Phosphorylation of starch and dextrin by dry-heating in the presence of phosphate, and their calcium phosphate-solubilizing ability.

Starch and dextrin were phosphorylated by dry-heating in the presence of phosphate, and their properties were examined. The phosphorylation of starch was accelerated with decreasing moisture, rising incubation temperature and prolongation of the incubation period. However, a rise in incubation temperature, and lengthened incubation period caused increased browning and degradation. A decrease in the pH from 5.5 to 3.0 resulted in a modest increase of phosphorylation, but also marked browning and degradation. When potato starch was phosphorylated at 140 degrees C and pH 5.5 for 24 h, its phosphorus content was increased up to 3.47%, with fewer side reactions. Phosphorlylated starch and dextrin had calcium phosphate-solubilizing abitity. Phosphorylated dextrin with 2.42% phosphorus had about half the calcium phosphate-solubilizing ability of casein phosphopeptide (CPP). The possibility of substituting of phosphorylated starch and dextrin for CPP as a calcium phosphate-absorption enhancing material is discussed herein.