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.