Influence Of Salt-Tolerant Yeasts On Soy-Sauce Flavor During The Low-Salt Solid Fermentation

Soy sauce is a condiment which is closely linked with people’s lives, playing an important part in people’s diet life. The fermentation of soy sauce is divided into high-salt liquid fermentation and low-salt solid fermentation according to the production process. In recent years, soy sauce with low content of salt is popular, with increased the health conscious and food culture. Yeast strains are not usually added during the low-salt solid fermentation which is a specific technology in our country. Therefore, the flavor of soy sauce is not vigorous and mellow enough and nutrition of soy sauce is lower compared with that of soy sauce produced by high-salt liquid fermentation.In this study, the corn was used instead of some wheat bran as starchy material with starter propagation by Aspergillums oryzae A100-8. Meanwhile, the T yeast and S yeast were added in the process of fermentation. The growth of yeasts, the physical and chemical criteria (pH, total acid, amino acid nitrogen, total nitrogen, saline-free soil solution mass, reducing sugar, etc.) and dynamic analysis of aroma compounds of soy sauce were detected. The extraction technology which affected the flavor of soy sauce was elementary studied.It was found that the first class shake culture of yeasts was27h, the second class shake culture was16h. The T yeast entered stationary phase at the12th day, and improved metabolism and fermentation after brief growth in the soy-sauce mash. The contents of reducing sugar and total acid reduced, but it could no difference of the other chemical criteria. The contents of ethanol by fermentation of adding yeasts were higher than the control, moreover it was improved1.6times by fermentation of adding T yeast. The Macromolecule substances were broke down into small molecular substances of raw materials at the13th day, the contents of protein was7.7%, the contents of starch was3%, so it is the best time to adding the yeasts. The contents of lactate, citric acid, alcohol, HEMF and4-EG of the soy sauce produced by fermentation of adding T yeast were higher than other samples. Therefore, the preferred plan is adding T yeast. In addition, the contact area of enzymes was enhanced in extraction technology, which made fermentation uniform and improved the flavor of soy sauce. Ethanol was improved by up to77.9%and isobutyl alcohol was raised by98.7%. Moreover, propanoic acid were improved1.5times, HEMF was enhanced about2.3times compared with the control.