Modification of internal carbon dioxide and oxygen levels in apple fruit by postharvest calcium application and modified atmospheres

Abstract

Abstract Carbon dioxide levels in the core of ‘Cox's Orange Pippin’ and ‘Braeburn’ apples, stored in air at 1°C in 1984 and 1985, were higher than in surrounding air. The CO 2 gradient between core and air for both cultivars over the two years averaged 1.1% at 1°C and 3.5% after transfer to ambient temperatures. Vacuum infiltration of apples with calcium solutions increased internal CO 2 and decreased O 2 levels, and increased gradients between core and outside air, in fruit stored in either air or in modified atmospheres, compared with untreated fruit. Drenching of fruit with calcium did not influence internal gas levels or gradients. Highest internal CO 2 and lowest O 2 levels were generated in vacuum-infiltrated fruit subsequently stored in microperforated polymeric film bags at both 1°C and after transfer to ambient temperatures, although gradients were less than in air stored fruit. The results suggest that vacuum infiltration of apple fruit with calcium solutions filled the intercellular spaces of the outer cortical tissue forming a barrier to gas diffusion thus reducing exchange of CO 2 and O 2 between the fruit tissue and the surrounding atmosphere.