Improvement of Soy Sauce Quality by Yeast with High HEMF Productivity
4-Hydroxy-2(5)-ethyl-5(2)-methyl-3(2H)-furanone(HEMF)in soy sauce flavor substances is the main component contributing to the flavor of soy sauce.Candida versatilis(hereinafter referred to as C yeast)is an important microorganism producing HEMF during soy sauce fermentation.In this paper,the new strains C-l,C-2 and C-3 that can tolerate high concentration of HEMF are used.After random amplified polymorphic DNA(RAPD)experiments,it is confirmed that the genes of the three excellent strains are different from those of the starting strain,which proves that the gene recombination is successful.They are applied to fermentation and comparative analysis,and it is found that compared with the starting strain,the content of ammonia nitrogen and total nitrogen of C-1 increases by 3.20%and 7.20%respectively,and the content of HEMF of C-1 increases by 29.40%.Through sensory evaluation,it is found that the flavor of soy sauce is improved.The total biogenic amine content is less than 1 000 mg/L,and the ethyl carbamate content is less than 20 μg/L,which ensures the safety of soy sauce.In conclusion,the yeast with high HEMF productivity improves the quality of soy sauce.