Thermal and enzymatic recovering of proteins from untanned leather waste

The laboratory trials of a process to treat untanned leather waste to isolate valuable protein products are presented. In this comparative study, both thermal and enzymatic treatments of leather waste were performed. The enzymatic method utilizes commercially available alkaline protease at moderate temperatures and for short periods of time. The concentration of the enzyme was 500 units per gram of leather waste which makes the method cost-effective. Amino acid composition in the hydrolysate obtained by the enzyme hydrolysis of untanned leather waste is determined. Chemical and physical properties of protein powder products from untanned leather waste were evaluated by spectrophotometric and chromatographic methods and by use of electron microscope. The results of microbiological assays confirm that these products agree to food safety standards. This relatively simple treatment of untanned leather waste may provide a practical and economical solution to the disposal of potentially dangerous waste. (C) 2000 Elsevier Science Ltd. All rights reserved.