Efficacy of lactic acid in reducing foodborne pathogens in minimally processed lotus sprouts

Fresh lotus sprout is easily browned and perishable due to microbial growth and degradation. Therefore, browning and foodborne pathogen have become the most serious problems. The objective of this study was to investigate the effect of lactic acid (0.25%, 0.5%, 1% and 2% (v/v)) on reduction of foodborne pathogens, such as Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes, in lotus sprouts. Tap water and sodium hypochlorite (200 mg/l) were used as control treatments. Results indicated that tap water caused a slight reduction (<0.5 log) in the microbial loads. The sodium hypochlorite treatment led to 1.3 log reductions of the microbial population. When treated with 0.5% and 2.0% lactic acid solutions, 1.5 and 2.3 log reductions were achieved, respectively. The effectiveness of lactic acid treatment increased with the increase of lactic acid concentration. Results showed that the lactic acid treatment at 0.5% or higher was effective to reduce foodborne pathogens in lotus sprouts. The L* values of samples treated with lactic acid decreased slightly during storage. Furthermore, the lactic acid treatment contributed to slow accumulation of red color on lotus sprouts, which was more effective than sodium hypochlorite treatment to reduce the discoloration of lotus sprouts. These results indicated that lactic acid can be used to improve the color and safety of minimally processed lotus sprouts.

► Lactic acid (>0.5%) could effectively reduce pathogens in lotus sprouts.
► Effects of lactic acid on pathogens increased as its content increased.
►  Lactic acid reduced the discoloration of the lotus sprouts during storage.
► Lactic acid could improve the color and safety of minimally processed lotus sprouts.