الملخص الإنجليزي
Banana (Musa spp.) is one of the most important types of fruit grown and consumed in Oman and in the world. It is a significant fruit in the human diet as a source of nutrients and contributes to the reduction of oxidative stress. However, there is lack of knowledge on the postharvest technology and physiology of locally grown banana cultivars in Oman to support the development of appropriate handling and storage techniques to reduce losses and improve storage potential. The objective of this study was to determine physiological responses and to measure the changes in postharvest quality of two banana cultivars (Musa, "Malindi' and 'Milk') under three different storage conditions (refrigerator: -95.5% RH and 11 - 12 °C, room: 82 – 85% RH and 20 - 22 °C and environmental chamber; 50% RH and 18 °C for 12 hours of darkness, and 28 °C for 12 hours of light). Significant differences (p < 0.05) were observed in the fruit physicochemical properties (i.e, weight loss, firmness, color, pH, total soluble solids (TSS), titratable acidity (TA), sugar : acid ratio, and vitamin C) and physiological responses, i.e. ethylene (C2H4) and CO2 evolution in the three stages of ripening (unripe, fully-ripe and over-ripe) during those three storage conditions for each cultivar studied. The least reduction in fruit mass and highest firmness of the fruit were found using refrigerator storage compared to room and enviromental chamber. The change in peel color of each cultivar was delayed under longer refrigeration time in comparison with the other two conditions where the color changed rapidly in a shorter period of time. However, pH value was about 5 in urripe 'Malindi' and 6 in 'Milk', and generally increased or decreased during ripening. Unripe 'Milk' banana had slightly higher TSS:TA ratio but this rose rapidly during ripening of both cultivars, reaching higher value in "Malindi'. 'Milk' had significantly higher vitamin C content at all stages of ripening than 'Malindi' but 'Malindi' had higher respiration rates and ethylene production, particularly at room temperature storage. Higher weight loss of fruit in the environmental chamber than in normal room condition could be attributed to the low relative humidity and cyclic warming of fruit in the chamber. The rates of C2H4 and CO2 production were low when fruits were stored under refrigeration, leading to inhibition of ripening process and maintaining green life. The present findings confirm that refrigerated storage offered significant benefits in postharvest handling of the locally grown banana cultivars by reducing fruit weight loss (~5% loss vs 21% loss at room condition in 7 days), extending storage life (21 days vs 7 days at room condition), and enhancing vitamin C retention and concentration in fruit during ripening. Further studies are required on the development of optimal storage techniques for other cultivars including the use of controlled atmosphere storage. The regulation of fruit ripening in these banana cultivars using ethlyene inhibitiors such as 1-Methylcyclopropene (1-MCP) also warrants investigation.
