糖基化大豆分离蛋白制备工艺优化及对其性质的影响

以大豆分离蛋白为试验材料,优化糖基化大豆分离蛋白制备工艺并研究经过葡萄糖处理对大豆分离蛋白溶解度、凝胶强度、乳化性以及热稳定方面的影响。结果表明:糖基化大豆分离蛋白最佳制备工艺为反应温度69.49℃、反应时间46.64 min、糖的添加量10.64%,凝胶强度最高为76.03;在相同p H下,经葡萄糖处理后的大豆分离蛋白溶解度较大,沉淀较少,而未糖基化的大豆分离蛋白沉淀量增加。糖基化处理的大豆分离蛋白乳化稳定性(emulsifying stability,ES)和热稳定性均有所增强。糖基化改性过程可显著提高大豆分离蛋白的溶解性和乳化性能,这为拓宽其在食品工业中的应用提供了理论基础。     

大豆乳清蛋白的热促凝聚及其对分离蛋白功能性的影响

分别在pH8.0和pH4.5对"碱提酸沉"法制备大豆分离蛋白过程中所得提取液进行热处理,研究了大豆乳清蛋白的热促凝聚效果及其对所制备分离蛋白功能性的影响。结果表明:加热处理可降低大豆乳清中乳清蛋白的含量,在pH8.0和pH4.5时提取液经70℃加热10 min分别使25.7%和40%乳清蛋白转移到分离蛋白产品中。以普通分离蛋白为对照,对3种分离蛋白产品进行功能性分析,发现3种产品均在pH4.5~4.8的范围内溶解度最小,70℃加热10 min所制备分离蛋白的持水性明显高于普通分离蛋白,但其持油性、起泡性、泡沫稳定性和乳化性均低于普通分离蛋白,而乳化稳定性无显著差异。     

微生物蛋白酶改性大豆分离蛋白的研究进展

本文主要综述了近十年来国内外微生物蛋白酶改性大豆分离蛋白的研究进展,分析了酶法改性蛋白质的特点和方式,简要介绍了几种微生物蛋白酶改性大豆分离蛋白的效果。包括Alcalase蛋白酶,枯草杆菌蛋白酶,米曲蛋白酶等,一般可改善大豆分离蛋白的溶解性、吸水性、乳化性、起泡性等。     

椰子分离蛋白起泡性、黏度及其影响因素的研究

分析了椰子分离蛋白(CPI)起泡性、泡沫稳定性、黏度及pH、离子强度、温度和蛋白质浓度对这些功能特性的影响。结果表明,椰子分离蛋白的起泡性和黏度与大豆分离蛋白(SPI)相近;而pH、离子强度、温度等因素对椰子分离蛋白的起泡性和黏度有显著的影响。在等电点(pH4.5)附近,CPI的起泡性和黏度最小,但却表现出最高的泡沫稳定性(91.25%);低离子强度可以提高椰子分离蛋白的起泡性,但高离子强度使CPI的起泡性、泡沫稳定性和黏度都变小;在70℃时CPI的黏度最大;蛋白质浓度变大时,CPI的黏度也显著增大。     

大豆分离蛋白酶解产物功能特性的研究

研究了大豆分离蛋白的碱性蛋白酶和木瓜蛋白酶水解产物各种加工功能性质的变化趋势,并比较了两种酶在各个不同酶解时间下水解产物的各种功能性质。结果表明:大豆分离蛋白酶解产物比大豆分离蛋白的溶解性、乳化性、发泡能力和吸油性都有所改善;大豆分离蛋白木瓜蛋白酶水解产物保水性、乳化性、吸油性、发泡能力、粘度、凝胶性均优于大豆分离蛋白碱性蛋白酶水解产物。     

大豆原料对分离蛋白加工及功能特性的影响

为研究不同大豆品种对大豆分离蛋白加工及功能特性的影响,选取了5个品种的大豆为原料,对比分析了原料对大豆分离蛋白得率、粗蛋白含量、凝胶特性、持水性、乳化特性的影响。结果显示,以冀豆12为原料制备的大豆分离蛋白得率最高,五星4最低;采用质构分析法对凝胶特性进行分析,以冀豆12为原料生产的大豆分离蛋白的凝胶强度值最高,五星3号最低;持水性最高为冀豆12,最低为五星3号;乳化性最高为五星3号,与冀豆12相差不大,乳化性最低为冀豆20。综上,以冀豆12为原料制备的大豆分离蛋白具备极高的持水性、凝胶特性和极佳的乳化特性,冀豆12适合高凝胶、高持水力、高乳化性的大豆分离蛋白的生产。     

