Bakeries can keep their facilities positively pressurized compared to the outside air in order to help keep the air in facilities clean. If bakeries are pumping in more filtered air than is being exhausted, that creates positive pressurization, which inhibits mold and other contaminants from getting in.
“By positively pressurizing — using filtered outside makeup air — you’re able to filter that air before it comes into your building,” said Mike Anderson, sales manager, Air Management Technologies. “The positive pressure creates, for lack of a better term, wind, which unwanted particulates and insects are not likely to infiltrate. They are going to be pushed away.”
Throughout most of the bakery, facilities will generally be using a filter with a MERV 8 rating, or minimum efficiency reporting value. MERV 8 is comparable to one used in most homes and is graded about 70% efficiency for mold particle sizes.
“Typically, a minimum MERV-8 filtration is used in zones prior to the oven. MERV-8 is an excellent balance between filtration efficiency, filter cost and energy needed to overcome the filter resistance,” Mr. Anderson said. “When finished product comes out of the oven and is open to the environment, contaminants in the air can settle on the product. Considering how long cooling times are for most products, that is a tremendous potential exposure.”
He added that products going from an oven or fryer to packaging should be considered a sanitary zone, and his company often recommends a MERV 14 or MERV 15 filtration provided the cooler and packaging area can be isolated from the rest of the bakery.
Higher filtration in open finished product zones can get rid of 90% of airborne mold spores, which is very advantageous.
The areas where products are cooled before packaging are often now enclosed to ensure positive pressurization and added filtration. This ensures that products are more protected. That’s because instead of being exposed to the general environment of the bakery, products may only have a minute or two going from the enclosed coolers into packaging, Mr. Anderson said.
This is important because even if more filtered air is coming into the bakery than is being exhausted, bakeries will still lose some pressurization.
“You’ll still lose about 5% to 10% very easily of that airflow without being exhausted,” he said. “It will find its own pathways out even if the building is pretty well sealed up. You want to bring in about 10% more outside air than is being used either for comfort exhaust — which is if you see the exhaust fans in the ceiling it would be considered comfort exhaust — or process exhaust, which is directly tied into something like an oven.”
Although the air is filtered coming into the bakery, contaminants can enter the bakery through other means.
“People are dirty,” said Karl Thorson, global food safety and sanitation manager, General Mills, Minneapolis. “You’re bringing in contaminants from the outside, you’re bringing in packaging that’s loaded with dust, you’re bringing in pallets and forklifts. There are just all kinds of sources of contamination.”
He added that when problems are persistent, bakeries should consult with outside experts, which can be consultants or trade organizations, to get help. He suggests checking in with bakery associates first.
“Start with your own people: your own mechanics, your own engineers, your own operators,” Mr. Thorson said. “But sometimes it’s harder to find. Maybe you’ve got your mold complaints and issues way down to a very low level, but you just can’t get it to that next level. Maybe you need to bring in an expert consultant or subject matter expert in that area to help you evaluate your system.”
This article is an excerpt from the August 2022 issue of Baking & Snack. To read the entire feature on Sustainability, click here.