil seed flour proteins were separated into their constituent albumin (ALB), globulin (GLB) and glutelin (GLT) fractions followed by determination of their structural and functional properties. The GLB fraction demonstrated superior solubility (84%–100%) at acidic and alkaline pH values when compared to the lower values for ALB and GLT. Amino acid composition analysis showed lower contents of hydrophobic and sulphur-containing residues for GLB. However, GLB had the highest in vitro protein digestibility, which may be due to lower contents of rigid secondary structure fractions like the β-sheet and β-turns. In contrast, water and oil holding capacities as well as gelling ability were better for GLT and ALB than GLB. The GLT fraction formed very poor emulsions at pH 3 and 5 but emulsification was significantly (p < 0.05) improved (smaller oil droplets) at pH 7 and 9. Foaming capacity was strongest for GLB, especially at pH 5, 7 and 9 where increase in protein concentration had a negative effect on foam formation. Overall, the protein type and pH of the environment had stronger effects on emulsion and foaming properties than the protein concentration.     

Effects of glutaminase deamidation on the structure and solubility of rice glutelin

The effects of glutaminase on deamidation of rice glutelin were investigated. Water-insoluble rice glutelin was deamidated to the extent of deamidation degree 52.29% in 200 mmol/L sodium phosphate buffer (pH 7.0) at 37 °C for 48 h. Zeta potential analysis indicated that the glutamines of rice glutelin were deamidated into glutamic residues. Size exclusion chromatography results demonstrated that glutaminase deamidation broke the hydrophobic, hydrogen and some intermolecular disulfide bonds in rice glutelin and thereby rearranged the molecular weight distributions without serious cleavage of the peptide bonds. Fourier transform infrared analysis revealed the transformation of α-helix to random coil and β-turn by deamidation and suggested that deamidated rice glutelin maintained more flexible or extended forms. Solubility properties of rice glutelin in mildly acid (pH 5) and neutral buffers (pH 7) were remarkably improved by glutaminase deamidation. These new features of deamidated rice glutelin suggested that glutaminase could be a potential tool for enhancing the usability of rice protein in the food industry.     

基于组成成分和米饭质构性状的东北粳稻聚类分析

以东北34种粳稻为研究对象,测定其组成成分及蒸煮后的米饭质构等15项指标,运用相关分析探索粳稻中各蛋白组分间的相互关系及其对米饭质构特性的影响,并通过聚类分析将其分为四类。结果表明:谷蛋白质量与米饭的硬度呈正相关(r=0.41),醇溶蛋白含量与米饭弹性呈显著负相关(r=-0.43),清蛋白含量与米饭的硬度呈极显著的负相关(r=-0.44),球蛋白含量与米饭的硬度和弹性呈极显著的负相关,相关系数分别为-0.50和-0.68。聚类分析结果为:第Ⅰ类粳米的谷蛋白含量较高,蒸煮米饭的弹性、胶着性较高,黏附性较小;第Ⅱ类粳米的清蛋白、球蛋白和醇溶蛋白的含量较高,蒸煮米饭的硬度、弹性、胶着性和回复性较低。第Ⅲ类松粳20,球蛋白和醇溶蛋白含量高,蒸煮后的米饭的硬度、弹性偏低;第Ⅳ类龙稻28,谷蛋白含量最高,蒸煮后米饭的硬度和黏附性高。     

Effects of interaction between rice glutelin and starch on starch gelatinization in a simulated storage system

Starch and protein are the two major components of rice and interaction between them will occur during storage. However, whether the interaction between starch and protein impacts rice starch gelatinization is still unclear. In this study, the effects of starch-protein interaction on starch gelatinization (japonica rice) were investigated using a glutelin–starch simulation system under high temperature and humidity storage conditions. A glutelin–starch ratio of 1:4 was used in the simulation system and stored in an artificial climate chamber (40 °C, 60% humidity) for 60 d. The interaction had a significant effect on starch gelatinization. Starch granule particles were broken down, and the bonds of starch granules weakened during interaction with glutelin. The secondary structure of glutelin loosened, as the starch disintegrated the α-helix structure. Correlation analyses revealed that peak viscosity (PV), trough viscosity (TV), and final viscosity (FV) had a significant negative correlation with carbonyl content, and disulfide bonds (P < 0.01), as well as a significant positive correlation with the active thiol content (P < 0.01). Moreover, setback (SB) had a significant positive correlation with the α-helix and a negative correlation with the β-turn content (P < 0.05). PV, TV, breakdown (BD), and FV were significantly related to β-sheet in glutelin (P < 0.05). These results suggest that glutelin and starch can interact and affect starch gelatinization.     

