The combination of microwave and hot-air drying to prepare collagen fiber powder from cowhide

In this study, a new and efficient method combining microwave and hot-air drying was developed to prepare collagen fiber powder (CFP) from cowhide. The cowhide was first dried to a certain humidity by microwave, and then dried under different hot-air treatment times (6 h, 12 h, 18 h, 24 h, 48 h). The physicochemical and functional properties of CFP were evaluated. The results indicated that extending the hot-air drying time increased the crushing rate and decreased the particle size of CFP. Ostwald de Waele model analysis showed that CFP solution was a typical pseudo-plastic fluid with shear-thinning behavior. Moreover, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis showed that the crystallinity and thermal stability of CFP decreased with the extension extending of drying time. In addition, the hydrogen bond content of CFP decreased by fourier transform infrared spectroscopy (FTIR) and secondary structure analysis, and the ordered structure of collagen changed into disordered structure gradually.