Papers by Keyword: Soy Protein Isolate

Abstract: Soy protein isolate (SPI)/kapok husk (KH) based biofilms were prepared by casting method. The effect of phthalic anhydride (PA) content on tensile properties and morphology were studied. The PA was use as a crosslink agent. It was found that the increasing PA content have increased the tensile strength and modulus of elasticity of biofilms, whereas the elongation at break decreased. At 1.5 % of PA showed the highest tensile strength and modulus of elasticity of crosslink biofilms. The morphology study indicates the crosslinking with PA improved the interfacial interaction between KH and SPI matrix.

Abstract: SPI/PVA films were successfully prepared with complex plasticizers containing urea and trethanolamin (TEA) by casting and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), ultraviolet (Uv-vis), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing. The results indicated that SPI/PVA films with the content of 40% complex plasticizers possessed better optical transmittance. All of the films exhibited only one T_g in DSC curves. Moreover, the SPI/PVA films with complex plasticizers had higher thermal stability and mechanical properties, as a result of the strong interaction between complex plasticizers and SPI/PVA. The SPI/PVA materials will be promising for the application in the field of package and container, substituting for the nongreen polymers.

Abstract: Soy protein isolate (SPI)-essential oil monomers edible composite films were prepared by casting and solvent evaporation method. Films antibacterial activity and preservation effect on chilled pork were investigated. The results indicated that composite films showed significant inhibitory effect on the growth of Escherichia coli, Staphylococcus aureus, Pseudomonas and yeast. And the antimicrobial activity of films containing cinnamaldehyde was the highest. The films containing 6% essential oil monomers had better preservation effect on the meat samples compared with those without package or packed with single SPI edible films.

Abstract: Gas-selective permeability of films obtained from soy protein isolate (SPI) solutions at pH 12 was discussed. The modification treatments (ultrasonic, microwave and ultrasonic/microwave assisted treatment) was carried out to regulate oxygen and carbon dioxide barrier properties of SPI films, further control gas-selective permeability of SPI films in this work. In addition, all films obtained were flexible and transparent. Gas-selective permeability coefficients of SPI film was from 0.39 to 1.25, as indicated that gas-selective permeability of SPI film could be regulated according to the actual needs of food systems.

Abstract: The objective of the study was to investigate the impact of soy protein isolate (SPI)-maltodextrin conjugates on the freeze-thaw stability of oil-in-water emulsions. Covalent coupling of maltodextrin to SPI was achieved by wet heating of SPI- maltodextrin mixtures of different weight ratios and different protein contents at 70,80,90,100°C for 1 to 5 h. The freeze-thaw stability was characterized by measurements of creaming index and oiling off after isothermal storage at -20 °C for 24 h and further thawing. Compared with those stabilized by SPI alone, o/w emulsions stabilized by SPI-maltodextrin conjugates showed a higher stability against freeze-thaw treatment, exhibiting a lower creaming index and oiling off.

Abstract: Soy proteins have shown great potential for use as renewable and environmentally friendly adhesives. The orthogonal experiments are designed for the urea-modified soy protein isolate(SPI) adhesives and the optimum formula is obtained. The mass concentrations of SPI and urea are 14% and 8%(relative to the total mass of SPI and water), the reaction temperature and time are 35°C and 60 min, respectively. Some basic and adhesion properties and its structure of the modified SPI adhesive for the optimum formula are measured. The viscosity is 43Pa.s, and the dry- and wet-state adhesion strengths of the urea-modified SPI optimum formula are 0.96MPa and 0.78MPa(>0.72MPa), respectively according to GB/T10724-2006, which satisfied with the requirement of the II-type plywood. Its surface hydrophobicity is improved and the thermal properties is slightly improved after 200°C. Recently, some concerns about environmental pollution, resource scarcity, and related health issues have pushed scientists to replace the petrochemicals-based synthetic polymers, which are used extensively in construction, packaging, glue and plywood industries, with the bio-based adhesives. SPI adhesives have shown great potential for use as environmentally friendly adhesives in plywood since 1930s when it’s first be developed. And it has been modified by chemical alkali[1], sodium dodecyl sulfate(SDS)[2,3], and urea[2], guanidine hydrochloride[4], etc. However, most of these modifications can not very well improve the water resistance and the bonding strength separately. Poor water resistance is a fatal weakness which seriously restricts the application in the industry. Many studies[5~8] have shown that the adhesives with some enhanced performances, for example, adhesion strength and water-resistant, can be obtained by unloading SPI molecular chain with the hydrophobic group using urea, SDS, other surfactant and guanidine hydrochloride, etc. And the unloading mechanism of the SPI molecular chain with the hydrophobic group is proclaimed. The optimum concentration of urea is 1mol/L for the water-resistant. The aim of this research was to improve the tacky strength and the water resistance[9] by using urea to modify SPI and evaluate the resulting adhesive’s potential for use in the plywood.

