Effect Of Enrichment Of Tetragenococcus Halophilus During Soy Sauce Fermentation On Soy Sauce Quality

Improvement of the quality of soy sauce by multi-species fermentation is the key brewing technology for modern soy sauce production.Enrichment of functional strains?salt-tolerant lactic acid bacteria and yeast?in the moromi mash during soy sauce fermentation process is one of the efficient measures to improve the quality and flavor of soy sauce.Therefore,discovering the interaction of functional strains in soy sauce fermentation process and their effect on soy sauce fermentation is of great significance for the development of technology for enhancement of functional microbes and precise regulation of fermentation process,and establishment of fermentation technology to improve its flavor and quality.This work focused on the processes of high-salt and diluted soy sauce fermentation and low-salt rapid soy sauce fermentation,systematically investigated the effects of different addition ways of Tetragenococcus halophilus and Zygosaccharomyces rouxii on microbial growth and soy sauce fermentation.The function of T.halophilus and the best way of adding it during soy sauce fermentation was also clarified.The main results are as follows:?1?The effect of co-culturing of functional strains on the growth of individual strains.Based on the study of co-culturing in a lactic acid bacteria culture system,it was found that T.halophilus and its extracellular metabolites showed inhibitory effect on the growth of soy sauce yeast,while yeast showed little effect on the growth of T.halophilus.Therefore,appropriate addition methods should be selected to avoid or reduce the effect of coexisting bacteria on the growth of functional bacteria when enriching functional strains during soy sauce fermentation.?2?To improve the quality of high-salt and diluted soy sauce by enriching T.halophilus.The pH of the soy sauce moromi mash decreased slightly,and the total acids content increased slightly with the addition of T.halophilus.Among the 5 ways of enriching,addition of Z.rouxii on 15 d and T.halophilus on 25 d had the most significant effect on amino acids content.The amino nitrogen and total amino acids content were increased by 12.7%and 34%;of which umami and sweet amino acids contents were increase by 34.2%and 26.9%.In addition,enrichment of T.halophilus promoted the production of alcohols,esters,aldehydes,phenols and other volatiles in soy sauce.Volatiles content in the soy sauce was 2.4 times higher than the control.Among them,adding Z.rouxii on 15 d followed by T.halophilus on25 d was found to be helpful in increasing the content of acids,phenols and miscellaneous;adding Z.rouxii on 15 d followed by T.halophilus on 35 d was found to be beneficial to alcohols and esters formation.?3?The addition of T.halophilus and Z.rouxii improved the quality of low-salt rapid fermented soy sauce.The best way to increase the flavor of low-salt rapid fermented soy sauce was to add Z.rouxii on 0 d followed by 10⁸ CFU?g^-1 T.halophilus on 10 d.After the addition of T.halophilus and Z.rouxii,the amino nitrogen content and total amino acids content in soy sauce were 30.2%and 43.8%higher than that of addition of Z.rouxii alone,and the effect of T.halophilus on the amino acid content was function within 5 days after the addition.Adding 10⁸ CFU?g^-1 T.halophilus 10 days after addition of Z.rouxii could increase the total amount of organic acids in soy sauce by 55.6%,and significantly increase the content of organic acids such as malic acid,acetic acid,lactic acid and propionic acid.Moreover,19 more volatiles were found in low-salt rapid fermented soy sauce with the addition of T.halophilus and Z.rouxii.This was 43.2%higher than the control.And the content of volatiles increased by 2.4 times.