长白山榛仁分离蛋白及其主要组分的功能性质研究

本文以长白山榛仁为原料,采用Osborne蛋白分级提取法得到纯度为72.32%、68.72%、40.60%的清蛋白(PAP),球蛋白(PGP)和谷蛋白(PLP),采用碱溶酸沉法得到纯度为90.31%的分离蛋白,对比分析四种蛋白的功能性质,结果显示:分离蛋白总巯基含量最高为6.71μmol/g,清蛋白暴露巯基和二硫键含量最高分别为2.28μmol/g和60.40μmol/g。四种蛋白起泡性和泡沫稳定性随p H增大趋势相反,在p H 5时,起泡性最低而泡沫稳定性最高,在偏酸或偏碱条件下,起泡性较好而泡沫稳定性皆较差。谷蛋白吸水性和吸油性均最高分别为3.40 m L/g和2.52 m L/g,清蛋白吸水性和吸油性最低分别为0.63 m L/g和1.79 m L/g。四种蛋白质的溶解性,乳化性以及乳化稳定性随p H变化趋势相似,在等电点时最低。清蛋白、球蛋白、谷蛋白和分离蛋白中必需氨基酸含量占总氨基酸含量的29.83%、32.14%、35.23%和30.32%,除蛋氨酸外均能满足FAO/WHO规定成人需要摄入量。     

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。     

紫苏分离蛋白功能性研究

为了开发紫苏蛋白在食品工业中的应用,以大豆分离蛋白为对照,研究紫苏分离蛋白的功能特性。结果表明：紫苏分离蛋白的溶解性与大豆分离蛋白的溶解性随pH值变化的趋势基本一致,但在等电点时紫苏分离蛋白的溶解性高于大豆分离蛋白。在pH7.0时,紫苏分离蛋白的持水性、起泡性及泡沫稳定性、乳化性和凝胶性均不及大豆分离蛋白。但紫苏分离蛋白的吸油性仅稍小于大豆分离蛋白,此外,在紫苏分离蛋白的蛋白质质量浓度为3g/100mL以后,其乳化稳定性与大豆分离蛋白的乳化稳定性基本相当。紫苏分离蛋白在食品加工中作为一种蛋白质强化剂具有一定潜力。     

紫苏分离蛋白的制备工艺研究

以脱脂紫苏粕为原料,采用碱溶酸沉法制备紫苏分离蛋白.研究了紫苏分离蛋白制备工艺条件,同时测定了产品的功能性质.通过单因素实验和正交实验得出紫苏分离蛋白制备的最佳工艺条件为:碱溶温度55℃,料液比1∶10,碱溶pH 10,碱溶时间60min/次(2次),酸沉pH 4.4.在此工艺条件下紫苏分离蛋白产品得率为24.5%,产品蛋白质含量为91.52%(N×6.25,干基).该产品的氮溶解指数为54.7%,持水性为3.57g/g,吸油性为1.67mL/g,乳化性为42%,乳化稳定性为95.24%.     

马铃薯蛋白组分的分离提取和功能性质研究

采用透析与等电点沉淀相结合的工艺方法提取分离马铃薯块茎蛋白组分;并对其理化性质和功能性质进行检测。结果显示：此提取工艺流程合理易行,马铃薯块茎酸性蛋白组分和碱性蛋白组分的得率分别为0 .535%、0.741%;纯度分别为92.5%、89.2%;酸性蛋白组分沉降系数5S,分子质量82kD;碱性性蛋白组分沉降系数8S,分子质量140kD。SDS-PAGE 电泳图谱表明5S 蛋白组分有1 条亚基带;8S 蛋白组分有4 条亚基带。5S 蛋白组分的表面疏水性、吸油能力、乳化性显著高于8S 蛋白组分;而8S 蛋白组分的总巯基含量以及起泡性高于5S 蛋白组分。马铃薯蛋白组分可以作为功能食品的蛋白添加原料。     

紫苏饼粕浓缩蛋白的制备及理化性质研究

以紫苏饼粕为原料,对其蛋白质的浓缩提取工艺以及理化性质和溶解性进行了研究.结果表明紫苏饼粕蛋白质制备的最佳优化工艺条件为料液比1:10、pH值9、温度50 ℃、时间60 min,此时紫苏浓缩蛋白质的得率为23.46%,蛋白质质量分数为83.67%.紫苏浓缩蛋白的氨基酸组成比较全面,必需氨基酸含量丰富.SDS-PAGE电泳分析发现该浓缩蛋白质分子质量集中分布在19.1～22.4 ku、32.9～36.2 ku和54.9ku区带.紫苏浓缩蛋白的氮溶解指数(NSI)随着pH值的升高而先降后升,在等电点时达到最小值5.3%.     

