We cook our food for two reasons: to make it more edible and to make it safer to eat because we know that enough heat will kill most, if not all, of the micro-organisms in the food.
So, if cooking makes our food safer, why not cook food processing equipment to get rid of the bugs deep inside the inner workings where conventional sanitizers simply can’t reach?
Anyone that has ever had to clean up a food processing line implicated in a recall because of a pathogen in a fully cooked product will tell you that there is as much good luck as good science behind finding and then eliminating a bug.
It was during such an event several years ago that I contacted a large processor in the U.S. to find out what methods they had tried and which had worked. To my surprise, they told me that in extreme cases they cooked every piece of equipment.
To do this they first stripped out the motors and sensitive electronics, broke the equipment down and then cooked it in one of their large ovens normally used for smoking meats. Yes, they had ruined some expensive equipment and, yes, tearing equipment apart and reassembling it was problematic, but it had worked for them. This approach reminded me of Russia’s desperate scorched-earth strategy to deal with the invading German army during the Second World War.
Thankfully, I didn’t have to go to that extreme, and I never heard of anyone else doing that since then, until very recently.
Fast forward to the International Production and Processing Exposition in Atlanta, Ga., this January, where I heard Steve Tsuyuki, senior director of Food Safety and Quality Assurance at Maple Leaf Consumer Foods, talk about what his company calls “heat intervention” (HI).
Heat Intervention Options
1. Oven cooking: Equipment is moved off the line and into large smoke house chambers or ovens where it is heated to at least 74ºC (165ºF) for at least 30 minutes. There are some drawbacks to this technique:
– Moving the equipment off line.
– Large pieces need to be broken down to fit into the available oven.
– Sensitive components have to be removed to avoid being heat damaged.
– Transporting the equipment off site if a large oven is not available onsite increases the risk of damage and re-contamination.
– Reassembly is required.
– Extended downtime.
2. Steaming in-place: Equipment is covered in a plastic vapor barrier shroud and then steam-heated to at least 74ºC (165ºF) for at least 30 minutes. Steaming in-place, or “tent steaming” as Maple Leaf calls it, has some advantages over oven cooking:
– Equipment is treated in-place.
– Individual pieces can either be treated independently or two or more pieces can be steamed together. The number of pieces one can do at once depends on the ability to build a secure envelope around the equipment and to provide enough steam to maintain the target temperature for 30 minutes within the enveloped area.
– Some sensitive components can be left in place. Proximity sensors should be removed. Maple Leaf has found that some heat-sensitive components can be safeguarded by covering them with a vapor barrier and then blowing compressed air at 10 psi over them during the steaming process.
– Relative to the cost of an oven, the materials needed to steam in-place are inexpensive and readily available. The suggested list includes a steam source with a flexible hose, a pipe (manifold) to disperse the steam, compressed air and tubing for cooling sensitive components left on equipment, temperature probes to track equipment temperatures, polyethylene vapor barrier roll stock, shrink wrap film, vapor barrier tape, scissors and tie wraps.
– The vapor barrier envelope is itself sterilized, minimizing the risk of recontamination during its removal.
– Significantly less reassembly is required.
– Down time is minimized if steaming is done as part of routine deep cleaning usually done on weekends.
HI is not a silver bullet. It is, in fact, a blunt instrument. Before implementing HI, conduct a safety risk assessment. And remember, this method must be regarded as another intervention step in your sanitation program, not a replacement for other validated sanitation measures. Keep the heat on pathogens.
Ron Wasik, PhD, MBA, is president of RJW Consulting Canada Ltd., www.rjwconsultingcanada.com