响应面法优化超声波辅助含酶反胶束体系后萃大豆蛋白的研究

将超声波技术应用于大豆蛋白质的后萃过程中,采用单因素实验法,考察了KCl浓度、超声温度、缓冲溶液pH、超声时间、超声功率、乙醇浓度等6因素对大豆蛋白后萃率的影响,并采用了响应面分析法的Box-Benhnken中心组合设计进行实验设计,确定了大豆蛋白后萃取的理想工艺条件,即KCl浓度为1.51mol/L、超声温度45℃、pH9.52、超声时间31.65min、超声功率240W、乙醇浓度为0.38%,最终大豆蛋白的后萃率达到(93.78±0.35)%。     

超声波辅助SDS反胶束前萃花生蛋白研究

采用SDS(十二烷基磺酸钠)/异辛烷―正辛醇反胶束体系萃取花生蛋白,并采用超声波辅助萃取,主要研究全脂花生粉加入量、缓冲溶液pH值、萃取时间、萃取温度、超声波功率、KCl浓度、SDS浓度、Wo对蛋白萃取率影响。设计正交实验优化萃取工艺,结果表明,最优前萃工艺条件为:花生粉加入量0.015 g/mL、缓冲溶液pH值9、萃取时间40 min、萃取温度35℃、超声波功率270 W、KCl浓度0.25 mol/L、SDS浓度0.07 g/mL、Wo为24;在此条件下,花生蛋白萃取率为89.62%±1.15%。     

反胶束萃取大豆蛋白前萃过程的动力学研究

系统研究了影响总传质系数的各个主要因素(缓冲溶液pH、反胶束含水量W0、表面活性剂浓度、KCl浓度、振荡速度操作温度),探讨了以丁二酸二异辛酯磺酸钠(AOT)/异辛烷反胶束体系萃取大豆蛋白前萃过程的动力学。结果表明,大豆蛋白前萃过程中总传质系数随缓冲溶液pH和KCl浓度的升高先增大后减小,分别在pH7.0和KCl浓度0.1mol/L附近出现最大值;随W0和AOT浓度的增加而增大,当W0大于12时,总传质系数基本不变;随温度的变化总传质系数变化不大。由此可以推断出蛋白质的加溶过程,不仅与蛋白质分子和表面活性剂之间的静电相互作用力和疏水力有关,而且与界面阻力有关。     

二次通用旋转组合设计法优化AOT反胶束体系萃取大豆蛋白质的研究

表面活性剂浓度、pH、温度、W0、电解质浓度、乙醇浓度与时间是影响AOT反胶束萃取大豆蛋白质的主要因素,采用二次通用组合旋转对AOT反胶束前萃取大豆蛋白质的工艺进行了研究,建立前萃工艺回归方程,得出前萃工艺优化条件分别为:W014、AOT浓度0.08 g/mL、pH值7.0、KCl浓度0.05 mol/L、萃取时间30 min、萃取温度40 ℃、乙醇浓度0.5%.在此条件下,蛋白质含量为24.14%,蛋白前萃率为65.82%.     

CAB/正庚烷/正己醇反胶束体系前萃大豆蛋白的研究

探讨了CAB／正庚烷／正己醇反胶束溶液萃取大豆蛋白的前萃机理和工艺，系统地研究了盐的种类、pH、KCl的浓度、表面活性剂CAB的浓度、加料量、萃取温度、萃取时间和w。对蛋白前萃率的影响，得到了以cAB／正庚烷／正己醇反胶束体系萃取全脂大豆粉中蛋白质的最佳前萃工艺条件。     

超声波辅助AOT反胶束体系后萃大豆蛋白的研究

研究超声波辅助反胶束体系(AOT/异辛烷)萃取大豆蛋白的后萃过程,并分析各因素对蛋白后萃率的影响,通过正交试验得到了AOT/异辛烷反胶束体系萃取全脂大豆粉中蛋白的最佳后萃工艺条件为:KCl浓度1.0 mol/L、pH值7.0、超声功率为270 W.在此条件下,蛋白质的后萃率为98.91%.     

反胶束法提取小麦胚芽蛋白前萃工艺的优化

采用由琥珀酸二(2-乙基已基)酯璜酸钠(AOT)-异辛烷-化钾缓冲溶液组成的反胶束体系从小麦胚芽中提取蛋白质,考查了AOT浓度、缓冲溶液pH值、KCl浓度、萃取时间、加入小麦胚芽粉量、W0、温度对小麦胚芽蛋白前萃提取率的影响,并在单因素基础上,通过响应面分析法确定前萃最佳工艺条件:A钾浓度为3.35/50 mL异辛烷,缓冲溶液pH 8.0,KCl浓度0.1 mol/L,萃取时间60 min,加入小麦胚芽粉量0.5 g,W0为.25,温度36℃,在此最佳工艺条件下,小麦胚芽蛋白前萃提取率达到34.55%.     

