Cooking sweetpotato roots increases the in vitro bioaccessibility of phytochemicals and antioxidant activities, but not vitamin C

•In vitro bioaccessibility of phytonutrients in cooked sweetpotato roots was evaluated.•Bioaccessibility of phenolics, flavonoids, carotenoids, and anthocyanins increased with cooking.•Vitamin C bioaccessibility decreased after cooking.•Peeling sweetpotato roots increased phenolics and flavonoids bioaccessibility.