Process optimization and flavor analysis of Shennongjia kiwifruit vinegar by multi-strains co-fermentation

Abstract

Using kiwifruit in Shennongjia as raw material, fruit vinegar was prepared by multi-strains co-fermentation. The fermentation conditions of alcohol and acetic acid were optimized by single factor and orthogonal tests, and the amino acids and volatile flavor components of fruit vinegar were analyzed by amino acid analyzer and GC-MS technology, respectively. The results showed that the optimum alcohol fermentation process of kiwifruit vinegar was as follows: yeast inoculum 0.9%, lactic acid bacteria inoculum 7%, initial soluble solids 19 °Bx, and fermentation temperature 27 ℃. Under these optimal conditions, the alcohol content was (8.82±0.57)%vol and the lactic acid content was (12.15±0.73) mg/ml. The optimum acetic acid fermentation process was as follows: fermentation time 8 d, acetic acid bacteria inoculum 12%, initial alcohol content 7%vol, and fermentation temperature 32 ℃. Under these optimized conditions, the acetic acid content was (4.34±0.17) g/100 ml, the sensory score was 80. A total of 15 amino acids in kiwifruit vinegar by multi-strains co-fermentation were detected, including 7 essential amino acids. A total of 37 volatile flavor compounds in kiwifruit vinegar by multi-strains co-fermentation were detected, including 17 esters, 5 acids, 2 aldehydes, 5 ketones, 2 benzenes, 4 alcohols, 1 phenol and 1 other type substance. In conclusion, multi-strains co-fermentation was beneficial to promote the formation of amino acids and volatile flavor substances and improve the quality of fruit vinegar.

Keywords

• kiwifruit vinegar|multi-strains co-fermentation|alcoholic fermentation|acetic fermentation|process optimization|amino acids|volatile flavor compound