苦荞麦分离蛋白的提取及功能性质研究

采用碱溶酸沉法制备苦荞麦分离蛋白,通过单因素试验进行提取条件的初步优化,然后采用正交试验确定最终提取工艺参数,优化的提取条件是:pH值9.0,提取时间30 min,料液比1∶10,温度35℃.此时,苦荞麦分离蛋白的提取率可达54.7%,纯度可达69.81%.试验还对苦荞麦分离蛋白功能(吸水性、吸油性、起泡性)性质进行了测定.     

银杏蛋白的提取及其功能性质研究

采用盐溶和盐析的方法,从银杏果中分离制备出清蛋白(GAP)、球蛋白(GGP)和盐溶蛋白(GSP)。确定了浸提银杏果盐溶蛋白的最佳条件为:NaCl浓度为0.14mol/L,pH为8.0,提取温度4℃,浸提时间4h,浸提次数大于3次,银杏蛋白中以清蛋白和球蛋白为主,研究了清蛋白和球蛋白的的乳化稳定性、黏度等功能性质,结果表明球蛋白乳化能力、乳化稳定性、黏度均高于清蛋白。     

杏鲍菇分离蛋白和清蛋白的理化性质及功能分析

以杏鲍菇为原料,分别利用碱溶酸沉法提取杏鲍菇分离蛋白（Pleurotus eryngii protein isolate,PEPI）、Osborne法分离主要蛋白组分,并研究其理化性质和功能分析。结果表明,杏鲍菇的蛋白质量分数为17.57%（以干质量计）,以杏鲍菇清蛋白（Pleurotus eryngii albumin,PEA）为主,占总分离蛋白组分的81.12%。PEPI和PEA中均含18?种氨基酸,且必需氨基酸含量分别占总氨基酸含量的40.80%和40.51%。与PEPI相比,PEA的表面疏水性（265.25）显著高于PEPI（164.27）（P＜0.05）,而总巯基、二硫键含量较低,分别为61.53?μmol/g和10.39?μmol/g;热变性温度（100.98?℃）低于PEPI（108.27?℃）,且PEA持水性（1.64?mL/g）、持油性（5.59?mL/g）显著低于PEPI（3.58、8.36?mL/g）（P＜0.05）。PEPI和PEA的溶解性、起泡性、泡沫稳定性、乳化性及乳化稳定性随pH值的变化趋势均相似,在等电点时均为最低。傅里叶变换红外光谱显示PEPI和PEA的二级结构主要是β-折叠和β-转角,扫描电镜观察PEPI呈蜂巢结构。相比PEA,PEPI具有更好的理化性质和功能特性。     

核桃蛋白及其组分构象和功能特性的研究

本文研究了核桃蛋白及其主要组分谷蛋白和球蛋白的物化特性与功能特性。研究表明:核桃蛋白的变性温度Td(104.42℃)和热焓值ΔH(12.93 J/g)都显著高于谷蛋白和球蛋白的变性温度、热焓值(p0.05),且变性协同性较好;谷蛋白和球蛋白的巯基含量较核桃蛋白高,且大部分巯基暴露在表面,而核桃蛋白巯基主要包埋在分子内部且二硫键含量为三者中最高(为5.2μmol/g);由荧光结果表明核桃蛋白有着较致密的三级结构,而球蛋白结构相对较疏松;表面疏水性指数由高至低依次为谷蛋白、核桃蛋白和球蛋白。谷蛋白表现出较高的乳化活性,但乳化稳定性最差,核桃蛋白的乳化活性较谷蛋白稍差,但乳化稳定性最好;球蛋白的巯基和二硫键含量较高,结构松散,作用位点较多,形成的凝胶强度高,其次是核桃蛋白和谷蛋白。     

Structure,physicochemical, and functional properties of protein isolates and major fractions from cumin (Cuminum cyminum) seeds

