ENZYMATIC-HYDROLYSIS OF THE HORN AND HOOF OF COW AND BUFFALO

With the aim of efficiently utilizing livestock waste as a protein res ource, we studied their enzymatic hydrolysis. Particles of a mixture o f horn and hoof from cow and buffalo with a diameter of less than 250 mu m were selected for use as substrate, and a proteinase from Bacillu s subtilis, selected from among various commercial proteolytic enzymes was used. For enzymatic hydrolysis of the substrate, heat treatment w as absolutely necessary prior to digestion and the conditions for the enzymatic reaction were determined to be as follows: reaction time, 30 to 60 min; pH, 8.3; temperature, 50 degrees C; weight ratio of substr ate to enzyme, 1:0.05; and concentration of substrate, 62.5 g/l. Even when a membrane reactor was used, the amount of enzyme required could not be reduced. However, repeated-batch reaction allowed us to reduce the added amount of enzyme. The enzyme was added only for the first ro und of the reaction in four rounds of repeated-batch reaction. As a re sult of this process, the weight ratio of substrate to the enzyme was reduced to 1:0.023 from 1:0.05 at a final substrate concentration of 6 1 g/l.