Monitoring of extremely low oxygen control atmosphere storage of 'Greenstar' apples using chlorophyll fluorescence
A chlorophyll fluorescence-based technology to monitor low-oxygen stress during controlled atmosphere (CA) storage was tested on apples (Malus domestica Borkh. cv. Greenstar). A static CA regime of 2% oxygen was established in a CA unit for the control fruit. In two other CA units apple fruit were exposed to extremely low oxygen conditions while monitoring the fluorescence signal. The latter spiked when the oxygen level was reduced below 0.2%. The oxygen level was subsequently set to 0.4% in one CA unit and 0.7% in the other. In all CA units the temperature and CO2 levels were maintained at 1.2±0.2°C and 3%, respectively. Instrumental measurements were used to analyze quality attributes of apples at harvest and after 1, 4.5, 7 and 10 months of storage plus 0 day and 7 days of shelf life. Sensory quality was evaluated after 4.5 and 10 months of storage. After 10 months of storage, apples stored in extremely low oxygen controlled atmosphere storage had a better color reten...