Enzymatic hydrolysis and their effects on conformational and functional properties of peanut protein isolate

The effects of limited enzymatic hydrolysis by Alcalase on the conformational and functional properties of peanut (Arachis hypogaea L.) protein isolate (PPI) were investigated. Acid subunits of arachin were most susceptible to Alcalase hydrolysis, followed by conarachin and the basic subunits of arachin. Enzymatic hydrolysis increased the thermal stability of arachin and led to a sharp increase in the number of disulphide bonds with a decrease of the sulphydryl group in PPI hydrolysates in comparison with PPI. The analysis of intrinsic fluorescence spectra indicated a more moveable tertiary conformation of PPI hydrolysates than PPI. The limited emzymatic hydrolysis improved the functional properties of PPI, such as protein solubility and gel-forming ability, but impaired the emulsifying activity index.     

Effect of peanut protein isolate on functional properties of chicken salt-soluble proteins from breast and thigh muscles during heat-induced gelation

In this study, we investigated the impact of peanut protein isolate (PPI) on the functional properties of chicken salt-soluble protein (SSP) prepared from breast and thigh muscles during heat-induced gelation. The addition of PPI increased the water-holding capacity, gel strength and elasticity of heat-induced chicken SSP mixed gel. Breast and thigh SSP had the best gel properties at the addition of 2.5% and 3.5% PPI, respectively. Rheology indicated that thigh SSP showed higher storage modulus (G') than breast SSP. Differential scanning calorimetry showed that the addition of PPI changed transition temperatures (Tmax) and enthalpy of denaturation (ΔH) of chicken SSP. Scanning electron microscopy indicated that the PPI-treated SSP gels had more compact ultrastructures than controls. The results suggested that PPI may be a potential protein additive for improve the characteristics of SSP gelations.     

Improvement of functional properties of peanut protein isolate by conjugation with dextran through Maillard reaction

Reaction mixtures containing peanut protein isolate (PPI) and dextran (1:1 weight ratio) were dry-heated at 60 °C and 79% relative humidity for 7 days. SDS-PAGE analysis indicated that PPI had become complexed with dextran to form conjugates of higher molecular weight. Arachin, accounting for 50% of peanut proteins, was hard to glycosylate with dextran, which might limit the extent of glycosylation of PPI. The thermal stability of PPI was remarkably improved by mixture/conjugation with dextran. Proteins in mixtures/conjugates might have a more compacted tertiary conformation than PPI. The protein solubility of conjugates at pH 4.5-6.0 was remarkably increased compared with the PPI/mixture. Mixture with dextran could significantly improve the emulsifying and foaming properties of PPI (p < 0.05). Conjugation with dextran could further enhance emulsifying and foaming properties of PPI.     

不同干燥方法对花生蛋白功能特性的影响

以花生蛋白为原料,分别采用热风干燥、真空干燥、微波干燥和微波结合真空干燥对花生蛋白进行干燥处理,比较不同的干燥方式对花生蛋白功能特性(吸油性、持水性、乳化性、乳化稳定性、起泡性能和起泡稳定性)的影响。实验表明,微波结合真空干燥的花生蛋白不仅干燥时间短,而且具有较好的功能特性,微波结合真空干燥是一种干燥花生蛋白的适宜方法。     

不同干燥方法对花生蛋白功能特性的影响

以花生蛋白为原料，分别采用热风干燥、真空干燥、微波干燥和微波结合真空干燥对花生蛋白进行干燥处理，比较不同的干燥方式对花生蛋白功能特性（吸油性、持水性、乳化性、乳化稳定性、起泡胜能和起泡稳定性）的影响。实验表明，微波结合真空干燥的花生蛋白不仅干燥时间短，而且具有较好的功能特性，微波结合真空干燥是一种干燥花生蛋白的适宜方法。     

碱提酸沉法制取花生分离蛋白的优化条件

采用碱提酸沉法研究了制取花生分离蛋白的优化条件.结果显示,当花生粕的匀浆料液比为1:8(m/V)、碱浸提液pH为8.2、浸提温度为60℃,重复浸提两次,每次浸提2 h,酸沉pH为4.5时,制取的花生分离蛋白纯度可达90.21%,蛋白质回收利用率可达75.74%.研究结果可为花生蛋白的合理有效利用奠定基础.     

响应面优化花生分离蛋白提取工艺的研究

采用碱提酸沉法从低变性花生粕中提取花生分离蛋白,以花生分离蛋白提取率为响应值,应用Box-BehnkenDesign（BBD）对碱提温度、时间、pH和液料比4因素进行响应面分析,确定碱提的最佳工艺条件为:碱提温度57.5℃、时间100min、pH9.2和液料比12∶1;通过单因素实验确定最佳酸沉pH为4.5。在此条件下,花生分离蛋白最高提取率为87.57%,与预测值87.88%相对误差约为0.4%。      

Effects of succinylation and deamidation on functional properties of oat protein isolate

The effects of two different modification methods (deamidation and succinylation) on the functional properties (solubility, water- and oil-binding capacity, foaming capacity and stability, emulsion activity and stability) of oat protein isolates were evaluated. Protein isolates extracted from defatted oat flour at alkaline pH were acylated by 0.20 g/g of succinic anhydride. The protein isolate was also modified using a mild acidic treatment (HCl, 0.5 N). Succinylation and deamidation improved solubility and emulsifying activity of the native protein isolate. Foaming capacity of oat protein isolate increased after deamidation, whereas succinylation decreased it. The deamidated and succinylated proteins had lower foam and emulsion stabilities than had their native counterpart. Water- and oil-binding capacity, in both modified oat proteins, was higher than those of the native oat protein isolate.     

