Hydrolyzed feather keratin obtained by microbial fermentation encapsulated with maltodextrin – A sustainable approach to increase digestible protein in feed

Abstract

Feathers are a bulky and problematic by-product of the poultry industry, consisting mainly of keratin that can be used as a protein source if appropriately hydrolyzed. The strain B4 successfully hydrolyzed feathers, reaching a maximum soluble protein concentration of 2.97 g/l with a productivity of 0.65 g/l/d in feather media previously standardized. After improving feather and yeast extract concentrations, the soluble protein increased to 9.26 g/l and the productivity to 1.53 g/l/d. The hydrolysate, showing peptides mass ranging from 500 to 1057 m/z, was microencapsulated with maltodextrin by spray-drying to produce powdered hydrolyzed feather (PHF). PHF had 11.4 g/100g of crude protein, 75.01 g/100g of starch, and 2.37% of moisture. The most abundant amino acids in PHF are leucine, valine, and glutamic acid, besides a high histidine and lysine concentration. Bacillus sp. B4 was also microencapsulated, and after 14 months, 80% of cells remained viable. This study describes a new biotechnological product based on microencapsulated feather hydrolysate. PHF was stable, soluble, with low moisture content, rich in amino acids, and maintained the viability of potential probiotic cells as Bacillus sp. B4, showing potential as a functional supplement for animal nutrition. • Feathers can be efficiently hydrolyzed by Bacillus sp. B4 in low mass peptides. • The hydrolysate was microencapsulated with maltodextrin to produce a powder (PHF). • PHF was rich in leucine, valine, glutamic acid, histidine, and lysine. • Bacillus sp. B4 was successfully microencapsulated with hydrolysate. • For the first time, feather hydrolysate was microencapsulated by spray-drying.