Effect of electrolysed water generated by sodium chloride combined with sodium bicarbonate solution against Listeria innocua in broth and on shrimp

Abstract Electrolysed water (EW) generated using sodium chloride (NaCl) and sodium bicarbonate (NaHCO3) as electrolytes shows strong bactericidal effects on pathogens. However, the sanitising effect of EW generated by adding NaHCO3 before and after electrolysis was not clear. The difference of the bactericidal mechanism in broth medium and real food system was not elucidated as well. This present study aimed to compare the antibacterial effect and inactivation mechanism of EW generated by the addition of NaHCO3 before and after electrolysis against Listeria innocua ATCC 33090 in broth and on shrimp. The addition of NaHCO3 before electrolysis enhanced both in vitro and in vivo antibacterial activity with greater bacterial reduction (2.9 log CFU/mL and 1.7 log CFU/g, respectively) compared with adding NaHCO3 after electrolysis. The antibacterial mechanism was further investigated by NMR-based metabolomics. The EW generated by adding NaHCO3 before electrolysis mainly affected amino acid metabolism and carbohydrate and energy metabolism in broth. The reduction of fewer types of amino acids and sugars was observed on the shrimp attributing to the different nutritional compositions of shrimp. Moreover, the accumulation of γ-aminobutyric acid and glutamate in L. innocua on shrimp compensated for the disrupted TCA cycle caused by the EW stress. Therefore, L. innocua was less sensitive to generated EW on shrimp as compared with in broth. The results provide comparative information on the responses of L. innouca to EW stress in broth and on shrimp and could serve as the basis to develop strategies to better control pathogens in food.