红衣组分对花生分离蛋白及其酶解产物理化和抗氧化性质的影响

以花生为原料,研究了花生红衣组分对花生分离蛋白及其酶解产物理化和抗氧化性质的影响。研究结果表明:含红衣的分离蛋白酶解速度低于不含红衣的;相同水解度条件下,含红衣的表面疏水性小于脱红衣的;GPC分布中,含红衣的峰值大于脱红衣的;红衣组分能够提高花生分离蛋白及其酶解产物的溶解性、乳化稳定性、乳化活性;在相同水解度条件下,含红衣的水解产物多酚含量显著高于脱红衣的,多酚含量的差异与花生分离蛋白及其水解产物的抗氧化性具有正相关性。     

高压均质对大豆分离蛋白功能性质的影响

为了了解高压均质技术对大豆分离蛋白（SPI）功能性质的影响,采用不同的均质压力、均质次数和料液比对大豆分离蛋白溶液进行了高压均质处理,并分析处理前后SPI功能性质的变化.结果表明：高压均质可在一定程度上提高SPI的溶解性、乳化活性及其稳定性和起泡性及泡沫稳定性.均质压力在0～70 MPa的范围内升高时,SPI的溶解性、乳化稳定性、起泡性和泡沫稳定性得到了相应的改善,而乳化活性在压力为40 MPa时达到最高;均质次数由1次向3次增加时,SPI的乳化稳定性、起泡性及泡沫稳定性得到了提高,而溶解性和乳化活性则降低;均质物料料液比在1∶16～1∶8 （g∶mL）的范围内逐步增大时,SPI的各项功能性质均有不同程度的提高,并在料液比为1∶8时达到了最高值.     

Structure,trypsin inhibitor activity and functional properties of germinated soybean protein isolate

The objective of this research was to investigate the effects of germination on functional and conformational properties as well as the in vitro trypsin digestibility of soy protein isolate (SPI). The influences of germination on the molecular properties of SPI were also evaluated. The germination degraded lipoxygenase, α, α' subunits of β‐conglycinin (7S) and acidic chains of glycinin (11S) of soybean. Concomitantly, the loss of tertiary structures of SPI occurred due to the germination. The trypsin inhibitor activity of germinated SPI presented a decreasing trend, followed by an increase in the growth of hypocotyls. The in vitro trypsin digestibility of germinated SPI followed a consistent trend with the trypsin inhibitor activity. The protein solubility (PS) and emulsifying properties of SPI were improved by the germination, in a hypocotyl length‐dependent manner. The data suggest that some selected functional properties and the in vitro digestibility of soy proteins can be improved by means of the germination.     

常压低温等离子处理提高花生分离蛋白水合性质的研究

采用常压低温等离子技术(ACP)处理花生分离蛋白粉。研究了ACP处理对花生分离蛋白水合作用的影响。试验结果表明,ACP处理能显著提高花生分离蛋白的溶解度和凝胶持水性。利用傅里叶变换红外光谱(FTIR)和荧光光谱技术,分析花生分离蛋白水合性质提高的原因。采用低场核磁共振(LW-NMR)快速分析水分分布状态。低温等离子处理3 min后,无规卷曲含量增加,α-螺旋和β-转角含量减少;表面疏水性指数降低,亲水性增强,蛋白表面结构从紧密变松散,更多的亲水活性位点被暴露; LW-NMR结果表明,随着ACP处理时间的延长,T_(21)弛豫时间的峰面积增大,T_(21)弛豫时间的峰面积变化与WHC结果一致。ACP是一种提高蛋白质水合作用的有效处理技术。     

酸性调控对大豆分离蛋白纤维功能性质的影响

近年来,蛋白淀粉样纤维因其独特的材料学特性,在结构化和功能化食品领域引起广泛的关注。然而人们对蛋白纤维基材料的功能特性及相关调控机理还不甚了解。本文研究了不同酸诱导剂对大豆分离蛋白(SPI)自组装纤维的结构、乳化特性、凝胶特性及成膜性质的影响。结果表明,经盐酸或醋酸诱导均能形成纤维化蛋白,蛋白质的二级结构则由α-螺旋转变为β-折叠结构。有趣的是,相较于盐酸诱导的短而硬的蛋白纤维(H-SPI),醋酸诱导的蛋白纤维(C-SPI)形状更加柔顺且规则。除此之外,C-SPI拥有更大的粒径、更高的凝胶硬度、更优的乳化稳定性和成膜性。因此,通过选择适宜的酸诱导剂种类能够改善蛋白纤维的理化和功能性质。     

