Physical and mechanical properties of compression molded and solution casting soybean protein concentrate based films

Property enhancement of soy protein isolate-based films by introducing POSS

To enhance the mechanical and water-resistant properties of soy protein isolate (SPI) based films, hydrophobic TriSilanolPhenyl polyhedral oligomeric silsesquioxanes (POSS) was incorporated to modify the SPI films. POSS has three SiOH groups in a molecular, which is employed to cross-link SPI with the help of 3-glycidoxypropyltrimethoxysilane (GPTMS). POSS is a structure of eight phenol groups, playing a critical role in improving the physical and mechanical properties. The X-ray diffraction (XRD) and attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR) were used to characterize the films. The degree of reaction of SiOH groups in the POSS was estimated to be 53.0% according with the absorbance of ATR FT-IR spectra. Although the elongation at break was reduced by 52.6%, the tensile modulus, tensile strength and 10% offset yield strength were significantly increased by 86.6%, 34.0% and 56.8%, respectively, due to the cross-linking reactions among SPI, GPTMS and POSS. The results of water-resistant tests showed that the 24-hour water absorption was dramatically reduced by 54.7%.

Soy protein isolate-based films cross-linked by epoxidized soybean oil

Property enhancement of soy protein isolate-based film was achieved by introducing an environmentally friendly cross-linking agent, epoxidized soybean oil.

Determination and Quantification of Molecular Interactions in Protein Films: A Review

Protein based films are nowadays also prepared with the aim of replacing expensive, crude oil-based polymers as environmentally friendly and renewable alternatives. The protein structure determines the ability of protein chains to form intra- and intermolecular bonds, whereas the degree of cross-linking depends on the amino acid composition and molecular weight of the protein, besides the conditions used in film preparation and processing. The functionality varies significantly depending on the type of protein and affects the resulting film quality and properties. This paper reviews the methods used in examination of molecular interactions in protein films and discusses how these intermolecular interactions can be quantified. The qualitative determination methods can be distinguished by structural analysis of solutions (electrophoretic analysis, size exclusion chromatography) and analysis of solid films (spectroscopy techniques, X-ray scattering methods). To quantify molecular interactions involved, two methods were found to be the most suitable: protein film swelling and solubility. The importance of non-covalent and covalent interactions in protein films can be investigated using different solvents. The research was focused on whey protein, whereas soy protein and wheat gluten were included as further examples of proteins.