Abstract
The pH values, total vitamin C contents, remaining vitamin C after heating at 100℃ for 5 min and the AsA oxidation capacity of 122 kinds (190 articles) of edible plant extracts which are commonly used in the daily life were investigated. For example spinach harvested in summer and winter were analyzed separately. Vegetables of 83 kinds and 112 articles; potatoes 4 kinds and 9 articles; and fruits 35 kinds and 69 articles were among those studied. When the pH values of extract was low, the oxidation volume was small. It was found that when the AsA/total vitamin C value of the extract was 10% or less, oxidation capacity was very high. So that 50% or more of total vitamin C could be retained when the extract was heated for 5 min under 100℃. It was necessary that the pH value is 6 or less and the oxidation volume of AsA is 500 μg/g or less.
