Effect of Ensilaging and Organic Solvent Treatment on Activity of Proteases from Chicken Intestine

Valorization of Proteins from Co- and By-Products from the Fish and Meat Industry

Large volumes of protein-rich residual raw materials, such as heads, bones, carcasses, blood, skin, viscera, hooves and feathers, are created as a result of processing of animals from fisheries, aquaculture, livestock and poultry sectors. These residuals contain proteins and other essential nutrients with potentially bioactive properties, eligible for recycling and upgrading for higher-value products, e.g. for human, pet food and feed purposes. Here, we aim to cover all the important aspects of achieving optimal utilization of proteins in such residual raw materials, identifying those eligible for human consumption as co-products and for feed applications as by-products. Strict legislation regulates the utilization of various animal-based co- and by-products, representing a major hurdle if not addressed properly. Thorough understanding and optimization of all parts of the production chain, including conservation and processing, are important prerequisites for successful upgrading and industrial implementation of such products. This review includes industrially applied technologies such as freezing/cooling, acid preservation, salting, rendering and protein hydrolysis. In this regard, it is important to achieve stable production and quality through all the steps in the manufacturing chain, preferably supported by at- or online quality control points in the actual processing step. If aiming for the human market, knowledge of consumer trends and awareness are important for production and successful introduction of new products and ingredients.

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

BACKGROUND

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.

RESULTS

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.

CONCLUSION

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.