草莓酵素发酵过程中氨基酸成分分析和蛋白质营养评价

为研究不同发酵时间草莓酵素发酵液中的蛋白质、氨基酸和非蛋白质氨基酸γ-氨基丁酸(γ-aminobutyric acid,GABA)含量及营养价值,利用氨基酸自动分析仪对草莓酵素发酵过程中的氨基酸含量进行分析,通过氨基酸评分标准评价其蛋白质营养成分,通过与WHO/FAO推荐的人体必需氨基酸模式进行对比,并利用氨基酸含量阀值评价发酵过程中不同风味氨基酸对发酵液口感贡献。结果得出:在草莓酵素发酵过程中,蛋白质含量在发酵前期明显增加,经小幅度下降后再缓慢增加;总氨基酸含量有明显上升,其中氨基酸含量最高的是天冬氨酸(Asp)和谷氨酸(Glu),在检测限范围内未检出甲硫氨酸(Met)、苯丙氨酸(Phe)和组氨酸(His);利用聚类分析可将不同发酵时间的草莓酵素氨基酸发酵液分为四类;比值系数分在发酵前期波动较大,后期有缓慢上升。不同时间发酵液中除Met外其它8种必需氨基酸得分均大于1,属较严重的营养过剩。除发酵前30 d外,SRC值均大于55%,在整个发酵过程营养价值由高到低依次是:155 d > 140 d > 110 d > 30 d > 75 d > 50 d;发酵过程中只有Asp和Glu两种鲜味氨基酸的含量阀值比大于1,其它风味氨基酸对草莓酵素风味的影响不明显。经过155 d的发酵,草莓酵素中蛋白质和氨基酸含量有所提高,其中必需氨基酸含量显著上升(p<0.05),草莓酵素营养丰富,适当的延长发酵时间,蛋白质营养均衡度也将有所提高。

Amino Acid Composition Analysis and Protein Nutrition Evaluation of Strawberry Jiaosu during Fermentation Process

The automatic amino acid analyzer was used to analyze the content of amino acid in strawberry jiaosu during fermentation so as to study the content of protein, amino acid, non protein amino acid (γ-aminobutyric acid, GABA) and nutritional value of strawberry jiaosu. The nutritional value of protein was evaluated by the scores of amino acid, compared with the recommended essential amino acid pattern of WHO/FAO. Moreover, the amino acid content of threshold evaluation during fermentation process was also evaluated for the fermentation flavor of strawberry jiaosu. The results showed that the content of protein increased significantly in the early stage of fermentation, and then increased slowly after small decline. The total amino acid content increased greatly with the highest content of amino acid Asp and Glu, but the Met, Tyr, Phe and His were not detected. The cluster analysis for amino acid in strawberries jiaosu at different fermentation time could be divided into four types. The score of ratio coefficient of amino acidwas fluctuated greatly in the early fermentation, while increased slowly in the later period. All eight other essential amino acid scores at different fermentation time exceeded 1 except methionine (Met), which was severe over nutrition. In addition to the pre-fermentation of 30 d, the SRC value was greater than 55% and the nutritional value of whole fermentation process was as follow that 155 d > 140 d > 110 d > 30 d > 75 d > 50 d. In the fermentation process, only the RCT values of Asp and Glu exceeded 1 and the influence of other flavor amino acids in strawberry jiaosu not obvious. After 155 days of fermentation, the content of protein and amino acid in strawberry jiaosu was increased, meanwhile the content of essential amino acid increased significantly (p<0.05), strawberry jiaosu was rich in nutrition and the nutritional balance of protein would be improved with the proper prolongation of fermentation.