Fruit maturity and timing of ethylene treatment affect storage performance of green tomatoes at chilling and nonchilling temperatures

Abstract

Green tomato (Lycopersicon esculentum 'Sunny') fruit were stored at 2.5, 5, 7.5, 10, or 12.5°C (36.5, 41, 45.5, 50, or 54.5°F) for 1, 3, 5, or 7 days to determine their sensitivity to chilling injury. In subsequent experiments, fruit were treated with ethylene at 20°C (68°F) until the breaker stage was reached, either before or after storage at 12.5°C for 0, 1, 3, 5, or 7 days, or 2.5°C for 3, 5, 7, or 9 days. Number of days to reach the breaker stage was used as an indicator of initial maturity. The chilling threshold temperature for green 'Sunny' tomatoes was near 7.5°C, with delayed ripening occurring in fruit stored for ≥5 days. Longer exposure times at chilling temperatures resulted in reduced marketable life, dull color, flaccidity, and delayed, uneven (blotchy) and nonuniform ripening. Chemical composition was generally unaffected by chilling, while loss of firmness as a result of chilling exposure time rather than chilling temperatures per se was observed. Increased storage time at either 2.5 or 12.5°C accentuated the initial differences in fruit maturity and thus resulted in less uniform ripening, especially for tomatoes stored before ethylene treatment, but the effect was much greater following 2.5°C storage. Exposure to 2.5°C for as little as 3 days before ethylene treatment caused blotchy ripening and decay, and reduced the marketable life of tomatoes by half compared to storage at nonchilling temperature. Treatment with ethylene before storage prevented chilling injury for up to 5 days at 2.5°C and prolonged the marketable life of tomatoes stored at either chilling or nonchilling temperature. Tomatoes became less responsive to poststorage ethylene treatment with increased storage time at either 2.5 or 12.5°C. More mature tomatoes and those treated with ethylene before 12.5°C storage lost less weight. Vitamin C content was lower in more mature tomatoes, but ethylene treatment resulted in better maintenance of vitamin C by shortening the time to reach the red stage. No other significant differences in color, firmness or chemical composition at the red stage were found between fruit with different initial maturities or fruit treated with ethylene before or after 2.5 or 12.5°C storage. Treating green tomatoes with ethylene before storage or transport is preferable to poststorage treatment because of faster and more uniform ripening, and also increased marketable life and reduced risk of injury in the event of exposure to chilling temperatures.