Main content area

CO2 partial pressure for respiratory quotient and harvestwatchtm dynamic controlled atmosphere for 'galaxy' apples storage

Brackmann, A., Weber, A., Both, V.
Acta horticulturae 2015 no.1079 pp. 435-440
acidity, anaerobiosis, apples, carbon dioxide, controlled atmosphere storage, ethylene production, firmness, fruit quality, fruits, oxygen, respiratory quotient, respiratory rate, shelf life
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 DCA storage method based on the respiratory quotient (RQ). However, the CO2 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 in CA, RQ DCA and HarvestWatch(TM) DCA (HW DCA) at three CO2 levels (1.2, 1.6 and 2.0 kPa). The O2 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 CO2 level and storage condition was observed on the quality parameters. ‘Galaxy’ apples stored at CA with 2.0 kPa CO2 maintained higher acidity, lower mealiness than those stored at 1.2 kPa CO2, probably as a result of the lower ethylene biosynthesis and respiration rate. At DCA storage, monitored with RQ or with HarvestWatchTM, these parameters showed an opposite behaviour, in which 1.2 or 1.6 kPa CO2 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 CO2 partial pressures to use in RQ-DCA storage. In standard CA storage, 2.0 kPa is the most appropriate CO2 partial pressure.