Composite Films

Combining various biopolymers is an obvious approach to tailor the functional properties of edible films and coatings to specific applications. Generally, polysaccharide and protein films provide limited resistance to moisture transmis sion due to the inherent hydrophilicity of such materials and to the notable amounts of incorporated hydrophilic plasticizers needed to impart adequate film flexibility. In contrast, hydrophobic lipids are effective moisture barriers. Composite films (prepared from emulsions or by lamination) made of lipids and polysaccharides or proteins combine the satisfactory structural and oxygen barrier properties of polysaccharide or protein films with the good moisture barrier characteristics of lipids. For example, bi-component films prepared from cellulose ethers and lipids (eg, waxes, acetylated monoglycerides, and fatty acids) effectively restricted moisture migration in simulated food products containing major components differing substantially in water activity (60). Coatings comprised of MC or HPMC and fatty acids also may be used to control diffusion of antimicrobial agents (eg, potassium sorbate) into foods (61). Recently, highly refined cellulose dispersions made from fibrous agricultural by-products were copulverized at high pressure with various polysaccharides (guar gum, alginate, carrageenan, pectin, and xanthan gum) and coconut oil to form emulsions, which were cast into films (62). Such films had substantially lower water vapor permeability than those of polysaccharide-based films reported in the literature. Coatings comprised of sucrose esters of fatty acids and the sodium salt of CMC (trade names Semperfresh and Pro-long) effectively reduced ripening rate of fresh produce (63,64). Edible coating compositions for multicomponent food products combining shellac, HPC, and, optionally, fatty acids have been patented (65). Bicom-ponent chitosan-lauric acid films had 50% lower water vapor permeability than chitosan films (66). Composite protein-lipid films had lower water vapor permeability values than control protein films (19,67). Sodium caseinate-stearic acid coatings reduced white blush on peeled carrots by alleviating surface dehydration (68). Besides lipid-polysaccharide or lipid-protein films, composite films combining proteins and polysaccharides, such as starch, also have been studied recently (69,70). Blending various protein and polysaccharide film-formers with inexpensive starch can substantially reduce the cost of edible film formulations (71).

Coconut Oil - The Healthy Fat

Coconut Oil - The Healthy Fat

The coconut tree is one of the most versatile plants in existence. Whilst we are all familiar with the coconut as a food source not many of us know the myriad of other benefits the coconut holds.

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