脱脂鸭蛋黄粉中卵黄高磷蛋白的提取优化

为优化NaCl溶液提取卵黄高磷蛋白的工艺条件,提高提取率,以卵黄高磷蛋白的得率为指标,选用Box-Behnken设计,采用4因素3水平的响应面分析法,探讨了洗涤次数、液料比、提取时间、NaCl浓度对卵黄高磷蛋白得率的影响。结果表明:各因素对卵黄高磷蛋白得率的影响的主次顺序为,洗涤次数>液料比>提取时间>NaCl浓度,卵黄高磷蛋白得率的理论极值为5.47%。卵黄高磷蛋白的最佳提取工艺参数为:NaCl浓度12%,提取时间5 h/次,洗涤次数5次,液料比(g∶mL)12∶1;在此条件下,卵黄高磷蛋白的得率为5.27%,提取率为88.16%。     

响应面法优化香茅精油提取工艺及其成分分析

采用水蒸气蒸馏的方法,在以NaCl溶液浓度、液料比、蒸馏时间、超声功率、超声时间为单因素分析的基础上采用中心组合响应面设计法(CCD)进行提取工艺优化,并利用GC-MS分析香茅精油的主要化学成分。结果表明:在NaCl溶液浓度9%,液料比15∶1,蒸馏时间170min,功率420W条件下超声65min,香茅精油提取得率可达到最大值2.69%,共含有44种化学成分,其中含量最高的物质是香茅醛,占比高达36.94%。     

鲨鱼肉盐溶蛋白凝胶质构参数的相关性分析及其提取条件优化

采用响应面分析法,对鲨鱼肉盐溶蛋白凝胶的质构参数进行相关性分析,并以鲨鱼肉盐溶蛋白凝胶硬度为指标,对NaCl浓度、提取溶液的pH和低温加热时间进行优化。结果表明:鲨鱼肉盐溶蛋白凝胶各质构参数线性相关显著;建立了盐溶蛋白凝胶硬度与提取条件的数学模型,其中NaCl浓度和低温加热时间对鲨鱼盐溶蛋白凝胶的硬度影响极其显著,提取溶液的pH对其影响显著。NaCl浓度为0.74mol/L,提取溶液的pH为6.56,低温加热时间为79.10min,鲨鱼肉盐溶蛋白凝胶的硬度达到最大预测值37.70g。     

黄米蛋白提取工艺研究

以陕北主产黄米为原料,经脱脂后采用碱溶酸沉法提取黄米蛋白,分析了提取时间、提取温度、料液比和p H值对蛋白提取率的影响,设计正交试验优化黄米蛋白的提取工艺条件。结果表明:提取因素对黄米蛋白提取率有影响,各因素对黄米蛋白提取率的影响主次顺序为p H值料液比提取时间提取温度,其中p H值对蛋白提取率的影响极显著,料液比和提取时间的影响显著,而提取温度的影响不显著。黄米蛋白的优化提取工艺条件为提取时间80min、提取温度30℃、料液比1∶2.5和p H值10,其蛋白提取率为86.93%。     

凡纳滨对虾肌肉盐溶蛋白提取工艺研究

本实验以凡纳滨对虾肌肉为原料,盐溶蛋白得率为指标,研究盐溶蛋白最佳提取工艺参数,得到其最佳提取条件:NaC1浓度0.6 mol/L;抽提时间25 h;料液比1∶4; pH值7.此条件下盐溶蛋白含量为105.73 mg/g,提取率为83.34％.     

响应面法优化鸭胸肉盐溶蛋白的提取工艺

为了得到鸭胸肉盐溶蛋白提取的最佳条件,在单因素实验的基础上,应用响应面法(RSM)优化鸭肉盐溶蛋白的提取条件确定最佳提取条件为:浸提溶液pH7.7,NaCl浓度0.5mol/L,固液比1∶5.2(g/mL),浸提时间12.3h,此时鸭胸肉盐溶蛋白的提取率可达19.9％,与理论预测值(20.4％)相差2.5％.本文为鸭肉盐溶蛋白的提取提供了一定的理论基础.     

