Carotenoid profile and retention in yellow-, purple- and red-fleshed potatoes after thermal processing

•Total of nine carotenoids were identified and quantified in potatoes.•Only (Z)-isomers of violaxanthin and neoxanthin were found.•Coloured cultivars contained only a fifth of the carotenoid levels present in yellow cultivars.•Boiling was more destructive towards carotenoids compared to baking.•Lutein, followed by β-carotene, were the most stable carotenoids. This research aimed to investigate the effect of thermal processing on carotenoid profile, quantity and stability in 22 colour-fleshed potato cultivars grown in the Czech Republic. The total of nine carotenoids was analysed by HPLC using a C30 column and PDA detection. The total carotenoid content for all cultivars ranged from 1.44 to 40.13μg/g DM. Yellow cultivars showed a much higher average total carotenoid content (26.22μg/g DM) when compared to red/purple-fleshed potatoes (5.69μg/g DM). Yellow cultivars were dominated by antheraxanthin, whereas neoxanthin was the main carotenoid in red/purple cultivars. Thermal processing significantly impacted all potato cultivars. Boiling decreased the total carotenoids by 92% compared to baking (88%). Lutein was the most stable carotenoid against thermal processing (decreased by 24–43%) followed by β-carotene (decreased by 78–83%); other carotenoids were degraded nearly completely. Increased formation of (Z)-isomers by thermal processing has not been confirmed.