Study On Optimization Of Soy Sauce Brewing Technology By Solid And Liquid Fermentation

Soy sauce is an indispensable condiment for Chinese residents.Soy sauce is produced by microorganism through fermentation industry.At present,there are mainly two kinds of soy sauce fermentation technology commonly used in China:low-salt solid-state fermentation and high-salt dilute fermentation.High-salt dilute fermentation has high quality and good flavor,but the fermentation period is long,it takes 4-6 months,and the process cost is high;while the soy sauce produced by low-salt solid-state fermentation has short period and low cost,but its quality is low and it is difficult to obtain good flavor.Solid-dilute fermentation soy sauce brewing technology combines the advantages of both.The early stage is high-temperature solid-state fermentation,and the protease activity is high.It can fully hydrolyze the protein in the raw material.Later,salt water is added again.Low-temperature fermentation can make soy sauce produce good flavor by using yeasts and lactic acid bacteria that fall into the air.This can ferment soy sauce with better quality in a shorter fermentation cycle.On the basis of solid-dilute fermentation,the activity of protease,glucoamylase and cellulase in koji was determined,and the optimum starter-making time was determined.Then the optimum solid-state fermentation time and the proportion of secondary brine were determined by using different solid-state fermentation time and the proportion of secondary brine during fermentation.After that,the physicochemical index was determined by using different heat preservation and dilute fermentation time.The change of the standard and the corresponding final product index determine the optimal fermentation time,and explore the influence of temperature control time and brine concentration on the fermentation process,determine the best fermentation scheme of solid-dilute fermentation method,and compare the solid-dilute fermentation process with the low-salt solid-state fermentation process,and analyze the effect of the two processes on the quality of soy sauce.It was found that when the ratio of raw materials was soybean meal:stir-fried wheat 6:4,the activities of protease,glucoamylase and cellulase reached the maximum at 36 hours,so the optimum time of starter harvesting was determined to be 36 hours.The solid-state fermentation time and the proportion of secondary brine were used to determine the physical and chemical indexes during the fermentation.The results showed that the solid-state fermentation time was 10 days and the proportion of secondary brine was 14%amino acid nitrogen and total nitrogen were better than other groups.Therefore,the optimum solid-state fermentation time and the proportion of secondary brine were determined to be 10 days and 14%respectively.By adopting different heat preservation and dilute fermentation time,following up and measuring the physical and chemical indexes,flavor substances,salt-free solids and amino acid nitrogen production rate of final products,it was found that the amino acid nitrogen,total acid,salt-free solids and amino acid nitrogen production rate of 17 days heat preservation and dilute fermentation time was higher than that of other groups,and the total nitrogen and reducing sugar content of 10 days heat preservation and dilute fermentation time were higher than those of other groups.The amount of flavor substances was higher than that of other groups,and there was no significant difference among them.The optimum time of dilute fermentation with heat preservation was determined to be 17 days.By comparing the low-salt solid-state fermentation process with the solid-dilution fermentation process,it was found that the solid-dilution fermentation process was superior to the low-salt solid-state fermentation process in amino acid nitrogen,total nitrogen and salt-free solids,and the solid-dilution fermentation group was superior to the low-salt solid-state fermentation process in flavor substances.The products fermented with soybean meal fried wheat as raw material were more obvious,and the main advantages were alcohol esters.On the other hand,soy sauce brewed by solid-dilute fermentation with soybean meal and fried wheat as raw materials can enrich the flavor of the product while maintaining its taste and nutrition compared with low-salt solid-state fermentation.