Proteolytic activity from chicken intestine and pancreas: extraction, partial characterization and application for hyaluronic acid separation from chicken comb

Abstract

The potential utilization of viscera and combs, by-products from the chicken-processing industry, was investigated. Chicken combs have been reported to consist of hyaluronic acid (HA) bound to protein. Thus proteases extracted from broiler viscera were applied to digest combs to separate HA, a high-value ingredient widely used in pharmaceutical and medical products. The highest activity of crude protease extracted from chicken intestine and pancreas was 0.35 U mg(-1) enzyme at 60 °C and pH 7.5. pH stability of the enzyme was attained from pH 6 to 8, while its thermal stability declined from 30 to 50 °C, with complete activity loss occurring after 30 min at temperatures above 60 °C. Therefore the optimal conditions for broiler comb digestion by crude protease in this study were chosen as pH 7.5 and 50 °C. The results showed that the yield of crude enzyme-extracted HA was lower (P < 0.05) than that obtained by commercial papain digestion. Similar identity of extracted HA and HA standard was verified by cellulose acetate electrophoresis and Fourier transform infrared spectroscopy. The crude enzyme extract from chicken intestine and pancreas had high proteolytic activity and could be used successfully to separate HA from broiler combs. The method provides an appropriate means to add value to poultry-processing waste.