Mechanical and barrier properties of thermoplastic whey protein isolate/ethylene vinyl acetate blends

2014 ◽  
Vol 131 (23) ◽  
pp. n/a-n/a ◽  
Author(s):  
Markus Schmid ◽  
Kerstin Müller ◽  
Sven Sängerlaub ◽  
Andreas Stäbler ◽  
Vanessa Starck ◽  
...  
Author(s):  
Bruna Rage Baldone Lara ◽  
Paulo Sérgio de Andrade ◽  
Mario Guimarães Junior ◽  
Marali Vilela Dias ◽  
Lizzy Ayra Pereira Alcântara

2021 ◽  
Author(s):  
Marina Fernandes Cosate de Andrade ◽  
Hugo Campos Loureiro ◽  
Claire Isabel Grígoli de Luca Sarantopóulos ◽  
Ana Rita Morales

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.


2020 ◽  
Vol 179 ◽  
pp. 109285 ◽  
Author(s):  
Hülya Çakmak ◽  
Yeşim Özselek ◽  
Osman Yağız Turan ◽  
Ebru Fıratlıgil ◽  
Funda Karbancioğlu-Güler

Coatings ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 58 ◽  
Author(s):  
David Schäfer ◽  
Matthias Reinelt ◽  
Andreas Stäbler ◽  
Markus Schmid

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.


2020 ◽  
Vol 21 (7) ◽  
pp. 2486 ◽  
Author(s):  
Andrey A. Tyuftin ◽  
Lizhe Wang ◽  
Mark A.E. Auty ◽  
Joe P. Kerry

The objective of this study was to assess the ability of producing laminated edible films manufactured using the following proteins; gelatin (G), whey protein isolate (WPI) and polysaccharide sodium alginate (SA), and to evaluate their physical properties. Additionally, films’ preparation employing these ingredients was optimized through the addition of corn oil (O). Overall, 8-types of laminated films (G-SA, G-WPI, SA-WPI, SA-G-WPI, GO-SAO, GO-WPIO, SAO-WPIO and SAO-GO-WPIO) were developed in this study. The properties of the prepared films were characterized through the measurement of tensile strength (TS), elongation at break point (EB), puncture resistance (PR), tear strength (TT), water vapour permeability (WVP) and oxygen permeability (OP). The microstructure of cross-sections of laminated films was investigated by scanning electron microscopy (SEM). Mechanical properties of films were dramatically enhanced through the addition of film layers. GO-SAO laminate showed the best barrier properties to water vapour (22.6 ± 4.04 g mm/kPa d m2) and oxygen (18.2 ± 8.70 cm3 mm/kPa d m2). SAO-GO-WPIO laminate film was the strongest of all laminated films tested, having the highest TS of 55.77 MPa, PR of 41.36 N and TT of 27.32 N. SA-G-WPI film possessed the highest elasticity with an EB value of 17.4%.


Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 745
Author(s):  
Sabina Galus ◽  
Magdalena Mikus ◽  
Agnieszka Ciurzyńska ◽  
Ewa Domian ◽  
Jolanta Kowalska ◽  
...  

This study aimed to determine the effect of edible coatings based on whey protein isolate and essential oils (lemon and lemongrass) on the colour, hardness, polyphenols and flavonoids content, structure, and sensory attributes of fresh-cut pears during storage at 4 °C. The optical and barrier properties of the edible films were also determined. Analysed films showed good transparency (Lightness 86.6–95.0) and excellent oxygen and carbon dioxide permeability, which were reduced due to the presence of lemon and lemongrass essential oils. Pears were coated by immersion in a solution containing 8% of whey protein isolate and the addition of lemon oil at 1.0% or lemongrass essential oil at 0.5%. Coating caused a reduction in colour changes, loss in hardness, polyphenols and flavonoids. The study showed that the highest efficiency was demonstrated by the whey protein isolate coatings without the addition of essential oils by preserving the colour and firmness of fresh-cut pears. For these samples, the highest sensory acceptability was also achieved.


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