Modification of erosive potential of citric acid containing drinks by soy milk.

Abstract

Previous studies revealed that citric acid containing drinks were erosive and a study showed that addition of cow’s milk to erosive beverages was capable to lesson enamel dissolution because high calcium content in milk probably enhanced remineralization of enamel. Since soy milk, containing high amount of calcium, nutritious like cow’s milk but more available and less expensive in Thailand, the objective of this study  to demonstrate the effect of soy milk on the reduction of erosive potential of citric acid containing drinks available in Bangkok. The experiment was performed by collecting 5 citric acid containing drinks, 3 samples per each drink. Soy milk, prepared from 100 % dried soy milk powder (20 g in 100 ml water), was added to obtain 3, 5, 10, 20, 30, 40, and 50% soy milk containing drinks. Before and after soy milk addition, pH was measured by pH electrode, buffer capacity was determined by titration with 0.1 M NaOH and erosive potential was calculated from the amount of phosphate dissolved after shaking 50 mg synthetic apatite in 5 ml citric acid containing drinks for 10 min. The differences between all variables were analyzed by Wilcoxon Signed Ranks test (p<0.05). The results showed that after addition of 20, 30, 40, and 50% of soy milk, the pH of all drinks significantly increased (p<0.05).The buffer capacity and the phosphate dissolution of all drinks significant decreased only at 20,30,40, and 50% of soy milk , (p<0.05). From these data, it was summarized that addition of 20% to 50 % soy milk could lessen the erosive potential of citric acid containing drinks.