Effects of modified atmosphere and sugar immersion on physiology and quality of fresh-cut 'Braeburn' apples

Abstract Fresh-cut fruits are highly perishable and show a short shelf life. Therefore, storage in sugar syrup is commercially used to delay undesirable metabolic changes and to prevent browning. Investigations on the effects of syrup application on volatile organic compounds (VOCs), important for the consumers’ acceptance, are rare. It is, however, known that low O2 availability, as found in fruit slices after immersion, may result in the formation of unwanted off-odour. This negatively affects the sensory quality of fresh-cuts. In the present study, fresh-cut 'Braeburn' apples were comparatively stored in air, in three modified atmospheres (O2: 10, 5 and approx. 0 %; CO2: 10, 15 and 20 %) or in sugar syrup (20 % sugar content). Relevant quality, physiological and microbiological parameters were evaluated on days 3, 6 and 10 of storage. Particular focus was laid on the evaluation of VOC emission to indicate biosynthetic responses that affect aroma-relevant VOCs. Atmospheric storage of apple slices, among others, increased the emission of ethyl acetate, which may create off-odour and negatively affects the customers’ acceptance. In contrast, syrup-immersion of apple slices resulted in a pronounced loss of aroma but prevented the occurrence of off-odour. The results indicated metabolic changes, which were independent of O2 availability. High CO2 or VOCs concentrations in the fruit tissue may inhibit esterification or may induce a feedback inhibition of VOC synthesis.