超声波辅助盐溶法提取杏鲍菇蛋白的工艺优化

文章使用超声波辅助盐溶法提取杏鲍菇中的粗蛋白,并通过正交试验、响应面试验对提取条件进行优化,以期获得最佳提取工艺条件。试验结果表明:在选取的几个条件中,对提取率影响最为显著的因素是料液比和温度,而不显著的因素是超声波功率和NaCl浓度,杏鲍菇粗蛋白提取的最佳条件为:NaCl浓度2%、提取温度57℃、料液比1∶38(g/mL)、超声波功率340 W和提取时间20min,在此条件下得到杏鲍菇蛋白的提取率为57.9%。     

提取条件对鲨鱼肉盐溶蛋白热诱导凝胶特性的影响

以鲨鱼肉为材料,研究NaCl 浓度、pH 值、静置提取时间及加热时间对鱼肉盐溶蛋白热诱导凝胶保水性和质构特性的影响。结果表明：鲨鱼肉盐溶蛋白凝胶的保水性、硬度、弹性和黏聚性与NaCl 溶液浓度呈正相关;在NaCl 溶液浓度0.8mol/L、pH6.5～7.0、静置提取时间24h、40℃加热40～60min 时形成的凝胶保水性及其质构指标较理想;40℃加热盐溶蛋白,有利于形成凝胶结构,但随着加热时间的延长,盐溶蛋白凝胶硬度增加,保水性降低。     

盐溶法提取桑椹籽蛋白质的参数优化

以桑椹籽为原料,对盐溶法提取桑椹籽蛋白质的参数进行了优化.通过单因素试验和正交试验,探讨了不同因素对盐溶法提取桑椹籽蛋白质提取率的影响,确定了盐溶法提取桑椹籽蛋白质的最佳提取参数.结果表明,桑椹籽蛋白质的等电点(PI)为4.3;各因素对蛋白质提取率的影响程度由大到小依次是料液比、氯化钠浓度、提取温度、提取时间.盐溶法提取桑椹籽蛋白质的最佳参数为:浸提液氯化钠溶液浓度0.3 mol/L,料液比1 40,浸提温度50℃,浸提时间40 min.在此条件下,蛋白质的提取率为28.80%.     

响应面法优化纳豆菌糖肽超声提取工艺

采用响应面分析法优化超声辅助提取纳豆菌糖肽工艺。在单因素试验的基础上,研究液料比、NaCl浓度、超声时间对纳豆菌糖肽提取得率的影响。通过Box-Behnken试验设计和响应面分析法确定提取BNP的最佳工艺条件。试验结果表明,超声辅助提取纳豆菌糖肽的最佳工艺条件是:液料比24∶1 mL/g,NaCl浓度0.15mol/L,提取时间41 min。在此条件下,BNP最高提取得率为1.89%。     

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.     

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。     

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...     

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.     

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.     

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。     

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.     

Effect of amidation on the foaming and physico-chemical properties of bovine serum albumin

Amidation of bovine serum albumin (BSA) was achieved by a water-soluble carbo-diimide, ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated reaction using ammonium chloride as the nucleophile. Partial and substantial amidation of 0.5% (w/v) BSA in 5.5 m ammonium chloride solution with 1 times 10-²mmol EDC over 120 min and 1 times 10^-1mmol EDC over 10 min respectively was achieved on a large scale using diafiltration for rapid termination of the reaction and purification. Residual ammonium chloride otherwise enhanced foaming properties. The amidated proteins were characterized by isoelectric focusing, electrophoresis and hydrophobicity and disulphide- and sulphydryl-group measurements. Compared with native BSA, partially amidated BSA (PA-BSA) produced enhanced foam expansion and foam stability values. This was attributed to minimal denaturation and to the presence of both acidic and basic components (pI range 5.25–7.50) within the single protein. In contrast, substantially amidated BSA (SA-BSA) (pI range 7–9.1) had similar foaming properties to those of the ultrafiltered BSA control which were slightly lower than those of native BSA. However SA-BSA interacted synergistically with native BSA producing enhanced foaming properties particularly at the 1:1 ratio through electrostatic interactions, conformational changes and increased hydrophobicity.     

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。     

芝麻蛋白研究概况

简述芝麻蛋白的结构及氨基酸组成、蛋白质性质和应用,并展望进一步研究芝麻蛋白的 前景。