Comparative Study On The Key Flavor Metabolite Of Zygosaccharomyces Rouxii For Soy Sauce

Soy sauce has been an indispensable condiment on the table. Its well taste is relevant to main flavor compounds in soy sauce during fermentation process.As a commen yeast adding to fermentation, the metabolite of Zygosaccharomyces rouxii(S) has closely connection with flavor. Z. rouxii 3-2(S3-2) was a new strain constructed previously using genome shuffling from the wild-type S yeast in our lab. It had not only higher salt-tolerant mutant strain but also heredity stability.In this study, we comparative analysised the metabolite difference of S and S3-2 from basic metabolism, gene expression level and fermentation characteristics.First we optimized and determined the study method of metobonomics:60% methanol-water was the best quenching reagent, the neat methanol was the best extraction method, adding OS-GC-MS for intracellular metobonamics and adding SPME-GC-MS, DSE-GC-MS for extracellular metobonamics.Using the method had been determined to roundly detect the intracellular and extracellular metabolite of S and S3-2 with different salt concentration. To yeast S, the total number of intracellular and extracellular metabolite wsa 94 and 44.To yeast S3-2, the total number of intracellular and extracellular metabolite wsa 91 and 45.And then determined PCA1 of two yeast through principal component analysis(PCA).S has 68 kinds of PCA1 and S3-2 has 67 kinds of PCA1. Comparative analysised PCA1 related to main flavor compounds in soy sauce.Finally we confired 3-Methylthiopropanol, 2-phenyl ethanol and isoamyl acetate as the key flavor compounds.Dynamic detected the anabolic synthesis of 3-Methylthiopropanol,2- phenyl ethanol and isoamyl acetate for S and S3-2.The salt consist in environment could stimulated S and S3-2 producted 3-Methylthiopropanol and 2-phenyl ethanol.Salt concertration had positive correlation with amount of synthetic metabolic with an acceptable range; along with the rising of salt concertration,metabolic capability of two alcohol with S3-2 was better than S.To isoamyl acetate, salt concertration had negatice correlation with amount of synthetic metabolic; along with the rising of salt concertration, metabolic capability of S3-2 was a little better than S.Dynamic detected the gene expression level of ARO10, PDC1 and ATF1.The result showed that salt consist in environment could stimulated ARO10 and PDC1 gene expression of S and S3-2 and the potentiation to S3-2 was stronger than S.But salt consist in environment could inhibited expression of ATF1.Adding S or S3-2 into soy sauce mash with different brewing technology to studied fermentation characteristics. The result showed that the categories of flavor compounds of added yeast was more than the group without yeast, and group added S3-2 contained more flavor compounds.3-Methylthiopropanol was not detected in guoup without yeast.To 2-phenyl ethanol and isoamyl acetate, amount of groups with yeast was higher than group without yeast. Whether in low-salt solid state fermentation or high-salt liquid state fermentation, the amount of three compounds producted by group S3-2 was higher than group S, and the advantage of group S3-2 be better under high-salt liquid state fermentation.