Casting edible films

Clear, water-soluble, oU-and grease-resistant films of moderate strength can be cast from hydroxyethylceUulose solutions. Elexible, nontacky, heat-sealable packaging films and sheets can be produced from hydroxypropylceUulose by conventional extmsion techniques. Both gums can be used in the formulation of coatings, and both can be used to form edible films and coatings. 

Animal proteins, such as milk casein, whey, albumin, collagen, gelatin, keratin, and myofibrillar, are also proposed as raw materials to form edible films (13-15). Extended stmctures formed by unfolding of protein molecules are required for film formation. Amorphous three-dimensional stmctures formed by noncovalent interactions among protein chains stabilize the films. At high water content, films are produced by casting of viscous solutions, and at low water content, films are produced by extmsion using thermoplastic properties of proteins (13). 

Antimicrobial Edible films were prepared from natural fiber of pectin and other food hydrocolloids for food packaging or wrapping by extrusion followed by compression or blown film method. Microscopic analysis revealed a well mixed integrated structure of extruded pellets and an even distribution of the synthetic hydrocolloid in the biopolymers. The resultant composite films possess the mechanical properties that are comparable to films cast from most natural hydrocolloids that consumed as foods or components in processed foods. The inclusion of polyethylene oxide) alters the textures of the resultant composite films and therefore, demonstrating a new technique for the modification of film properties. The composite films were produced in mild processing conditions, thus, the films are able to protect the bioactivity of the incorporated nisin, as shown by the inhibition of Listeria monocytogenes bacterial growth by a liquid incubation method. 

The current study provides a new type of edible, antimicrobial food packaging or wrapping films from food-grade natural fibers or hydrocolloid. Besides film casting, the films can also be produced by compression, extrusion blown methods. The inclusion of PEO hydrocolloid in natural fiber formulations makes films tougher and caused less permanent deformation when the films were subjected to an external force. Since the extrusion and compression were performed in mild conditions, nisin can be incorporated into films without diminishing its antimicrobial activity. 

Effect of modification of fillers on the thermal properties of soy protein composites was studied by Wang et al. (2013). They prepared edible films containing different ratios of SPI with wheat-bran cellulose (WC), microcrystaUine wheat-bran cellulose (MWC), and ultrasonic/microwave-modilied MWC (MMWC) by casting and thermal properties of the films were analyzed. It was found that different proportions and particle size of the fillers (WC, MWC, and MMWC) affected the thermal properties of each of the films. The SPI/MMWC film demonstrated the best... 

Echeverria I, Eisenberg P, Mauri AN (2014) Nanocomposites fi 1ms based on soy proteins and montmorillonite processed by casting. J Membr Sci 449 15-26 Espitia PJP, Du W-X, Avena-Bustillos R de J, Soares N de FF, McHugh TH (2014). Edible films from pectin Physical-mechanical and antimicrobial properties—a review. Food Hydrocolloids 35 287-296... 

TABLE 1 Water vapor permeability (WVP), oxygen permeability (OP), and mechanical properties (tensile strength, TS elastic modulus, EM and % elongation, %E) of various edible films from wet process (solution casting)... 

Ch-tapioca S based edible films Casting Antimicrobial activity and physical properties Vasconez etal., 2009... 

Preparation of films can be achieved by two main processes the "wet" and "dr) approaches. The "wet process" involves biopol5mier dispersion or solubilization in a film-forming solution (solutioncasting) followed by a second step, the suspension or film-forming solution is placed in a suitable mold and the solvent is evaporated under controlled conditions (Ciannamea et al., 2014 Hernandez-Izquierdo and Krochta, 2008). The result of the casting process depends mainly on the mixing conditions temperature, time, type and concentration of solvent, plasticizer and pH, and the dr nng relative humidity and temperature (Gallstedt et al., 2004). Most of the studies on polysaccharide-based films use this method because it is simple, reproducible in most laboratories, and useful as a first approximation to the formation of edible films. 

Previous studies have shown that films cast from high-amylose starch have better film-forming and mechanical properties [80, 108, 109]. Furthermore, both amylose and amylopectin have shown excellent oxygen-barrier characteristics, which is one of the advantages of using edible hydrophilic starch-based films for food protection [110]. 

Uses Barrier resin in pkg. materials, gas fill pkg., pkg. for oily foods, edible oils, min. oils, agric. pesticides, org. soivs. suitable for film extrusion, sheet coextrusion, blow rmlding coextrusion, cast film, blow molding, tubes, coex coating Features Thermoplastic... 

Uses Adhesive/sealant resin for use in blown and cast film extrusion applies, incl. meat/poultry/seafood/cheese pkg., cereal liners, medical/ pharmaceutical pkg., powd./granularfood and non-food pouches, carded display/skin packaging films edible oil, motor oil, other li prod, pouches, snack structures coextrusions with nylon or in other film structures as heat seal or tie layer Features High clarity grade Regulatory FDA 21 CFR 177.1330 compliant Properties Melt flow 1.5 dg/min f.p. 78 C m.p. 103 C Vicat soften, pt. 81 C ultimate tens. str. 33.1 MPa (MD) ultimate elong. 450% (MD) Spencer impact str. 29 J/mm Dart drop str. 7.9 g/pm Elmendorf tear str. 46.3 mN/pm 9% methacrylic acid... 

In all materials used in different aspects of cellulose applications in food packaging, the material characteristics including cellulose, plasticizers, etc., and the fabrication procedures like composites, nanocomposites, casting of a film-forming solution, thermoforming, and so on, must be adapted to each specific food product and the conditions in which it will be used such as relative humidity, temperature, etc. Furthermore, edible and biodegradable films must meet a number of specific functional requirements like moisture barrier, gas barrier, water solubility, color and appearance, nontoxicity, etc. 

In the case of edible composite films and coatings containing a biopolymer and a lipid, the formulation requires to heat the lipid above its melting point, to homogenate both phases, degas, and cast on the plate or product surface, with the final evaporation of the solvent (Krochta, 2002). Some drying methods that have been studied include... 

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