Abstract
The use of EOs nanoemulsion to develop active edible films offers a new way to modify transport properties and to release active compounds while improving mechanical resistance, transparency, and antioxidant and antimicrobial activity. The aim of this study was to study the influence of homogenization conditions and carvacrol content on the microstructure and physical properties of edible nanoemulsified chitosan films. Film-forming emulsions (FFE) were prepared with chitosan (1.5%), Tween 80 (0.5%), and carvacrol (0.25%, 0.5%, and 1.0%); two homogenization methods were used (rotor-stator and rotor-stator followed by high-pressure homogenization). Film internal and surface microstructure was characterized by scanning electron microscopy (SEM) and film physical properties, such as mechanical, optical, and water barrier, were evaluated. Results showed that the high-pressure homogenization method promoted a significant change on film microstructure, leading to improved properties. Carvacrol droplets were smaller and homogeneously distributed in the film when 0.5% (v/v) carvacrol was incorporated (1:1 Tween 80: carvacrol ratio). As a consequence, emulsified films obtained at high pressure were less opaque, had greater elongation, and had a lower permeability to water vapor than those obtained by the rotor-stator method. Therefore, high-pressure homogenization is a good method to obtain edible emulsified films with desirable properties for food preservation.
Highlights
Edible films and coatings have received considerable attention in the field of food preservation given the promising results obtained and their potential use as a green alternative to plastic packaging films [1,2]
Film thickness was not affected by the homogenization method and carvacrol content (Table 2)
Similar results have been obtained by Fernandez-Pan et al [42], who found no differences in thickness between chitosan films prepared with carvacrol
Summary
Edible films and coatings have received considerable attention in the field of food preservation given the promising results obtained and their potential use as a green alternative to plastic packaging films [1,2]. Edible films and coatings have been used to improve gas and moisture barriers, mechanical properties, sensory perceptions, convenience, and microbial protection [3], all of which enhance the quality and shelf life of food products. These films can be prepared from a variety of biopolymers, including proteins, polysaccharides, lipids, and their combinations [4,5]. Chitosan coatings and films have poor water vapor barrier properties due to their hydrophilic nature [12] This is an important drawback because effectively controlling moisture transfer is a desirable property for most foods
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