The slaughter of animals for meat is one of the few industries that turn almost every piece of waste into a useful by-product. Hide, hair, glands, fat, bones, organs and intestines arc converted into raw materials for a wide range of industrial. medical, human and animal food products.But there is one waste product that is exceptionally difficult to deal with, and until recently has defied efforts to find a satisfactory solution for its disposal. That is blond residue.In 1982 more than 800,000 tons were dumped into public drainage systems throughout Europe.The hidden cost to taxpayers of pollution and of the burden on sewage purification plants is high. In biological terms, the problem of disposal lies in neutralizing the protein proportion, 140,000 tons, of the blood residue.Several countries have developed methods of protein recovery. In Denmark and Finland it is partially processed into animal feed for mink farms.But the cost of that partial recovery is high and the protein recovered represents only a quarter of that available.Two years ago France, which has the biggest slaughterhouses in Europe, began a two-year study into how abattoir blood residues might be used rather than simply neutralized for efficient disposal.The outcome was a biotechnology process producing an alternative to soya or whey proteins, the additions to sausages, patés, cooked meats and meat pies which supplement meat content or provide certain functional properties,The process was perfected in conjunction with the Danish biotechnology company Novo Industri, a large manufacturer of industrial enzymes, which has developed a biotechnology-based process. It separates the haem (colouring pigment) from the globin in blood pigment, thus allowing all of the protein available in residue to be recovered.
A plant on a commercial scale is to be tested in France soon.
The process is a combination of biochemical conversion with special enzymes and mechanical filtration that turns most of the original dark fluid into a cream-coloured powder.
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