Quercetin in Foods: Sources, Bioavailability, and nanoencapsulation Strategies

Bioactive compounds are naturally occurring food constituents with recognized antioxidant properties and potential health benefits. Among these compounds, quercetin, a flavonoid widely distributed in fruits and vegetables, stands out. However, its practical use is limited by low bioavailability, influenced by its chemical structure, physicochemical properties, and food matrix interactions. The objective of this study was to evaluate extraction technologies, bioavailability limitations, and nanoencapsulation strategies associated with quercetin. To identify gaps, an analysis of peer-reviewed articles published between 2015 and 2025 was conducted across major scientific databases (such as Web of Science, Scopus, and PubMed). A total of 962 records were identified, of which 186 underwent full-text assessment and 29 met the inclusion criteria for the final review. The results showed that extraction efficiency depends on the plant matrix, solvent, and extraction technology. Compared with non-encapsulated quercetin, nanoencapsulation generally improved stability, solubility, controlled release, and bioaccessibility. However, only a few studies have incorporated nanoencapsulated quercetin into food systems, and among those, only a limited number have evaluated sensory acceptance and industrial applicability. Therefore, despite promising technological advances, additional studies addressing food applications, large-scale production, safety, and in vivo validation are essential for the successful implementation of quercetin-based delivery systems in the food industry.