Variations in antioxidant properties of strawberries grown in Brazilian savannah and harvested in different seasons.

BACKGROUND: Strawberries are nutritive fruits and a source of antioxidants. We evaluated antioxidant properties of 'Camino Real' strawberries grown in the Brazilian savannah, harvested in different seasons. Analytical and meteorological data were analyzed by partial least squares regression. RESULTS: Fruits from May showed the lowest contents of total phenolics (1789.78 mg kg⁻¹ fresh weight (FW)), catechin (21.37 mg kg⁻¹ FW), quercetins (4.89 mg kg⁻¹ FW) and total ellagic acid (208.68 mg kg⁻¹ FW) and the lowest antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) (11.39 mg Butylated hydroxytoluene (BHT) eq. g⁻¹ FW) and ferric reducing antioxidant power (FRAP) (22.01 mg ferrous sulfate eq. g⁻¹ FW) assays. Strawberries harvested in July presented the lowest concentrations of total (190.61 mg kg⁻¹ FW) and individual anthocyanins (73.88 mg kg⁻¹ FW and 5.96 mg kg⁻¹ FW for pelargonidin-3-glucoside and cyanidin-3-glucoside, respectively), but the highest contents of vitamin C (685.47 mg kg⁻¹ FW), DPPH (18.87 mg BHT eq. g⁻¹ FW) and FRAP (39.30 mg ferrous sulfate eq. g⁻¹ FW). The highest contents of free ellagic acid (26.11 mg kg⁻¹ FW), pelargonidin-3-glucoside (291.82 mg kg⁻¹ FW) and cyanidin-3-glucoside (11.84 mg kg⁻¹ FW) were found in strawberries from September. Rain in the previous 30 days to harvest influenced negatively many phenolics and antioxidant activity of strawberries harvested in May. In July, longer photoperiod and lower temperature at 30 days previous to harvest probably led to higher antioxidant activity and vitamin C. Increased photoperiod and temperature at the final stage of maturation seem to raise pigments and free ellagic acid in strawberries. CONCLUSION: It was possible to observe significant relationships among meteorological and antioxidant variables for strawberries grown in the Brazilian savannah.