Interaction of Ternary Biopolymers Obtained from Microwave Dry-heated Mixtures of Gluten, Whey Protein Concentrate and Kaolinite

Gluten, whey protein concentrate and kaolinite mixtures were irradiated at microwave oven for different period of time. Based on these powders, ternary gluten, whey protein, kaolinite biopolymer composites were obtained by dispersing in water and heating for 30 min at 80 degrees C. Produced biopolymer composites were dried in a thermostatic cabinet. The optimal irradiation time was determined by measuring small strain rheological properties using an oscillatory rheometer. The mixture of gluten and whey protein concentrate produced several times stronger gels than the singular proteins. It suggests that microwave heating propagated interactions between gluten and whey proteins. The biggest hardness was noted for composites obtained from powders irradiated for 30 s. SEM and elements mapping showed good dispersion of kaolinite particles in the gluten/whey protein matrix. Dry-heating of the mixed gluten, whey protein and kaolinite at 30 s caused interactions (probably mostly disulphide bridges) between unfolded protein molecules. Longer irradiation time than 30 s probably led to highly crosslinked network which negatively affected the properties of bioplastics.