Impact of sea salt concentration and salting time on Bacillus cereus contamination and on the physicochemical qualities of napa cabbage (Brassica rapa subsp. Pekinensis)

Abstract

This study examined the effects of varying sea salt concentrations (60, 80, 100, 120, and 140 g/L) and immersion period (6, 8, and 10 h) in brine on the viability of natural microbiota (total viable counts, coliforms, and Bacillus cereus) in napa cabbage. Additionally, it assessed how these brine conditions impacted B. cereus reduction, along with salinity, Brix, hardness, and moisture content. The results showed that total viable counts were reduced by 0.70-3.81, 1.09-4.65, and 1.85-4.89 log CFU/g after 6, 8, and 10 h of salting at sea salt concentrations of 60-140 g/L, respectively. Coliforms exposed to brine for 6-8 h at 60 g/L salt were reduced by 1.26-1.58 log CFU/g. The inoculated B. cereus was reduced by more than 3 log after 6-10 h in 120-g/L salt, which is significant as a 3-log reduction meets the microbial safety threshold set by the Korea Ministry of Food and Drug Safety (MFDS) for vegetables. The moisture content ranged from 89.04 to 84.99% depending on sea salt concentration. Overall, the study suggests that salting napa cabbage with 120-140 g/L salt for 6-10 h effectively reduced B. cereus contamination by over 99.9% without compromising its quality.