Postharvest gamma-aminobutyric acid application mitigates chilling injury of aonla (Emblica officinalis Gaertn.) fruit during low temperature storage

Aonla is a nutrients rich underutilized subtropical fruit. It has short shelf life and is prone to chilling injury (CI) below 6 degrees C. So, the effect of gamma-aminobutyric acid [5 mmol L-1 (GABA)] was investigated on aonla fruit CI mitigation during low temperature storage at 5 +/- 1 degrees C for 24 d. Results showed that GABA treatment markedly suppressed CI, decay incidence, membrane permeability, malondialdehyde, superoxide anion and hydrogen peroxide in contrast with control. Treated fruit showed higher activity of glutamate decarboxylase (GAD) and GABA transaminase (GABA-T) enzymes which ultimately resulted in increased endogenous GABA content accumulation. Similarly, GABA application stimulated the activities of Delta(1)-pyrroline-5-carboxylate synthetase (P5CS) and ornithine aminotransferase (OAT) enzymes which thus enhanced proline accumulation. The GABA treated fruit exhibited higher phenylalanine ammonia lyase (PAL) and reduced polyphenol oxidase (PPO) enzyme activity and showed higher total phenols accumulation. In addition, total flavonoids, ascorbic acid and glutathione content were also significantly higher in GABA treated aonla fruit. In addition, GABA treated aonla fruit exhibited markedly higher ascorbate peroxidase (APX) catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) activities in comparison with the control. In addition, GABA treated fruit showed lower total soluble solids, ripening index and juice pH along with markedly higher concentration of titratable acidity. In conclusion, GABA treatment could be used for CI mitigation and overall quality maintenance of cold stored aonla fruit.

Automated summary

The study demonstrated that GABA treatment effectively reduced chilling injury in aonla fruit, increased endogenous GABA content, and promoted the accumulation of proline and total phenols.