Effect of boiling on the total phenolic, anthocyanin and carotenoid concentrations of potato tubers from selected cultivars and introgressed breeding lines from native potato species

• Color-fleshed potatoes showed a high variability in phytochemical composition.
• Introgressed potato breeding lines show high phenolic and carotenoid levels.
• Phytochemical losses after boiling were higher than those previously reported.
• Phytochemical losses highly correlated with phytochemical content in raw tubers.
• Total phenolic content correlated with dry matter in potato tubers.

Potato tubers are considered an important source of bioactive compounds, although the concentrations of different phytochemicals are affected by cooking and other processes. The present study was focused on evaluating the effect of boiling on total phenolic, anthocyanin and carotenoid concentrations of ten promising introgressed breeding lines from native potato species (Solanum tuberosum subsp. andigena Hawkes and Solanum stenotomum Juz. & Bukasov) and three heirloom Spanish S. tuberosum L. cultivars (Jesús, Morada and Zamora). In addition, three commercial cultivars (Vitelotte, Kasta and Monalisa) with different flesh color were used as testers. Breeding lines NK-08/349 and NK-08/362 showed high total phenolic (TP) and total anthocyanin concentrations (TA), whereas breeding lines NK-08/286, NK-08/356 and NK-08/370 and the cultivar Morada were characterized by a high carotenoid concentration (TC). In general, purple cultivars and breeding lines (Vitelotte, Morada, Jesus, Kasta, NK-08/349 and NK-08/362) stood out with showed high phenolic and anthocyanin concentrations. The comparative analysis of raw and boiled tubers showed high losses of phenolics, anthocyanins and carotenoids. TP, TA and TC concentrations in boiled tubers were directly correlated with their corresponding concentration in the raw product. In addition, significant correlations (p ≤ 0.05) between TA and TP concentrations, in both raw and boiled tubers, have been observed. The utilization of peeled and diced tubers, with the subsequent surface increase, seems to be a determinant factor explaining why phytochemical losses were so high.