Effect of pH and Stirring Speed on the Collagenous Protein Extraction from Chicken Bone Waste in a Well Agitated Extraction System

Abstract

Chicken bones waste is commonly used for the production of animal feed and fertilizer. Fortunately, chicken bones are also rich in collagenous protein that possesses various functional properties. Considering this fact, the aims of this work are to determine the effect of pH and stirring speed on the alkaline extraction of collagenous protein from chicken bone. The experiments were carried out in a standard three necked flask equipped with heat supply, condensing and agitation facilities to perform isothermic well mixed extraction system. The extraction was conducted using caustic soda solution as solvent, extraction time (1 hour), temperature (80oC), the ratio of chicken bones:solvent (g/mL) = 1 : 4, and bone powders particle size (425 μm). The studied variables are pH: 9, 10, 11 and stirring speed: 100, 200, 300 rpm. The results showed that higher stirring speed and alkalinity of the extraction process resulted in higher protein yield. However, at very high stirring speed (300 rpm) and too alkaline (pH 11) extraction condition, the extraction lost its efficiency. The highest protein yield was achieved when the extraction was performed at pH 10 and stirring speed of 200 rpm for 60 minutes.