Effect of hypobaric treatment on off-flavour development and energy metabolism in ‘Bruno’ kiwifruit

Kiwifruit (Actinidia deliciosa cv. Bruno) can more easily acquire ‘alcoholic flavour’ due to the accumulation of ethanol under normal ripening conditions compared to the other cultivars of kiwifruit. In this study, the effects of hypobaric treatment (25 ± 5 kPa for 30 min) one time (T1) and two times (T2) on fruit quality, ethanol metabolism and energy metabolism in ‘Bruno’ kiwifruit were investigated during room temperature storage. The results showed that T2 treatment effectively reduced fruit decay and weight loss during the whole storage period, and both T1 and T2 treatments maintained higher values of total phenolic, quinic acid and citric acid than CK during the late stage of storage. Moreover, the hypobaric treatments reduced alcoholic flavour development, while T2 treatment was more effective than T1 treatment. The mechanism for this effect might involve two aspects. On the one hand, T2 treatment enhanced aerobic metabolism by increasing the energy level and the activities of succinic dehydrogenase (SDH), cytochrome c oxidase (CCO) and H+-adenosine triphosphatase (H+-ATPase) during the late stage of storage. On the other hand, T2 treatment inhibited anaerobic metabolism by decreasing the concentrations of acetaldehyde and ethanol and the activities of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH). In conclusion, we speculated that the effect of hypobaric treatment on ‘Bruno’ kiwifruit might be involved in the regulation of aerobic and anaerobic metabolisms during storage at room temperature.