Sequential application of plasma-activated water and mild heating improves microbiological quality of ready-to-use shredded salted kimchi cabbage (Brassica pekinensis L.)

Abstract

Improving the microbiological quality of salted Chinese cabbage, used in kimchi, an important part of the Asian culinary scene, is critical for minimising exposure to foodborne pathogens. This study evaluated the effects of a sequential combination of washing treatments using plasma-activated water (PAW), tap water, and sodium hypochlorite (NaOCl) and mild heating (MH) at 60 °C on the inactivation of background microbiota and inoculated foodborne pathogens and the quality of shredded salted Chinese cabbages. Treatment with 120-PAW alone resulted in 2.0, 2.2, 1.8, and 0.9 log CFU/g reduction in mesophilic aerobic bacteria, lactic acid bacteria, yeast and moulds, and coliforms, respectively, while subsequent MH treatment reduced the counts of lactic acid bacteria, yeast and moulds, and coliforms to below detection limits. Sequential combination of washing with 120-PAW followed by MH caused 3.4 and 3.7 log CFU/g reductions in Listeria monocytogenes and Staphylococcus aureus inoculated into salted Chinese cabbages. The combined treatment caused negligible changes in moisture content, reducing sugar content, instrumental hardness, and CIE colour values. The salinity and peroxidase activity were significantly (P < 0.05) reduced compared to that of the untreated cabbage. Thus, sequential treatment of washing with PAW and MH at 60 °C can improve the microbiological quality of salted Chinese cabbage.