[目的]明确甜杏仁分离蛋白的相关理化性质,研究蛋白质性质变化与产品加工特性间的关系,开发高质量的甜杏仁产品.[方法]通过碱溶酸沉法制得甜杏仁粗蛋白,经Osborne分级法制备分离蛋白—清蛋白、球蛋白、醇溶蛋白和谷蛋白,利用全自动氨基酸分析仪、环境电子扫描显微镜(ESEM)、圆二色光谱(CD)、差示扫描量热法(DSC)、热重法(TGA)及流变仪等,研究甜杏仁分离蛋白的氨基酸组成、表面形态特征、二级结构、热性质及流变性,并拟合出温度与分离蛋白黏度间的线性方程,计算其活化能Ea及频率因子K0.[结果]甜杏仁4种分离蛋白的氨基酸组成丰富,含有17种人体所需的氨基酸,包括8种必需氨基酸(含组氨酸),谷氨酸含量最多;清蛋白、球蛋白及醇溶蛋白表观结构较为紧密,呈聚集态,而谷蛋白则表现为松散、多孔的片状;分离蛋白二级结构分子构象中,α-螺旋及无规则卷曲占主要部分.由DSC结果可知清蛋白、球蛋白、醇溶蛋白和谷蛋白的热变性温度分别为62.84、72.98、78.33和45.70℃,热稳定性关系为:醇溶蛋白＞球蛋白＞清蛋白＞谷蛋白,结合DSC与ESEM可知聚集程度为:清蛋白＞醇溶蛋白＞球蛋白＞谷蛋白.4种甜杏仁分离蛋白的溶液均属于非牛顿流体,其黏度与温度符合阿累尼乌斯(Arrhenius)指数方程,能够很好地对实际情况进行拟合,可运用于指导实际生产.[结论]甜杏仁分离蛋白可作为一种优质植物蛋白来源,本研究结果对甜杏仁蛋白质产品的开发具有参考意义,有利于在产品开发及生产加工过程中对含蛋白产品的功能及品质进行控制,提高其附加值进而促进甜杏仁产业发展.%[Objective] The aim of this study is to investigate the physical and chemical properties of sweet almond albumin,globulin,gliadin and glutelin.The relationship between the change of protein's properties and product processing features was also studied to promote the development of high-quality sweet almond products.[Method] Alkali-solution and Acid-isolation was employed upon the skimmed sweet almond to extract crude protein,and,subsequently,Osborne classification method was adopted to extract the albumin,globulin,gliadin and glutelin.The amino acid composition was determined by Automatic Amino Acid Analyzer.ESEM was used to observe the morphological characteristics of above mentioned proteins;CD spectra scanning was utilized to measure its secondary structure;thermal properties were determined by using DSC and TGA;Rheometer was applied to determine the influence of shear rate,moreover,the linear equation between temperature and viscosity of proteins was determined,and,therefore,the value of Ea and K0 could be calculated.[Result] Various amino acids were detected in isolated proteins derived from sweet almond,containing 17 kinds of amino acids which the human need.It should be noticed that eight kinds of essential amino acids (including histidine) are completely embraced,among which the content of glutamic acid is the highest.Albumin,globulin and gliadin show a state of close aggregation structure,while glutelin shows a state of loose and porous plate.As for the constitution of the secondary structure,alpha helix and random curl are dominant in the isolated proteins compared with other forms of secondary structures.The denaturation temperatures for albumin,globulin,gliadin and glutelin are 62.84,72.98,78.33 and 45.70℃C,respectively.Therefore,the thermal stability should coincide with the following order:gliadin ＞ globulin ＞ albumin ＞ glutelin.Combined DSC with ESEM,the aggregation degree should conform to the following order:albumin ＞ gliadin ＞globulin ＞glutelin protein.The aqueous solution of the four kinds of isolated proteins derived from sweet almond are non-newtonian fluid and,furthermore,the relationship between temperature and viscosity is conform to the Arrhenius index equation,and the linear equation matches the parameters in processing well.[Conclusion] Sweet almond isolated protein can be regarded as a high-quality source for plant protein.Results of this study will make greater contributions to the development of sweet almond protein products.Besides,this study definitely do contribution to the function and property control of the protein products derived from sweet ahnond both in development and processing of the products,which could enhance the additional value and promote the development of sweet almond industry.
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