蛋白酶对反胶束体系前萃率规律影响的研究

主要研究利用4种蛋白酶在SDS/异辛烷/正辛醇反胶束体系萃取大豆蛋白的同时,对其酶解,考查酶加入量、缓冲溶液pH、W0、萃取温度、萃取时间,乙醇浓度等六因素对蛋白前萃率的影响规律,确定碱性蛋白酶萃取蛋白的最佳工艺条件是:W0值、缓冲溶液的pH、萃取时间、乙醇浓度、酶加入量、萃取温度,分别为16.1、7.5、30 min、0.4%、5%、45℃。为今后研究蛋白质分子空间结构和分子量大小与反胶束"水池"微观结构相互关系的规律奠定基础。     

响应面法优化反胶束提取花生粕蛋白后萃工艺

以二辛基琥珀酸磺酸钠(AOT)-异辛烷-氯化钾缓冲溶液为前萃体系,对从前萃体系中提取的花生粕蛋白的后萃工艺条件进行研究。考查了KCl缓冲溶液的浓度、加入量以及pH对花生粕蛋白后萃率的影响,并在单因素试验基础上,通过响应面试验确定后萃最佳工艺条件为KCl缓冲溶液的浓度1.02 mol/L、加入量1.49 mL、pH 8.83。在此最佳工艺条件下,花生蛋白后萃率达到84.4%。     

反胶束法萃取蒜氨酸前萃工艺的优化

采用由十六烷基三甲基溴化铵(CTAB)-正庚烷-正辛醇和氯化钾缓冲溶液组成的反胶束体系从大蒜粉中提取蒜氨酸,考察了CTAB浓度、萃取时间、KCl浓度、温度、缓冲溶液pH值、蒜粉加入量对蒜氨酸前萃提取率的影响,并在单因素基础上,通过正交实验确定前萃最佳工艺条件:CTAB浓度0.07mol/L,缓冲溶液pH 7.0,KCl浓度0.3mol/L,萃取时间30min,加入蒜粉含量0.5g/30mL,温度40℃,在此最佳工艺条件下,蒜氨酸前萃提取率达到1.62%。     

大豆蛋白溶解性研究

该文概述大豆蛋白溶解特性及其与一般物质溶解差异,介绍提高大豆蛋白溶解性改性方法及研究现状,对比不同改性增溶方法优、缺点,并提出今后大豆蛋白改性研究方向。     

Co-precipitation of whey and pea protein – indication of interactions

The aim was to optimise the yield of co-precipitation of whey protein isolate (WPI) and pea protein isolate (PPI) and compare co-precipitates and protein blends with respect to solubility. The yield of co-precipitates was tested with different protein ratios of WPI and PPI in combination with different temperatures and acid precipitation (pH 4.6). The highest precipitation yield was obtained at protein ratios WPI < PPI, high temperature and alkaline protein solvation. The solubility was measured by an instability index and absorption spectroscopy of re-suspended precipitated proteins at pH 3, 7 and 11.5. Co-precipitates had significantly lower solubility than protein blends. Protein ratios WPI > PPI, low precipitation temperature and high pH showed the highest solubility. Differences in protein composition between co-precipitates and protein blends were observed with SDS-PAGE and matrix-assisted laser desorption ionisation time-of-flight, and indicated different protein–protein interaction in samples, which needs further investigations.     

Physicochemical and Functional Properties of Soy Protein Substrates Modified by Low Levels of Protease Hydrolysis

ABSTRACT: Endo-protease treatments achieving low degrees of hydrolysis (DH 2% and 4%) were used to improve functional properties of hexane-extracted soy flour (HESF), extruded-expelled partially defatted soy flour (EESF), ethanol-washed soy protein concentrate (SPC), and soy protein isolate (SPI). These substrates had protein dispersibility indices ranging from 11% to 89%. Functional properties, including solubility profile (pH 3 to 7), emul-sification capacity and stability, foaming capacity and stability, and apparent viscosity were determined and related to surface hydrophobicity and peptide profiles of the hydrolysates. Protein solubilities of all substrates increased as DH increased. Emulsification capacity and hydrophobicity values of the enzyme-modified HESF and EESF decreased after hydrolysis, whereas these values increased for SPC and SPI. Emulsion stability was improved for all 4% DH hydrolysates. Hydrolyzed SPC had lower foaming capacity and stability. For substrates other than SPC, foaming properties were different depending on DH. Hydrolysis significantly decreased the apparent viscosities regardless of substrate. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated differences in the molecular weight profiles of the hydrolysates. HESF and EESF, which had high proportions of native-state proteins, showed minor changes in the peptide profile due to hydrolysis compared with SPC and SPI.     

