Insights into polyphenols' encapsulation in cyclodextrins: An updated systematic literature review

Polyphenols are phytochemicals derived from fruits, leaves, flowers, roots, and other parts of various plants and other natural resources. These secondary metabolites, with some currently could be chemically synthesized, are associated with a plethora of bioactivities, including anti-inflammatory, antimicrobial, antioxidant, hypolipidemic, and anti-diabetic activities. Recently, polyphenols have attracted a huge amount of attention in the food industry, as they are natural preservatives with some used as colorants and flavoring agents. However, the poor solubility and rapid degradation when exposed to environmental conditions, astringency and bitter taste, as well as the limited bioavailability of polyphenols hindered their applications in food products and pharmaceuticals. This work main objective is to provide an up-to-date overview of polyphenols' encapsulation in cyclodextrins (CDs) as reliable tools to overcome the aforementioned challenges. An overview of CD types, inclusion properties and the main techniques used to prepare and characterize inclusion complexes (ICs) will be provided. Interestingly, we systematically reviewed the current knowledge about CDs' encapsulation of phenolic acids, flavonoids, stilbenes, tannins, and other phenolic molecules. The use of CDs as encapsulation agents for chemically characterized phenolic-rich extracts will also be discussed. This review also covers bioavailability, various applications, limitations, and future perspectives on CD/polyphenol ICs.