Physicochemical characterization, antioxidant activity and total phenolic and flavonoid content of purple prickly pear (Opuntia gosseliniana) at two stages of coloration

Nopal (Opuntia gosseliniana) is considered a food product of interest due to its functional properties, including its antioxidant activity. The objective of this work was to evaluate the physical- chemical properties (color, pH and total soluble solids), antioxidant activity (DPPH, ABTS and FRAP), content of total phenols and flavonoids, and betalain content. As well as the evaluation of the toxicity of ethanolic extracts of nopal at two stages of coloration: green and purple. Color was characteristic for each coloration stage. No significant differences were observed in pH and SST values at each coloration stage. The % moisture was higher in green nopal (81 %) compared to purple nopal (76.65 %). Regarding the degree of toxicity, purple nopal extracts showed less toxicity than green nopal extracts. The highest values for total phenols and flavonoids were found in purple samples, with values of 2.31 mg EAG/gps and 3.06 mg EQ/gps, respectively. Similarly, in the antioxidant activity (in the three techniques used) and betalain content, higher values were obtained at the purple color stage. Therefore, this species of cacti could be a potential source of antioxidants and pigments of agro-industrial interest.