Enhancement of antioxidant defense mechanism by preharvest GABA spray on postharvest quality of strawberries

• GABA treatment improved antioxidant defense mechanisms of strawberry. • GABA treatment reduced microbial activity and decay incidence of strawberry. • GABA attenuated oxidative stress of strawberry. Strawberries is a non-climacteric, nutrient-rich fruit that exhibits a short shelf life and is prone to decay during cold storage. In this study, the impact of preharvest γ-aminobutyric acid (10 mM L -1 GABA) spray was investigated on ‘Rubygem’ and ‘Calinda’ strawberries for decay and to enhance post-harvest storage quality during cold storage at 2±1 °C and 90% RH for 21 d. Results revealed that preharvest GABA-sprayed strawberries in both cultivars exhibited significantly reduced, a* color values, weight loss, browning index, decay incidence, microbial counts, malondialdehyde (MDA), and H 2 O 2 than the control. GABA preharvest strawberries demonstrated markedly lower polyphenol oxidase (PPO), but higher phenylalanine ammonia lyase (PAL) enzyme activity, total phenols (TPC), total flavonoids (TFC), vitamin C, endogenous GABA content and free radical scavenging capacity (FRSC) than the control. In addition, preharvest GABA-sprayed strawberries displayed distinctly greater superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), and catalase (CAT) activities, but lower hydrolytic enzymes polygalacturonase (PG), pectinmethylesterase (PME), xylanase, and α-amylase than the control. In addition, GABA preharvest strawberries showed lower total soluble solids (TSS), TSS/acid ratio, and pH alongside higher titratable acidity (TA), firmness, membrane stability index (MSI) and sensory evaluation. In conclusion, preharvest spray of GABA at 10 mM could be used as a promising tool for maintaining the overall quality of cold-stored strawberries.