Heat Treatment as a MeBr Alternative

Jim Rosborough
Pepsico Foods Canada, Inc.
Quaker Petersborough Plant
34 Hunter Street West
Petersborough, Ontario
Canada K9J 7B2
e-mail: jim.rosborough@pcfci.com

The majority of food processing facilities are perfect homes for many food-infesting insects, providing food, warmth, and shelter. At the same time, insecticides such as methyl bromide are being phased out and new ones are taking a long time in the approval process. As the chemical tool kit shrinks, interest in heat treatment as an insect control method is increasing.

The PepsiCo Foods Canada Inc., Quaker Peterborough Plant has been using heat treatment as part of its integrated pest management program for over 30 years. Though insects subjected to 50° C to 60° C will die within minutes, this facility maintains 50° C minimum for 24 hours to ensure that the majority of surfaces reach this lethal temperature.

Planning plays an important part in the heat treatment schedule. A tentative annual plan is developed for the period from Easter to Thanksgiving (mid-October in Canada). This schedule is fine-tuned as the year progresses based on pheromone trap findings and knowledge of insects and trouble spots. Once the date for treatment has been finalized the following areas are prepared: the areas to be heated, heaters, building, equipment, sprinkler system, and employees.

A number of steps are taken to prepare the area to be heated: equipment and ingredient/work-in-process bins are emptied; garbage/salvage receptacles are emptied and cleaned; heat-susceptible ingredients and packaging material are removed; and circulating fans are placed. Insect test cages are put in areas where it is difficult to heat and, if allowed, a residual spray is applied at doorways between heated and unheated areas.

Heater preparation is one of the key steps in ensuring a successful heat run. The heaters and traps are cleaned, and the fans are started to be sure they are functioning properly. New equipment installations or building modifications are also reviewed to determine how air movement may have been affected. This may require the placement of additional fans or the installation of new heaters or relocation of existing heaters.

Building preparation involves the closure and sealing of all doors, windows, and vents. This sealing does not have to be as airtight as for fumigation, but it should restrict the flow of warm air out of or cold air into the structure. Heating, ventilating, and air-conditioning (HVAC) systems and dust collectors are shut off, and plastic is used to seal off areas not being heated. To avoid thermal shock, the following rules are adhered to: 90° F differential rule between inside and outside temperatures and a 10° F temperature rise per hour. (If in doubt, consult a structural engineer.)

There are some precautions that need to be taken when preparing equipment for heat treatment. Catch pans should be in place over product zones because the oil in gearboxes will expand and the lubricant could be forced out of seals. Conveyor belts need to be loosened to prevent stretching. Electrical equipment, such as computers and controllers, must be powered down or removed. (Contact the manufacturer for advice on this.) Wherever possible, equipment should be opened to allow for maximum heat penetration.

The facility sprinkler system must not be overlooked during preparation for heat treatment. High temperature heads should be used in all heated areas: 286° F within 10 feet of heaters and 212° F for all other areas. Also, be prepared for an activated head: know shut-off valve locations and operations and prepare a salvage plan to limit damage to equipment, ingredients, and packaging material.

The success of any insect control activity is highly dependent on the people involved. This is true for heat treatments as well. To be successful, a multidisciplinary team is required consisting of electricians, plumbers, stationary engineers, cleaning crews, sealing crews, temperature monitoring crews, production planning, purchasing, quality assurance, sanitation, and production. Predefining each group's role in the treatment will reduce the chances of errors and increase the rate of success. A special note should be made concerning the temperature monitoring crews: safety is paramount for these employees. The crews must physically be able to work in 50° C to 60° C conditions for limited periods of time, crews must be made up of a minimum of two employees, cool areas must be provided for rest periods, fluids must be available to prevent dehydration, and these employees must be trained to recognize signs of heat stress.

Once the heat treatment is completed, the following steps should be performed prior to plant start-up: ensure window and door screens are in place for cool down, remove sealing material, close equipment, tighten conveyors, and look for lubricant leakage and top up gearboxes as needed. Personnel responsible for the facility's pest control program should also monitor and record insect fallout, collect and analyze test cages, and review the temperature records from the heat run. This will provide valuable information on insect hot spots within the plant, which could lead to changes in cleaning and inspection practices, as well as point out areas that may require changes to the heater and/or fan placements prior to the next heat treatment.

Regardless of the alternative, we all have the same goal and heat is just another tool in the integrated pest management tool kit.

Last Updated: April 9, 2004