Antioxidants and other chemical and physical characteristics of two strawberry cultivars at different ripeness stages

Abstract

The present work evaluated the quality and antioxidant characteristics of ‘Osogrande’ and ‘Camino Real’ strawberries at different ripeness stages. Strawberries (Fragaria x ananassa Duch.) were harvested, selected, graded according to ripeness (green, pink or 3/4 ripe and ripe) and evaluated for pH, total soluble solids, total titratable acidity, sugar/acid ratio, vitamin C, total phenolic compounds, total ellagic acid, total and individual anthocyanins and antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The highest total soluble solid content was found for pink (7.5° Brix) and ripe (7.9° Brix) ‘Osogrande’ strawberries. At pink stage, this cultivar showed higher amounts of total phenolics (2909.48 mg kg⁻¹ FW) and total ellagic acid (454.16 mg kg⁻¹ FW). Pink ‘Camino Real’ strawberries presented the highest content of vitamin C (528.55 mg kg⁻¹ FW). Antioxidant activity was higher for ‘Osogrande’ cultivar, at green stage, according to DPPH (11.91 μmol BHT g⁻¹ FW) and FRAP (36.75 μmol ferrous sulphate g⁻¹ FW) assays and at ripe stage, only for DPPH assay (12.83 μmol BHT g⁻¹ FW). Anthocyanins increased along ripening, with more elevated concentrations in ripe ‘Camino Real’ strawberries (292.9 mg kg⁻¹ FW). Cyanindin-3-glucoside showed a higher concentration for the same treatment (17.23 mg kg⁻¹ FW), which might contribute to a more redish color. Although ripe berries have a better flavor and are more appreciated, higher antioxidant contents and activities were observed at pink stage in which higher amounts of total phenolics, total ellagic acid and vitamin C were noticed for both cultivars.