PROTEINS AS AGRICULTURAL POLYMERS FOR PACKAGING PRODUCTION

Advantages, types, formation, and properties of agricultural packaging materials based on proteins, with examples, are reviewed in detail. P roteins have long and empirically been used to make biodegradable, ren ewable, and edible packaging materials. Numerous cereal and vegetable proteins (such as corn zein, wheat gluten, and soy proteins) and anima l proteins (such as milk proteins, collagen, gelatin, keratin, and myo fibrillar proteins) are commonly used to form agricultural packaging m aterials. Two technological processes have been investigated to make m aterials based on proteins: the ''wet (or solvent) process'' based on dispersion or solubilization of proteins in a solvent medium, and the ''dry process'' based on the thermoplastic properties of proteins unde r low water content conditions. The macroscopic properties (including solubility in water, mechanical properties, and barrier properties) of agricultural packaging materials based on proteins are dependent main ly on the structure of the macromolecular three-dimensional network an d on interactions between proteins, plasticizers, and cross-linking ag ents.