萝卜籽蛋白提取及其功能性质研究

以萝卜籽为原料,用正己烷脱脂得萝卜籽粕,采用碱溶酸沉法对萝卜籽粕中的蛋白质进行提取,并测定其等电点。通过考察料液比、碱溶p H、浸提时间和浸提温度对萝卜籽蛋白提取率的影响,确定最佳的萝卜籽蛋白提取条件,并对所提取的萝卜籽蛋白和大豆分离蛋白进行功能性质的对比。结果表明:萝卜籽蛋白溶解度为84.9%,有很高的营养价值;在料液比1∶20、碱溶p H 9.0、浸提时间120 min、浸提温度50℃的条件下,萝卜籽蛋白提取率为52.3%;萝卜籽蛋白等电点有两个,分别为p H 0.5和p H 4.5;萝卜籽蛋白吸油能力为328.67%,乳化性及乳化稳定性与大豆分离蛋白相近,起泡性及泡沫稳定性较大豆分离蛋白好。     

油牡丹籽粕蛋白质提取工艺优化及其抗氧化活性研究

以经超临界CO2萃取提油后的油牡丹籽粕为原料，研究油牡丹籽粕蛋白质提取工艺、氨基酸组成和抗氧化活性。通过Osborne分级法分离出四种蛋白质，并对清蛋白、醇溶蛋白、谷蛋白及球蛋白提取工艺进行初步优化，采用响应面法分析油牡丹籽粕主要蛋白质清蛋白最佳提取条件，分析四种蛋白质的氨基酸组成。在此基础上，通过DPPH及ABTS自由基清除率评价四种蛋白的抗氧化效果。研究结果表明：油牡丹籽粕清蛋白、球蛋白、醇溶蛋白、谷蛋白的最佳提取条件为粉碎度100目，提取温度依次为45、40、50、30℃，提取时间依次为86、100、100、60 min，清蛋白提取率为47.02%。此外，四种蛋白质均为完全蛋白质具有较强的DPPH自由基清除能力及ABTS自由基清除率能力。油牡丹籽粕蛋白是优质蛋白质资源，本研究为油牡丹籽粕综合利用奠定理论基础。     

萝卜籽粕中蛋白质的提取及抗氧化活性研究

采用碱溶酸沉法提取萝卜籽粕中的蛋白质,通过单因素试验和正交试验确定最佳的提取条件;对蛋白质的抗氧化活性进行研究;采用SDS-PAGE法测定各蛋白质组分相对分子质量分布。结果表明:萝卜籽粕中蛋白质的最佳提取条件为料液比1∶50、碱溶pH 10、提取温度60℃、提取时间90 min、酸沉pH 4.5,在此提取条件下,蛋白质提取率可达80.2%,蛋白质纯度为89.5%;萝卜籽粕中蛋白质对DPPH·、NO_2~-、H_2O_2、·OH具有很好的清除能力;萝卜籽粕中蛋白质约有5种亚基分离组分,其中4种亚基分离组分相对分子质量由小到大分别约为22.0、31.0、43.0、66.2 k Da,1种亚基分离组分的相对分子质量在66.2~97.4 k Da之间。     

牡丹籽粕蛋白的提取工艺优化及其性质研究

采用碱溶酸沉法提取牡丹籽粕蛋白，通过单因素和正交试验优化牡丹籽粕蛋白提取工艺，并对牡丹籽粕蛋白的理化性质和功能性质做出测定。结果表明，对蛋白质得率影响因素为：pH>提取时间>提取温度>料液比。在料液比1:20 g/mL、提取温度70℃、pH9、提取时间45 min的最佳条件下，牡丹籽粕蛋白的得率为79.83%±1.22%。SDS-PAGE显示，牡丹籽蛋白有五种分子量的蛋白质，分别有两种在15～25 kDa之间，有两种在35～40 kDa之间，有一种在55～70 kDa之间。傅里叶红外显示，牡丹籽粕蛋白中主要为α-螺旋和β-折叠，同时含有分子间氢键和少量碳水化合物。扫描电镜显示，牡丹籽粕蛋白中主要由β-折叠构成。与大豆蛋白、花生蛋白、豌豆蛋白对比发现，牡丹籽粕蛋白具有较好的持油性，达到4.5 g/g，和大豆蛋白相似的起泡性和乳化性。本研究可为牡丹籽粕蛋白在食品工业中的应用提供参考依据。     

