Review of Process and Extraction Effects on the Bioavailability of Anthocyanins in Grapes

Grapes are widely consumed worldwide in various forms, including fresh and dried, or processed into products like juice, vinegar, wine, and so on. Anthocyanins, mainly found in grapes, are responsible for various health-promoting effects and contribute to their colours such as red, purple, and blue. Although grapes contain a high quantity of anthocyanins, their bioavailability is considered limited. Anthocyanins may be absorbed by the gastrointestinal wall, undergo intensive first-pass metabolism, and emerge as metabolites in systemic circulation. A significant percentage of some anthocyanins can enter the large intestine and undergo breakdown induced by digestive system microorganisms. Several factors, such as pH, temperature, light, and solvents, can affect anthocyanin bioavailability, and processing grapes into products may impact their bioavailability. Considering the high market share of grapes and grape products, it is important to understand the effects of processing on anthocyanin bioavailability. This review discusses changes in the bioavailability of anthocyanins found in grapes and grape products during food processing, the effect of extraction conditions on bioavailability, as well as the health-promoting effects of grapes and grape products.