CO_2 Partial Pressure for Respiratory Quotient and HarvestWatch Dynamic Controlled Atmosphere for 'Galaxy' Apples Storage

摘要

Apples stored in low oxygen conditions, especially in dynamic controlled atmosphere (DCA), change from aerobic to anaerobic respiration, which if not excessive, reduces the quality losses during storage and at shelf life. Our group developed a new DCAstorage method based on the respiratory quotient (RQ). However, the CO_2 level in this new DCA method and in the already commercially established method was not yet studied. Therefore, this work evaluated the quality of 'Galaxy' apples after storage inCA, RQ DCA and HarvestWatch~(TM)DCA (HW DCA) at three CO_2 levels (1.2, 1.6 and 2.0 kPa). The O_2 in the CA condition was 1.2 kPa. All fruits were stored at 1.0°C for 9 months and additional 7 days in shelf life at 20°C. The fruit assessment was carried out after the shelf life period. 'Galaxy' apples stored in RQ DCA resulted in lower ethylene biosynthesis rate, which in turn, maintained higher flesh firmness, lower mealiness and higher percentage of 'healthy' fruits. An interaction between CO_2 level and storage condition was observed on the quality parameters. 'Galaxy' apples stored at CA with 2.0 kPa CO_2 maintained higher acidity, lower mealiness than those stored at 1.2 kPa CO_2, probably as a result of the lower ethylene biosynthesis and respiration rate. At DCA storage, monitored with RQ or with HarvestWatch~(TM), these parameters showed an opposite behaviour, in which 1.2 or 1.6 kPa CO_2 partial pressure resulted in better fruit quality. Therefore, this work concluded that RQ DCA maintained better apple fruit quality after long-term storage and 1.2 to 1.6 kPa are the best CO_2 partial pressures to use in RQ-DCA storage. In standard CA storage, 2.0 kPa is the most appropriate CO_2 partial pressure.