Shellac resin effect on the properties of zein film (original) (raw)
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Properties of films from corn zein reacted with glutaraldehyde
Journal of Applied Polymer Science, 2007
To improve the mechanical properties of zein films, a commercial white zein was reacted in glacial acetic acid (HAc) with glutaraldehyde (GDA) from 0.5 to 16% by weight based on the weight of zein. Amounts of 4% or higher GDA-modified zein, when cured in a closed system, generated a gel. That gel was insoluble in organic solvents known to solubilize zein. Zein solutions cast within a silicon rubber gasket sealed onto Teflon-coated plates, when air dried, generated 0.7-0.9-mm thick films. Those films from 8% GDA-modified zein had a water vapor permeability of 5.9 Â 10 À8 g cm/Pa s m 2. Overall, results indicate that our thicker films gave higher water vapor permeability than values reported in the literature. To achieve consistent and comparable results with differential scanning calorimetry (DSC) and dynamic mechanical analyses (DMA), film samples had to be heated to remove residual HAc. An increase in the glass transition temperatures for those films from GDA-modification of zein, observed with both DSC and DMA, was attributed to the crosslinking of zein. Physical testing of tensile bars cut from GDA-modified zein films showed minor enhancement of tensile strength, percent elongation, and Young's modulus in the 0.5% GDA-modified zein films, which increased and leveled off with 4% or higher amounts of GDA for the modifications. When the 4 to 16% GDA results are averaged, the tensile strength for the modified zein films increased 1.8-fold when compared with unmodified zein control films. On the same note, percent elongation showed a 1.8-fold increase and Young's modulus showed a 1.5-fold increase. GDA reaction with zein generated films with improved tensile strength, ductility, and stiffness when compared with respective zein control films that retained their integrity when subjected to either boiling water or extensive soaking.
Biodegradable Zein-Based Blend Films: Structural, Mechanical and Barrier Properties
Food Technology and Biotechnology, 2015
The eff ect of adding a hydrocolloid on the structural, mechanical and barrier properties of zein-based blend fi lms is evaluated. Zein-oleic acid blend fi lm with added xanthan gum (Z-OA-XG) showed higher water solubility (13.09 %) and opacity (8.49 AU/mm) than zein-oleic acid (Z-OA) fi lm (10.80 % and 5.19 AU/mm, respectively). Furthermore, Z-OA fi lm had greater fl exibility with lower Young's Modulus (YM=5.02 MPa) and higher elongation at break (η=10.62 %); nonetheless, it was less resistant to tension (tensile strength σ=8.5 MPa) than Z-OA-XG fi lm, which showed YM, η and σ of 6.38 MPa, 6.66 % and 10.485 MPa, respectively. Both fi lms had glossy and homogeneous structure with comparable water vapour and oxygen barrier properties around 4.39•10-11 and 1.82•10-13 g/(Pa•s•m), respectively. Based on that, xanthan gum structure infl uenced mainly mechanical and light barrier properties of zein-oleic acid blend fi lms.
Iranian Polymer Journal
Z ein (prolamin of corn) has good film forming properties. The pure zein film is very brittle and plasticizers can improve its mechanical and film making properties and represses its permeability to gases. Polyols are natural plasticizers for food biopolymers. In this research, three types of polyols (sorbitol, manitol, and glycerol) were used as plasticizers and the water vapour permeability (WVP), contact angle and microstructure of different zein films were studied. The pure zein film had high WVP and adding glycerol and sorbitol by 0.7 g/g zein lowered WVP but this effect was not observed in films containing manitol. The films containing glycerol had the lowest WVP. The zein films containing glycerol had the highest water contact angle compared with the plasticized films. The pure zein films and the films containing manitol had the higher critical surface tension of wetting (γ c) than the films containing glycerol and sor-bitol. Adding polyols to zein films increased the surface...
