Synergistic effects ofUV‐Clight in combination with chitosan nanoparticles against foodborne pathogens in pomegranate juice with enhancement of its health‐related components

Abstract

The effect of chitosan nanoparticles (ChNPs), UV-C lights alone, and their combination on inactivating foodborne pathogens (Escherichia coli O157:H7 and Listeria monocytogenes) was evaluated in vitro and in pomegranate juice (PJ). As well as study the effect of these treatments on the microbial quality and health-related components in PJ. ChNPs at a concentration of 175 μl ml−1 showed 90% and 100% inhibition of E. coli O157:H7 and L. monocytogenes, respectively. Log reductions of 6.1 and 7.22 logs have been achieved for E. coli O157:H7 and L. monocytogenes by UV-C alone after 45 and 35 min, at doses of 0.682 and 0.445 J/cm−2 respectively. Compared with individual treatments, the sequential application with ChNPs (1/2 MIC) and UV-C at dose of 0.356 J/cm−2 for 30 min, E. coli O157:H7 and L. monocytogenes were completely inactivated in vitro. In PJ, when individual ChNP or UV-C treatments were used, microbial numbers decreased, and they did not reach more than 4 log CFU ml−1 during the storage period. While, the combined ChNPs (100 μl ml−1) UV-C (at dose 0.178 J/cm−2) treatment produced a greater microbial reduction than the treatment of each one alone, and complete inactivation of aerobic bacteria, yeast, and mold for 30 days. In ChPNs and UV-C combination, until the last storage time (30 days) E. coli and L. monocytogenes cells inoculated in the PJ were not determinable. The combination of ChNPs at low concentration (1/2 MIC) and UV-C with shorter time (20 min at dose 0.178 J/cm−2) had achieved preserving the microbiological quality and safety in PJ for 30 days at 4°C, in addition to retaining the health-related components (total phenol, vitamin C, anthocyanin content and antioxidant); this, in turn, preserves the functional role of pomegranate juice. The synergistic effect observed in this study allows the possibility to design double treatments with a safe and economical technique for the decontamination of fruit juices. Novelty impact statement The application of chitosan nanoparticles in combination with UV-C light technique can be a safe alternative to thermal pasteurization or chemical additives to maintain the microbiological quality and safety in pomegranate juice. The combination of ChNPs with UV-C light is a promising hurdle for good retention of quality, nutritive value, health-related components (functional juices) in pomegranate juices. The combinational treatment at a low dose from chitosan nanoparticles with UV-C for a shorter time has a practical and significant economic return.