Total phenolic, total anthocyanin and phenolic acid concentrations and antioxidant activity of purple-fleshed potatoes as affected by boiling

The effect of boiling on concentrations of total phenolics (TP), total anthocyanins (TA) and phenolic acids (PA) and on antioxidant activity (AA) of purple-fleshed potatoes belonging to (Solanum andigenum) was determined in four native Andean accessions. Extraction methods for each parameter were optimized for raw and boiled freeze dried samples. The concentration of methanol strongly influenced the extraction of TP and antioxidants to be evaluated for AA, with 80% and 60% methanol, being more efficient for raw and for boiled potato samples, respectively. The predominant PA in raw and boiled potato tubers was chlorogenic acid (CA). Caffeic acid was also present in raw tubers but drastically decrease in boiled tubers. For all accessions, the concentrations of TP and AA determined in boiled tubers were higher than in raw tubers. However, with the exception of Guincho, the TA and CA concentrations determined in raw and boiled tubers of the accessions were not significantly different. The deep purple-fleshed accession Guincho showed the highest TA concentration (418 mg/100 g, FW) and AA (17,305 μg Trolox equivalent/g, FW). Boiled purple-fleshed potatoes are a good source of TA and show high AA, and can probably contributes significantly to the intake of health-promoting phenolic compounds.