The effect of frying on anthocyanin stability and antioxidant activity of crisps from red- and purple-fleshed potatoes (Solanum tuberosum L.)

• Seven coloured-flesh potato cultivars, raw and fried, were studied for bioactive compounds.
• Frying affected content and composition of anthocyanins in colour-fleshed potato crisps.
• Pelargonidin and malvidin derivates were most stable during frying.
• Crisps obtained from colour-fleshed potatoes exhibited high antioxidant activity.

Red- and purple-fleshed potatoes (Solanum tuberosum L.) are a good source of polyphenols, mainly anthocyanins as one of the most important components. The chemical composition with reducing sugars and the total polyphenol contents were analyzed in four purple potato varieties (Salad Blue, Vitelotte, Valfi, Blue Congo) and three red-fleshed potato varieties (Rosalinde, Herbie 26, Highland Burgundy Red). The anthocyanin composition of raw potato and potato crisps was characterized by high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) method. Moreover, the antioxidant activity was measured with the radical scavenging assays using 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical as well as ferric reducing ability of plasma assay (FRAP). In addition, colour parameters in prepared potato crisps were evaluated. Both red and purple-fleshed potato varieties contained high levels of total polyphenols (227–845 mg 100 g−1 dry weight) and anthocyanins (21–109 mg 100 g−1 dry weight). The process of frying caused degradation of anthocyanin compounds (38–70%). The HPLC–MS/MS analysis showed that pelargonidin and malvidin derivates were more stable during frying than petunidin derivatives. Although frying process affected the anthocyanin and polyphenol levels, obtained potato crisps exhibited bright intensive colour and good antioxidant activity.