Thermoplastic Processing of Proteins for Film Formation—A Review

Abstract

Increasing interest in high-quality food products with increased shelf life and reduced environmental impact has encouraged the study and development of edible and/or biodegradable polymer films and coatings. Edible films provide the opportunity to effectively control mass transfer among different components in a food or between the food and its surrounding environment. The diversity of proteins that results from an almost limitless number of side-chain amino-acid sequential arrangements allows for a wide range of interactions and chemical reactions to take place as proteins denature and cross-link during heat processing. Proteins such as wheat gluten, corn zein, soy protein, myofibrillar proteins, and whey proteins have been successfully formed into films using thermoplastic processes such as compression molding and extrusion. Thermoplastic processing can result in a highly efficient manufacturing method with commercial potential for large-scale production of edible films due to the low moisture levels, high temperatures, and short times used. Addition of water, glycerol, sorbitol, sucrose, and other plasticizers allows the proteins to undergo the glass transition and facilitates deformation and processability without thermal degradation. Target film variables, important in predicting biopackage performance under various conditions, include mechanical, thermal, barrier, and microstructural properties. Comparisons of film properties should be made with care since results depend on parameters such as film-forming materials, film formulation, fabrication method, operating conditions, testing equipment, and testing conditions. Film applications include their use as wraps, pouches, bags, casings, and sachets to protect foods, reduce waste, and improve package recyclability.

Effect of storage time on physicochemical and textural properties of sausages covered with oxidized banana starch film with and without betalains

“…For example, its high water content (Mali, Sakanaka, Yamashita, & Grossmann, 2005) and high rate of water vapor transmission (Krochta & Hernández-Izquierdo, 2008) have been studied. However, these disadvantages can be eliminated by chemical modification of the starch (Pérez-Gallardo et al, 2012).…”

Edible coatings as encapsulating matrices for bioactive compounds: a review

“…However, the barrier and mechanical properties are compromised by moisture owing to their inherent hydrophilic nature; as moisture increase, the plasticization induces loss barrier performances. Proteins present a large variety of possible interactions and chemical reactions (Hernández Izquierdo and Krochta 2008); they may participle in chemical reactions through covalent (peptide and disulfide) linkages and noncovalent interactions (ionic hydrogen and van der Waals bonding). In addition, hydrophobic interactions occur between non-polar groups of amino acids chains (Guerrero et al 2010).…”

Pharmaceutical films made from the waste material from the preparation of propolis extracts: development and characterization

“…The use of natural residues has increased as general ecological consciousness and awareness have grown with the implementation of the three Rs concept (reduce, reuse, recycle) (Dowdle, 2005;Larney, Van Aardt, 2010). Agricultural, pharmaceutical, livestock, fishery, and food industries, among others, produce waste products that are rich in biopolymers and display film-forming characteristics (Hernandez-Izquierdo, Krochta, 2008). The utilization of these byproducts is for the exclusive purpose of being environmentally friendly, because they also could be important sources of active compounds such as proteins, enzymes, natural polymers and volatile oils, which are largely responsible for the activity of natural products (Coelho et al, 2001).…”