Nanoencapsulation techniques for compounds and products with antioxidant and antimicrobial activity - A critical view.

Oxidative decay and microbial spoilage are issues of concern, as they constitute threats to human health. Natural antioxidants and antimicrobials hamper the negative impact of synthetic compounds and they need appropriate delivery systems. Different nanostructures can be developed: association colloids-based nanostructures, nanoemulsions, nanoliposomes, nanolaminates, nanofibers, carbon nanotubes, nanocomposites. The main nanoencapsulation techniques applied to antioxidants and antimicrobials are described: association colloid-based nanoincorporation, lipid-based nanoencapsulation techniques, encapsulation techniques based on biologically-derived polymeric nanocarriers, encapsulation techniques based on non-biological polymeric nanocarriers, cyclodextrin incorporation, electrospraying and electrospinning, carbon nanotubes and nanocomposite encapsulation. Several nanoencapsulation methods can be followed by freeze-drying or spray-drying. Protection of bioactive compounds and controlled release are achieved, but the impact of the nanomaterials on human health and on the environment should be considered. The influence of the nanoencapsulation techniques on the antioxidant/antimicrobial activity is discussed. The choice of the appropriate encapsulation method is vital. Bioactivity increase, preservation or decrease, depend on the interactions established between the functional groups of encapsulated compound and the encapsulating nanomaterial.