Values-added utilization of protein and hydrolysates from animal processing by-product livers: A review

Livers, by-products from animal processing, serve as an excellent source of high-quality protein and bioactive enzymes. The need for animal protein resources encourages the search for and use of unconventional supplies. However, animal livers are commonly sold unprocessed at a low price since their unique properties and high-value utilization have not been fully explored. Fully use of animal livers provides an opportunity to utilize existing resources of food protein to the utmost and reduce the environmental pollution from the meat production when these raw materials not properly processed. Efficient and environmentally-friendly extraction of liver protein and its hydrolysates, biological activities and potential applications are reviewed in this contribution. In addition, value-added utilization of liver protein and its hydrolysates are discussed. Furthermore, certain liver proteins, bioactive enzymatic hydrolysates and natural enzymes, as well as their potential utilization in agriculture, food, and medicine are evaluated. Key finding and conclusions: Innovative technologies guarantee effective conversion of animal processing by-products into biologically active protein hydrolysates and procurement of high activity proteases. Animal liver protein and its hydrolysates have attracted much interest due to their broad applications in food, healthcare, animal feed and veterinary products. However, there is a need for intensive research on biological activity of liver protein and its hydrolysates in organism as well as on the regulation in animal by-products. Therefore, liver protein and its hydrolysates produced at industrial level would offer a value-added product for meat processing industry, and helps achieving resource sustainability.