Chemical composition of apple fruit, juice and pomace and the correlation between phenolic content, enzymatic activity and browning

- Apple fruit, pomace and juice characterized by different phenolic groups.
- Enzymatic browning is strongly correlated to total phenolic content.
- Enzymatic browning is moderately correlated to enzymatic activity.
- High potential of local 'Majda' cultivar for fresh cut apple fruit.

Primary and secondary metabolites were evaluated in apple fruit, juice and pomace of scab resistant and leading European apple cultivars. The primary goal was to study the chemical composition of apple fruit fractions in correlation with their enzymatic browning. Additional goal was to assess the suitability of apple pomace for the extraction of phenolic compounds. Furthermore, the cultivars were grouped according to their suitability for fresh-cut fruit slices by measuring their enzymatic activity, total phenolic content (TPC) and the rate of browning. Highest TPC was determined in 'Granny Smith' pomace suggesting its optimal suitability for phenolic extraction among the analyzed apple cultivars. 'Majda' fruit (investigated for the first time) can be offered to the market as fresh-cut slices as almost no changes in pulp color have been detected due to oxidation. The correlation test showed that oxidation of apple pulp is highly dependent on TPC and weakly correlated to the activity of polyphenol oxidase. Contrary, no significant correlation has been determined between the rate of oxidation and the activity of peroxidase.