Physical, Morphological, and Barrier Properties of Edible Casein Films with Wax Applications

Abstract

The overall research objective was to investigate the effects of wax application to casein films on the physical, morphological, mechanical, and water barrier properties of the films. Casein films were prepared by cross‐linking with zein hydrolysate using transglutaminase. Wax was either incorporated into the film‐forming solution or coated onto the casein films. The physical, morphological, and mechanical properties of wax‐incorporated or wax‐coated casein films were characterized. The wax‐casein films exhibited darker color than casein film, and the film thickness ranged from 0.2 to 0.4 mm. Wax application significantly decreased the tensile strengths and Young's Modulus of casein films. The wax‐incorporated films exhibited a greater reduction in tensile strength and Young's Modulus than the wax‐coated films. The microstructures of wax‐casein films were relatively smooth and uniform when observed under a scanning electron microscope. Wax applications significantly decreased the water vapor permeability (WVP) of the casein films, and the wax‐coated casein films exhibited a greater decrease in WVP than the wax‐incorporated films.

Development of flexible zein–wax composite and zein–fatty acid blend films for controlled release of lysozyme

“…On the other hand, no significant change occurred in tensile strength and Young's modulus values of the films by addition of waxes or oleic acid to form a composite or blend film structure (P > 0.05). These results contradicted with Sohail, Wang, Biswas, and Oh (2006) who incorporated paraffin wax into casein-zein hydrolizate films and reported a reduced tensile strength for these composite films.…”

Physical and chemical methods used to enhance the structure and mechanical properties of protein films: A review

“…On the other hand, smooth microstructures were indicative of a more glassy and brittle material (Ogale et al, 2000). A smooth and uniform microstructure can also indicate homogeneity of the manufactured film, as reported for protein films with incorporated additives (Wan et al, 2005;Sohail et al, 2006). McHugh and Krochta (1993) used SEM to evaluate the cross-sections of whey protein films plasticized with sorbitol.…”

“…One of the most common solutions is using the appropriate film formulation and preparation conditions. Many researchers explored the effects of plasticization (Siew et al, 1999;Sothornvit and Krochta, 2000a, 2000bShaw et al, 2002;Wan et al, 2005;Jongjareonrak et al, 2006a), pH alteration (Brandenburg et al, 1993;Avena-Bustillos and Krochta, 1993;, or lipid addition (Avena-Bustillos and Krochta, 1993;Shellhammer and Krochta, 1997;Chick and Hernández, 2002;Jongjareonrak et al, 2006b;Sohail et al, 2006) on the functional properties of protein films. Crosslinking of proteins is another solution that can lead to stronger and less permeable films.…”

“…Hydrophobic materials, such as lipids and waxes, have thus been incorporated into protein films to improve their WVP properties (Avena-Bustillos and Krochta, 1993;Shellhammer and Krochta, 1997;Chick and Hernández, 2002). These materials can be applied to the films by either lamination over the film or by incorporation into the film-forming solution (Sohail et al, 2006). Krochta (1993) added 12.5%, 25%, and 37.5% acetylated monoglycerides or 20%, 50%, and 80% beeswax to sodium caseinate films, and showed that increasing the percentage of lipid resulted in significantly reduced WVP.…”

The Influence of Surfactants on Casein Membrane Preparation and Separation Technologies

“…However, casein membranes has less extensibility and water resistance due to its structure [1], which could restrict its practical applications. Chemical modification and blending with other materials like surfactants, or including cross-linkers [2] and polymers [3] for the casein have been attempted to correct its deficiencies.There are two types of membranes, namely simple and composite membranes. In this research simple casein membranes are obtained by a uniform casting of the solution with: casein/water-acetic acid/ glycerol/surfactant on a glass plate.…”