scholarly journals Impact of Hydrolyzed Whey Protein on the Molecular Interactions and Cross-Linking Density in Whey Protein Isolate-Based Films

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Markus Schmid ◽  
Sandra Pröls ◽  
Daniel M. Kainz ◽  
Felicia Hammann ◽  
Andreas Stäbler
Keyword(s):  
Whey Protein ◽  
Molecular Interactions ◽  
Noncovalent Interactions ◽  
Barrier Properties ◽  
Protein Isolate ◽  
Cross Linking ◽  
Disulphide Bonds ◽  
Swelling Studies ◽  
Solubility Studies ◽  
The Cross

The effect of the amount of hydrolyzed WPI (h-WPI) in WPI-based films on the technofunctional properties and structure of the films has not hitherto been systematically researched. The main objective of this study was therefore to explore the quantitative and qualitative molecular interactions and structures of these films. Different buffer systems were used for the solubility studies to obtain information about the qualitative molecular interactions. Swelling studies were performed to provide qualitative statements about the WPI network. In addition, the cross-linking density (CLD) of the WPI-based films was derived from the swelling tests. The measurements showed that increasing the h-WPI content decreases the CLD significantly. The CLD values of films with 0% and 50% h-WPI content were1.61·10-4 mol·cm−3and0.25·10-4 mol·cm−3. The study indicates that noncovalent interactions have more influence on barrier properties than the cross-linking density through disulphide bonds. In general, the results of the swelling tests correlated with the solubility studies.

scholarly journals UV Radiation Induced Cross-Linking of Whey Protein Isolate-Based Films

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Markus Schmid ◽  
Tobias Konrad Prinz ◽  
Kerstin Müller ◽  
Andreas Haas
Keyword(s):  
Whey Protein ◽  
Uv Radiation ◽  
Reference Sample ◽  
Barrier Properties ◽  
Protein Isolate ◽  
Cross Linking ◽  
Protein Films ◽  
Disordered Protein ◽  
Radiation Induced ◽  
The Cross

Casted whey protein films exposed to ultraviolet irradiation were analyzed for their cross-linking properties and mechanical and barrier performance. Expected mechanical and barrier improvements are discussed with regard to quantification of the cross-linking in the UV-treated whey protein films. Swelling tests were used to determine the degree of swelling, degree of cross-linking, and cross-linking density. When the UV radiation dosage was raised, a significant increase of the tensile strength as well as an increase in Young’s modulus was observed. No significant changes in water vapor and oxygen barrier properties between the UV-treated films and an untreated reference sample could be observed. The cross-linking density and the degree of cross-linking significantly increased due to UV radiation. Combined results indicate a disordered protein network in cast films showing locally free volume and therefore only minor mechanical and barrier improvements.

scholarly journals Mechanical and Barrier Properties of Potato Protein Isolate-Based Films

Coatings ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 58 ◽  
Author(s):  
David Schäfer ◽  
Matthias Reinelt ◽  
Andreas Stäbler ◽  
Markus Schmid
Keyword(s):  
Whey Protein ◽  
Functional Properties ◽  
Barrier Properties ◽  
Whey Protein Isolate ◽  
Protein Isolate ◽  
Cross Linking ◽  
Potato Protein ◽  
Water Sorption Isotherm ◽  
Barrier Performance ◽  
Cross Links

Potato protein isolate (PPI) was studied as a source for bio-based polymer films. The objective of this study was the determination of the packaging-relevant properties, including the mechanical properties and barrier performance, of casted potato protein films. Furthermore, the films were analyzed for cross-linking properties depending on the plasticizer concentration, and compared with whey protein isolate (WPI)-based films. Swelling tests and water sorption isotherm measurements were performed to determine the degree of swelling, the degree of cross-linking, and the cross-linking density using the Flory–Rehner approach. The effects of different plasticizer types and contents on compatibility with potato protein were studied. Glycerol was the most compatible plasticizer, as it was the only plasticizer providing flexible standalone films in the investigated concentration range after three weeks of storage. Results indicated that increasing glycerol content led to decreasing cross-linking, which correlated in an inversely proportional manner to the swelling behavior. A correlation between cross-linking and functional properties was also reflected in mechanical and barrier characterization. An increasing number of cross-links resulted in higher tensile strength and Young’s modulus, whereas elongation was unexpectedly not affected. Similarly, barrier performance was significantly improved with increasing cross-linking. The overall superior functional properties of whey protein-based films were mainly ascribed to their higher percentage of cross-links. This was primarily attributed to a lower total cysteine content of PPI (1.6 g/16 g·N) compared to WPI (2.8 g/16 g·N), and the significant lower solubility of potato protein isolate in water at pH 7.0 (48.1%), which was half that of whey protein isolate (96%). Comparing on an identical glycerol level (66.7% (w/w protein)), the performance of potato protein isolate was about 80% that of whey protein isolate regarding cross-linking, as well as mechanical and barrier properties.

