The Phytochemical Profile and Antioxidant Activity of Thermally Processed Colorful Sweet Potatoes

Abstract

The effects of home cooking methods (e.g., boiling, steaming, oven, and microwave) on the contents phenolic compounds, biogenic amines, and precursor amino acids in colored-fleshed sweet potatoes were investigated in this study. Sixteen genotypes of colored sweet potatoes (cream/white, yellow, orange, and purple pulp) were analyzed using spectrophotometry for their total phenolic compounds, total flavonoids, antioxidant capacity (DPPH and MDA) and pigments. Of these, five genotypes with orange and purple pulps were investigated using HPLC-DAD for their polyphenols, biogenic amines and precursor amino acids. The results revealed that orange-fleshed sweet potatoes contain higher amounts of phenolic compounds, carotenoids, amino acids, and beneficial amines, especially when cooked in a microwave or in an oven, wrapped in aluminum foil. For the purple sweet potatoes, superior quantities of bioactive were found after cooking with steam, microwave, and in the oven with aluminum foil protection. In general, the colored genotypes showed a superior phytochemical profile than the traditionally commercialized ones before and after heat treatments, characterizing them as richer sources of the bioactive compounds of interest for producers, consumers, and industry.