14 January 2000

Abattoir steam can blow away Ecoli bacteria

By Emma Penny

STEAM pasteurisation in abattoirs could help reduce risk of E coli 0157 infection transferring from carcasses through the food chain.

Thats the premise behind a MAFF LINK trial to develop a steam pasteurisation system suitable for use in UK slaughterhouses, which is now undergoing tests in a Leics abattoir.

According to government statistics, the incidence of food poisoning caused by E coli 0157 has risen from 600 cases in 1992 to almost 1500 in 1997.

The Pennington report, produced in the aftermath of the Lanarkshire E coli outbreak, recommended that producers took steps to ensure animals being sent to abattoirs were clean. But also recommended that the meat industry should examine steam pasteurisation as a means of reducing contamination.

Steam pasteurisation is widely used in the US. Air blowers dry the surface of carcass sides, which then pass through a steam chamber at 85-95C (185-203F) for 8-12 seconds. The process is similar to pasteurising milk, with a short burst of high temperature inactivating a large proportion of bacteria on carcass surfaces.

Now, the process is being investigated in the UK under a MAFF LINK project involving the MLC, Campden and Chorleywood Food Research Association, the University of Nottingham, Dawn Meats, Dawkins abattoir and Marks and Spencer.

Marks and Spencer livestock technologist Chris Brown points out that E coli 0157 is found on the surface of meat, so pasteurisation could help reduce risks.

MLC meat scientist Kim Matthews says the steam pasteurisation process fits in well with HACCP – hazard analysis critical control points – as it provides another control point.

However, carcasses are just being cleaned at the end of the process, and there is a danger consumers will think all bacteria in meat are killed.

"Clean cattle, clean knives and so on are all critical, and steam pasteurisation is just another step in trying to reduce risks. Only cooking will help kill all bacteria in meat," he says.

But while steam pasteurisation is widely used in the US, the equipment is generally too large and too expensive for most UK abattoirs. "We needed to develop a smaller, cheaper option. This has been developed and is currently being evaluated," he says.

The trials will answer questions about steam pasteurisation under UK conditions, including the time and temperature required to kill bacteria, as well as its effect on eating quality. This may differ because UK carcasses are leaner.

"We also age meat for longer in the UK than in the US, and so need to evaluate bacteria growth in storage. There is potential to re-introduce bacteria when carcasses are cut, as remaining bacteria will grow more rapidly in the absence of competition, but trials so far indicate no additional risk."

Regulatory approval must also be sought for steam pasteurisation. But Mr Matthews believes this is unlikely to be a problem because carcasses will be inspected before pasteurisation, and only water is being used in the process, with no other additives.

"The pasteurisation plant is in and working at Dawkins abattoir, and we have established the optimum temperature and time for treatment. We are about to start a full-scale evaluation to see whether the system actually increases food safety."

During the evaluation, 150 carcasses will be assessed, with one side of each carcass being pasteurised and the other side processed as normal. Both sides will be checked to see whether there is a difference between the two. These carcasses will not be sold because they are just for testing the process.

"If the process proves effective, it may be that all UK abattoirs will have a steam pasteurisation plant," adds Mr Matthews. "Its one more tool in the armoury for ensuring food safety."

STEAM PASTEURISATION

&#8226 Used throughout US.

&#8226 Now in UK trial.

&#8226 Cuts bacterial loading.

STEAM PASTEURISATION

&#8226 Used throughout US.

&#8226 Now in UK trial.

&#8226 Cuts bacterial loading.