Abstract: Carotenoids, a group of natural pigments in many fruits and vegetables, have provitamin A activity and can be used as biological antioxidants, thereby playing an important role in human health. Lipophilic carotenoids released from foods are incorporated into lipid droplets and transferred to the small intestine to form mixed micelles together with bile salts and lipids. The carotenoids in micelles are finally absorbed by intestinal cells and undergo further metabolic process. in vitro digestion models have been used to imitate the digestion of carotenoids in the gastrointestinal tract and its bioavaiability in vitro has been investigated. A great deal of factors may affect the bioavailability of carotenoids, including the species and structures of carotenoids, food matrix, lipids, sample processing and preparation, different in vitro models, and detection methods. These factors may exhibit different impacts on different kinds of catotenoids and synergistic effects may be observed between these factors.

Key words: carotenoids, in vitro digestion, bioavailability