三种大豆分离蛋白的比较研究和物化特性相关性分析

对3种不同大豆分离蛋白的基本化学组成、游离巯基、二硫键和表面疏水性进行了测定;对3种不同大豆分离蛋白的粘度、乳化性和凝胶性进行了分析;采用SPSS软件对物化特性与大豆分离蛋白的基本化学组成、游离巯基、二硫键和表面疏水性的相关性进行了分析,确定了大豆分离蛋白的粘度、乳化性和凝胶性与蛋白质含量、二硫键、游离巯基含量的相关性。     

乳清浓缩蛋白和大豆分离蛋白的营养价值评价

采用国际上通用的营养价值评价方法,分别测定了蛋白粉中乳清浓缩蛋白(WPC)和大豆分离蛋白(SPI)粗蛋白含量和氨基酸组成,对它们的营养价值进行全面评价.分析结果显示,乳清浓缩蛋白和大豆分离蛋白必需氨基酸含量较高,分别占其氨基酸总量的40.8%和38.5%,蛋白质的氨基酸评分(AAS)、化学评分(CS)、必需氨基酸指数(EAAI)、生物价(BV)、营养指数(NI)和氨基酸比值系数分(SRCAA)分别为66.3、61.4、69.5、64.1、56.0、82.0和48.3、44.6、62.3、56.2、51.1、76.6.结果表明乳清浓缩蛋白和大豆分离蛋白是良好的蛋白质来源.     

pH、离子强度等因素对椰子分离蛋白溶解性和乳化性的影响

分析椰子分离蛋白(CPI)溶解性、乳化性、乳化稳定性及pH、离子强度和温度对这些功能特性的影响。结果表明,与大豆分离蛋白和棉籽分离蛋白相比,椰子分离蛋白具有较好的溶解性、乳化性、吸油性和吸水性;而pH、离子强度和温度等因素对椰子分离蛋白的溶解性、乳化性和乳化稳定性有显著影响。在等电点附近,椰子分离蛋白表现出最低的溶解性与乳化性;低离子强度可提高椰子分离蛋白的溶解性和乳化性,而高离子强度降低了其溶解性和乳化性;CPI在60℃时有较好的溶解性和乳化性。     

用蛋白酶组合对大豆分离蛋白改性的研究

用蛋白酶组合对大豆分离蛋白进行有限水解,所得水解液不苦,具有良好的风味.改性后的大豆分离蛋白的氮溶指数由未水解的82提高到95,20℃时溶解度在25%以上.经正交试验得到的大豆分离蛋白水解的最佳工艺参数为:加酶量,0.55%(w/w);固液比,1∶8(w/w);酶解时间,60 min.     

Properties of protein concentrates and hydrolysates from Amaranthus and Buckwheat

Protein concentrates and pepsin hydrolysates were made after isoelectric precipitation of the proteinaceous liquor from wet-milling of grain of five Amaranthus and one buckwheat genotype. The Amaranthus protein concentrates exhibited better solubility, foaming, and emulsification than two commercial soy protein controls. Many protein properties depend on solubility, and Amaranthus protein concentrates were more soluble than soy protein isolate. The buckwheat protein concentrate was highly soluble with excellent emulsification, but poor foaming ability. Partial pepsin hydrolysis further improved solubility of the protein concentrates and also altered their foaming property. Fractionation and subsequent characterization of protein concentrates revealed that glutelins, albumins, and globulins predominated, with prolamins present in minor quantity. SDS-PAGE showed that globulins and glutelins were comprised of several subunits with varying molecular weights from relatively high to low while albumins were mostly of low molecular weight. The prolamin fraction of the buckwheat concentrate was comprised of intermediate to low molecular weight subunits while those of Amaranthus concentrates were only of low molecular weight. This study demonstrated the feasibility of producing potentially useful functional protein concentrates as by-product of Amaranthus and buckwheat starch extraction.     

Proximate composition and selected functional properties of African Breadfruit and sweet potato flour blends

Full-fat African breadfruit flour was used to replace 30, 40, 50, 60 and 70% of sweet potato flour. The chemical composition and functional properties of composite flours showed that they contains more protein, fat, and ash and less carbohydrate than sweet potato flour. With increasing level of supplementation of breadfruit, ash, protein and fat contents increased while carbohydrate decreased. The composite flours possessed higher water absorption than sweet potato flour. The water absorption capacity increased from 20% for sweet potato flour to the range of 85–120% for composite flours. The oil absorption capacities for some composite flours were higher than that for sweet potato but less than that of breadfruit. Composite flours had good foaming capacity but lacked foaming stability. The bulk density of the composite flours was found to be low which will be an advantage in the preparation of weaning food formulations.     