Novel Whey Protein Isolate/Polyvinyl Biocomposite for Packaging: Improvement of Mechanical and Water Barrier Properties by Incorporation of Nano-silica

2021 ◽  
Author(s):  
Bruna Rage Baldone Lara ◽  
Paulo Sérgio de Andrade ◽  
Mario Guimarães Junior ◽  
Marali Vilela Dias ◽  
Lizzy Ayra Pereira Alcântara
Keyword(s):  
Whey Protein ◽  
Barrier Properties ◽  
Whey Protein Isolate ◽  
Protein Isolate ◽  
Nano Silica ◽  
Water Barrier

scholarly journals Mechanical Properties and Biodegradability of the Kenaf/Soy Protein Isolate-PVA Biocomposites

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Jong Sung Won ◽  
Ji Eun Lee ◽  
Da Young Jin ◽  
Seung Goo Lee
Keyword(s):  
Mechanical Properties ◽  
Soy Protein ◽  
Low Cost ◽  
Soy Protein Isolate ◽  
Natural Fibers ◽  
Protein Isolate ◽  
Poly Vinyl Alcohol ◽  
Cross Linking ◽  
Adhesion Properties ◽  
The Cross

The effective utilization of original natural fibers as indispensable components in natural resins for developing novel, low-cost, eco-friendly biocomposites is one of the most rapidly emerging fields of research in fiber-reinforced composite. The objective of this study is to investigate the interfacial adhesion properties, water absorption, biodegradation properties, and mechanical properties of the kenaf/soy protein isolate- (SPI-) PVA composite. Experimental results showed that 20 wt% poly (vinyl alcohol) (PVA) and 8 wt% glutaraldehyde (GA) created optimum conditions for the consolidation of the composite. The increase of interfacial shear strength enhanced the composites flexural and tensile strength of the kenaf/SPI-PVA composite. The kenaf/SPI-PVA mechanical properties of the composite also increased with the content of cross-linking agent. Results of the biodegradation test indicated that the degradation time of the composite could be controlled by the cross-linking agent. The degradation rate of the kenaf/SPI-PVA composite with the cross-linking agent was lower than that of the composite without the cross-linking agent.

scholarly journals Improved Gel Properties of Whey Protein-Stabilized Emulsions by Ultrasound and Enzymatic Cross-Linking

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 135
Author(s):  
Yanli Zhao ◽  
Shiqi Xue ◽  
Xinyue Zhang ◽  
Tiehua Zhang ◽  
Xue Shen
Keyword(s):  
Whey Protein ◽  
Disulfide Bonds ◽  
Noncovalent Interactions ◽  
Textural Properties ◽  
Industrial Applications ◽  
Cross Linking ◽  
Similar Frequency ◽  
Soluble Aggregate ◽  
Gelation Behavior ◽  
Cross Links

This study investigated the effects of high-intensity ultrasound (HUS) and transglutaminase pretreatment on the gelation behavior of whey protein soluble aggregate (WPISA) emulsions. HUS pretreatment and TGase-mediated cross-linking delayed the onset of gelation but significantly increased (p < 0.05) the gel firmness (G′) both after gel formation at 25 °C and during storage at 4 °C. The frequency sweep test indicated that all gels had a similar frequency dependence at 4 and 25 °C, and the elasticity and viscosity of the WPISA-stabilized emulsion gel were significantly enhanced by HUS pretreatment and TGase-mediated cross-linking (p < 0.05). HUS and TGase-mediated cross-linking greatly improved the textural properties of WPISA-stabilized emulsion gels, as revealed by their increases in gel hardness, cohesiveness, resilience, and chewiness. HUS pretreatment and TGase-mediated cross-linking significantly increased the water-holding capacity but decreased the swelling ratios of the gels (p < 0.05). Interactive force analysis confirmed that noncovalent interactions, disulfide bonds, and TGase-induced covalent cross-links were all involved in the formation of gel networks. In conclusion, the combination of HUS and TGase-mediated cross-linking were beneficial for improving the gelation properties of WPISA-stabilized emulsion as a controlled release vehicle for potential food industrial applications.

scholarly journals Blends of poly(butylene adipate-co-terephthalate) and thermoplastic whey protein isolate: a compatibilization study

2021 ◽  
Author(s):  
Marina Fernandes Cosate de Andrade ◽  
Hugo Campos Loureiro ◽  
Claire Isabel Grígoli de Luca Sarantopóulos ◽  
Ana Rita Morales
Keyword(s):  
Whey Protein ◽  
Complex Viscosity ◽  
Barrier Properties ◽  
Whey Protein Isolate ◽  
Mechanical Tests ◽  
Protein Isolate ◽  
Degree Of Crystallinity ◽  
Force Microscopy ◽  
Rate Region ◽  
The Matrix

Abstract This work assesses the influence of the plasticizer polyethylene glycol (PEG) on the compatibilization of poly(butylene adipate-co-terephthalate) (PBAT) and thermoplastic whey protein isolate (WPIT) blends. To prepare the blends, WPI was denatured at 90 oC, in the presence of PEG, to become a thermoplastic material. Dried WPIT was later mechanically blended with PBAT using a torque rheometer at 160 oC and 80 rpm. Two blends were prepared: 90% of PBAT/10% of WPIT (90_10) and 70% of PBAT/30% of WPIT (70_30). Scanning electron microscopy (SEM) analyses showed a homogenous blend morphology and good interaction between the dispersed phase and the matrix. Atomic force microscopy-based infrared spectroscopy (AFM-IR) showed PBAT and WPIT bands in all studied regions of both blends, which suggests that these materials presented partial miscibility. The viscosity ratio of the PBAT/WPIT system was less than 3.5 in the high shear rate region in complex viscosity curves, which indicates that droplet break-up of WPIT may occur by the drop fibrillation mechanism. The addition of WPIT reduced the degree of crystallinity of PBAT in the blends in comparison to pristine PBAT as shown by X-ray diffraction (XRD). Mechanical tests showed that blend tensile strength and elongation at break decreased with the addition of WPIT. Elastic modulus of the blends increased compared to pristine PBAT. Barrier properties were also evaluated showing that the oxygen permeability coefficient reduced by 20% for the blend with 30% of WPIT and vapor water permeability increased with the addition of WPIT.

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