橡胶籽分离蛋白的组成及功能性质

以低温脱脂橡胶籽粕为原料,采用等电点沉淀法制备橡胶籽分离蛋白。对橡胶籽分离蛋白的组成及功能性质进行测定,结果表明:橡胶籽分离蛋白中清蛋白、球蛋白、醇溶蛋白和谷蛋白所占比例依次为33.5%,4.8%,0.9%和60.8%。氨基酸组成比较全面,其中谷氨酸含量较高,达到19.894 g/100 g。p H值对橡胶籽分离蛋白的功能性质影响较大;橡胶籽蛋白浓度与其乳化性和起泡性呈正相关;在温度为60℃时,橡胶籽蛋白乳化性和起泡性分别达到34.29 m L/g和31.2%。     

响应面法优化牡丹籽粕蛋白提取工艺及其功能性质

以脱脂牡丹籽粕主要原料,在碱溶酸沉法的基础上,采用超声波辅助酶解法提取其中蛋白质。研究超声温度、超声时间、料液比、糖化酶剂量对蛋白质得率的影响,利用响应面法优化牡丹籽粕蛋白质提取工艺条件,并将提取的牡丹籽粕蛋白功能性质与大豆分离蛋白进行对比。结果表明:提取牡丹籽粕蛋白的最佳工艺条件为料液比1∶10 (g/mL)、超声温度50℃、超声时间120 min、糖化酶添加量2%;影响因素大小按顺序排列为超声温度>超声时间>糖化酶剂量>料液比;最优工艺条件下的牡丹籽蛋白质得率为26.65%,其蛋白质含量为91.02%;牡丹籽粕蛋白的持水性、泡沫稳定性和乳化稳定性比大豆分离蛋白强,但其吸油性、乳化性和起泡性弱于大豆蛋白。     

马齿苋籽粕蛋白功能性质分析及应用

以马齿苋籽粕蛋白为原料,以持水性等蛋白质功能性质和HLB值为指标,对马齿苋籽粕蛋白的功能性质进行了研究,并考察了马齿苋籽粕蛋白对核桃乳浊液稳定性的影响。结果表明:马齿苋籽粕蛋白的持水性和起泡性均低于大豆分离蛋白,但持油性略高,且乳化性和乳化稳定性远高于大豆分离蛋白;经分析测定马齿苋籽粕蛋白的HLB值为11,其在核桃乳浊液中单独使用的最适添加量为5 mg/g,沉淀率为0.034 g/m L;混合乳化剂的最优配方为,马齿苋籽粕蛋白、Tween-80和Tween-20的质量分数分别为55%、26%和19%,此混合乳化剂最适添加量为4 mg/g。说明马齿苋籽粕蛋白具有一定的乳浊液稳定性。     

不同提取方式对红花籽粕蛋白提取率及其功能特性的影响

通过盐提、碱提、碱溶酸沉和超声波辅助法得到红花籽粕蛋白,测定提取液中蛋白质提取率、多肽及游离氨基酸含量,比较蛋白的乳化性及乳化稳定性、起泡性及起泡稳定性。实验表明:超声波辅助碱溶酸沉法得到的蛋白提取液中蛋白质含量和提取率为最高,达到51.49 mg/mL和26.53%,蛋白质中多肽含量最高,达到6.56 mg/mL;碱法中游离氨基酸含量最高,达到2.14 mg/mL;不同提取方式对红花籽粕蛋白功能特性有影响;红花籽粕蛋白乳化性和乳化稳定性与大豆蛋白类似,当pH7.5时趋于稳定上升,均大于20%,且盐溶法蛋白乳化性最好,超声波辅助法最差;当pH5时红花籽粕蛋白起泡性和起泡稳定性优于大豆蛋白,均超过30%。     

牡丹籽粕蛋白提取工艺优化和功能性质分析

以酶水解-超声辅助碱溶酸沉法提取蛋白工艺为基础,初步对牡丹籽中粗蛋白进行分离提取。通过单因素实验和响应面试验,考察料液比、超声温度、酶用剂量、超声时间四个因素对牡丹籽粕蛋白提取率的影响,确定最佳提取工艺,并测定其功能特性。结果表明,酶水解-超声辅助碱溶酸沉法提取牡丹籽粕蛋白最优工艺条件为：料液比为1:9.8(w/v),超声温度为49.5℃,酶用剂量为1.9%,超声时间为119 min。在此条件下,蛋白质提取率达到90.95%。此时所得蛋白与常规法提取蛋白相比,氨基酸种类齐全、必需氨基酸含量均有所提高,功能特性如持水性、吸油性、乳化性皆优于常规法提取蛋白的功能特性,且乳化的稳定性更优,由此推测可作为食品加工乳化剂。因此酶水解-超声辅助碱溶酸沉法提取的牡丹籽粕蛋白具有更高的营养价值和更好的功能特性。     

