Impact of Innovative Controlled Atmosphere Storage Technologies and Postharvest Treatments on Volatile Compound Production in Cv. Pinova Apples

Organically grown apples cv. Pinova harvested at two different dates were stored at 1.3 degrees C for up to 4 months in air, up to 7 months in ULO (1.5 kPa of O-2 and 1.3 kPa of CO2) and in dynamic controlled atmosphere (DCA) conditions (0.4-0.6 kPa of O-2 and 0.6-0.8 kPa of CO2); the DCA storage method involved the use of a chlorophyll fluorescence monitoring system in order to detect low-O-2 stress in apples and to allow for the dynamic adaptation of storage atmosphere to O-2 levels that were lower than in ULO but still tolerated by fruits. A postharvest 1-MCP treatment (for 24 h at 1.3 degrees C) and a hot water treatment (for 180 s at 50 degrees C) were also tested on apples stored afterward in ULO and air, respectively. Volatile compounds isolated from the pulp of fruits were measured after 4 and 7 months, just upon removal from storage and after 11 days at 22 degrees C. Total amount of aroma compounds-detected in apples stored in DCA was markedly higher (from 2- to 4-fold) than in fruits exposed to 1-MCP + ULO but, at most sampling times, significantly lower than in ULO fruits. Moderate differences in storage atmosphere composition between ULO and DCA significantly affected both total amount and profile of volatile esters. Analogous effects were observed on the alcohol precursors of the main esters. Exposure to 1-MCP inhibited biosynthesis of straight-chain esters more than that of branched-chain esters. The hot water treatment did not seem to produce marked changes in volatile composition after four months of air storage, except for a sharp accumulation of aldehydes during the shelf-life time. DCA storage technology, besides avoiding any chemical treatment, can preserve apple aroma compounds better than 1-MCP + ULO during long-term storage.