February 2001 - Newsline

Aussies Claim Invention of BSE-Free Rendering Process

By Tina Caparella

Australian Dehydration Technologies (ADT) Pty., Ltd., has developed a new process that its developers claim delivers sterile resource recovery of animal wastes, including elimination of the prions that cause bovine spongiform encephalopathy (BSE). This new technology is a result of Phill Kemp, an animal nutritionist who originally set out to produce high quality protein meals from waste products.

“We set out to develop a simple and readily incorporated process that would have application across the full spectrum of the existing industry applications,” said Kemp, ADT managing director. “Further, we wanted to enable both small and large-scale plants to be able to be sited and operate within environmentally sensitive areas.” ADT stated that as the technology developed and internationally published data was considered, that BSE control could possibly be achieved. Clinical testing is currently being arranged to verify this claim. Dr. David Taylor, a BSE scientist, has introduced the application for consideration of United Kingdom government funding.

“I have confidence that transmissible spongiform encephalopathy (TSE) agents are reliably inactivated by hot alkali which stemmed originally from my own work [and that of others] in which autoclaving at 121 degrees Celsius was carried out in the presence of alkali,” said Taylor. “Encouraged by these data, it was considered that much lower temperatures could also be effective. This led to the work that I carried out with the 301V strain of mouse-passaged BSE agent, in which inactivation was achieved by simply boiling for one minute in alkali. The likely reliability of combining heat and alkali is reflected in the fact that such methods now feature as the recommended inactivation procedures in the World Health Organization guidelines on dealing with human
TSE agents.”

“The so-called BSE ‘prions’ are proteinaceous infectious particles thought to be responsible for spongiform encephalopathies,” said Professor John Nolan, an Australian nutritional biochemist at the School of Rural Science and Natural Resources in Armidale, New South Wales, who evaluated ADT’s technology. “Prions are extremely resistant to heat and chemicals, [but] ADT’s process appears to me to generate chemical and other necessary conditions for destroying protein functionality.”

The process is hydrolytic and does not rely on heat alone to achieve sterilization. It has been operating in Australia on a pilot commercial scale producing over 1,000 tons of protein meal from various sources.

“The ADT process relies on a hydrolytic reaction to break down the primary structure of the organic compounds including the prion proteins responsible for TSE,” explained Kemp. “This hydrolytic reaction is achieved by using relatively cheap and simple additives [desiccant] at lower temperatures than normally associated with even low temperature rendering. The resultant benefits of this are many, including lower energy input, higher protein digestibility, and improved sterility. The protein digestibility is enhanced by the lower temperatures not causing unwanted reactions, like Maillard reactions, to tie up amino acids, but also the hydrolytic effect of effectively predigesting the proteins to smaller peptide chains and elementary amino acids.”

ADT claims the technology is very simple and may be adaptable to some existing wet rendering systems but not dry rendering systems. The technology utilizes conventional equipment, but the concept differs quite radically in some respects, which allows the elimination of some conventional components. All organic wastes such as animal and poultry offals, meat processing wastes, fish and fish offals, and food processing wastes can be put through the process. The proteins derived from the system have a digestibility of up to 98 percent, according to ADT officials, with proven sterility from bacterial and viral pathogens, along with theoretical sterility of TSEs, including BSE and scrapie.

Rendering companies from around the world are currently evaluating the process and, according to ADT, are impressed with its qualities.

“Reduction of energy costs, about 10 percent better product, and significant capital cost reductions are very important considerations,” said Terry Mackenna of Cargill, Inc. “The sterility is the bonus.”

Features of the system include lower temperature operation; negligible, non-toxic odor emissions; operation in batch or continuous mode; does not require steam and is adaptable to a wide range of protein and oil content; and is suitable for integrated sites or stand-alone resource recovery operations and can utilize waste heat as its source. The process has Australian Environmental Protection Agency and local government approval.