Abstract: The mechanical properties difference between soy protein isolate-based film and whey protein-based film was researched. The elongation at break, tensile strength of the pure soy protein isolate film both are better than that of the pure whey protein concentrate film, which is respectively 10 times and 25 times. After compounding the property of the whey protein concentrate film ameliorates. The elongation at break, tensile strength of the whey protein concentrate film increases respectively by 9 times and 16 times after the glutin is mixed. The elongation at break, tensile strength of the whey protein concentrate film increases by 1.1 times and 12 times after the chitosan is added.

Abstract: In this study, physical properties and antimicrobial activity of soy protein isolate edible films incorporated with essential oil monomers were tested. Adding amount of essential oil monomers could significantly change the physical properties of the films. Water-solubility of soy protein isolate edible films could be significantly reduced when adding essential oil monomers. With the essential oil monomers’ content increasing, the water vapor permeability increased at the beginning and then decreased. Tensile strength reduced with cinnamicaldehyde and eugenol content increasing, but the tensile strength of cinnamaldehyde-eugenol (1:1) compound films reduced at first and then increased. The breaking elongation of cinnamaldehyde-eugenol (1:1) compound edible films was the highest. Using cinnamaldehyde, eugenol and cinnamaldehyde-eugenol (1:1) compound as the antibacterial agent respectively, antibacterial activities of soy protein isolate edible films incorporated with1, 2, 3, 4, 5and6% essential oil monomer were evaluated against Escherichia coli, we found that antibacterial activities of soy protein isolate edible films incorporated with essential oil monomers were significant, film containing cinnamaldehyde was the most effective.

Abstract: Soybean proteins have shown great potential for use as renewable, environmentally friendly adhesives. In this research, poly(vinyl acetate)(PVAc) latex and some auxiliary agent were used to modify soy protein isolate(SPI). The chemical microstructure of the adhesives was obtained by means of Fourier transform infrared spectrometry (FTIR). The influence factors of the bonding strength and the water resistance of SPI adhesive were studied by different mass ratios of the SPI and PVAc latex, the blending time and the crosslink time. A better synthesis condition is as follow, the mass concentration of SPI is 13%; the mass concentrations of urea, PVAc latex and the crosslinker is 6%, 11.1% and 1.5%, respectively(relative to the total mass of SPI and water), and the crosslink time is 1.5h. The thermal properties are studied and the mechanism is discussed.

Abstract: Using amino nitrogen content ( AN for short ) as standards, the conditions of low molecular weight polypeptides with three kinds of enzymes hydrolysis as well as the sequence and way of adding enzymes with microwave heating was found in this paper, which was examined by fluorescence analysis method, seperated by Sephadex G-50. The result shows that three kinds of enzymes hydrolysis were prefer to one enzyme obviously, amino nitrogen was higher for 2813.4 mg/L, the relative molecular mass of soybean polypeptides was mostly below 1000 D. Soybean polypeptide was well tested and seperated by Sephadex G-50 and fluorescence analysis method.