Emulsions Incorporated in Polysaccharide-Based Active Coatings for Fresh and Minimally Processed Vegetables

Abstract

The consumption of minimally processed fresh vegetables has increased by the consumer’s demand of natural products without synthetic preservatives and colorants. These new consumption behaviors have prompted research on the combination of emulsion techniques and coatings that have traditionally been used by the food industries. This combination brings great potential for improving the quality of fresh-cut fruits and vegetables by allowing the incorporation of natural and multifunctional additives directly into food formulations. These antioxidant, antibacterial, and/or antifungal additives are usually encapsulated at the nano- or micro-scale for their stabilization and protection to make them available by food through the coating. These nano- or micro-emulsions are responsible for the release of the active agents to bring them into direct contact with food to protect it from possible organoleptic degradation. Keeping in mind the widespread applications of micro and nanoemulsions for preserving the quality and safety of fresh vegetables, this review reports the latest works based on emulsion techniques and polysaccharide-based coatings as carriers of active compounds. The technical challenges of micro and nanoemulsion techniques, the potential benefits and drawbacks of their use, the development of polysaccharide-based coatings with natural active additives are considered, since these systems can be used as alternatives to conventional coatings in food formulations.

Current Trends in the Utilization of Essential Oils for Polysaccharide- and Protein-Derived Food Packaging Materials

“…The miscibility of the two phases plays a major role in the PIT method. The emulsion inversion phase (EIP) is another method whereby a change in the concentration of a dispersed phase causes the surfactant to move towards that phase [ 180 ]. Most of the low-energy approaches require a high concentration of synthetic surfactants to produce a stable emulsion, which limits their application.…”

Lipid-Polymeric Films: Composition, Production and Applications in Wound Healing and Skin Repair

“…Lipophilic films are generally applied onto the skin to exploit their moisture barrier properties [ 50 ]. Due to their nonpolar nature, the incorporation of a lipid into a polymeric film can make it even more lipophilic [ 51 ]. The most used lipid materials are waxes, resins, fatty acids and alcohols, acetyl glycerides, and cocoa-based compounds and their derivatives [ 52 , 53 ].…”

Stabilization Techniques of Essential Oils by Incorporation into Biodegradable Polymeric Materials for Food Packaging

“…An emulsion represents a colloidal system consisting of at least two immiscible liquids; the oil, which is a property of main interest in food packaging materials, and the aqueous phase, wherein one liquid (the continuous phase) includes a dispersion of droplets of the other liquid (the dispersed phase) [58]. Based on the size order of the droplets, emulsions are categorized into three classes, namely: (i) conventional emulsions, comprising droplets with diameters greater than 1000 nm, (ii) nano-emulsions (NE), which include drops with diameters from 20-1000 nm, and (iii) micro-emulsions, droplets with sizes in the 5-100 nm range [59]. The conventional emulsions are prone to phase separation, droplets coalescence and Ostwald ripening, as a consequence of thermodynamic instability [60].…”

“…Even if in the case of nano-emulsions, the process activation energy has positive values (∆G* > 0), meaning thermodynamic instability; they are considered metastable systems due to their kinetic stability. Nevertheless, in a particular thermal regime and specific composition nano-emulsions can remain stable for prolonged periods of time [59].…”