Glycine betaine treatment attenuates chilling injury and maintains nutritional quality of hawthorn fruit during storage at low temperature

Low-temperature storage delays senescence and helps to maintains nutritional quality, which recommended for extending the postharvest life of fruit and vegetable. But, under low temperature storage, hawthorn fruit pitting as a physiological manifestation of chilling injury (CI) symptom can develop visually. In this study, the effects of glycine betaine (GB) treatment applied by immersion (0, 2.5, 5 and 10 mM, for 15 min at 20 °C) on chilling injury and nutritional quality of hawthorn fruit during storage at 1 °C for 20 days was investigated. The results showed that GB treatment, especially at 10 mM, significantly delayed fruit pitting development. Also, GB treated hawthorn fruit exhibited significantly higher endogenous GB and proline accumulation, which was concurrent with higher antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activity leading to lower H2O2 accumulation. Also, hawthorn fruit treated with GB exhibited significantly higher phenols, flavonoids and anthocyanins accumulation resulting from higher phenylalanine ammonia lyase (PAL) enzyme activity, which concomitant with higher ascorbic acid accumulation leading to higher DPPH scavenging capacity during storage at 1 °C for 20 days. These results suggested that GB treatment not only can be used as a useful strategy for attenuating chilling injury of hawthorn fruit by enhancing antioxidant enzymes activity leading to lower reactive oxygen species (ROS) accumulation, but also is useful for maintaining nutritional quality of hawthorn fruit by triggering antioxidant molecules accumulation which is beneficial for human health.