Effect of citric acid combined with UV-C on the quality of fresh-cut apples

The aim of this study was to evaluate the effect of 0.5% citric acid (CA), UV-C alone, and their combination (CA + UV) on native microflora survival, phenolic composition, browning, firmness and weight loss of fresh-cut ‘Fuji’ apples during refrigerated storage. Results showed that CA, UV alone and UV + CA had no significant effect on the firmness and total phenolic content but increased the polyphenol oxidase activity of fresh-cut apples. CA alone aggravated the browning and increased the weight loss of fresh-cut apples, while UV or UV + CA treatment significantly decreased the occurrence of browning reactions and reduced the weight loss as compared to control. The bacterial count of fresh-cut apples were reduced by 1.5, 2.1 and 2.6 log CFU/g after treatment with CA, UV and CA + UV, respectively. All these treatment retarded the microbial growth during storage and CA + UV treatment maintained the lowest growth rate among all treatment samples. Furthermore, the content of chlorogenic acid, (−) epicatechin, (+) catechin and caffeic acid in CA + UV treated sample was higher than the control after 15 d storage. Overall, these results suggest that CA + UV might be applied as an effective and safe preservative for fresh-cut apples.