Engineering Zein Films with Controlled Surface Morphology and Hydrophilicity
Journal of Agricultural and Food Chemistry, 2009
A new method to engineer zein films with controlled surface morphology and hydrophilicity has been developed. The resulting surface morphology and surface hydrophilicity have been studied by tapping mode atomic force microscopy (TP-AFM) and a combination of water contact angle measurements and X-ray photoelectron spectroscopy (XPS), respectively. Our AFM results revealed that zein films cast from acetic acid showed much smoother surfaces as compared to those cast from ethanol aqueous solutions. Furthermore, zein films of controlled hydrophilicity have been engineered through the use of UV/ozone treatment, which can efficiently decrease the water contact angles of zein films from ∼80°to less than 10°within 130 s. XPS results suggest that the difference in surface hydrophilicity of zein films is due to the difference in surface elemental composition, and UV/ozone treatment converted some of the surface methyl groups mainly to carbonyl groups, therefore decreasing the water contact angles and increasing the surface hydrophilicity of zein films. This research opens up new opportunities of using zein as barrier materials and delivery vehicles for functional food ingredients, drugs, and dietary supplements.
Food Science and Technology International, 2017
Active zein films with different levels of Zataria multiflora Boiss. essential oil were produced successfully. To enhance properties of this biopolymer for food packaging applications, sodium bentonite clay was used at two levels (2 and 4%). The results indicated that the addition of Z. multiflora Boiss. essential oil caused a reduction in tensile strength and Young’s modulus and slight increase in the percent of elongation at break of the films. Maximum solubility in water and water vapor permeability was observed by incorporation of 10% Z. multiflora Boiss. essential oil in the zein matrix. Transmission electron microscopy micrographs of zein film were verified by the exfoliation of the layers of sodium bentonite clay in the zein matrix. Stronger films with lower water vapor permeability and water solubility were evident of good distribution of sodium bentonite clay in the zein matrix. According to the results, 2% sodium bentonite clay was selected for evaluation of nano active fi...
Food Research International, 2006
Zein is the most important protein in corn. Zein has good film forming properties. One of the film forming methods is production of zein resin and then thermomolding by hot press. Pure zein film is very brittle. Plasticizers can improve mechanical and film making properties of zein. In this research, sugars (fructose, galactose and glucose) were used as plasticizers and rheological properties of zein resin were studied by dynamic oscillatory tests for determination of plasticization effectiveness. Effect of plasticizers on thermal properties of resins was investigated by DSC at À100 to 150°C. No crystallization and melting peaks related to zein and plasticizers were observed. As well as there was not significant difference at glass transition temperature between zein resins containing various sugars. Zein films were prepared from zein resins by rolling and hot press and then mechanical properties of films were measured. Films containing galactose had better tensile properties than other films and showed higher tensile strength, strain at break, and Young modulus than films containing fructose and glucose.
Zein films with unoxidized or oxidized tannic acid
Journal of the Science of Food and Agriculture, 2017
BACKGROUND: Corn zein is a predominatly hydrophobic protein, forming films with relatively good water resistance. Tannic acid, especially in its oxidized form, is supposed to crosslink proteins including zein, which may be explored to further enhance the water resistance of zein films. The effects of different contents (0-8
LWT - Food Science and Technology, 2007
Sugars are natural plasticizers for food biopolymers and zein is the most important protein of corn. In this research, sugars (fructose, galactose and glucose) were used as plasticizers and the water vapor permeability (WVP), contact angle and microstructure of the zein films were studied. The pure zein film had high WVP and adding of sugars to 0.7 g/g zein caused to decrease of WVP. Films containing galactose had the lowest WVP. All samples had the lowest contact angle with ethanol and the highest contact angle with water. The zein films containing galactose had the highest water contact angle within the plasticized films. The pure zein films and the films containing fructose had higher critical surface tension of wetting (g c) than the films containing glucose and galactose. Adding sugar plasticizer to zein films increased the surface tension of zein films. In the unplasticized zein films, loose structures with a lot of cavities and voids were observed. The films plasticized by fructose had smooth surface and plasticizer particles distributed throughout of the films.
International Journal of Molecular Sciences
Zein is a biodegradable and biocompatible material extracted from renewable resources; it comprises almost 80% of the whole protein content in corn. This review highlights and describes some zein and zein-based materials, focusing on biomedical applications. It was demonstrated in this review that the biodegradation and biocompatibility of zein are key parameters for its uses in the food-packing, biomedical and pharmaceutical fields. Furthermore, it was pointed out that the presence of hydrophilic-hydrophobic groups in zein chains is a very important aspect for obtaining material with different hydrophobicities by mixing with other moieties (polymeric or not), but also for obtaining derivatives with different properties. The physical and chemical characteristics and special structure (at the molecular, nano and micro scales) make zein molecules inherently superior to many other polymers from natural sources and synthetic ones. The film-forming property of zein and zein-based materia...