Microbial and physiochemical properties of Cheonggukjang fermented using Bacillus strains with antibacterial or antifungal activities

Abstract

Cheonggukjang was produced with improved functionalities and safety using Bacillus subtilis W42 with an antibacterial activity and B. amyloliquefaciens MJ1-4 with an antifungal activity as starters with coinoculation of B. subtilis W42 and B. amyloliquefaciens (MW Cheonggukjang). Control cheonggukjang was prepared by inoculation of B. subtilis 168 (BS cheonggukjang) or a commercial cheonggukjang prepared using traditional methods (TM cheonggukjang). Cheonggukjang samples were immediately spiked with B. cereus ATCC11778 (1x10(5) CFU/g of dry soybean) and Penicillium sp. that produced ochratoxin (1x10(5) spores/g of dry soybean). During 72 h of fermentation at 37A degrees C, total Bacillus counts increased, reaching 10(9) CFU/g in MW and BS cheonggukjang. Numbers of B. cereus and Penicillium sp. decreased. The largest reduction was observed in MW cheonggukjang. Fungi were not detected after 24 h in MW and BS cheonggukjang. Fibrinolytic activity was detected only from MW cheonggukjang and the antioxidant activity was highest in MW cheonggukjang.