樟树籽仁蛋白的物理性质及安全性的研究

开发樟树籽仁蛋白作为一种新型植物蛋白资源。以石油醚低温脱脂的樟树籽仁为原料,采用Osborne法对樟树籽仁蛋白进行分级,得到清蛋白、球蛋白、醇溶蛋白和谷蛋白4种组分。为了较全面系统地了解樟树籽蛋白进行理化性质及动物毒性的测定。结果表明,樟树清蛋白、球蛋白、醇溶蛋白和谷蛋白分别占总蛋白的25.64%,23.51%,2.32%和18.39%;等电点分别为3.1,3.5,3.3和4.5;变性温度分别为45.35℃,46.15℃,43.53℃和52.56℃;清蛋白、球蛋白和谷蛋白的必需氨基酸含量丰富,醇溶蛋白含量较低;清蛋白和谷蛋白表面较规则,球蛋白和醇溶蛋白表面发亮;清蛋白、球蛋白和谷蛋白的二级结构主要为β-折叠,醇溶蛋白主要为无规卷曲。MTT和ELISA测定结果表明,在推荐膳食浓度(1.2 g/kg)下不会对BALB/c小鼠肝细胞和脾细胞引起凋亡及免疫炎症的反应,说明在动物水平上樟树籽仁蛋白是安全无毒的。试验对樟树籽仁分离蛋白的研究,为樟树籽仁蛋白质资源的开发利用奠定基础,也为其他植物蛋白质的研究提供理论依据。     

Characterisation and functional properties of watermelon (Citrullus lanatus) seed proteins

BACKGROUND: People in developing countries depend largely on non‐conventional protein sources to augment the availability of proteins in their diets. Watermelon seed meal is reported to contain an adequate amount of nutritional proteins that could be extracted for use as nutritional ingredients in food products. RESULTS: Osborne classification showed that globulin was the major protein (≥500 g kg ^?1) present in watermelon seed meal, followed by albumin and glutelin. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that the polypeptides had low molecular weights ranging from 35 to 47 kDa. Isoelectric focusing revealed that the isoelectric point of most proteins was in the acidic range 4–6. These proteins are rich in aspartic acid, glutamic acid and serine. An increase in pH (5–9) significantly (P < 0.05) decreased the denaturation enthalpy of these proteins. Among functional properties, albumin exhibited a much higher dispersibility index (810.3–869.6 g kg^?1) than globulin (227.8–245.4 g kg^?1), glutelin (182.1–187.7 g kg^?1) and prolamin (162.3–177.7 g kg^?1). Digestibility was in the ranges 760.6–910.0 and 765.5–888.5 g kg^?1 for Mateera and Sugar Baby watermelon protein fractions respectively, while surface hydrophobicity ranged from 126.4 to 173.2 and from 125.8 to 169.3 respectively. The foaming and emulsifying properties of albumin were better than those of the other proteins studied. CONCLUSION: The good nutritional and functional properties of watermelon seed meal proteins suggest their potential use in food formulations. Copyright © 2010 Society of Chemical Industry     

热变性大米蛋白的结构和性质研究Ⅰ米蛋白加热前后的溶解特性和氨基酸变化

为探讨热变性米蛋白的性质与结构关系,分析了大米蛋白加热前后的溶解性能和氨基酸组成变化。结果表明,米渣中各种蛋白质的含量大大低于未受高温处理的原料大米;米渣蛋白中胱氨酸含量比大米谷蛋白提高83%,说明大米醇溶蛋白、球蛋白和清蛋白等受热后也存在于米渣中;米渣谷蛋白胱氨酸含量比米渣蛋白降低23%,说明胱氨酸是影响米渣蛋白溶解的重要因素。     

Walnuts (Juglans regia L): proximate composition,protein solubility,protein amino acid composition and protein in vitro digestibility

