Preservation of Xinyu Tangerines with an Edible Coating Using Ficus hirta Vahl. Fruits Extract-Incorporated Chitosan

Abstract

Xinyu tangerine is a citrus fruit that has enjoyed great popularity in China for its fewer dregs and abundant nutrients. However, it is considered an easily perishable fruit that is vulnerable to various pathogenic fungal infections, especially by Penicillium italicum, which reduces its storage life and commercial value. Normally, to reduce the losses caused by fungal deterioration of harvested fruit, polysaccharide-based edible coating, containing natural antimicrobial agents (e.g. plant extracts), have been applied. In current study, we evaluated the effects of Ficus hirta Vahl. fruits extract (FFE)–incorporated chitosan (CS) edible coating on Xinyu tangerines during cold storage at 5 °C. The results showed FFE has efficacy as an antifungal against P. italicum in a dose-dependent manner in vivo, with an EC50 value of 12.543 mg·mL−1. It was found that the edible coating of FFE–CS exhibited a higher reduction of total soluble solid (TSS), titrable acid (TA), and ascorbic acid (AsA) content by reducing the fruit decay rate, weight loss, respiration rate, and malondialdehyde (MDA) content during cold storage at 5 °C. Moreover, the activities of protective enzyme such as superoxide dismutase (SOD), peroxidase (POD), and phenylalanine ammonia-lyase (PAL), which have been linked with reactive oxygen species (ROS) and the phenylpropanoid pathway, were higher in the FFE–CS-coated fruits. On the basis of these study results, the FFE–CS edible coating could reduce postharvest loss and enhance the storability of Xinyu tangerines due to the in vivo antifungal activity of FFE.