[Study on Extraction Conditions of Water-Soluble Substances—Purity Test (4) for Polyvinylpolypyrrolidone Listed in Japan's Specifications and Standards for Food Additives].

The food additive polyvinylpolypyrrolidone is approved for use as a filter aid. The water-soluble substances test of polyvinylpolypyrrolidone often shows poor reproducibility. The instruction "boil gently while stirring using a stirrer" was considered critical, and so this issue was examined.