Effects of salinity on bacterial communities, Maillard reactions, isoflavone composition, antioxidation and antiproliferation in Korean fermented soybean paste (doenjang)

The purpose of this study was to investigate bacterial communities and health-benefit-related parameters in doenjang prepared with various brine concentrations (8, 12, 16, and 20%). Phenolic, flavonoid, melanoidin and isoflavone contents, antioxidation, and antiproliferation of doenjang (AD8, AD12, AD16, and AD20) aged for 3 months were compared with those of initial doenjang (ID8, ID12, ID16, and ID20). The ID8 and AD8 doenjang, made with 8% brine, contained higher phenolics, melanoidins, and isoflavones than those with high salinity. As results of bacterial communities, Enterococcus was a dominant bacterium in most doenjang, while Lactobacillus was predominant in AD8. Trolox equivalent antioxidant capacity (32.5 µmol TE/g dwb) and DPPH radical-scavenging capacity (57 µmol TE/g dwb) values of AD8 were the highest among samples. The EC50 of HT-29 cell proliferation treated with AD8 was 0.47 mg/mL, while EC50 of AD20 was 1.07 mg/mL, indicating stronger antiproliferative activity in low-salinity doenjang.