Thymol contributes to preserving the postharvest freshness of blueberries by enhancing antioxidant and ascorbate-glutathione (AsA-GSH) cycle

Abstract

Abstract Blueberries are prone to softening and rotting shortly after harvest, which not only complicates post-harvest preservation but also significantly impairs their quality. In this study, the regulatory mechanism of thymol pre-harvest treatment on the quality and ascorbic acid-glutathione (AsA-GSH) cycle of blueberries during storage was investigated. The results demonstrated that thymol treatment impeded the decline of total flavonoids, total phenols, reducing sugars, and starch content in blueberry fruit. In addition, thymol treatment suppressed the activities of α-amylase, β-amylase, and total amylase. In addition, thymol increased the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR) and maintained high AsA and GSH contents and AsA/(AsA + DHA) and GSH/(GSH + oxidized glutathione (GSSG)) ratios in blueberries. In conclusion, thymol improved the overall postharvest antioxidant capacity of blueberries and maintained their quality by delaying the reduction of antioxidants, inducing antioxidant enzyme activities, and enhancing the metabolic activities of the AsA-GSH cycle. Therefore, thymol pre-harvest treatment can serve as an efficient and natural pre-harvest treatment agent for preserving postharvest blueberry quality, effectively maintaining the post-harvest quality of blueberries and extending their storage life.