Key volatile compounds of ‘Fuji Kiku’ apples as affected by the storage conditions and shelf life: Correlation between volatile emission by intact fruit and juice extracted from the fruit

Abstract

For the 'Fuji Kiku' apple, this study aimed: (i) to evaluate the volatile compounds (VCs) from headspace storage chambers with static controlled atmosphere (CA) and with dynamic controlled atmosphere based on chlorophyll fluorescence (DCA-CF) and based on respiratory quotient (DCA-RQ1.5) at ninth month of storage, during 1 and 7 days of shelf life of intact fruit, and in apple juice headspace and (ii) to determine the correlation of the VCs in the headspace from storage chambers and fruit during shelf life with the headspace VCs from apple juice as markers of quality. The VCs were isolated by solid phase microextraction (HS-SPME) and analyzed by gas chromatography. In the storage chambers, ethyl linear chain esters were detected mainly in DCA-RQ1.5, while acetaldehyde and (E)-2-hexenal were more abundant in DCA-CF. At seven days of shelf life, fermentative metabolic compounds had reduced emissions given the opening time of the chamber, while there were higher emissions of branched chain esters, especially ethyl 2-methyl butanoate in DCA-RQ1.5. The correlation was high and positive between the VCs present in the juice and those emitted by the intact fruit during seven days of shelf life, demonstrating that the concentration of VCs in juice can be used to estimate the emissions from whole fruit. DCA-RQ1.5 storage promoted the synthesis of VCs typical of the 'Fuji' apple aroma after a prolonged storage period, even under extremely low partial pressure of oxygen (average 0.15 kPa), contributing to better quality control of characteristic fruit odor and aroma.