Effect of Melatonin on Physical and Chemical Changes of ‘Hom Thong’ Banana during Storage

Melatonin (MT) has been shown to enhance the antioxidant system, leading to quality maintenance in several fruits. This present research focused on the effect of MT application in delaying ripening and physical and chemical changes of 'Hom Thong' bananas after harvest. The bananas were washed and sanitized with 200 ppm NaOCl, then divided into four treatments as follows: no MT treatment (control), dipping in 0.1 mM, 0.5 mM and 1.0 mM concentrations of MT for 2 h each. After air drying to remove excess solution, they were stored at 25°C for 5 days. There were no significant differences among treatments in terms of weight loss of bananas, which ranged from 11.06% to 11.74% after 5 days of storage. The bananas treated with 0.5 mM of melatonin (MT) exhibited a delay in peel color changes as expressed in L* and b* values. Furthermore, the bananas treated with 0.5 mM MT showed significantly lower rates of respiration and ethylene production, along with higher firmness and total sugar content compared to the control group (p ≤ 0.05). This treatment also delayed the decrease in phenolic content and antioxidant capacity compared to the control group. The untreated sample exhibited a phenolic content of 1.28 μg GA/g FW and 28.48% scavenging activity in the DPPH assay, while the sample treated with 0.5 mM MT revealed a phenolic content of 1.72 μg GA/g FW and a scavenging activity of 38.17% in the DPPH assay, respectively. In conclusion, dipping in 0.5 mM MT can delay ripening and maintain the quality of bananas compared to other treatments