In vitro fermentation of anthocyanins encapsulated with cyclodextrins: Release, metabolism and influence on gut microbiota growth

• Influence of human gut microbiota on the degradation of CDs coverage was evaluated.
• A cinematic study showed a maximum release of anthocyanins at 30 min.
• After 3 h of in vitro fermentation only 50% of the anthocyanin was metabolized.
• Phenolic acids were identified as anthocyanin fermentation products.
• Bacterial interaction with liberated anthocyanins and their metabolites was observed.

Anthocyanins are thought to exert protective influences on chronic gut disorders such as colon cancer and inflammatory bowel disease. They may also positively modulate intestinal bacterial populations. However, their bioavailability in the gastrointestinal tract is an important determinant factor for their in vivo activity. In this study, we attempted to increase their stability by encapsulation with cyclodextrins. From anaerobic batch-culture fermentation experiments with gut bacteria, release of anthocyanins and the formation of phenolic microbial metabolites were quantified. Despite a rapid release of anthocyanins observed within the first 30 min, encapsulation allowed anthocyanin degradation to be slowed down. As a consequence of anthocyanin degradation phenolic acids were formed. Quantitative analysis of bacterial populations revealed that there was a significant growth of members of the domain Bacteria in vessels with malvidin-3-glucoside, compared to the negative control, and there was inhibition of the Clostridium histolyticum group in those vessels where delphinidin-3-glucoside or cyanidin-3-glucoside was added. These results illustrate the ability of encapsulation to increase bioavailability of anthocyanins, allowing them to be released in the colon and to exert their potential health benefits.