Antioxidative Activities of Browning Products from Tannic Acid

Abstract

The following three kinds of browning tannic acid solution were prepared : Tannic acid dissolved in water (unadjusted=pH 3.8), adjusted to pH 7.0 or 9.0 and turned into brown Tannic acid dissolved into water (unadjusted=pH 3.8), turned into brown by heating at 100°C for 30 or 60 min. Tannic acid dissolved in water (pH 3.8 and pH 7.0), added with amino acids (7 kinds), sugar substances (5 kinds) or organic acids (4 kinds) and then turned into brown by heating at 100°C for 30 minutes.
The chemical properties (reducing power, degrees of browning and pH) and antioxide-tivities of these above solutions were determined.
The results obtained are as follows :
1) The compartment of tannic acid alone showed low pH value as a result of heating.
2) The solution of the compartment of tannic acid alone was alkaline and showed strong coloring and fairly strong reducing power.
3) Strong antioxidativity was showed in the compartment with low pH and 30 minute-heating.
4) In terms of the antioxidativity of amino acid, sugar substance and organic acid compartments, the latter compartment showed a remarkable action.