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The development of edible films based on the natural biopolymer feather keratin (FK) from poultry feathers is of great interest to food packaging. Edible dialdehyde carboxymethyl cellulose (DCMC) crosslinked FK films plasticized with glycerol were prepared by a casting method. The effect of DCMC crosslinking on the microstructure, light transmission, aggregate structure, tensile properties, water resistance and water vapor barrier were investigated. The results indicated the formation of both covalent and hydrogen bonding between FK and DCMC to form amorphous FK/DCMC films with good UV-barrier properties and transmittance. However, with increasing DCMC content, a decrease in tensile strength of the FK films indicated that plasticization, induced by hydrophilic properties of the DCMC, partly offset the crosslinking effect. Reduction in the moisture content, solubility and water vapor permeability indicated that DCMC crosslinking slightly reduced the moisture sensitivity of the FK films. Thus, DCMC crosslinking increased the potential viability of the FK films for food packaging applications, offering a value-added product.

Wang N., Gao Y.Z., Wang P., Yang S., Xie T.M., Xiao Z.G. (2016): Effect of microwave modification on mechanical properties and structural characteristics of soy protein isolate and zein blended film. Czech J. Food Sci., 34: 180-188.Soy protein isolate (SPI) and zein were blended at different ratios, and native and microwave-modified films were prepared at pH 12 in an ethanol/water (20 : 80) mixture. The effect of the microwave modification on the mechanical properties and structural characteristics of the SPI and zein blended films was investigated. The results show that the microwave-modified blended film of 3 : 1 SPI-zein demonstrated the best mechanical properties: the highest breaking strength (2900 g) and the highest fracturing distance (16.08 mm). The morphology of the microwave-modified film was more homogeneous and had fewer pinholes than the zein-only film. In addition, the glass transition temperature of the microwave-modified film rose by nearly half compared to the zein-only film, while the melting temperature increased by almost 2.5%. The secondary structure analysis indicates that a moderate amount of microwave treatment will promote a decrease in α-helix, β-turn, and random coil content and an increase in β-sheet content. This study provides an edible material with better flexibility for food packaging.

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