Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/1996
Publication Date: N/A
Interpretive Summary: About one-third of the fruits and vegetables grown in the U.S. are subject to chilling injury when stored at low, nonfreezing temperatures commonly encountered in commercial storage facilities. Tomatoes are susceptible to chilling injury, particularly in the mature green stage of maturity. Florida, which is the largest producer of tomatoes in the U.S., ships almost its entire production mature green. Prestorage heat treatments recently have been shown to reduce chilling injury in some fruits and vegetables. The objective of this study was to compare short and long term heat treatments on chilling tolerance of tomatoes. Parameters evaluated included chilling injury, ripening, lipid composition and flavor volatiles. We found that prestorage short and long term heat-treated tomato fruit can be successfully stored at chilling temperatures. Heat-treated tomatoes appeared to ripen normally and the changes in lipids and flavor volatiles did not seem to be detrimental to overall quality.
Technical Abstract: The main objective of this study was to determine the effects of prestorage heat treatments on chilling tolerance of tomatoes. Mature-green tomato fruit (Lycopersicon esculentum Mill.), either C2H4-treated or not, were immersed in 42C water for 60 min or held in 38C air for 48 hours or not treated, and then stored at either 2C (chilled) or 13C (nonchilled) for 14 days before ripening at 20C. Heat-treated fruit stored at 2C and transferred to 20C ripened normally while nonheated fruit decayed before reaching red ripe. Color (a/b ratio), lycopene content, and internal quality characteristics of fruit were similar at the red ripe stage irrespective of heat treatment. In red ripe fruit, free sterol levels were significantly higher in chilled fruit compared with nonchilled fruit. Heating fruit in 38C air resulted in significantly higher levels of some free sterols compared with heating fruit in 42C water. Of the 15 flavor volatiles analyzed, 12 showed decreased concentrations as a result of C2H4-treatment and nine showed decreased concentrations when stored at 2C prior to ripening. Some volatiles were decreased by the heat treatments, especially 42C water. Prestorage short and long term heat treatments could allow for storage of mature green tomatoes at lower temperatures with little loss of their ability to ripen normally.