Response of melatonin on postharvest qualities and shelf life of pineapple cv. Kew at ambient storage

Melatonin is a pleiotropic molecule which plays a pivotal role in extending shelf life and maintaining the postharvest quality of fruit. Pineapple fruits harvested at different stages of maturity had marked variations in physico-biochemical qualities and shelf life during storage. The present study aimed to determine the potential effectiveness of different concentrations of postharvest melatonin applications on pineapple cv. Kew fruit in ambient storage. Different concentrations of melatonin (MT) solution viz. T1: MT at 0.25mM, T2: MT at 0.5 mM, T3: MT at 1 mM, T4: MT at 2 mM, T5: MT at 4 mM and T6: MT at 8 mM were used for the study and compared with T7: untreated fruits (control). At 20 days after storage, fruits dipped in 8 mM melatonin resulted in lowest physiological weight loss (11.84%), fruit decay (13.33%), decrease in fruit length (3.29%) and diameter (3.42%), juice content (58.27%), titratable acidity (0.91%), flesh translucency (2.0) and crown condition (2.6) these resulted in the decrease with the increase in concentration of melatonin. Maximum shelf life (23.33 days), fruit firmness (39.24 Ncm2), TSS (10.3⁰Brix), total sugar (10.10%), reducing sugar (8.85%), TSS: Acid ratio (11.30), ascorbic acid (19.3 mg 100g-1), total Carbohydrate (10.08%), total phenol (35.64mg 100g-1) and antioxidant activity (48.14%) increased depending on increment in melatonin concentration as compared to control. Results of the study showed that Melatonin @ 8mM has a marked influence in extending the shelf life while maintaining the physico-chemical quality of stored pineapple and thus can be a good option in using the technique for commercial shelf life extension in ambient conditions.