Disinfection by-products generated by sodium hypochlorite and electrochemical disinfection in different process wash water and fresh-cut products and their reduction by activated carbon

Abstract

Antimicrobial treatment of fresh produce process wash water (PWW) needs to be optimized to improve the microbiological safety while minimizing the presence of disinfection by-products (DBPs) that can be adsorbed by the washed produce. In this study, the occurrence of DBPs including trihalomethanes (THMs) and chlorate in the PWW of shredded lettuce, baby spinach and shredded carrots treated with sodium hypochlorite (NaClO), and electrochemical disinfection (ED) was assessed. The potential of activated carbon (AC) filtration treatment for the reduction of DBPs was also evaluated. Results showed that both antimicrobial treatments caused the accumulation of DBPs in PWW, reaching concentrations above the legal limits for potable water. However, there were significant differences in the concentration of DBPs due to the type of washed product and antimicrobial treatment. There was a lower accumulation of THMs in spinach PWW compared with lettuce and carrot PWWs. Electrochemical disinfection generated higher concentrations of DBPs in the PWW, but a significant reduction was observed when using AC. Such reduction led to a lower accumulation of chlorate in the washed produce. The presence of THMs in PWW was not relevant when using these chlorine-based antimicrobial treatments as there was a limited transfer of THMs to the washed produce. On the contrary, a significant migration of chlorate from the PWW to the washed product occurred, even when the AC was used as a mitigation treatment.