HEAT-TREATMENT OF MATURE-GREEN TOMATOES - DIFFERENTIAL-EFFECTS OF ETHYLENE AND PARTIAL RIPENING

Mature-green 'Sunbeam' tomatoes (Lycopersicon esculentum Mill.) were t reated in varying order with C2H4, 42 degrees C water for 1 hour, 38 d egrees C air for 2 days, held 2 days at 20 degrees C (partial ripening ), or not treated and then stored at 2 degrees C (chilled) for 14 days before ripening at 20 degrees C. Heat-treated fruit stored at 2 degre es C and transferred to 20 degrees C ripened normally, while 63% of no nheated fruit decayed before reaching the red-ripe stage. Partially ri pened fruit developed more chilling injury, were firmer, were lighter, and were less red in color than fruit not partially ripened. Lycopene content and internal quality characteristics of fruit were similar at the red-ripe stage irrespective of sequence of C2H4 exposure, heat tr eatment, or a partial ripening period. Of the 15 flavor volatiles anal yzed, 10 were reduced by storage at 2 degrees C. Exposure to C2H4 befo re the air heat treatment reduced the levels of four volatiles, while C2H4 application either before or after the water heat treatment had n o effect on flavor volatiles. Two volatiles were decreased and two wer e increased by partial ripening. Storage at 2 degrees C decreased the level of cholesterol and increased levels of campesterol and isofucost erol in the free sterol pool. Exposure to C2H4 before or following hea t treatments, the method of heat treatment, and partial ripening had l ittle effect on free sterols, steryl esters, steryl glycosides, or acy lated steryl glycosides in the pericarp of red-ripe fruit. A short- or long-term heat treatment of mature-green tomatoes could permit storag e at low temperatures with little loss in their ability to ripen norma lly, whereas partial ripening did not reduce chilling injury.