In this study, cumin protein isolates (CPI) and major protein fractions were extracted and separated from cumin seeds, their structure, physicochemical, and functional properties were investigated. Albumin (62.29%) and glutelin (25.16%) were the predominant protein fractions of cumin seeds. Glutamic acid (Glu) and aspartic acid (Asp) were the major amino acids of cumin proteins, whereas more hydrophobic and aromatic amino acids were predominantly found in chickpea protein isolates. Electrophoresis profiles indicated that CPI have more disulphide bonds than major protein fractions. The intrinsic fluorescence data revealed that glutelin displayed greater exposure of tyrosine (Tyr) and tryptophan (Trp) residues compared to albumin and CPI. Circular dichroism (CD) data showed CPI presented more α-helix (14.4%) and less β-strand (30.7%) than albumin and glutelin. The atomic force microscope (AFM) profile and hydrodynamic diameter (D_h) determination showed the presence of low particle size in albumin fractions. Differences in the hydrophobicity (H_o) and the zeta-potential (ζ) of CPI, albumin, and glutelin were also observed due to their difference in structure and amino acid composition. Compared with CPI and glutelin, albumin exhibited the highest emulsifying activity (103.67 m²/g) and stability (42.84 min) and the smallest emulsion particle size (4.29 μm). The CPI, albumin and glutelin presented typical U-shaped protein solubility–pH curves, with the lowest solubility at pH 4.0. Rheological investigation demonstrated that CPIs were efficient in forming a gel at 80.6°C, whereas glutelin could form the hardest gel at 92.6°C. The overall results suggested that the cumin proteins can be a promising protein source for the food industry.     

Physicochemical and functional properties of albumin,globulin and glutelin fractions of green lentil seed

Defatted lentil seed flour proteins were separated into their constituent albumin (ALB), globulin (GLB) and glutelin (GLT) fractions followed by determination of their structural and functional properties. The GLB fraction demonstrated superior solubility (84%–100%) at acidic and alkaline pH values when compared to the lower values for ALB and GLT. Amino acid composition analysis showed lower contents of hydrophobic and sulphur-containing residues for GLB. However, GLB had the highest in vitro protein digestibility, which may be due to lower contents of rigid secondary structure fractions like the β-sheet and β-turns. In contrast, water and oil holding capacities as well as gelling ability were better for GLT and ALB than GLB. The GLT fraction formed very poor emulsions at pH 3 and 5 but emulsification was significantly (p < 0.05) improved (smaller oil droplets) at pH 7 and 9. Foaming capacity was strongest for GLB, especially at pH 5, 7 and 9 where increase in protein concentration had a negative effect on foam formation. Overall, the protein type and pH of the environment had stronger effects on emulsion and foaming properties than the protein concentration.     

豌豆蛋白的功能特性研究

本论文对豌豆球蛋白(7S、11S)和豌豆分离蛋白(PPI)的物化和功能特性进行了分析和比较。结果表明,豌豆球蛋白具有良好的功能特性,其溶解度(PS)、乳化能力、乳化稳定性均显著高于PPI。荧光光谱和表面疏水性(H0)分析表明,PPI是部分变性的蛋白,其制备过程中的酸碱处理导致蛋白分子伸展、H0增加。DSC表明,11S热稳定性比7S要高,豌豆分离蛋白和豌豆7S出现不同程度的蛋白变性。     

Functional properties of protein isolates,globulin and albumin extracted from Ginkgo biloba seeds

In this study, the functional properties of Ginkgo seed protein isolate (GPI), Ginkgo seed globulin protein (GGP) and Ginkgo seed albumin protein (GAP) extracted from Ginkgo biloba seeds were investigated. The protein contents of GPI, GGP and GAP were 91.0%, 93.4% and 87.8%, respectively in the samples in which the sugar, polyphenol and crude fibre were removed by the preparation procedure. For functional properties of Ginkgo seed proteins in the natural state, GAP showed the highest oil-absorption capacity (9.3 ml/g), foaming capacity (67.8%), emulsifying capacity (65.4%) and emulsion stability (90.6%); while GPI showed the highest water absorption capacity (1.93 ml/g), and GGP showed the highest foam stability (55.5%). The differences of the chemical components, surface hydrophobicity, disulphide bond (SS) and sulfhydryl group (SH) contents of GPI, GGP and GAP, which were correlated significantly with functional properties of Ginkgo seed proteins, were also investigated. The improved functional properties, such as water absorption capacity, solubility, foaming properties and emulsifying properties of Ginkgo seed proteins were observed in a pH range of 8.0–10.0 or sodium chloride concentration of 0.5–0.75 M.     

Food Protein Functionality in a Liquid System: A Comparison of Deamidated Wheat Protein with Dairy and Soy Proteins

ABSTRACT: Solubility, surface properties, overrun, foam stability, apparent viscosity, and emulsification properties were evaluated for 3% protein dispersions of deamidated wheat protein (DWP), sodium caseinate (SC), soy protein isolate (SPI), and whey protein isolate (WPI). DWP dispersion had the highest apparent viscosity, 25% higher emulsion activity index (EAI), and 82% higher emulsion stability index (ESI) when compared to SPI dispersions. Dispersions of DWP had similar foaming properties and surface properties when compared to SC, but had 50% higher EAI and 1000% greater ESI when compared to the 2 dairy proteins. The utilization of DWP could be expanded into liquid food systems currently using dairy proteins.