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Canola meal (CM), a by-product of canola oil extraction, was modified by poly (styrene-co-glycidyl methacrylate) (PSG) and could potentially be used as a sustainable natural composite. Infrared analysis indicated that PSG could efficiently react with the proteins in CM and become covalently bonded. DSC results revealed that the modified CM composites showed new glass transition temperatures ( T g ) decreasing with the introduction of PSG, which were attributed to the disruption of intermolecular association. Torque curves and melt flow index tests showed the flow property of the modified CM composites increased due to interference by PSG of the hydrogen and disulfide bonding among the protein species. DMA results showed greater amorphous character for the modified CM composites and new glassy plateaus with increased storage moduli, indicating a change in molecular structure and enhancement in mechanical property and usability below T g . Furthermore, the thermostability, the tensile strength, and the elastic moduli of the modified CM composites increased because of the formation of cross-linked proteins in the CM composites, which will potentially increase the application value in some fields, such as single-use agricultural planting containers replacing high-impact polystyrene (HIPS) containers, and food or coffee trays. [ABSTRACT FROM AUTHOR]

To increase the usage value of canola meal (CM), a by-product of canola oil extraction, poly (styrene- co -maleic anhydride-co-glycidyl methacrylate) (PSMG) was prepared and used as a novel chain extender to modify CM. FTIR tests showed that cross-linking took place in the CM matrix and PSMG was covalent bonded with canola proteins; furthermore, the surface of fibers present in the CM composite was covered by proteins, attributed to the reactivity of anhydride groups on PSMG. The modified CM composites showed more apparent amorphous characteristic with the addition of PSMG, according to DSC results. DMA results suggested that cross-linked proteins could be further coupled by glycerol reacting with the anhydride groups remaining in the cross-linked proteins, and thus the storage moduli and the glass transition temperature ( T g ) of the modified CM composites increased with the addition of more PSMG. The reactions of proteins with proteins, proteins with fibers, and proteins with glycerol were further confirmed by TGA. SEM images showed that the CM matrix became much denser and the interfacial adhesion between fibers and the CM matrix was increased by the chemical modification, which also contributed to an increase in the tensile strength of the modified CM composites. [ABSTRACT FROM AUTHOR]

Two branched canola protein isolates (CPI) with different branching degree were prepared using bis-epoxide as a chain extender. It was found that the branching reaction may take place in any protein fraction in native CPI; furthermore, by increasing the amount of chain extender, more native protein chains in CPI were coupled to form branches. In the study of flow properties of native and branched CPI solutions, it was found that the apparent viscosities of two branched CPI remarkably increased compared to that of native CPI over all concentrations tested. At 22 °C and pH 7, native CPI solution showed slight shear thinning behavior with the increase of shear rate; however, shear thickening was observed at low shear rate for branched CPI. Furthermore, shear thickening was more pronounced with the increase of branching degree and concentration of branched CPI solution. Shear thinning behavior of native CPI became marked at pH 11; however, the shear thickening property of branched sample was weakened at high pH. The novel findings in flow properties of the branched CPI solution could be potentially applied in the food industry, such as increasing foaming property and gelling ability of food products. [ABSTRACT FROM AUTHOR]

Cross-linked canola protein isolate (CPI) films were prepared using a bisepoxide as a chain extender by wet cast followed by heat compression. By DSC measurements, it was verified that the cross-linking reaction took place in the CPI matrix and was completed in 10 min at 90 °C. FTIR analysis confirmed that the chain extenders were covalently bonded with CPI chains. The reaction led to the formation of a cross-linked architecture which was revealed by an increase in molecular weight of the modified CPI films. The newly formed chain architecture increased the thermostability of CPI as evaluated by TGA; furthermore, the thermostability increased with the increase in cross-linking degree of the modified CPI films. DMA results of the unmodified CPI film showed that microcosmic phase separation occurred between two major proteins, cruciferin and napin in CPI; however, the extent of phase separation decreased with the increase of chain extenders and finally disappeared because of the increased compatibility between cruciferin and napin. Elastomeric mechanical behavior was observed with the introduction of cross-linked architecture in the modified CPI films. At low humidity of 55%, the cross-linked CPI films showed an increase in tensile strength and a decrease in elongation at break. At high humidity of 98%, the increase in hydrophobicity of cross-linked CPI matrix resisted the decreasing tensile strength seen in unmodified films. [ABSTRACT FROM AUTHOR]