When vitamin C was added in the carbonated drink, it is decomposed by the coexistence of chlorine. It was found, however, that such a decomposition of vitamin C was inhibited by the addition of a small amount of polyphosphoric acid, for instance, in the case of "Ramune" containing 0.3 ppm of Cl_2,the addition of 0.16% of polyphosphoric acid was enough to prevent the decomposition of vitamin C in the drink at 20℃.
