Natural products are useful for delaying the ripening process, preserving quality and reducing biochemical changes in fruits. Effect of gum arabic (GA) 10% and chitosan (CH) 1% edible coatings on physiological and biochemical properties of mango (Mangifera indica L. cv. Choke Anan) fruit were investigated. Mango fruit were stored at 13°C and 80% relative humidity for 28 days. Significant (P≤0.05) differences were observed in fruits treated with GA 10% and CH 1% as compared to the control. The results showed that GA 10% and CH 1% treatments significantly reduced weight loss than the control fruits. The application of CH 1% coating effectively inhibited the increase in soluble solid concentration (SSC), respiration rate and ethylene production. But no significant differences were observed in terms of ascorbic acid loss between treated fruits and control during the entire storage period. Furthermore, the combined application of GA 10% + CH 1% alleviated decay incidence and retained high firmness of mango fruit. These results suggested that application of GA 10% coating combined with CH 1% as a bio preservative might be a simple and effective technique for delaying ripening and maintaining quality of mango fruit during cold storage without the use of fungicides.
The effect of γ-aminobutyric acid (GABA) treatment at two concentrations (1 mM or 5 mM) on papaya fruit stored at 4°C and 80%-90% relative humidity for 5 weeks was investigated. The application of GABA at 5 mM apparently inhibited chilling injury, internal browning, electrolyte leakage, malondialdehyde (MDA), hydrogen peroxide (H2O2), polyphenol oxidase (PPO), phospholipase D (PLD), and lipoxygenase (LOX) activities of papaya fruit. Fruit treated with 5 mM GABA enhanced the activities of ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), superoxide dismutase (SOD), glutamate decarboxylase (GAD), and phenylalanine ammonia-lyase (PAL). In addition, GABA treatment significantly displayed higher levels of proline, endogenous GABA accumulation, phenolic contents, and total antioxidant activity than the nontreated papaya. The results suggested that GABA treatment may be a useful approach to improving the chilling tolerance of papaya fruit by reducing oxidative stress and enhancing the defense system.