Microencapsulation of active ingredients in functional foods: From research stage to commercial food products

Background: Twelves categories of active ingredients have been recognised to enhance human health. They are to some extent susceptible to certain conditions such as heat, light and low pH. To reduce their susceptibility and achieve controlled release at the target site, various microencapsulation strategies have been introduced. Scope and approach: In this review, the chemical structures, physicochemical properties and beneficial effects of the active components are summarised. Different encapsulation techniques and tailored shell materials have been investigated to optimise the functional properties of microcapsules. Several encapsulated constituents (e.g., amino acids) have been successfully incorporated into food products while others such as lactic acid bacteria are mostly used in the free format. Encapsulating some of these active ingredients will extend their ability to withstand process conditions such as heat and shear, and prolong their shelf stability. Key findings and conclusions: The functional properties of a microcapsule are encapsulation efficiency, size, morphology, stability, and release characteristics. Several microencapsulation strategies include the use of double emulsions, hybrid wall materials and crosslinkers, increasing intermolecular attraction between shell and core, physical shielding of shell materials, and the addition of certain ions. Other approaches such as the use of hardening agents, nanoencapsulation, or secondary core materials, and the choice of shell materials possessing specific interactions with the core may be used to achieve targeted release of active ingredients. The physicochemical properties of shell materials influence where the active ingredients will be released in vivo. A suitable microencapsulation strategy of active ingredients will therefore expand their applications in the functional foods industry.