Abstract: Several common food spoilage bacteria and pathogens, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella, Rhizopus, Penicillium, Mucor, and Aspergillus were used as test bacteria and fungi to explore the antimicrobial properties and stability of yellow water, a byproduct of Chinese liquor fermentation. Antimicrobial properties were measured by the Oxford cup method and minimum inhibitory concentration (MIC) was determined by the double dilution method. Staphylococcus aureus and Escherichia coli were used as indicator bacteria to investigate the effects of pH, temperature, ultraviolet, sodium chloride, saccharose and metal ions on the stability of the antimicrobial. The results showed that yellow water could inhibit Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella, Penicillium and Aspergillus, but had little effect on the growth of Mucor and Rhizopus. The MIC values were 6.25% for all four species of bacteria, and 1.56% and 3.13% for Penicillium and Aspergillus, respectively. Antimicrobial activity of yellow water increased at acidic pH, and decreased slightly at alkaline pH, but it was still high. Antimicrobial activity of yellow water decreased slightly after high temperature treatment but was hardly affected by ultraviolet light. This antimicrobial activity was slightly enhanced with increased concentrations of sodium chloride and saccharose. Metal ions showed little effect on the stability of the antibacterial. Moreover, Fe2+ could enhance the antimicrobial activity.

Key words: Chinese liquor fermentation, yellow water, antimicrobial properties, stability