Aim: Dehydrated beef proteins are a co-product of edible meat from the fat rendering process that are underutilized in human food. The valorization of these bovine co-products would increase protein resources of good nutritional quality. Giving value to such co-products would reduce the amount of waste and therefore it would contribute to a more sustainable and profitable meat industry. Method: In this study, two beef co-products were first characterized with regard to their composition. Second, the response surface methodology was used to characterize and optimize protein solubility and gelling properties by modulating pH (4 to 7), protein concentration (5% to 20%) and ionic strength (0 to 0.4M NaCl). The responses of gelling characteristics as a function of the three factors were adjusted to second-order polynomial models. Results: These products mostly consisted of proteins (ExtraBeef80: 83.71%±1.17; K85G: 62.32%±0.00), with molecular weights ranging from 10 to 300 kDa, corresponding to sarcoplasmic, myofibrillar and connective tissue (collagen) proteins in the soluble fraction. Protein concentration was the most significant factor for almost all the characteristics measured. However, basic pH significantly decreased water loss of ExtraBeef80 gels, and high ionic strength positively affected deformation at the rupture of ExtraBeef80 gels, and the water loss of ExtraBeef80 gels. Optimum conditions have been determined for each characteristic, in order to get closer to the performances of commercially available beef gelatins. Conclusion: This information of the composition and gelling properties of proteins co-products can be useful in guiding the development of functional ingredients suitable for specific uses.