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BACKGROUND: The production and consumption of chicken has doubled in the last 17 years. Since slaughter yields range from 70 to 80%, during production various chicken waste residues are generated. One of these residues is waste created after the mechanical separation of chicken meat (W‐MSM). The goal of the circular economy is to manage this waste and transform it into a valuable product. RESULTS: W‐MSM was subjected to hydrolysis by the proteolytic enzymes pepsin and papain to obtain bioactive compounds. Papain digestion resulted in several times higher yields of chondroitin sulfate (CS), hyaluronic acid (HA), peptides and amino acids in comparison with pepsin. The hydrolysis conditions were further optimized using the software Design Expert to evaluate the impact of added enzyme, buffer and duration of the hydrolysis. In addition, the scale‐up of this process was verified with 5 kg of W‐MSM and the obtained product contained approximately 77% (w/w) of peptides, 9% (w/w) of CS, 7% (w/w) of HA and 4% (w/w) of amino acids. CONCLUSIONS: We tested and optimized the method for evaluating the direct waste from poultry processing and transformed it into a product containing bioactive compounds which can be utilized as an ingredient for improving the properties of feed. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

ABSTRACT BACKGROUND Millions of tons of feather waste from the poultry industry are disposed of annually despite containing a high level of keratin. The aim of this study was to compare the hydrolysis of non-treated feather waste using three different approaches (whole cell microbial digestion, enzymatic and chemical cleavage) and to test the use of hydrolysates as peptone substitutes in a culture medium. RESULTS Among bacterial isolates, Pseudomonas sp. P5 exhibited the highest keratinolytic activity and efficiency to hydrolyse raw feather material. The hydrolysates contained up to 301 mg L−1 of free amino acids and 6.2 g L−1 of peptides. Hydrolysates obtained by digestion using semi-purified keratinase from Pseudomonas sp. P5 were richer in amino acids (1191 mg L−1, 56% essential ones) but peptides were present in lower amounts (up to 3.3 g L−1). The third approach was feather treatment under mild alkaline conditions. This provided the highest amount of peptides (17.2 g L−1) but a significantly lower level of amino acids, especially the essential ones. CONCLUSIONS All approaches tested could convert raw feather waste into products of commercial value with proven use in a cultivation medium. The level of peptides, their molecular size and amino acid composition was dependent on the method used. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]