Comparative analysis of enzymatic activity, phenolic and ascorbic acid stability and browning dynamic in white and red-fleshed apple (Malus domestica Borkh.) cultivars post-air exposure

This study investigates enzymatic browning in several white- and red-fleshed apple cultivars by analyzing polyphenol oxidase (PPO) and peroxidase (POX) activities, total phenolic content (TPC), anthocyanins, ascorbic acid, and color changes during air exposure. Six white-fleshed cultivars (‘Topaz’, ‘Opal’, ‘Red Boskoop’, ‘Golden Delicious’, ‘Crown Prince Rudolph’, ‘Idared’) and the red-fleshed cultivar ‘Baya Marisa’ were evaluated. Results revealed cultivar-specific enzymatic activity influencing browning susceptibility. ‘Idared’ exhibited the highest PPO activity and the strongest browning potential, while ‘Baya Marisa’ showed low PPO but unexpectedly high POX activity. All white-fleshed cultivars were prone to browning, as indicated by a significant increase in browning index (BI) from 0 to 480 minutes. In contrast, ‘Baya Marisa’ showed minimal color change and no significant BI variation, suggesting limited browning. However, due to high a⁎ values, BI may not be suitable for assessing browning in red-fleshed cultivars. ‘Golden Delicious’ had the highest initial ascorbic acid concentration and the slowest degradation rate. ‘Baya Marisa’ consistently exhibited the highest TPC, attributed to elevated anthocyanin levels. These findings emphasize the importance of cultivar selection in managing browning and highlight limitations of BI as a universal indicator, particularly for red-fleshed apples. • ‘Idared’ had the highest polyphenol oxidase (PPO) activity among cultivars • ‘Baya Marisa’ had a high peroxidase (POX) activity despite lower (PPO) activity • Anthocyanins play a crucial role in reducing browning in ‘Baya Marisa’ • Total phenolic content (TPC) decreases after slicing and post-air exposure