Comparison of Nutrients and Antioxidant Activities in Sweet Potatoes

Abstract

Sweet potato has played an important role in human diets for centuries. Sweet potato is an excellent source of nutrients and natural health-promoting chemicals such as carotenoids, vitamin C, and polyphenols. In this article, we selected forty-eight sweet potato cultivars to evaluate the contents of proximate compositions, phytochemicals, and total antioxidative capacity (TAC). In addition, the sensory taste test was conducted as well. The concentrations of chemical constituents varied significantly among the 48 cultivars. The starch content ranged from 10.58% to 28.08%. The protein concentration was between 2.00% and 12.16%. A noticeable variability was found in vitamin C (8.17–66.09 mg·100 g−1), total polyphenols (0.32–13.82 µg·g−1), and carotenoids (0.22–559.70 µg·g−1). 3,5-dicaffeoylquinic acid was the dominant phenolic acid derivative in all varieties, followed by chlorogenic acid. The content ranges of 3,5-dicaffeoylquinic acid and chlorogenic acid were 0.41–92.18 µg·100 g−1 and 1.59–63.98 µg·100 g−1, respectively. Remarkable DPPH (0.19–0.59 µg·g−1) and ABTS+ (0.19–1.42 µg·g−1) antioxidant activities were also observed in these sweet potatoes. TAC was related to vitamin C, carotenoids, total polyphenols, and caffeic acid derivatives. The purple flesh cultivars, especially Mianzishu-9, Jiheishu-1, and Qianshu-18-5-1, rich in protein, starch, and antioxidants, had immense potential to improve malnutrition and hidden hunger. The dark orange flesh cultivars Hongxiangjiao and Ziyunhongxinshu performed best in sensory taste evaluation, but the nutrients and antioxidant effects were ordinary. These cultivars were suitable for enriching the human food systems.