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Title: Effect of pretreatment of intact 'Gala' Apple with ethanol vapor, heat, or 1-Methylcyclopropene on quality and shelf life of fresh-cut slices

item Baldwin, Elizabeth - Liz
item Mattheis, James

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2004
Publication Date: 7/1/2004
Citation: Bai, J., Baldwin, E.A., Soliva-Fortuny, R.C., Mattheis, J.P., Stanley, R., Perera, C., Brecht, J.K. 2004. Effect of pretreatment of intact 'Gala' Apple with ethanol vapor, heat, or 1-Methylcyclopropene on quality and shelf life of fresh-cut slices. Journal of the American Society for Horticultural Science. 129(4):583-593.

Interpretive Summary: Fresh-cut fruits and vegetables are the fastest growing portion of the fresh produce industry, with most of the sales being in vegetables (peeled carrots and bagged salads). Fresh-cut fruits have lagged behind in sales because they are more problematic due to higher water content, and delicate nature. Cutting the fruit causes production of the plant hormone ethylene which causes deterioration and discoloration of the cut product. This research tests pretreatments of intact apple fruit that would affect the subsequent fresh-cut apple slice quality and shelf life, in order to develop a commercial cut apple product. Treating whole apple fruit with heat, ethanol vapor, or 1-methylcyclopropene, reduced production of ethylene by the apple slices. The result was extension of the cut apple shelf life by 5 to 7 days over untreated fruit, although there was slight loss and/or alteration of flavor.

Technical Abstract: `Gala' apples were treated with ethanol vapor (5 mL kg fruit-1 for 24 h at 25 °C), heat (4 d at 38 C and >98% RH), or 1-methylcyclopropene (1-MCP; 1 or 0.675 L L-1 for 18 h at 20 °C) prior to processing into slices, then dipped in an anti-browning solution with calcium salt, drained, and packaged in perforated polyethylene bags. Residual effects of pretreatments on fresh-cut slice physiological and quality attributes were investigated during storage for up to 20 d at 5.5 °C. Ethylene production was reduced by ethanol, heat and 1-MCP pretreatments, while ethanol and heat also reduced slice respiration. Heat and 1-MCP pretreatments inhibited slice texture changes while ethanol had no effect on instrumental texture measurements but reduced sensory firmness. Ethanol pretreatment increased ethanol and ethyl esters in slices but reduced acidity, while heat reduced both acidity and aroma volatile levels. Both ethanol and heat pretreatments led to lower sensory scores for apple flavor and ethanol-pretreated slices also received higher scores for altered flavor. Slice acidity was best maintained by 1-MCP pretreatment, but none of the pretreatments affected soluble solids levels. Shelf life based on appearance was 14 d for ethanol-pretreated slices and 12 d for heat-pretreated slices compared to that of control, which was 9 d, while 1-MCP pretreatment promoted decay development on the cut surface, and the shelf life was 8 d. Obvious separations were determined between ethanol- and heat-pretreated slices and untreated control by canonical discriminant analysis in headspace volatile levels determined by GC and electronic nose.