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.

A Review of the Efficacy of Ultraviolet C Irradiation for Decontamination of Pathogenic and Spoilage Microorganisms in Fruit Juices

“…To further enhance the antimicrobial efficiency of UV-C irradiation, a combination of UV-C irradiation and other preservation techniques has been investigated. For instance, UV-C irradiation combined with microwave heating [ 23 ], mild heat [ 21 , 22 , 25 , 37 , 39 ], encapsulated vanillin and citral emulsions [ 22 ], chitosan nanoparticles [ 42 ], ohmic heating [ 43 ], nisin [ 30 ], ultrasonic atomizer nozzles [ 44 ], and ultra-high-pressure homogenization [ 33 ] have been reported to exhibit synergistic and/or additive microbial inactivation effects.…”