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The increase in consumer requirements for safe and high-quality food has promoted the development of active and edible packaging materials based on biopolymers. In this study, composite tapioca starch films by addition of processed rice bran (PRB) microparticles, containing or not the natural antimicrobials natamycin and nisin, were studied in relation to their physicochemical properties and antimicrobial activity. It was observed that the presence of PRB addition (0.1–0.3% w/w) increased yellowness proportionally to fiber content in films with or without antimicrobials but did not influence on thickness and water vapor permeability. Films with 0.2% PRB allowed the highest increase of tensile strength and strain at break and reduced the solubility in water, showing the optimal compatibility between PRB and starch matrix containing or not antimicrobials. Analysis by FTIR also suggested a good compatibility between filler and matrix through hydrophilic groups. Additionally, the analyzed composite films allowed the diffusion of the natural preservatives verified through zones of inhibition formed in the halo test against Saccharomyces cerevisiae and Listeria innocua. Consequently, the developed biocomposites can be used as an active packaging for food preservation.

The antimicrobial effectiveness of nisin and potassium sorbate, incorporated individual and combined, in films made with tapioca starch and its mixtures with hydroxypropyl methylcellulose were studied. The combination of antimicrobials was more effective against Listeria innocua and Zygosaccharomyces bailii than their individual incorporation, with the added advantage of providing greater inhibitory spectrum. The effect of the formulation on some physical properties was also evaluated. The blended biopolymers-based films showed an increase of stress (σr) and elastic modulus (E) but a decrease of the strain at break (er). In turn, the water vapour permeability and solubility in water were enhanced. In addition, these films were clearer than those made only with starch. It must be remark that, despite the antimicrobial agents modified films physical properties, producing a lower σr and E, a higher er, solubility and darker films, they maintained a suitable behaviour as a packaging material.

Over the last years, considerable research has been conducted to develop and apply edible films and coatings made from a variety of agricultural commodities and/or wastes of food product industrialization. Such biopolymers include polysaccharides, proteins, and their blends. These materials present the possibility of being carriers of different additives, such as antimicrobial, antioxidant, nutraceuticals, and flavorings agents. In particular, the use of edibles films and coatings containing antimicrobials has demonstrated to be a useful tool as a stress factor to protect foodstuff against spoilage flora and to decrease the risk of pathogen growth. The more commonly antimicrobials used are organic acids, chitosan, nisin, the lactoperoxidase system, and some plant extracts and their essential oils. For the selection of an antimicrobial, it must be considered the effectiveness against the target microorganism and also the possible interactions among the antimicrobial, the film-forming biopolymer, and other food components present. These interactions can modify the antimicrobial activity and the characteristics of the film being these key factors for the development of antimicrobial films and coatings. The main objective of this article is to review the bibliography of the last years concerning the main hydrocolloids and antimicrobials used for developing edible films and coatings, the methods used to evaluate the antimicrobial activity, the applications and the legislation concerning edible films and coatings. Also, the different strategies related to the modification of structural characteristics and the future trends in the development are discussed. The information update will help to improve the design, development, and application of edible films and coatings tending to increase the safety and quality of food products and to prepare for food legislation changes that might be necessary while identifying future trends concerning a better functionality of edible films thought as a stress factor for lengthening shelf life of food products. Fil: Campos, Carmen Adriana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina Fil: Gerschenson, Lia Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina Fil: Flores, Silvia Karina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina

The release and antimicrobial activity of potassium sorbate (KS) supported in tapioca starch–glycerol edible films prepared by different gelatinization/drying techniques against Zygosaccharomyces bailii was studied. Antimicrobial release in liquid media of different pHs (3.0–6.0) could be approximated to a pseudo first-order kinetic model and was almost accomplished after 30 min. Filmmaking method involving slow gelatinization and drying rate resulted in the highest fraction of KS released at equilibrium. Rate constant was higher when pH of the receiving media was 4.5 and fast gelatinization/fast drying had been used. The effectiveness of the preservative released for controlling the microbial growth depended on the pH of the receiving media, being higher at pH 3.0. No effect of filmmaking method was observed. In relation to film effectiveness as a barrier to contamination, it was observed that the preservative was available to prevent an external Z. bailii contamination and also to control yeast growth in an acidified (pH 4.5) high water activity (a w = 0.980) semisolid product.