Polysaccharide-lipid edible films

Biodegradable films made from edible biopolymers from renewable sources could become an important factor in reducing the environmental impact of plastic waste. Proteins, lipids, and polysaccharides are the main biopolymers employed to make edible films and coatings. Which of these components are present in different proportions and determine the properties of the material, as a barrier to water vapor, oxygen, carbon dioxide, and lipid transfer in food systems (Gomez-Guillen et al. 2002 and 2009). 

Edible moisture barriers usually include hpids. Because of their apolar nature, these hydrophobic substances are capable of forming a water-impervious structure and reduce efficiently the water transfer. However, lipid-based materials are most of the time brittle so they are frequently combined with proteins and/or polysaccharides to improve their mechanical and structural properties (Wu et al. 2002). Several reviews focussing specifically on edible moisture barriers (Debeaufort et al. 2000 Koelsch 1994) and/or lipid-based edible films have been published (Baldwin et al. 1997 Callegarin et al. 1997 Greener and Fennema 1992 Hernandez 1994 Quezada-Gallo et al. 2000). The most recent review on lipid-based moisture barriers is that of Morillon et al. (2002). 

Edible films from polysaccharides, proteins, and/or lipid compounds are used in various food products to control gas transfer (15-17). 

The main natural biomaterials for bioplastics are proteins, cellulose derivatives, alginates, pectins, starch and other polysaccharides. The solubility in water of the polysaccharide film is advantageous in situations where the film is consumed with the product, resulting in little change in the food s sensory properties. " Edible films based on proteins, polysaccharides or lipids minimize special care with the final package and increase food quality. ... 

Proteins and polysaccharides produced on an annual kiloton scale in the world have attracted extensive research attention as potentially the most significant eco-materials as well as edible and biodegradable films and coatings (Thakur and Thakur 2014a, b, c). Edible films made from polysaccharides and proteins act as excellent barriers to nonpolar substances such as O2, CO2, and lipid, particularly at low relative humidities. In contrast to synthetic polymers having a simpler and more random structure, biopolymers are complex molecular assemblies with precise and... 

Unlike protein and polysaccharides, lipid and resin are not polymers so they could not form stand-alone films. Edible lipids include waxes and oils for example, paraffin wax, beeswax (BW), candelilla wax, camauba wax, rice bran wax, jojoba oil, triglycerides (milkfat fractions), fatty acids, fatty alcohols, and sucrose fatty acid esters. Resins include shellac and terpene (Krochta, 2002). Due to their hydrophobic nature, lipid-based films and coatings exhibit high water resistance and low surface energy (Han and Gennadios, 2005). Generally, edible lipids have been incorporated into proteins and polysaccharides as emulsion or multilayer composite films to improve moisture barrier. 

Edible films and coatings are produced from edible biopolymers and food-grade additives. Film-forming biopolymers can be proteins, polysaccharides (carbohydrates and gums) or lipids. Plasticizers and other additives are combined with the film-forming biopolymers to modify the physical properties or functionality of films. The composition of the film must be chosen according to specific food applications, the type of food products and the major mechanisms of quality deterioration. 

Johnston, 1997 Wu et al, 2002 development and application of multicomponent edible coatings and films a review). Properties of polysaccharide-lipid films have been studied extensively by different leading researchers in the field (Perez-Gago Krochta, 2001 Morihon etal, 2002, Karbowiak, Debeaufort Voihey, 2007, Hambleton etal, 2008)... 

The materials used in these type of films include lipids, polysaccharides, and proteins. Starch (Maizura and others 2007), methylcellulose (Olivas and others 2003), hydroxypropyl cellulose (Brindle and Krochta 2008), chitosan (No and others 2007), xanthan gum (Mei and others 2002), alginate or zein (Zapata and others 2008), and soy protein (Park and others 2001) have been used for edible coatings. 

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