Preharvest Soybean Oil and Postharvest 1-Methylcyclopropene (1-MCP) Application to 'Golden Delicious' Apples Affects Volatile Aroma Production after Controlled Atmosphere Storage

To study the effect of growing season applied soybean oil on pre- and post-storage volatile aroma regeneration capacities and fatty acid metabolism of apples, one single treatment (21 days before harvest) of soybean oil emulsion (1% food grade oil, 0.1% Latron) was administered to 'Golden Delicious' apple trees. Apples were harvested at commercial maturity. At the time of storage a second treatment was applied to either control or soybean oil treated pre- climacteric fruit, consisting of 0.70 mu l.L-1 1-methylcyclopropene (1-MCP). The fruit were then stored for up to 140 days at 0.5 degrees C under 1% O-2 and 0.2% CO2 controlled atmosphere (CA) storage conditions and analyzed after holding at 22 degrees C for 0, 3, 7, 11 and 15 days. No significant effects due to soybean oil treatment were noted for fatty acid distribution. 1-MCP treated fruit lost linolenic acid (C18:3) at a slower rate and linoleic acid (C18:2) did not increase as fast compared to untreated fruit stored under CA conditions. Soybean oil application significantly increased the mean volatile and aldehyde emission, as well as hexanal and 2-hexenal levels of fruit directly after CA storage (day 0). No significant treatment effects were observed for mean alcohol concentrations of fruit after storage and/or at-harvest shelf-life period. Soybean oil application did improve regeneration capacities of straight chain esters and significantly increased the emission of the branched chain ester 2-methyl-butyl acetate compared to untreated fruit.