Daily sanitation programs in ready-to-eat meat and poultry product plants are employed to keep product contact surfaces in ready-to-eat production areas clean and Listeria-free. Some surfaces, like electrical boxes, wiring harnesses, or other interior surfaces of equipment are difficult or impractical to thoroughly clean at all, let alone on a daily basis. Steve Tsuyuki, senior director, food safety, Maple Leaf Foods, explained how heat treatment of equipment can successfully reduce microbial counts in even the most difficult to clean places.

Tsuyuki told the participants at the Improving Food Safety, Maintenance and Sanitation Workshop, presented by the American Meat Institute, during the International Production & Processing Expo, that heat treatment is like the semiannual teeth cleaning that we all get at our dentist’s office. We still brush our teeth every day, just as we perform daily sanitation in the processing plant, but the dental hygienist is able to remove tartar that our daily brushing just doesn’t remove.

Killing Listeria where daily cleaning can’t

Listeria is easily killed by heat, and Tsuyuki said that heat intervention attacks bacteria where they live and grow. He said that raising the temperature of the equipment to 160 F for at least 30 minutes is usually enough to kill off bacteria, particularly Listeria, on equipment.

Tsuyuki said that steam tenting is a relatively simple heat treatment process that can be used on many pieces of equipment. He said that when they started steam tenting they had to develop their own protocols. Besides wet steam, you need compressed air, sheet polyethylene to wrap the equipment, a steam manifold, temperature probes, tape and shrink wrap. The compressed air is used to keep the steam out of sensitive areas where it could be detrimental to components.

Maple Leaf uses 10 psi of compressed air to provide positive pressure in sensitive areas and the compressed air also helps to inflate the tent. Shrink wrap and the tape are used to seal the tent. Tsuyuki said that they use 30 psi saturated steam to provide the heat and moisture. He said that wet steam is required to get a good kill of the microbes. By trial and error, he said they learned that you need to turn off any air handling equipment near equipment that you are steam tenting, otherwise it can take too long to get the temperature up inside the tent.

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Microbial data determines success

It is important to swab the equipment both before and after steam tenting, so you can determine how much of an effect you are having. The steam and the air pumped into the tent form a sauna bubble. You have to cut back the steam when you reach the target temperature. Tsuyuki said that you need temperature probes to monitor hot and cold spots and to maintain the target temperature for at least 30 minutes, or longer depending on your program. When you are done, you cut the plastic to let the steam come out.

Swab results will let you know how long you need to maintain the target temperature for, and over time you can develop a protocol for steam tenting each piece of your equipment. Tsuyuki said that you don't have to steam tent, because ovens or smoke houses can be used to heat treat some portable equipment, but you need to have moisture as well as heat for effective treatment. He said that clean-out-of-place tanks can work well for small pieces of equipment. Portable steamers can also be effective for small localized areas that can’t go into a clean-out-of-place tank.

Benefits outweigh risks  

Steam tenting can be used for things like conveyors, basically anything you can wrap. He stressed that heat treatment is not a replacement for regular cleaning; it is an addition to it. Tsuyuki said that heat treatment can be a replacement for a total tear down.

He said that some companies still don't steam tent equipment, but that they should. Tsuyuki said that benefits of heat treatment far exceed the risk.