Abstract
The potential food and nutrition applications of keratin are very promising. The physicochemical and nutritional profile of keratin is discussed in relation to its suitability for human consumption as well as the challenges that may limit its food applications. Various physical, chemical, microbial and enzymatic extraction techniques have been reported for the solubilization and hydrolysis of keratin. All the methods have advantages and disadvantages and vary in their safety, efficacy and effects on the final keratin product. Several examples of keratinase-producing microorganisms (keratinolytic fungi, bacteria and actinomycetes) are presented, and their mechanisms of keratin dissolution are discussed. The potential application of keratin and keratin hydrolysates in food and nutrition is discussed. Keratin and keratin hydrolysate amino acid profiles suggest high-quality protein supplemented with limiting amino acids. The sensory properties, consumer acceptability and their safety for human consumption need further research, but current information is very promising. Keratin hydrolysates or peptides have been found to exhibit various biological properties, such as antioxidant, Angiotensin I-converting enzyme (ACE) inhibitory, and antidiabetic or dipeptidyl peptidase-IV (DPP-IV) inhibitory activities. Overall, keratin has great potential to be utilized in food and nutrition as an alternative protein to combat food crises and to improve the physicochemical and nutritional profiles of food.