Further studies on the controlled atmosphere storage of avocados

Abstract

The effects of controlled atmospheres (CA) of six different compositions, on the keeping quality of stored ‘Hass’ avocado fruit were studied. Atmospheres containing 1, 3 and 8% carbon dioxide in combination with 21% oxygen and atmospheres containing 0.5, 3 and 8% carbon dioxide in combination with 3% oxygen were tested. Storage temperature was 5°C and shelf-life (ripening) temperature was 20°C for all treatments. Results show that elevated carbon dioxide and reduced oxygen concentrations in the atmosphere retarded ripening (softening and peel colour changes), and reduced the development of chilling injuries during storage at 5°C. The 8% carbon dioxide concentration was more effective than 3%, in combination with either oxygen concentration. An atmosphere containing 3% oxygen and 8% carbon dioxide was the best with respect to the parameters mentioned above, and made 9 weeks of avocado storage possible. These results indicate that the two gases have a synergistic effect on inhibiting ripening processes. Following CA storage, fruits softened normally and the peel went through the usual, typical colour changes. However, these two ripening processes were not always in step, suggesting that CA may have a differential effect on ripening of avocado peel and pulp.