Micro and nano encapsulation, retention and controlled release of flavor and aroma compounds: A critical review

Encapsulation of flavor and aroma in an appropriate form is an important concern for a long time. Encapsulation is the most successful way not only to preserve or mask flavor and aroma compounds but also to enhance their thermal and oxidative stability, overcome the limitations of high volatility, to control the fast release and improve the poor bioavailability, as well as to increase their application in food systems. This review focuses on the recent advances in micro and nano-encapsulation of flavor and aroma compounds. We comprehensively highlight the suitability of micro and nano-encapsulation approaches for the retention of flavor and aroma including emerging techniques, new formulations and novel encapsulate systems, to illustrate the flavor release mechanisms, and depict the industrial applications of encapsulated flavor and aroma compounds. Nano-encapsulation has attracted more attention compared to microencapsulation; showing better encapsulation efficiency, enhanced stability of capsule, and more control on flavor release. Recently, spray chilling and spray freeze drying as an alternative to spray drying, can overcome the thermal loss of flavor, promising for the microencapsulation of heat sensitive compounds. In contrast, electro-spraying and electro-spinning in combination with the emulsion or coaxial approach are novel and promising for the nano-encapsulation of flavor and aroma compounds. The combination of carrier materials, e.g. polysaccharide with protein can improve the encapsulation efficiency and capsule functionality. However, application of micro and nano-encapsulates into different food and gastrointestinal systems needs to be explored in order to expose their release mechanisms and application efficiency.