Micro and nanoencapsulation of bioactive compounds for agri-food applications: A review

Bioactive compounds (BCs) extracted from plants have been under study since ancient times due to their outstanding features such as antioxidant, anticancer, anti-inflammatory, and antimicrobial properties. This has led to the development of various extraction techniques, which are classified as conventional (e.g., Soxhlet extraction, maceration, and hydrodistillation) and non-conventional (e.g., ultrasound-assisted extraction, ohmic extraction, supercritical fluid extraction), both seeking high yields and recovery effectiveness. However, these compounds have an important disadvantage, as they are very susceptible to degradation when exposed to heat, light, and humidity, among other factors. Micro and nanoencapsulation can protect the BCs from these factors allowing their controlled release, favoring their application in this manner. To build these systems several techniques and materials are used, and they must be properly selected as they directly influence their functionality and structural characteristics. Recently, micro and nanostructures have also been explored as carriers for BCs with the aim of combating microbial attacks on crops and extending the food products shelf life. This review covers relevant and updated information on BCs from plants, describing and discussing different extraction techniques and encapsulation processes. It also presents an updated summary about the most frequently used wall materials for encapsulating BCs. There is a review of the advantages that micro and nano encapsulation of BCs from plants can provide, showing that their design can improve their properties, which represents an excellent alternative to potentiate future applications that cover needs in several areas, mainly in the agri-food industry.