In recent years, the replacement of synthetic colorants with natural ones has attracted increasing consumers’ and market interest. Natural colorants include different groups of pigments, many of which possess also pronounced biological potential. This review addresses the main issues related to the use of natural pigments in foods, starting from the sources available in nature, their chemical properties, stabilization processes, and applications in real foods, as discussed in the scientific literature reported in the main databases relevant to this topic (Scopus, Web of Science, PubMed, ScienceDirect, and Google Scholar). Notably, several natural pigments are available to cover different needs in terms of hues and intensities, and whose use is permitted in foods by the main regulatory agencies. However, their use is still frequently limited by their higher price and lower stability than synthetic counterparts. This review discusses in detail the main sources for natural pigments, focusing on the recent trends towards those more economically favorable, such as microbial sources and agro-industrial residues. It also examines the most suitable stabilization systems to protect the highly reactive and unstable molecules of natural pigments from negative physical and chemical changes, as well as to minimize the interactions with food systems.

This review presents a critical analysis of food-grade delivery systems, which are suitable for the delivery of essential oils (EOs) for food applications. In particular, the main colloidal systems, investigated in vitro for the encapsulation of essential oils, such as nanoemulsions, solid lipid nanoparticles, nanostructured lipid carriers, carbohydrate-based carriers, protein-based carriers, liposomes and gelatin, have been described in details, with a special focus on their formulation, the type of oils encapsulated, and the fabrication processes, as well as on the resulting antimicrobial activity with respect to free oils. Currently, among these food-grade colloidal systems, only nanoemulsions, liposomes, and biopolymeric particles have found use in real foods, because of their easily-scalable production processes, loading capability with EOs, as well as cost-effectiveness. The main applications in foods are discussed, with reference to the possible methods of incorporation of encapsulated essential oils in foods, such as direct mixing, washing or infusion, and coating within active biopolymeric matrices. In addition, also the use of encapsulated essential oils in several other fields is presented, such as in organic farming, pest control or luring, as well as in pest-repellent textiles. Finally, the main regulatory issues are discussed.