Study On Preparation Technology Of Lentinus Edodes Soy Sauce By High-salt Dilute Fermentation

Soy sauce is an indispensable condiment in cooking.With the increasing maturity of fermentation technology and the continuous improvement of people’s demand for nutrition and healthy life quality,more and more new soy sauce begins to face the market.Lentinus edodess taste delicious and unique,rich in nutritional value,containing polysaccharides,polyphenols,peptides and other bioactive substances,popular among the public.Therefore,using Lentinus edodes as raw material to brew soy sauce can not only improve the nutritional value of soy sauce,but also give soy sauce unique flavor of Lentinus edodes,which is a soy sauce product of great development value.In this paper,Lentinus edodes were used as excipients to make koji fermentation with soybean meal and wheat,and soy sauce without Lentinus edodes was used as control group to compare the quality and flavor of soy sauce with different processes.The results were as follows:(1)Aspergillus oryzae strains were selected for subsequent optimization of yeast production after the domestication,primary screening and rescreening of Lentinus edodes.Under 30℃,the single factor-orthogonal experiment was used to optimize the koji production process.The optimal conditions for the koji production process of Lentinus edodes soy sauce were as follows:the inoculation amount of Aspergillus oryzae was 0.8×10~6 PCS/g,the addition amount of Lentinus edodes was 3%(w/w),the koji production time was 54 h,and the water amount of koji production was 54%(w/w).Under the optimized conditions,the neutral protease activity of the prepared Lentinus edodes soy sauce koji can reach 4414.31 U/g dry koji.(2)At room temperature,the single factor orthogonal experiment was used to optimize the fermentation process of Lentinus edodes soy sauce,and the fermentation was carried out for 17 days.The optimal fermentation combination was as follows:the yeast content was 1.5×10~6 PCS/m L,the salt concentration was 16%(w/v),and the solid-liquid ratio was 1:2.1(w/v).According to the optimized combination of the process,high salt dilution method was used for fermentation,and the physical and chemical indexes were measured by sampling every 15 d.After fermentation,the amino acid nitrogen content of dry Lentinus edodes soy sauce was 0.88 g/100 m L,fresh Lentinus edodes soy sauce was 0.98 g/100 m L,and the control group was 0.96 g/100 m L,all of which reached the standard of special grade soy sauce.According to the overall physicochemical index measurement,the quality of fresh Lentinus edodes soy sauce is better than that of dry Lentinus edodes soy sauce and control group,so the addition of fresh Lentinus edodes is more conducive to the improvement of soy sauce quality.(3)The bioactive ingredients and antioxidant capacity of soy sauce in the three groups were measured.The addition of Lentinus edodes increased the content of bioactive ingredients in soy sauce on the whole,and the antioxidant capacity was slightly higher than that of the control group.Correlation analysis between bioactive components and antioxidant capacity showed that DPPH free radical scavenging capacity was strongly positively correlated with polyphenols and peptides(r>0.8),and negatively correlated with amino polysaccharide process(r<-0.8),both of which had strong significance(p<0.001).The reducing power was positively correlated with amino polysaccharides and negatively correlated with polyphenols,both of which had significant differences(p<0.05).(4)The content of free amino acids,organic acids and volatile flavor compounds in soy sauce was determined and analyzed.The content of free amino acids in soy sauce was increased by adding shiitake Lentinus edodes,and the content of dry Lentinus edodes and fresh Lentinus edodes soy sauce was 3.38%and 16.05%higher than that in control group.No malic acid and fumaric acid were detected in the soy sauce of the three groups.The content of lactic acid was the highest in fresh Lentinus edodes and control group,while acetic acid was the main organic acid in dry Lentinus edodes soy sauce.30 kinds of dry Lentinus edodes soy sauce,37 kinds of fresh Lentinus edodes soy sauce and 15 kinds of flavor compounds in the control group were detected respectively,including alcohol,aldehyde,ester,acid and ketone compounds.The types of flavor compounds in the two groups were significantly more than those in the control group,and 1-octene-3-ol,1-octene-3-ketone and 3-octene-ketone were detected in the Lentinus edodes soy sauce,which were the key flavor compounds of Lentinus edodes flavor.Therefore,the addition of Lentinus edodes endowed the soy sauce with richer and unique aroma and flavor.(5)The soy sauce in the three groups was evaluated by six senses:color,umami,saltiness,sweetness,fruity and scorchiness.The total score was ranked as fresh Lentinus edodes>dry Lentinus edodes>control group from high to low.Therefore,the addition of Lentinus edodess,especially fresh Lentinus edodess,can not only improve the quality and nutritional value of soy sauce,but also improve the taste and taste of soy sauce.