Comparison of Two Moulding Processes for Dog Chew Manufacture Made by Cowhide Offcuts

The common tailing, cowhide offcuts, was selected as raw material for dog chew products. Meanwhile, several techniques, such as differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and so on, were applied to analyze physicochemical properties of product in order to distinguish the influences of two processes on properties of products. Many efforts were invested on the effect of protein structure modification on product properties. The results revealed that compared with the product made by the injection molding process, the one obtained by the single screw extrusion forming process had significant better performance in apparent density, hardness and chewiness (p<0.05), which ascribed to the different extent of protein molecule structure modifications in these two processes. In the extrusion process, protein molecules preferred to contain more β-sheet and random coil with the cost of α-helic and enhanced cross-linking process. As a result, in generally, the product made by single screw extrusion forming process presented better quality than the one made by the injection molding process.