Technical Abstract: The cattle hide, a major byproduct of the US meat industry, is the tanner’s substrate, and also the source of collagen for the food and biomaterials industries. Conversion of animal hides into leather is a multistep process that continually evolves in response to economic and environmental concerns. Processing changes are generally evaluated in terms of impact on tannery costs and quality of leather produced. Because the basis for tanning and other biomaterial applications is the stabilization of the collagen matrix, changes to the molecular characteristics of hide collagen may be expected to impact these applications. In previous studies, we began the development of protocols for production and utilization of powdered hide from specific steps in beam-house processing. In this study, the effects of pretanning processes on the structure, stability and reactivity of hide collagen with tanning materials are evaluated. For example, exposure to pickling conditions dramatically lowered the denaturation temperature for powdered hide collagen. The results are anticipated to assist the tanner as well as the manufacturers of collagen-based biomaterials and gelatin to better understand their substrate and changes to it that may occur when beam-house processes are altered