Production of feather protein hydrolyzed by B. subtilis AMR and its application in a blend with cornmeal by extrusion

Abstract

The poultry industry produces approximately 6 million tons of feathers as a by-product annually. The major constituent of feather is protein (80–90% of which is keratin). In order to use feather protein in animal feedstuffs, it must be hydrolyzed by chemical, physical or enzymatic processes. The aim of this study was to improve the production of chicken feather hydrolysates using keratinolytic Bacillus subtilis AMR and evaluate the effectiveness of a blend of this hydrolysate with cornmeal produced by extrusion. The addition of sucrose (0.5 g/L) to the feather medium increased the keratinolytic activity of B. subtilis AMR by 1.3 fold. The highest enzymatic activity and production of soluble protein were achieved at pH 8.0. The fermented feather medium presented large amounts of protein with low molecular weight that provided greater nutrient bioavailability. The physicochemical properties of the extrudates showed that the addition of hydrolyzed feather improved the ash and total N content. All essential amino acids were detected in the corn–feather hydrolysate extrudate. This work represents the first study that describes the use of microbial feather hydrolysate in a blend with cornmeal to make an extruded product. These results demonstrated the potential use of this hydrolysate as a supplement in animal feed.