米胚分离蛋白营养和功能性评价

利用氨基酸自动分析仪检测米胚4种Osborne分离蛋白中的氨基酸组成,以氨基酸评分(AAS)、蛋白质功效比值(PER)、生物价(BV)及体外消化率为评价标准,对米胚蛋白各组分的营养价值进行评价。结果表明:谷蛋白的氨基酸评分最高,为80.90,清蛋白、球蛋白、谷蛋白符合FAO/WHO推荐的参考蛋白模式,其PER值与优质蛋白的衡量标准值2.00接近,BV值较高,在体外的营养消化效率较好,醇溶蛋白的品质相对较差。对米胚四种蛋白的起泡性、起泡稳定性、吸水性、吸油性等功能性质进行测定,结果表明:pH 5时4种蛋白的起泡性最低,起泡稳定性最好;清蛋白、球蛋白的吸水性比醇溶蛋白、谷蛋白好,醇溶蛋白的吸油性最好;米胚蛋白各组分的表面疏水性较高,需进一步进行改性处理。     

蛋白组分对籼米粉糊化特性的影响机理探讨

通过逐一去除蛋白组分的方法研究了蛋白组分对籼米粉糊化特性的影响,并分析了影响这些变化的蛋白结构基础。RVA和DSC分析结果表明,不同组分的蛋白在去除之后,峰值粘度、热糊粘度和最终粘度均有不同程度的升高,崩解值、回生值及糊化温度均有不同程度的降低。SDS-PAGE和显微结构分析表明,各组分对糊化特性的影响机理应有差异:谷蛋白通过与纤维素类物质的紧密结合,在糊化过程中阻碍淀粉粒的溶胀;醇溶蛋白可能是通过蛋白体自身的溶胀与淀粉相互作用而影响;清、球蛋白通过活性蛋白对籼米成分的水解或合成等改变而影响;淀粉粒结合蛋白则可能对籼米的基础糊化特性影响较大。与分离重组法比较,逐一去除蛋白组分的方法因为蛋白组分之间的相互作用影响较大,对糊化特性的影响与分离重组法略有差异。     

Processing of commercial rice bran for the production of fat and nutraceutical rich rice brokens,rice germ and pure bran

Successive sieving of commercial rice bran on the basis of particle size was performed and different fractions were obtained of which the rice brokens and rice germ fractions contained fat 33 g/kg and 207 g/kg, oryzanol 400 mg/kg and 874 mg/kg, total tocols (tocopherols and tocotrienols) 16.5 mg/kg and 87.8 mg/kg, and total phytosterols 128.7 mg/kg and 769.6 mg/kg respectively, thus indicating that these fractions are a good source of fat and nutraceuticals. The residual fat (6 g/kg) from commercial defatted rice bran contained high oryzanol content of 4.8 g/100 g, indicating that commercial defatted rice bran as a source of oryzanol. The fat from pure rice bran fraction of commercial rice bran decreased in the color value (48.5%) indicating that sieving could also improve the quality of crude rice bran oils.     

Transglutaminase treatment of brown rice flour: A chromatographic, electrophoretic and spectroscopic study of protein modifications

Recently, it was shown that transglutaminase (TGase) treatment of brown rice (BR) flour results in textural improvements of gluten-free bread. In this study, changes in the protein profiles of BR flour and protein fractions induced by TGase treatment were investigated to better understand the activity and specificity of the enzyme. Size-exclusion HPLC (SE-HPLC) profiles of flour extracts, under reducing conditions, revealed the presence of macromolecular protein complexes, as well as low molecular weight proteins. After TGase treatments (10 U/g of proteins) a general reduction in peak intensities indicated the polymerisation of BR proteins into larger, insoluble complexes. Microchip capillary electrophoresis and two-dimensional (2D) gel electrophoresis revealed that the α and β glutelin subunits were primary substrates for the polymerisation reaction, whereas albumins and globulins were only slightly affected. SE-HPLC of the protein fractions revealed glutelins’ polymerisation into high molecular weight structures after TGase treatment. Dynamic light scattering measurements showed that new supramolecular aggregates of glutelins co-existed with the macromolecular complexes already present in the untreated fraction. Front-face fluorescence approaches indicated that TGase treatment caused a decrease in protein surface hydrophobicity of BR flour, but not of the glutelin suspensions. It is concluded that the large protein complexes resulting from glutelin polymerisation and the stronger hydrophobic interactions among proteins result in the improved textural properties of TGase-treated BR bread.     