酶改性大豆分离蛋白的制备及产品功能性的研究

为了改善碱溶酸沉法大豆分离蛋白产品(简称SPI)的功能性,采用有限酶解的方法,从6种蛋白酶中选出中性蛋白酶(Neutrase)作为改性用酶.通过单因素实验,分析了底物浓度,E/S,反应时间对水解度和氮收率的影响,并通过正交实验确定制备酶改性大豆分离蛋白(简称ESPI)的最佳工艺参数为:底物浓度为3%,E/S为1 200U/g,时间为60 min.得到的ESPI的蛋白含量与SPI相近,但NSI由SPI的90%提高到97%.而且在功能性方面,ESPI也得到了很好的改善,尤其是乳化性和起泡性.     

Effect of pH on phosphorylation of potato protein isolate

Potato protein isolate (PPI) was phosphorylated with sodium trimetaphosphate (STMP) at ambient temperature and various reaction pH (5.2, 6.2, 8.0 and 10.5) to improve the functional properties without impairing the nutritional availability. Changes in chemical composition (total and coagulable protein content, ash and minerals content and amino acid composition), functional properties (protein solubility index, emulsifying activity and foaming capacity, water and oil absorption capacity) and phosphorus were determined. The chemical composition and functional properties of phosphorylated potato protein isolate (PP-PPI) were significantly different (p < 0.05). The PP-PPI at pH 5.2 was characterised by the highest content of all amino acids, whereas, PP-PPI under alkaline conditions (pH 10.5) caused decrease in these compounds. PP-PPI at pH 8.0 had the highest oil absorption capacity, emulsion activity and foam capacity, whereas, PP-PPI at pH 10.5 had the highest WAC.     

赤藓糖醇对豌豆分离蛋白结构和功能特性的影响

为研究赤藓糖醇对豌豆分离蛋白结构和功能特性的影响,利用8-苯胺基-1-萘磺酸钠荧光探针法、紫外和荧光光谱法,研究赤藓糖醇对豌豆分离蛋白溶解性、持水性、起泡性、乳化性及表面疏水性等的影响。结果表明:随赤藓糖醇质量分数的增加,豌豆分离蛋白的溶解性基本呈先增加后下降趋势,且均在pH4.0处最低。持水性逐渐增加,且均在pH5.0处最低。起泡性和乳化性均先增加后趋于平稳。当赤藓糖醇质量分数在0~10%范围内,表面疏水性逐渐增加,随后趋于稳定。随赤藓糖醇质量分数增加,色氨酸残基暴露在蛋白质分子表面,荧光强度先增加后趋于稳定,且与表面疏水性变化趋势相同。该研究表明,适度赤藓糖醇处理可改善豌豆分离蛋白的结构和功能特性。     

米糠蛋白的分离及其营养特性的研究

米糠中含有较高的蛋白质，其必需氨基酸组成近似于人体需要量模式，本文基于此原因，主要介绍了米糠蛋白的分离方法以及营养特性，相信米糠蛋白将成为食品工业的一种新型蛋白质。     

榛子分离蛋白提取及其功能特性的研究

以低变性榛子饼为原料,经脱脂后采用碱提酸沉法提取榛子分离蛋白,确定了最佳提取工艺条件,并分析了榛子分离蛋白的功能特性.结果表明,提取榛子分离蛋白的最佳工艺条件为:料液比1:15,碱提pH9.0,碱提温度50℃,碱提时间70 min,酸沉pH4.5.最佳条件下榛子分离蛋白的溶解性、持水性和吸油性分别为34.0%、2.6 mL/g和2.15 mL/g,乳化性、乳化稳定性、起泡性和泡沫稳定性分别为61.2%、85.0%、86.5%和24.0%,榛子分离蛋白的等电点为4.52.     

马来酸酐酰化改性对大豆分离蛋白功能性质的影响

研究马来酸酐酰化改性对大豆分离蛋白功能性质的影响。结果表明:随着马来酸酐用量的增大,大豆分离蛋白的酰化度增大,等电点降低;随着酰化度的增大,大豆分离蛋白构象松散,色氨酸残基的微环境趋向于暴露于水的状态,亲水性增强;经马来酸酐酰化改性后,大豆分离蛋白的溶解性、发泡性、乳化性及乳化稳定性均显著提升,但泡沫稳定性有所下降。研究表明,马来酸酐酰化改性大豆分离蛋白是一种非常有前景的功能性食品添加剂。     

超声物理改性对SPI功能特性的影响

采用超声仪对大豆分离蛋白（SPI）溶液进行超声处理，研究了不同超声处理时间，不同功率处理后SPI功能特性的变化。结果表明，超声处理后大豆分离蛋白的溶解性、起泡性、乳化性和凝胶性都有明显的提高。