Inactivation of Pectobacterium carotovorum subsp. carotovorum on Chinese cabbage (Brassica rapa L. subsp. pekinensis) by wash treatments with phenolic compounds

This study evaluated bactericidal effects of chlorogenic acid (CGA), caffeic acid (CFA), coumaric acid (CMA), and ferulic acid (FA), against Pectobacterium carotovorum subsp. carotovorum (PCC) on Chinese cabbage using suspension and direct inoculation tests. Among suspension tests with four phenolic acids, CGA at 5-7 mM or CMA at 7-10 mM for 30 min effectively eliminated PCC, whereas CFA and FA effectiveness increased on prolonging treatment time to 60 min. For cabbage, CGA at 5-7 mM or CMA at 10 mM for 60 min achieved a log10 reduction of ≥3.98 log10 CFU/g. On comparison of soft rot development on Chinese cabbage after treatment with phosphate-buffered saline (negative control), 1% sodium hypochlorite (positive control), and 5 mM of CGA at 20 °C for 72 h, the first soft rot symptoms were observed after 12 h only for PBS treatment, and there were no significant differences between positive control and CGA treatment up to 36 h, after which the decay rate increased significantly. These results suggest that CGA at 5-10 mM for 60 min might allow significant shelf life extension of cabbage and prevent quality loss in kimchi by controlling the spread of the soft rot symptoms on cabbage.