Emulsion-based encapsulation and delivery systems for polyphenols

Background: Instability and low bioavailability of polyphenols greatly limit their potential health benefits in preventing ageing, cancer, inflammation and neurodegenerative diseases. Utilization of protected encapsulation and delivery system can improve the stability and bioavailability of polyphenols. A wide range of technologies have been developed to encapsulate polyphenols. Among these, emulsion-encapsulation is regarded as one of the most promising techniques for protection and delivery of polyphenols, due to its high-efficiency encapsulation, maintenance of chemical stability and controlled release. Scope and approach: In this review, preparation, applications and limitations of emulsion-based encapsulation and delivery systems for polyphenols, including single, multiple and nano-emulsions, are discussed. Key findings and conclusions. Utilization of encapsulated polyphenols instead of free molecules improves both the stability and bioavailability of the molecules in vitro and in vivo. Many emulsion-based delivery systems for polyphenols have been well established, including single, multiple and nano-emulsions. However, variations in composition and preparation technologies result in the formation of a range of emulsions of new properties with great potential in delivery of polyphenols or other bioactive nutrients, e.g., using unsaturated fatty acids as the oil phase, which can achieve the delivery of multiple nutrients at the same time. Furthermore, very few studies have been done on the in vivo absorption, transportation and release of polyphenols incorporated emulsions, which are essential to their deeper and wider applications. Hence, systematic and intensive investigation of metabolism and physiological effects of encapsulated polyphenols or other potential bioactive nutrients in vivo are required