Quality and antioxidant activity of a grain drink with lactic acid bacteria-fermented purple sweet potato powder

This study aimed to evaluate the functional properties of grain drinks by adding purple sweet potato fermented powder at varying levels. Specifically, the sweet potato was fermented using Leuconostoc inhae and Weissella koreensis, and grain drinks containing 0% (control), 10% (G1), 20% (G2), 30% (G3), and 40% (G4) of the resulting fermented powders were prepared. As the amount of fermented powder increased, the moisture, fat, and protein contents of the products decreased, while carbohydrate content increased. Antioxidant activity, assessed by DPPH radical scavenging activity and total flavonoid content, improved with higher levels of fermented powder, with L. inhae treatments showing higher values than those of W. koreensis. Total polyphenol content showed a similar trend, but W. koreensis-treated samples had higher values than those with L. inhae. Tannin content followed a pattern similar to that of polyphenol content. These findings suggest that sweet potato fermented powder enhances the antioxidant properties of grain drink, with functional differences depending on the type of microbial strain used.