Feathers constitute between eight and 10 percent of chicken live weight, and currently Australian poultry processors produce somewhere in the region of 86,000 to 111,000 tonnes of feather waste annually. The majority of this is rendered for animal feed application, with a return of less than one dollar per kilogram. With about 90 percent protein content, poultry feather is potentially a rich and renewable source of protein. However, the protein in feather is in the form of keratin, which is highly complex and inaccessible.
Hydrolysed keratin can be used in many industrial applications including animal feed, fertiliser, cosmetics for skin and hair treatments, leather tanning, biodegradable films, and as a carrier for insecticides and other active agents. The cost of cosmetic grade keratin hydrolysate currently ranges between $50 and $130 per kg. Thus, efficient conversion of feathers into hydrolysed keratin has the potential to add significant value to feather waste, as well as mitigate environmental issues associated with its disposal.
Dr Netsanet Shiferaw Terefe and her team at CSIRO is currently investigating the potential for recovering high quality keratin hydrolysates from feather waste in a CRC-funded project (Sub-Project 2.2.6 – Value addition to feather from poultry processing waste). Using a combination of ultrasonic and biological processes, Netsanet’s project is aimed at producing an efficient and cost effective ultrasound assisted enzymatic process to add value to this current waste stream.
Netsanet explained, “There are several approaches described in literature for converting keratinaceous materials into more accessible keratin hydrolysates. Broadly, these are hydrothermal, thermochemical or biological processes. The majority of patented processes for keratin hydrolysis use a thermochemical approach. Biological processes involve the use of keratolytic microorganisms, or enzymes produced by such organisms. Keratinases from Bacillus sp., especially from Bacillus licheniformis, are well documented”.
She continued, “Microbial and enzymatic processes have the advantage of being environmentally friendly, yield high quality hydrolysates with better digestibility and bioavailability and maximal retention of liable amino acids. The main drawback of biological processes is the cost of processing (with the long processing time) and the high cost of enzymes. A possible approach for improving the efficiency of keratin hydrolysis is via the use of ultrasonics. The application of ultrasound at appropriate conditions can enhance the kinetics of enzymatic reactions, potentially reducing enzyme dosage or reaction time”.
To date, Netsanet’s work has managed to successfully develop a laboratory scale process for the hydrolysis of feather, and further purification of the hydrolysate. “A product with about 80 percent purity was obtained after the final nanofiltration and freeze drying steps” she said. The hydrolysate has excellent solubility, amino acid profile, emulsifying and foaming properties comparable to protein ingredients such as whey protein isolate, and very high antioxidant capacity comparable to strawberries. “The separation process may need to be further optimised based on the desired functionality and peptide profile for a given application”.
Outcomes from this project have the potential to enable the poultry processing industry to generate significant income from feathers, improving the economic and environmental sustainability of the industry.
