Inhibitory Effect of Low Temperature Plasma-Activated Water on the Surface Microorganisms and the Quality Attributes of Blueberry

This study aimed to investigate the inhibitory effect of low temperature plasma-activated water (PAW) on the surface microorganisms and the quality attributes of blueberry. In this study, the blueberry fruits were treated by submerging them in the PAW generated at different plasma-activated time (Deionized water was activated by plasma treatment for 20, 40 and 60 min. Accordingly, the samples after treatment were named as PAW20, PAW40, and PAW60). The effects of PAW on microbial loads and quality attributes of the treated blueberries such as surface color of peels, anthocyanin contents, ascorbic acid content, carotenoid contents and radical scavenging capacity, and the changes in firmness and decay incidence during the storage at 4 and 25 °C were studied. The results showed that compared with controls (blueberries were treated with deionized water), after PAW60 treatment, the total number of bacteria decreased by 1.09 lg(CFU/g), the number of Saccharomyces cerevisiae, Alternariaalternate and Botrytis cinerea decreased by 1.47, 1.43 and 2.02 lg(CFU/g), respectively. PAW treatment significantly reduced the decay incidence of blueberries (P<0.05) and maintained the firmness of blueberries during the storage. The ΔE values determined in this study were less than 1.5 in PAW20 and PAW40 groups, however, it was approximately 1.7 in PAW60 group. The β-carotene content of blueberries significantly decreased after PAW treatment (P<0.05). The ascorbic acid content of blueberries increased after PAW20 and PAW40 groups, but it decreased after PAW60 treatment (P<0.05) . The anthocyanin content and free radical scavenging ability of blueberries significantly increased after PAW40 and PAW60 treatment (P<0.05). In conclusion, PAW treatment could effectively inhibit the growth of microorganisms on the surface of blueberries, reduce the decay incidence of blueberries, and improve the quality of blueberries during the storage. This study would provide a reference source for the application of PAW technology in blueberry preservation.