Honey-mediated aggregation of soymilk proteins

Gluconic acid, the major organic acid in honey, is a partial hydrolysate of glucono-d-lactone, typically used as a coagulant in preparing tofu. The present study aimed to examine the coagulation potential of five different types of honey at different concentrations, upon addition to soymilk. In some samples, aggregates formed in the upper layer at a higher honey concentration, while in others, aggregates precipitated at an intermediate honey concentration. Both phenomena were reproduced by adding different mixtures of glucono-d-lactone and glucose, indicating that gluconic acid concentration and total sugar content of honey can trigger soymilk coagulation. Interestingly, honeys with a high concentration of gluconic acid showed a low total sugar content. Furthermore, in a trial product, the mixture of blended honey with soymilk was determined to be pasty. Our results indicate that honey can coagulate soymilk, which may provide a new and convenient method to prepare soymilk-based industrial products.