Sources of variation in firmness and ester content of 'Cox' apples stored in 2% oxygen

The contribution of various factors to variation in the quality of 'Cox' apples after storage in 2% oxygen at 3.3°C was investigated. Within one season variation in the firmness of fruits from different orchards could be largely accounted for by correlations with firmness at harvest and the position of the fruit on the climacteric at the time of harvest. However, different relationships were found between these variables in different seasons. The butyl and hexyl acetate contents of fruit were influenced by season and source of fruit, but little affected by maturity at harvest. Ester content was inversely correlated with fruit firmness after storage. Other factors which were expected to influence the ripening of fruit during storage were found to be unrelated to firmness and ester content. These included the respiration rate of fruit during storage, the resistance of the fruit to gaseous diffusion and its specific gravity. Carbon dioxide production was nearly constant at about 2.3 ml kg^-1h^-1 across seasons, sources and harvest dates. Specific gravity seemed to be particularly affected by season, whereas diffusive resistance decreased with maturity.