Maintain The Quality of Winter Guava (Psidium guajava L.) Fruits By Post-Harvest Application of Melatonin and Methyl Jasmonate Under Vacuum-Packaged and Low-Temperature Storage

Abstract

Guavas (Psidium guajava L.) has a limited capacity to be stored under cold storage for long periods. Moreover, it is climacteric and undergoes quick post-harvest ripening within a few days under normal conditions; it ripens and turns overripe and mealy within a week. When stored in a cold environment, the fruit can preserve its quality for 15 days at a temperature of 8-10 °C and a relative humidity of 85-90%. Winter guava fruits were treated by different concentrations of melatonin and methyl jasmonate (MeJA ) and combined with vacuum packaging under cold storage at 4 ± 1°C with 90 ± 5% RH for two distinct seasons to improve storability and maintain quality. The results showed that the microbial load (CFU/g) decreased by application of high concentrations of melatonin and methyl jasmonate under vacuum packing. Additionally, these treatments resulted in a substantial reduction (p˂0.05) in weight loss percentage. Moreover, no chilling injury (CI) was observed in guava fruits when treated by melatonin (0.2 mM) under vacuum packaging. Simultaneously, it indicated that the most effective treatment in decreasing respiration rate and maintaining higher acidity and ascorbic acid was MeJA (2mM) under vacuum packaging. Applying melatonin and MeJA at a high concentration under vacuum packaging enhanced chilling tolerance and maintained the quality of guava fruit at 4°C for 28 days.