Effect of Freezing and Frozen Storage on Phenolic Compounds of Raspberry and Blackberry Cultivars

Abstract

The phenolic compounds in raspberry and blackberry cultivars grown in Turkey were determined by liquid chromatography–mass spectrometry (MS)/MS in fresh, just-frozen, and stored fruits at −22 °C for 6 months period. The major phenolic compounds in water extracted samples were ellagic acid (1,350.36–727.9 mg/kg fresh fruit), ferulic acid (820.78–338.27 mg/kg fresh fruit), caffeic acid (754.85–202.78 mg/kg fresh fruit), p-coumaric acid (361.68–142.63 mg/kg fresh fruit), p-hydroxybenzoic acid (534.20–233.29 mg/kg fresh fruit), and quercetin (46.97–27.31 mg/kg fresh fruit) in raspberry and ellagic acid (1,828.07–1,555.13 mg/kg fresh fruit), ferulic acid (757.69–413.82 mg/kg fresh fruit), caffeic acid (736.85–337.89 mg/kg fresh fruit), p-coumaric acid (877.45–287.15 mg/kg fresh fruit), and quercetin (74.69–56.78 mg/kg fresh fruit) in blackberry. The varietal differences in the phenolic compound contents were larger among the blackberry cultivars (from 1,828.07 to 56.78 mg/kg fresh fruit) than among the raspberry cultivars (1,350.36 to 27.31 mg/kg fresh fruit). A significant decrease was observed in the content of p-hydroxybenzoic acid (from 534.20 to 114.30 mg/kg; Aksu Kirmizisi) and the least decrease was in the content of caffeic acid (from 545.42 to 530.91 mg/kg; Heritage) in raspberry cultivars. On the other hand, ferulic acid (from 475.16 to 113.33 mg/kg) decreased significantly in blackberry (Bursa 2) after storage for 6 months.