Effect of exogenous γ-aminobutyric acid (GABA) treatment on chilling injury and antioxidant capacity in banana peel

• Chilling injury was alleviated by GABA treatment in postharvest banana fruit.
• GABA enhanced P5CS and PAL activities, while inhibited PDH activities.
• GABA treatment promoted proline accumulation.
• Antioxidant capacity was enhanced by GABA treatment.

In order to evaluate the effects of γ-aminobutyric acid (GABA) on chilling injury (CI) of banana fruit, CI index, malondialdehyde (MDA), total phenolics, proline, the activities of peroxidase (POD), phenylalanine ammonia-lyase (PAL), Δ1-pyrroline-5-carboxy-late synthetase (P5CS), proline dehydrogenase (PDH), ferric reducing antioxidant potential (FRAP) assay and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity were analyzed after pretreated 20 mM GABA vacuum infiltration and stored at 7 °C for 20 days. GABA treatment retarded the increase of CI index, electrolyte leakage and MDA content, while promoted the accumulation of total phenolics and proline. GABA treatment significantly enhanced the activities of P5CS, POD and PAL, while inhibited the activity of PDH. FRAP assay and DPPH radical scavenging activity of GABA-treated banana fruit were significantly higher than control fruit in the first 10 days. The results suggest that application of GABA plays an important role in alleviating banana fruit chilling injury through proline accumulation and enhancement of antioxidant defense system. GABA treatment may act as a promising approach in inhibiting chilling injury and maintaining quality of banana fruit.