Comparison of functional and structural properties of native and industrial process-modified proteins from long-grain indica rice

Rice proteins, as a cheap plant protein source from the by-products of rice dreg processing, could potentially replace commonly used proteins such as soy and whey proteins in selected food products. In this study, the functional properties, surface hydrophobicity (H₀), sulfhydryl and disulfide bond contents, thermal properties, as well as secondary structures of native rice endosperm protein (REP) and processed rice dreg protein (RDP) extracted from long-grain indica rice, were compared. RDP was found to have a higher solubility associated with its relatively higher emulsifying and foaming properties than REP, as well as its water/oil holding capacity, although it was a denatured protein. The emulsifying properties were dependent on the solubility and H₀, while solubility was also related to the disulfide bond contents. Distinct differences in H₀, thermal properties, and disulfide bond contents between REP and RDP could be due to the conformational changes, as the industrial processing steps in the production of rice syrups caused an increase in β-turns at the expense of β-sheets and random coils of REP, leading to the unfolding of β-sheets into higher-ordered supramolecular structures for RDP, which could be responsible for its better functional properties.     

Comparison of functional and structural properties of native and industrial process-modified proteins from long-grain indica rice

Rice proteins, as a cheap plant protein source from the by-products of rice dreg processing, could potentially replace commonly used proteins such as soy and whey proteins in selected food products. In this study, the functional properties, surface hydrophobicity (H₀), sulfhydryl and disulfide bond contents, thermal properties, as well as secondary structures of native rice endosperm protein (REP) and processed rice dreg protein (RDP) extracted from long-grain indica rice, were compared. RDP was found to have a higher solubility associated with its relatively higher emulsifying and foaming properties than REP, as well as its water/oil holding capacity, although it was a denatured protein. The emulsifying properties were dependent on the solubility and H₀, while solubility was also related to the disulfide bond contents. Distinct differences in H₀, thermal properties, and disulfide bond contents between REP and RDP could be due to the conformational changes, as the industrial processing steps in the production of rice syrups caused an increase in β-turns at the expense of β-sheets and random coils of REP, leading to the unfolding of β-sheets into higher-ordered supramolecular structures for RDP, which could be responsible for its better functional properties.     

Functional and Rheological Properties of Amaranth Albumins Extracted From Two Mexican Varieties

The functional and rheological properties of amaranth albumins isolates extracted from two new Mexican varieties were determined. Functional properties tested were protein solubility, foaming, water and oil absorption capacities, emulsifying activity, and emulsion stability. The maximum solubility values for both amaranth albumins were found above pH 6 and values were compared to the solubility of egg albumins. Albumins from amaranth showed excellent foaming capacity and foaming stability at pH 5, suggesting that this protein could be used as whipping agents as egg albumins, also the water and oil absorption capacities reached their maximum values at acidic pH, suggesting that amaranth albumins could be appropriate in preparation of acidic foods. The rheological test based on farinograms and alveograms showed that wheat flour supplemented with 1% amaranth albumins improves the dough properties due to higher mixing stability and the bread had better crumb characteristics. In addition of the known high nutritional values of amaranth albumins, our results indicate the high potential for use of these proteins as an ingredient in food preparations.     

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...     

碱性蛋白酶对大豆浓缩蛋白起泡性的影响

制取低成本、高蛋白含量的大豆浓缩蛋白时,乙醇产生变性作用,从而降低了大豆浓缩蛋白的功能特性,因此本研究采用碱性蛋白酶对醇法大豆浓缩蛋白进行改性.通过对酶浓度、底物浓度、改性时间与改性温度的单因素实验,针对起泡性进行研究,然后进行正交实验,最终得出碱性蛋白酶提高醇法大豆浓缩蛋白起泡性最佳工艺条件:酶用量(E/S)为6%、底物浓度为(W/V)8%、酶解时间为2h、酶解温度为50℃,在此条件下测得的起泡能力为113.3%,起泡稳定性为56.7%,分别提高到酶改性前的2.5、3.6倍.     

Functional properties of protein from Lesquerella fendleri seed and press cake from oil processing

This investigation determined the functional properties of protein in Lesquerella fendleri seed and press cake from oil processing. L. fendleri seeds were heat-treated at 82 °C (180 °F) during 120 min residence time in the seed conditioner, and then screw-pressed to extract the oil. Unprocessed ground, defatted lesquerella seeds and press cakes were analyzed for proximate composition and protein functional properties. Protein from unprocessed lesquerella seed showed the greatest solubility (≥60%) at pH 2 and 10 and was least soluble (25%) at pH 5.5–7. Unprocessed lesquerella protein also had high surface hydrophobicity index (S_o), as well as, excellent foaming capacity and stability, emulsifying properties, and water-holding capacity (WHC) at pH 7. Protein solubility profile of the press cake showed up to 50% reduction in soluble proteins at nearly all pH levels, indicating heat denaturation during cooking and screw-pressing. Foaming capacity of the press cake protein decreased slightly, but foam stability was completely lost. Press cake protein also had markedly reduced values for S_o, emulsifying properties and WHC, further confirming lesquerella protein’s sensitivity to heat treatment.