Slaughterhouse by-products became discredited during the BSE (Creutzfeldt-Jakob disease) euphoria - however, the disease is conceived while the animal is alive and calls for prompt action in order to stop the spreading and control the damages and that is what government entities do. When slaughtering healthy animals and collecting slaughterhouse by-products as gelatine, skin, brain, blood, organs, glands, etc., the product becomes a natural and environmentally compatible raw material for the industry in general.

What are slaughterhouse by-products used for?
Slaughterhouse by-products are mainly used as additives to human or animal feed products.
The equipment for processing and drying slaughterhouse by-products has undergone radical changes with regards to environmental, health, and safety requirements. These changes and increasing demands from the slaughterhouse by-products industry for hygiene have led GEA Niro to develop state-of-the-art processes with minimum energy consumption, reduced effluents loads, and reduced fresh water consumption with optimal value adding to the raw materials focusing on health and safety for plant personnel and end-user.

Hygienic standards of processing 
The collection, transportation, and processing of slaughterhouse by-products intended for human or animal consumption must comply with hygienic standards that are certified and controlled by health and safety authorities. The hygienic demand calls for specialized processing factories that handle sufficiently large volumes of product in order to ensure and certify the necessary standards requested by the authorities.

75 years of experience in world-wide industrial process development, design, construction, and maintenance of food production facilities enables GEA Niro to provide tailormade solutions for any specific industrial need including filtration, carbon treatment, ion exchange, fractionation, hydrogenation, extraction, evaporation/concentration, fluid bed drying, spray drying, and freeze drying.

Animal blood
Animal blood is either spray dried as regular whole blood or after separation into plasma and red albumin. To ensure an economically feasible drying process, all blood products are concentrated in a falling film evaporator until they reach around 150 centipoises viscosity before drying. All slaughterhouse by-products are dried at low temperatures in order to prevent heat coagulation or Maillard reaction. Both nozzle and rotary atomization can be used in co-current flow dryers.

Animal gelatine
Animal gelatine is either spray dried as simple gelatine or hydrolyzed gelatine, i.e. partial or total splitting of the long gelatine molecules into smaller fragments. This is done with chemical or enzymatic processes followed by refining and other unit operations for obtaining the required product cleanness and or property. To ensure an economically feasible drying process, all gelatine products are concentrated in a falling film evaporator until they reach around 150 centipoises viscosity before drying. Again, the processes and equipment are designed with respect to raw material and final product specifications. Both nozzle and rotary atomization can be used in co-current flow dryers. 

Animal skin 
Slaughterhouse skin by-products can be treated and become a good protein source with efficient water binding properties. The skin is shredded into 3 x 3 mm pieces and washed. The wash water is filtrated for impurities and the dissolved proteins are concentrated in a falling film evaporator reaching up to 300 centipoises. The concentrated protein is mixed back into the clean and centrifuged skin-shreds; the skin-shreds absorb the concentrated protein and can be dried in a fluid bed with a special inlet section with agitated powder layer. The dry material will contain approx 7 percent water and have an acceptable industrial shelf life.

Animal mucus
Intestines are usually washed in the slaughterhouse; the intestine wash water contains valuable mucus that can be recovered, cleaned for pathogen material, concentrated to 150 centipoises, and spray dried. Both nozzle and rotary atomization can be used in conventional dryers depending on the required powder properties.

Animal brain, organs, glands, and ligaments 
The above by-products are either disintegrated to particles less than 100 micron, concentrated to around 150 centipoises viscosity, and stabilized to become suitable feed for the spray drying process, or hydrolyzed, filtered, and stabilized before spray drying. However, since these products are somewhat thermoplastic and hygroscopic or have a high percentage of free fat, a  Fluidized Spray Dryer FSD™ is most appropriate for the drying process.

Some of the above by-products contain high valued compounds. The high market price of these compounds/products makes a profitable opportunity for the “mining” for lipo-proteins, peptides, enzymes, hormones, insulin, etc. that can be extracted out of glands and organs, concentrated, dried for storage, and further processed or sold as raw material for other industries. For the extraction process with acid/alkali water or water-solvents mixtures, GEA Niro recommends the CONTEX™ counter current extractor.

Process equipment for slaughterhouse by-products
Spray drying is one of GEA Niro’s core businesses and perhaps the most important continuous drying technique for converting solids suspended or dissolved in a liquid formulation into powders. The feed is atomized into droplets; these droplets are directed into a controlled flow of hot air, powder particles are formed as moisture evaporates from each droplet, and the dried product is discharged from the drying chamber. Depending on the type and the desired properties of the final powder, various spray dryer designs are selected.

When low thermoplastic and low hydroscopic products and low final powder temperature are required, a conventional spray dryer with powder transport and cooling is optimal. For more thermoplastic and hydroscopic products such as hydrolyzed protein or products rich on fat, the Fluidized Spray Dryer FSD™ with a high pressure nozzle and integrated fluid bed is recommended. Also, an Integrated Filter Dryer IFD™ with a high pressure nozzle, integrated plug flow fluid bed, and bag filters inside the drying chamber can be used.

For production facilities where odor is an issue, GEA Niro recommend sdifferent odor removing equipment depending on the environmental requirements. For moderate odor removal requirements, GEA Niro recommends an exhaust air wet scrubber. For conservative odor removal requirements, GEA Niro recommends a drying system in a semi-closed cycle where part of the exhaust air is incinerated and the rest is circulated after being washed.