Sweet potato is the sixth most important crop widely cultivated around the world with abundant varieties. Different varieties gain different phenolic profiles which has drawn researchers’ attention for its unique health benefits. Our study evaluated the phenolic profiles, total and cellular antioxidant activities, antiproliferative activities, and cytotoxicity in 10 cultivated varieties of sweet potato in different colours. Among fourteen metabolites detected in our study, hyperoside, ferulic acid and caffeic acid were considered as prominent in SPSRs. According to the principle component analysis, phytochemical composition of HX22, YS15 and YS7 was quite similar. The results also evidenced that purple-fleshed varieties, such as YS43, YZ7 and YY153, have higher total phenolics content and corresponding stronger total antioxidant capacities as well as cellular antiproliferative activities against human liver cancer HepG2 cells than other varieties. The extremely significant correlation between phenolics and total antioxidant activity was also revealed by Pearson correlation analysis (p < 0.05). However, no significant relevance was found between intracellular antioxidant activity and total phenolic content or flesh colour of sweet potatoes.

Carotenoids and folate are two mandatory supplying micronutrients for children or pregnant women. Inadequate intake of these two nutrients was relevant to a higher mortality of both children and pregnancies. This study is intended to investigate the thermal impact on the changes of carotenoids and folate in sweet potato roots (SPRs). Carotenoids were identified by high performance liquid chromatography (HPLC) while the folate was estimated using a microbial assay. An obvious decline was observed in total carotenoids after heating. Nevertheless, the content of provitamin compound β-carotene exhibited incredible stability during steaming and α-carotene multiplied in certain varieties, evidencing that SPRs could be an efficient way for addressing Vitamin A deficiency (VAD). As for the total folate contents, two varieties were found no significant loss after thermal process while the others showed a significant decrease. The results indicated that steaming process led to generally loss of both carotenoids and folate while the α-carotene and β-carotene were well preserved. The information provided by this study might help with enhancing the food quality in processing industry and the understanding in the nutrition changes during steaming.