Effect of photochemical treatment in the preservation of fresh tomato (Lycopersicon esculentum cv. Capello) by delaying senescence

The effect of hormic dosage of ultraviolet radiation in delaying the senescence of tomato was investigated. Mature-green tomato fruit (var. Capello) were irradiated with ultraviolet light (UV-C, 200–280 nm) corresponding to 0, UV–3.7×103 J m−2 and UV-24.4×103 J m−2, and were stored at 16°C, under high relative humidity for a period of 35 days. Attributes of senescence such as weight loss, color, texture, respiration rate, ethylene production and putrescine were monitored periodically throughout the storage period. A dose of UV-3.7×103 J m−2 was found to be beneficial (hormic) in delaying ripening and senescence, while the higher dose impaired ripening and caused abnormal browning, manifested as sun-scalding of the fruit's surface. The development of color and softening of tissue were significantly retarded during storage in response to the treatment with the hormic dose (UV-3.7×103 J m−2). In addition to a delay in the climacteric response by at least 7 days, the respiration rate and ethylene production of the treated fruit were also reduced. The delay in senescence was attributed in part, to the maintenance of a high level of putrescine (antisenescence agents exerting opposite physiological effect to ethylene). The results suggest that photochemical treatment may have potential for preservation of fresh fruit and vegetables.