Progress beyond the state-of-the-art
In the process of production of meat for human consumption approximately 50% of the animal is turned into animal by-products. Around 15 m Mt of slaughter animals by-products are produced in total by the meat industry each year (EFPRA 2006-2009 statistics on European countries Austria, Belgium, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Lithuania, Netherland, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, UK). Over 9 m Mt tons comes from animals declared fit for human consumption. The rendering and fat industry provides the vital outlet for half of these materials by transforming them into a wide variety of products. From this raw material, 2.5 m Mt of fat and 3.4 m Mt of protein & mineral meal are produced annually as shown in Figure 1 and 2 (P. Coelenbier, EFPRA, Munich 2006).
Unfortunately most of the above is subjected to incineration or used as compost for soil fertilization
For decades the rendering of the animal by-products represented a substantial contribution to the European economy. As shown in Fig. 3, in 1995 the annual turnover of this attained 750 M€ (EFPRA).
The generic Rendering is depicted schematically below:
Traditional rendering technologies are based on long-term heating of the mixed residues (bones, meat trimmings, visceral residue, blood clot, legs& heads, feathers) in cookers at temperatures about 100°C and humidity 80%. This approach provides inactivation of infectious agents (viruses and bacteria), somewhat improves digestibility and allows separation of the input material into solid fraction and liquid tallow/ fat which are utilized separately.
However, this cooker technology consumes much energy because it requires heating big amounts of water (4 volumes per 1 volume of the input material) and subsequent removal of this water by vacuum and disc drying. Besides, cooking causes degradation of biologically valuable components (e.g. hydrolysis of deficient thermolabile amino acids methionine and cysteine, oxidation and hydrolysis of lipids) as well as appearance of abnormal and biologically harmful compounds in liquid and gas states (polyamines, mercaptanes, benzopyrenes, organic peroxides, ketones and aldehydes).
These mentioned factors convert the balanced protein of the input material to a meal with compromised alimentary and functional properties and low commercial price.
Nearly the same technology is now applied in Russia, where the final product of the rendering is transformed to feed ingredient (protein-mineral meal) in compliance to GOST 17536-82.