细菌中蛋白质样品制备方法研究进展

细菌在生长繁殖时,细菌蛋白的表达受到环境影响而存在较大差异,使得细菌蛋白表达具有复杂性。在食品生产加工过程中可能会受到致病菌污染,细菌产生的内毒素和外毒素均会对人体健康构成威胁,因此需要高灵敏度和高特异性的检测方法来定量分析和鉴定食品中的细菌毒素。蛋白组学方法可以揭示细菌蛋白组成及其潜在的生物学功能,感染过程中菌体蛋白表达变化和致病机制理。其中,细菌蛋白样品的前处理作为细菌蛋白组学研究的关键步骤,直接影响鉴定的细菌蛋白质量。本文主要阐述目前细菌蛋白组学研究中菌体蛋白和胞外蛋白样品制备方法及其对蛋白鉴定和定量的影响,将为更深入的开展细菌蛋白组学研究提供参考。     

大豆分离蛋白改性对其功能性质影响

大豆分离蛋白是大豆蛋白最为精制形式,广泛应用于食品工业,并在不同产品中表现出不同功能。该文综述近年来大豆分离蛋白物理、化学、酶法及基因工程改性对其功能性质影响,经不同方式改性可产生合适功能性质,从而拓宽大豆分离蛋白在食品工业中应用。     

几种新型花生蛋白产品的生产

本文从花生蛋白质利用的角度介绍了几种新型花生蛋白产品的加工工艺，针对我国人民膳食结构中蛋白质的摄入水平较低的实际情况，论述了花生蛋白开发利用的必要性，展望了花生蛋白开发利用的广阔前景。     

大豆蛋白生产与应用现状

该文综述大豆蛋白制品—大豆蛋白粉、大豆分离蛋白、大豆浓缩蛋白、大豆组织蛋白生产现状、存在问题及大豆蛋白在面制品、肉制品、乳制品、饮料制品等中应用现状。     

Effects of silage protein degradability and fermentation acids on metabolizable protein concentration: A meta-analysis of dairy cow production experiments

A meta-analysis was conducted using data from dairy cow production studies to evaluate silage metabolizable protein (MP) concentrations. The data consisted of 397 treatment means in 130 comparisons, in which the effects of silage factors (e.g., date of harvest, wilting, silage additives) were investigated. Within a comparison, a fixed amount of the same concentrate was fed. A prerequisite of data to be included in the analysis was that silage dry matter (DM), crude protein (CP), ammonia N, lactic acid (LA), and total acid (TA) concentrations and digestibility were determined. A smaller data set (n = 248) comprised studies in which silage water-soluble N concentration was also analyzed. The supply of MP was estimated as amino acids absorbed from the small intestine using a model with constant values for ruminal effective protein degradability (EPD) and intestinal digestibility of rumen undegraded protein. Microbial protein was calculated on the basis of digestible carbohydrates and rumen degradable protein (RDP). Alternative models were used to estimate microbial protein formation, assuming the energy values of RDP and TA to be equivalent to 1.00, 0.75, 0.50, 0.25, and 0 times that of digestible carbohydrates. Because EPD values are seldom determined in production trials, they were derived using empirical models that estimate them from other feed components. The goodness of fit of models was compared on the basis of root mean squared error (RMSE) of milk protein yield (MPY) predicted from MP supply (adjusted for random study effect) and Akaike's information criterion. Metabolizable protein supply calculated from basal assumptions predicted MPY precisely within a study (RMSE = 16.2 g/d). Variable contribution of RDP to the energy supply for microbial synthesis influenced the precision of MPY prediction very little, but RMSE for MPY increased markedly when the energy supply of rumen microbes was corrected for TA concentration. Using predicted rather than constant EPD values also increased RMSE of MPY prediction. These observations do not mean that the supply of MP from undegraded feed protein is constant. However, it suggests that our current methods overestimate the range in EPD values and that the techniques have so many inherent technical problems that they can mask the true differences between the feeds. Including new elements in feed protein evaluation models may not improve the precision of production response predictions unless the consequent effects on the supply of other nutrients are taken into account.     

中国植物油料蛋白生产现状与发展趋势

对中国主要植物油料蛋白--大豆蛋白、花生蛋白、棉籽蛋白、菜籽蛋白工业的生产现状与发展趋势进行了论述,同时对这4种蛋白的氨基酸组成、营养效价和生物价进行了比较.结果表明,菜籽蛋白的生物价和营养效价最高,其次为大豆蛋白,再次为棉籽蛋白,最后为花生蛋白.目前我国对大豆蛋白开发利用最多,而对于菜籽蛋白和棉籽蛋白,由于脱毒技术等原因,开发利用不足.随着人民生活水平的提高、技术的成熟,这些油料蛋白将得到进一步的开发、利用,市场潜力巨大.     

The structures and functions of ice crystal-controlling proteins from bacteria

Many organisms have evolved into unique mechanisms which minimize freezing injury due to extracellular ice formation. Specifically, certain bacteria have produced a few proteins each with different functions. For example, the ice nucleation protein acts as a template for ice formation, which is responsible for imparting ice nucleating activity. The anti-nucleating protein inhibits the fluctuation of ice nucleus formation by a foreign particle in the water drop. Also, the antifreeze proteins depress the freezing temperature, modify or suppress ice crystal growth, inhibit ice recrystallization, and protect the cell membrane from cold-induced damage. In this article, a review on the current knowledge of the structure and the function of these three types of proteins, which are capable of interacting with ice itself or its nuclei from bacteria.