Walnuts contained 16.66% protein and 66.90% lipids on a dry weight basis. Non‐protein nitrogen values ranged from 6.24 to 8.45% of the total nitrogen when the trichloroacetic acid concentration was varied within the range 0.25–1.0 M . Albumin, globulin, prolamin and glutelin respectively accounted for 6.81, 17.57, 5.33 and 70.11% of the total walnut proteins. Walnut proteins were minimally soluble at pH 4.0. The majority of total walnut protein polypeptides had estimated molecular weights in the range 12 000–67 000. The Stokes radius of the major protein in walnuts (glutelin fraction) was 66.44 ± 1.39 Å. Lysine was the first limiting essential amino acid in total walnut proteins as well as in the globulin and glutelin fractions. Leucine and methionine plus cysteine were the second limiting essential amino acids respectively for the prolamin and albumin fractions. Hydrophobic and acidic amino acids dominated the amino acid composition in all protein fractions. Native and heat‐denatured walnut glutelins were easily hydrolysed by trypsin, chymotrypsin and pepsin in vitro. © 2000 Society of Chemical Industry     

Extractability and Chromatographic Characterization of Wheat (Triticum aestivum L.) Bran Protein

About 70% of the protein for human consumption is derived from plants, with cereals as the most important source. Wheat bran protein has a more balanced amino acid profile than that of flour. We here for the first time report the amino acid, size exclusion, and SDS‐PAGE profiles of bran Osborne protein fractions (OPFs). Moreover, we also investigated how OPFs are affected when physical barriers which entrap proteins in bran tissues are removed. Albumin/globulin is the most abundant OPF. It is richer in lysine and asparagine/aspartic acid than other OPF. Most bran albumin/globulin proteins have a molecular weight (MW) lower than 30 k and their chromatographic profiles differ from those of flour. The prolamin has high levels of proline and glutamine/glutamic acid. It is rich in proteins with a MW of 30 to 45 k and about 66 k reflecting contamination with gliadin from endosperm. The glutelin has high levels of glycine, proline, and glutamine/glutamic acid. Its protein is of intermediate and high MW with little protein with MW lower than 30 k. The high (MWs from 80 to 120 k) and low (MW around 45 k) MW glutenin subunits of flour are also present in bran. The glutelin of wheat endosperm is named glutenin. Ball milling releases albumin/globulin and glutelin but not prolamin. Not all glutelin was endosperm glutenin as a substantial part was entrapped in the aleurone cells.     

Japanese barnyard millet (Echinochloa frumentacea): Protein content,quality and SDS–PAGE of protein fractions

Total protein from five varieties of Japanese barnyard millet (Echinochloa frumentacea,) was separated into albumin/globulin, prolamin and glutelin fractions. The protein fractions were examined by sodium dodecylsulphate polyacrylamide gel electrophoresis. Total protein of the varieties ranged from 110·5 to 139·3 mg g^?1 of which 11·3–17·2% was albumin/globulins, 6·8–9·3% prolamins, 7·5–11·6% prolamin–like, 5·9–9·1% glutelin-like and 39·3–54·4% true glutelins. Amino acid analyses of the total protein showed that the varieties had essentially the same ammo acid composition. With the exception of lysine the amino acid levels adequately matched the provisional FAO scoring pattern. The amino acid composition of the protein fractions was also very similar. Electrophoretic analysis showed that the albumin/globulin fraction contained three or four components; the prolamin and glutelin fractions each had five components. The glutelin fraction had higher molecular weight components than the other two fractions.     

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。     

美藤果蛋白的分级提取、理化性质鉴定及抗氧化活性研究

为了探究美藤果分级蛋白的理化性质和抗氧化活性,以榨油后的美藤果粕为原料,采用超临界萃取法去除残留油脂,并用Osborne法进行美藤果粕分级蛋白的提取。结果显示,4种美藤果分级蛋白的氨基酸组成不同,美藤果清蛋白的营养价值最高。4种分级蛋白在不同pH值下的溶解度变化结果显示,4种分级蛋白的等电点大小为球蛋白(pH11)>醇溶蛋白(pH5)>谷蛋白(pH3,pH4)>清蛋白(pH2)。傅里叶红外光谱(FT-IR)分析结果证明清蛋白二级结构的稳定性最好,谷蛋白最差。差示扫描量热法(DSC)结果显示,醇溶蛋白的热稳定性最好,清蛋白的热稳定性最差。综合DPPH自由基清除率、ABTS+自由基清除率和还原力的试验结果,4种分级蛋白中,清蛋白的抗氧化活性最好,优于其他3种分级蛋白。     

