米胚分离蛋白营养和功能性评价

利用氨基酸自动分析仪检测米胚4种Osborne分离蛋白中的氨基酸组成,以氨基酸评分(AAS)、蛋白质功效比值(PER)、生物价(BV)及体外消化率为评价标准,对米胚蛋白各组分的营养价值进行评价。结果表明:谷蛋白的氨基酸评分最高,为80.90,清蛋白、球蛋白、谷蛋白符合FAO/WHO推荐的参考蛋白模式,其PER值与优质蛋白的衡量标准值2.00接近,BV值较高,在体外的营养消化效率较好,醇溶蛋白的品质相对较差。对米胚四种蛋白的起泡性、起泡稳定性、吸水性、吸油性等功能性质进行测定,结果表明:pH 5时4种蛋白的起泡性最低,起泡稳定性最好;清蛋白、球蛋白的吸水性比醇溶蛋白、谷蛋白好,醇溶蛋白的吸油性最好;米胚蛋白各组分的表面疏水性较高,需进一步进行改性处理。

Nutritional and Fuctionai Properties of Rice Germ Protein Isolates

Automatic amino acid Analyzer was used to detect the amino acid composition of rice germ protein isolates.Based on the amino acid composition,amino acid score(AAS),protein efficiency ratio(PER)and Biological value(BV) were estimated.These estimated parameters and vitro digestibility were applied to general nutrition assessment of rice germ protein isolates.Results showed that amino acid score of glutelin(80.90) was the highest in four proteins.In albumin,edestin,glutelin,the proportion of essential amino acids was suitable and conformed to recommended reference pattern of FAO/WHO,PER values closed to the standard values of quality protein(2),BV value was higher,vitro digestive efficiency was better.The quality of prolamine protein is relatively poor.Moreover,the functional properties such as foam ability,foam stability,water and oil holding capacity,surface hydrophobicity were also discussed.Results showed that foam ability of the four proteins reached the minimum at pH5,while foam stability reaching the maximum.Albumin,edestin were better than glutelin,prolamine in water absorbing capacity.Prolamine's oil absorbing capacity was the best.Surface hydrophobicity of rice germ protein isolates was high.Thus,rice germ protein isolates need further modification so that they can be more widely used in the food.