Assessment of protein fractions of three cultivars of <Emphasis Type="Italic">Pisum sativum</Emphasis> L.: effect of germination

Protein composition, nitrogen and amino acid content of Osborne fractions in different cultivars of Pisum sativum L. (cv. ucero, cv. ramrod and cv. agra) seeds were investigated and the effect of germination on these parameters was also analysed. Albumins comprised the main protein fraction in raw seeds, globulins were constituted mainly by vicilin, with a smaller proportion of the glutelin and prolamine fractions. Regarding the amino acid profile of pea protein fractions, although differences among pea cultivars were found, in general albumin, glutelin and prolamine fractions presented Asp, Glu and Gly as the major non-essential amino acids (NEAA) and Lys as the main essential amino acid (EAA). The globulin fraction, however, presented Asp, Glu, Gly and Arg as the major NEAA and Leu, Phe, Lys, and Thr as the main EAA. In general, the albumin fraction accounted for more sulphur amino acids and Lys, followed by the glutelin + prolamine fraction. Germination caused an increase in the total protein content of P. sativum cv. ucero and P. sativum cv. ramrod. In the albumin fraction a wide number of proteins underwent degradation and convicilin disappeared from the globulin fraction of pea sprouts whilst vicilin and legumin decreased slightly. In general, all the Osborne fractions of pea sprouts presented higher EAA contents than raw seeds. The estimated essential amino acid indexes of protein fractions for P. sativum cv. ucero (EAAI_adult and EAAI_egg) improved with the germination process whilst for P. sativum cv. ramrod and P. sativum cv. agra depended on the Osborne fraction.     

Selenium accumulation in protein fractions during germination of Se-enriched brown rice and molecular weights distribution of Se-containing proteins

This study investigated the accumulation of selenium (Se) in protein fractions of albumin, globulin, prolamin and glutelin extracted from Se-enriched brown rice and the molecular weight distribution of Se-containing proteins. Results showed that the amount of total Se (T-Se) and protein-bound Se (PB-Se) in brown rice was significantly (P < 0.05) increased after germination with 10–60 μmol/l sodium selenite. Except prolamin, the amount of all the other three protein fractions decreased significantly (P < 0.05) with the increase of germination time. Low Se concentrations had promoting effects on degradation of albumin and globulin, while no significant effects were observed on prolamin and glutelin. The accumulation of T-Se and PB-Se were in the order of albumin > glutelin > globulin > prolamin. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) analysis showed that Se was distributed in all the proteins of which molecular weights varied from 13.6 to 121.4 kDa; however, 84.34% of Se was observed in the proteins whose molecular weights less than 36.3 kDa.     

Functional properties of protein fractions obtained from commercial yellow field pea (Pisum sativum L.) seed protein isolate

Commercial pea protein isolate was separated into water-soluble (WS), salt-soluble (SS), alkaline-soluble (AS) and ethanol-soluble (ES) fractions. AS fraction was the most abundant, constituting about 87% of the proteins in PPI followed by WS, SS and ES fractions in decreasing order. ES fraction consistently formed emulsions with a narrow range of smaller oil droplet sizes (0.6–19 μm) at pH 4.0, 7.0 or 9.0 compared to a wider range of sizes for emulsions stabilised by WS, SS and AS fractions. Emulsions formed with ES fraction were also the most stable (p < 0.05) over the 3 h test period at all the pH values used in this work. The WS fraction had significantly highest (p < 0.05) protein solubility and foaming capacity at all the pH values when compared to solubility of PPI, SS, and ES. Except for AS and ES fractions, foaming capacities of the protein fractions were higher at pH 9.0 than at pH 4.0 or 7.0.     

粳稻粒位间蛋白质及其组分与品质性状间的相关性研究

为了研究不同粒位间籽粒总蛋白质及其4种组分含量与其他品质性状的关系,选用不同稳型粳稻为材料,按照穗部位置分为27个粒位,分析了它们之间的相关性。结果表明,粳稻穗内不同粒位间籽粒的总蛋白质及其4种组分含量与蒸煮食味品质、淀粉RVA谱特征、外观品质和碾米品质都有显著的关系。总蛋白质、醇溶蛋白和谷蛋白含量对食味有显著负面影响,而球蛋白含量对其则有显著正面影响;总蛋白质、清蛋白、醇溶蛋白和谷蛋白含量与直链淀粉含量和胶稠度有负相关性,与糊化温度有正相关性。总蛋白、清蛋白、醇溶蛋白和谷蛋白含量与峰值黏度、热浆黏度、崩解值、透明度和整精米率呈显著或极显著负相关,与消减值、垩白率、垩白度呈显著或极显著正相关;球蛋白表现规律则与之相反。粳稻不同粒位间籽粒的总蛋白质及其4种组分含量与RVA谱4个特征值、蒸煮食味品质和垩白性状的关系表现最为密切。