Abstract: In order to address the problem of insufficient flavor of traditional high-salt pickled mustard, Lactiplantibacillus plantarum QT038 and LJ065 were used for the secondary fermentation of mustard. The sensory characteristics, color, texture, physicochemical indexes, and volatile composition of fermented mustard with different strains were investigated, and the antagonism between the strains and their safety were also evaluated. The results showed that inoculated fermentation improved the sensory quality of mustard, and fermented mustard with a 1:1 mixture of QT038 and LJ065 scored high in color, taste and texture and had the highest total acid content of 11.71 g/kg and the lowest nitrite content of 2.16 mg/kg. The amino nitrogen content was relatively high (0.078%). A total of 89 volatile components were detected in fermented mustard, with the major ones being esters, alcohols, aldehydes, nitriles and phenols, and the types and contents of flavor substances in fermented mustard with the two-strain cocktail were significantly higher than those fermented mustard with single strains (P < 0.05). The greatest increase (36.56%) in the content of volatile components was observed compared with the uninoculated control group. Based on odor activity value (OAV) and variable importance in projection (VIP) score, 22 key flavor compounds and 37 differential flavor compounds were selected, which greatly contributed to the formation of the overall flavor of fermented mustard. Furthermore, the two strains did not have any obvious antagonistic effects on each other and were safe. In conclusion, fermented mustard with the QT038:LJ065 (1:1) combination has the best sensory quality and physicochemical properties with a stronger fermented flavor. These findings provide a theoretical basis for the secondary inoculated fermentation of salted mustard.

Key words: lactic acid bacteria; mustard; secondary fermentation; quality changes