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Submitted to: HortScience
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/13/2006 Publication Date: 2/1/2007 Citation: Wall, M.M. 2007. Postharvest quality and ripening of Dwarf Brazilian bananas (Musa sp.)after x-ray irradiation quarantine treatment. HortScience 42:130-134. Interpretive Summary: The use of a quarantine treatment for surface disinfestation of bananas would expand the export of Hawaii's bananas by reducing the need for inspections. The possible rejection of a shipment due to the presence of insects poses a high financial risk for growers. The quality, composition, and ripening behavior of specialty bananas was determined after low dose irradiation to establish the limits of fruit tolerance to this quarantine treatment. Bananas ripened normally and quality was maintained following irradiation doses up to 600 Gy. This research supports a USDA, APHIS rule allowing the export of irradiated bananas from Hawaii. Exporters can develop markets for Hawaii's bananas with confidence that fruit quality will not be compromised by irradiation treatment at a maximum dose of 600 Gy. Technical Abstract: The fruit quality and ripening response of Dwarf Brazilian bananas (Musa sp., group AAB) were determined following x-ray irradiation for surface disinfestation of quarantine pests. The proximal and distal hands from winter- and summer-harvested bunches were treated with 0, 200, 400, 600, or 800 Gy doses, stored for 7 days at 14C, and ripened at 20C. Irradiation did not extend banana shelf-life or affect soluble solids content, but titratable acidity decreased with increasing dose. Starch and total sugar concentrations were similar between control fruit and irradiatied fruit at all doses. However, sucrose contents decreased linearly as dose increased, while glucose and fructose concentrations increased, indicating an acceleration of sucrose hydrolysis in treated bananas. Irradiation increased peel firmness but not pulp firmness for winter-harvested fruit, and had a minimal effect on peel and pulp firmness of summer-harvested fruit. For irradiated fruit, the respiratory climacteric rates decreased relative to control fruit, but CO2 and ethylene production increased one day after irradiation stress. Proximal fruit had higher respiration and ethylene production rates than distal fruit after irradiation, but differences in physiological maturity between hands did not affect soluble solids, titratable acidity, starch, or total sugar content of ripe fruit. Bananas from distal hands treated with 800 Gy irradiation developed peel injury when harvested in either the winter or summer months. Summer-harvested fruit also were damaged at the 600 Gy dose for distal fruit only. Treatment of fruit from the proximal half of bunches at doses less than or equal to 600 Gy would ensure visual quality while providing quarantine security for Dwarf Brazilian bananas. |
