Exploitation of bones-rich poultry by-products to produce protein hydrolysates: optimization of hydrolysis parameters and chemical characterization.

A significant quantity of bone-rich poultry by-products must be disposed of by poultry processors. These products still contain a significant amount of nutritionally valuable animal proteins. In the present work, a hydrolysis protocol was optimized to recover the protein fraction of bone-rich poultry by-products while simultaneously minimizing the amount of water required for hydrolysis (thus reducing drying costs) and recycling the hydrolytic broth up to three times, to reduce the cost of the proteolytic enzyme. The final hydrolysis conditions involved the use of (protease from B. licheniformis, ≥2.4 U/g; 0.5 V/w of raw material) and a hydrolysis time of 2 hours at 65°C. The protein hydrolysate obtained has a high protein content (79-86%), a good amino acid profile (chemical amino acid score equal to 0.7-0.8) and good gastric digestibility (about 30% of peptide bonds are already hydrolyzed before digestion). This supports its use as an ingredient in food, pet food or animal feed formulations.