Effect of different halophilic microbial fermentation patterns on the volatile compound profiles and sensory properties of soy sauce moromi

The effect of inoculated or co-cultured halophilic lactic bacteria (Tetragenococcus halophilus) and yeasts (Zygosaccharomyces rouxii and Candida versatilis) on the quality of soy sauce moromi was investigated. Results showed no significant change in the major physicochemical properties of soy sauce moromi such as amino nitrogen, total acid, and reducing sugar at the end of fermentation, whereas the composition of free amino acids slightly changed with different fermentation patterns. In the sample inoculated with T. halophilus, the concentration of proline and tryptophan decreased by 18.83 and 50.87 % compared with the blank sample, whereas tyrosine and histidine increased by 32.41 and 27.04 %. In the sample inoculated with Z. rouxii and C. versatilis, the concentration of bitter-tasting lysine, tyrosine, and phenylalanine increased by more than 20 %, and the concentration of tryptophan decreased by 56.71 %. The proportion of amino acids with sweet taste increased by 0.8 % through the co-culture of the three strains. Meanwhile, the total amount of volatile compounds increased by 117.66, 23.28, and 216.88 % in the T. halophilus inoculated sample, two yeast strain inoculated sample, and three strain inoculated sample, respectively. Increased odour activity values of the nine compounds that mainly contributed to the flavour of moromi ranged from 1 to 7.87 times in the three strain inoculated sample. These findings revealed that the co-culture of the three strains during moromi fermentation was beneficial to the improvement of flavour of soy sauce moromi.