紫苏籽中不同蛋白组分的功能性质研究

以紫苏籽为原料,经粉碎过60目筛后石油醚脱脂得到紫苏籽脱脂粉,然后采用不同方法提取得到紫苏籽分离蛋白、清蛋白和球蛋白,研究了3种蛋白的氨基酸组成及持水性、溶解性、乳化性等功能特性。结果表明:紫苏籽脱脂粉中蛋白质含量丰富,不同紫苏籽蛋白的氨基酸组成相近,其中谷氨酸含量最高,且均含有8种必需氨基酸;分离蛋白的热变性温度稍高于其他两种蛋白;清蛋白的持水性、持油性较好;在pH 1～10范围内,3种蛋白的溶解性均呈现出U型变化趋势,其中球蛋白的溶解性最好;在不同pH下,球蛋白的乳化活性和乳化稳定性高于其他两种蛋白。     

4种花生粕蛋白的理化性质及功能特性研究

以花生粕为原料,采用分级提取工艺提取花生清蛋白、球蛋白、醇溶蛋白和谷蛋白,研究4种花生粕蛋白的理化性质和功能特性。扫描电镜观察,4种花生粕蛋白的形态结构各不相同。SDS-PAGE法测定分子量表明,清蛋白含有4种亚基,相对分子量分别为70kDa、40kDa、30kDa、25kDa和15kDa;醇溶蛋白含有2种亚基,分子量分别为25kDa和15kDa;球蛋白含有5种亚基,分子量分别为40kDa、38kDa、30kDa、25kDa和15kDa;谷蛋白含有4种亚基,分子量分别为40kDa、30kDa、25kDa和15kDa。花生清蛋白、醇溶蛋白、球蛋白、谷蛋白的等电点分别为pH3.6、pH5.2、pH4.6、pH5.0。功能性质研究表明,球蛋白的持水性最好,为1.52mL/g,其次为谷蛋白1.10mL/g,清蛋白和醇溶蛋白的持水性较低分别为0.49mL/g、0.14mL/g;清蛋白的持油量相对较高为8.21mL/g,其次为球蛋白为7.16mL/g,谷蛋白和醇溶蛋白的持油量相对较低,分别为3.82mL/g和5.49mL/g;清蛋白的乳化性和乳化稳定性相对较高,乳化能力EC值和乳化稳定性ES值分别为71.4% 和83.33%,谷蛋白次之,EC和ES值分别为66.7% 和82.86%,醇溶蛋白和球蛋白相对较低,EC值分别为64.0% 和62.2%,ES值分别为82.35% 和76.67%。综上,花生粕清蛋白的持油性、乳化性和乳化稳定性相对较好。     

Preparation and characterization of high‐quality rice bran proteins

Rice bran contains 120–200 g kg^?1 protein in addition to a large amount of fat, carbohydrate, and phytic acid. Rice bran protein (RBP) fractions were refined by a two‐step preparation to eliminate residual carbohydrate. The first step involved the sequential extraction of defatted rice bran into RBP fractions using their distinct solubility to give 37 g kg^?1 of albumin, 31 g kg^?1 of globulin, 27 g kg^?1 of glutelin, and 2 g kg^?1 of prolamin. In the second step, carried out by dissolving in respective solvent and isoelectric precipitation, the protein content of each fraction increased from 69% to 97% for albumin, from 71% to 90% for globulin, from 74% to 83% for glutelin, and from 18% to 20% for prolamin. The low protein content in the prolamin fraction might be due to its low solubility in the protein assay. Emulsifying stability index and surface hydrophobicity increased in the second‐step preparation of albumin and globulin, but not of glutelin. Emulsifying properties of RBPs were lower than that of a soybean protein isolate. Denaturation temperatures and enthalpy values of denaturation for albumin, globulin, glutelin, and prolamin were 50.1 °C/1.2 J g^?1, 79.0 °C/1.8 J g^?1, 74.5 °C/3.0 J g^?1, and 78.5 °C/8.1 J g^?1, respectively. No significant differences in the denaturation temperatures and enthalpy values of denaturation of RBP fractions were obtained with these two‐step preparations (P < 0.05). Copyright © 2007 Society of Chemical Industry