Enzyme hydrolysis extracts protein from the by-products of animal processing. These are typically waste materials from slaughterhouses and fish processors. They include meat and fish scraps, cartilage, bones, intestines, feathers, scales, blood, skin and hair. Animal protein hydrolysates have a range of food and non-food applications.
Amino acids make up the chain structure of proteins. Hydrolysis is the breaking of the covalent bonds between the amino acids. Some substrates can become more soluble after hydrolysis. Increased solubility brings a range of value-adding benefits. These benefits include improved digestibility, emulsification, foaming, viscosity, mixability, and water absorption. Extensive protein hydrolysis can even reduce allergenicity.
The first step in the production of meat and fish protein hydrolysates is the application of endo-proteases. Endo-proteases cleave peptide bonds in the interior of polypeptide chains. That solubilizes the by-product and creates protein hydrolysates.
The degree of hydrolysis (DH) is a key parameter of a protein hydrolysate. DH is the percentage of peptide bonds cleaved. Flavor intensity (e.g. meat, fish, vegetable, umami) increases as the protein is broken down. Eventually, hydrolysis breaks proteins down into small peptides and amino acids.
Bitterness is an unwanted taste sensation associated with hydrolysis. It’s thought that it’s caused by peptides of a certain size with terminal hydrophobic amino acids. Exo-peptidases degrade the bitter peptides. That’s why a blend of endo- and exo-peptidases is usually recommended to reduce the bitterness of high DH hydrolysates. Adding a glutaminase to the final step further develops a premium umami flavor. Every step in this process adds more value to the final protein hydrolysate product.
Enzymes are used in pet food to hydrolyze protein for flavor generation. Spraying the hydrolysates on the outside of dry kibble enhances flavors and palatability. Hydrolysates used inside the kibble improve taste. When used directly in wet pet foods they act as an overall flavor system.
Enzymes are also used to extract gelatin and hydrolyzed collagen from animal by-products. These are sourced from bones, hides and skins. Soaking and liming times in gelatin and hydrolyzed collagen production can be up to 12 weeks. By using enzymes you can reduce this to as low as 17 days. Saving production time reduces costs and increases capacity.
Glycosaminoglycans (GAGs) can be extracted from lungs, intestinal mucosa, trachea, rooster combs, skin and other tissues. GAGs are covalently linked to surrounding tissues and core proteins. Enzymatic hydrolysis breaks these down. Enzymes can reduce or even eliminate the need for traditional alkaline hydrolysis. They can also improve process efficiency and sustainability, while reducing costs.
Poultry feathers contain 80–90% keratin – an excellent source of protein for animal feed. But its poor digestibility limits its value. Enzymatic hydrolysis of feathers improves digestibility. That unlocks the value of this waste stream while reducing its environmental impact.
Enzymes can also hydrolyze yeast cells. The result is a yeast extract. This is separated from the cell wall material at the end of the hydrolysis process. Traditional yeast extract production uses endogenous enzymes released when cells rupture. Exogenous enzymes complement this process by helping to separate the yeast extract from the cell walls.
