Abstract
The vitamin C (VC) content and 1,1-dipheny1-2-picrylhydrazyl (DPPH) radical-scavenging activity of sweet potato were lower immediately after cooking, but the residual value after vacuum cooking and storage were higher than those after boiling, while the polyphenol content remained unchanged. The loss in VC content and DPPH radical-scavenging activity of sweet potato was significantly suppressed by the addition of sugar with both cooking methods, but was promoted by soy sauce with the vacuum cooking of Japanese radish and taro. While the DPPH radical-scavenging activity of sweet potato was mainly correlated with the amount of ascorbic acid, that of Japanese radish and taro was mainly correlated with the polyphenol content. Vacuum-cooked potatoes were preferred overall to the boiled variety, while the texture of boiled Japanese radish was preferred to that of the vacuumcooked type.
