Pre–Ripening Irradiation on Tomato Quality at Market Ripeness

Abstract

Mechanical and / or hand harvest of full and over – ripe tomato ( Solanum lycopersicum L  ) fruit and management , lead to yield loss . Pre – ripening gamma irradiation on tomato quality at market ripeness was used to  minimize loss and prolong shelf  – life . Prior  to irradiation , Chemical analysis was conducted on fruit at different stages of ripening .The results revealed that ascorbic acid was increased as titratable acidity decreased , while ph increased slightly as ripening progressed. The carotenoid, phytoene , a precursor for almost all arytenoids lycopene , a potent antioxidant, and principle carotenoid of red–genotype tomato was not detected in fruit at mature – green ,greenish – red and full red  . The carotenoid  lycopene , the main carotenoid at marketable stage was only detected at low concentration in fruit at greenish – yellow stage , but steadily increased as ripening continued , while β – carotene, a potent antioxidant and vitamin A precursor was present in mature – green and full – red and had its highest level in greenish – red fruit . In mature – green and greenish – yellow  fruit  irradiated with 3 and 4 Gy at 24 and 48 hours after harvest , ascorbic acid at marketable ripeness accounted for only 17.97 to 34.06 of control fruit . In fruit irradiated with 1 or 2 Gy ,ascorbic acid was less affected and accounted to 38,81 to 84.28 of control fruit . The highest level of severely rotten fruit were in fruit irradiated with 3 or 4 GY , while the lowest levels of severely rotten fruit  were in fruit irradiated with 1 or 2 Gy .  Fruit irradiated with 1  to 4 Gy  at 24 or 48 hrs after harvest , when greenish – yellow  , had the highest weight loss at 7 and 16 days after irradiation . Fruit irradiated when mature - greenish had the most weight – loss at 7 and 22 days after harvest. Gamma irradiation from 0.5  to 4 Gy  had no effect on pH or titratable acidity at market ripeness when fruit were irradiated at mature – green and greenish – yellow stages 24 and 48 hrs after harvest .

Keywords: Solanum  lycopersicum,  fruit , pre – mature , market ripeness .