Changes in the inner quality parameters of apple fruit from technological to edible maturity

The changing dynamics of organic acids, sugars, phenolics and antioxidant potential in apples from technological to edible maturity was studied. During the time of storage, the content of citric and malic acids generally decreased. The content of sucrose, fructose and glucose decreased significantly in some varieties, while it increased in others. The content of total sugars changed only slightly over the storage period. In the apple pulp, the content level of single phenolics generally changed to a minor extent during storage. In the peel, the content levels of the rutin and quercetin-3rhamnoside flavonoids remained generally constant during storage, while the level of p-coumaric acid increased slightly; on the other hand, the content levels of epicatechin and catechin decreased. In the pulp of most cultivars, there was no significant decrease in total phenolics at edible maturity. In contrast, the apple peel usually has a higher content level of total phenolics at edible maturity than at the time of technological maturity. Therefore, the antioxidant activity of the peel increased from technological to edible maturity.