Stability assessment of anthocyanins from black soybean, grape, and purple sweet potato under in vitro gastrointestinal digestion

Anthocyanins are glycosylated derivatives of anthocyanidins, whose hydroxyl groups are occasionally acylated with organic acids. The effect of anthocyanin composition on their stability under in vitro gastrointestinal digestion was investigated. Black soybean had all glycosylated anthocyanins with monosaccharide, grape contained glycosylated anthocyanins with disaccharide (23%) and acylated anthocyanins bound with two sugars (77%), and purple sweet potato had all acylated anthocyanins bound with three sugars. The order of total anthocyanins content was purple sweet potato, grape, and black soybean. Gastric digestion did not significantly decrease anthocyanins content in three samples, while intestinal digestion resulted in the significant decrease of total anthocyanins content in black soybean (40%), grape (45%), and purple sweet potato (25%). This indicates that the degree of glycosylation and acylation of anthocyanins affects their stability under the gastrointestinal conditions. Phenolic acids derived from anthocyanin degradation increased total phenolic content as well as ABTS radical scavenging activity.