The Effect of Pasteurization Time on Phytochemical Composition and Antioxidant Capacity of Two Apple Cultivars Juices

The objective of this study was to characterize two varieties of apple (Florina and Liberty) grown in the North-West of Romania, with a focus on their volatile compounds, bioactive compounds and their antioxidant capacity. The content of bioactive compounds and antioxidant capacity was also tracked during pasteurization at different times (15, 20 and 25 minutes). Among bioactive compounds, the total phenol content was determined, as well as the total flavonoid and vitamin C content. The antioxidant capacity of fruits and pasteurized juice was evaluated by three different methods (DPPH, FRAP and ABTS). Of the 2 apple cultivars, Florina showed a remarkably higher content of total phenolic compounds (657.97 mg GAE/kg fw), flavonoids (122.07 mg QE/kg fw) and vitamin C (94.62 mg/kg), compared to the Liberty cultivar. Following pasteurization, the vitamin C contents decreased significantly relative to pasteurization time. However, in the case of total phenols content, only insignificant decreases were registered, compared to unpasteurized juice. The content of total flavonoids increased significantly after 15 minutes of pasteurization in apple cultivars juices. The apple varieties investigated are rich in bioactive compounds, and pasteurization treatment does not lead to drastic decreases in these compounds and in the antioxidant capacity of apple juices.