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How Polyurea Technology Is Preventing Food Processing Plants Risk of Contamination

Food processing plants that provide ready-to-eat (RTE) foods, particularly meats, cheeses, and other assorted products that require refrigeration, unfortunately, present ideal conditions for microbiological contamination. Listeria monocytogenes, for instance, is generally found in pasteurized milk, soft cheeses, ice cream, raw vegetables, fermented raw-meat sausages, raw and cooked poultry, and deli meats. One answer to preventing bacterial contamination is maintaining flat surfaces throughout the plant, including walls, ceilings, floors, and food preparation surfaces, which are easy to clean and sanitize. 

Microscopic view of Listeria monocytogenes by StockTrek Images

There have been much food recalls due to Listeria contamination, which has drawn attention to plant sanitation, design, and construction. As one possible solution, VersaFlex, a supplier of high-performance polyurea coatings, liners, and joint sealants, has developed a polyurea system specifically designed to provide desirable surfaces, even in aging plants with angled construction.

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The largest Listeria outbreak in the United States occurred in 2011 and was traced to contaminated cantaloupes; 146 people across 28 states became ill, 142 hospitalized, and 33 died. Hispanic-style cheeses sold by Roos Foods were recalled after a Listeria outbreak was traced to the company’s products early in 2014. Another cheese—Crave Brothers Farmstead Cheese—was a source of a Listeria outbreak in 2013. Apples were a recent cause of contamination at Bidart Bros. apple processing plant near Bakersfield, CA (January 2015) and Appeeling Fruit Inc. of Dauberville, PA (September 2015). Also, in the same month, the Maryland Department of Health and Mental Hygiene stated that numerous products produced by Picnic Gourmet Spreads might have been contaminated. On April 20, 2015, Blue Bell Creameries voluntarily recalled all of its products on the market made at all of its facilities, including ice cream, frozen yogurt, sherbet, and frozen snacks, due to potential contamination from Listeria. According to the information posted on the Centers for Disease Control (CDC) website, ten people with Listeriosis related to this outbreak were confirmed from four states, with three deaths reported.


Listeria is gram-positive bacteria that grow under anaerobic and aerobic conditions and can, unlike most bacteria, multiply at fridge temperatures and withstand freezing. They are also extensive in the environment, including soil and water, the manure of many animal species, and the feces of healthy human adults. In humans, Listeria infections can be serious to fatal for the elderly, the very young, and people with weakened immune symptoms, but typically do not cause healthy adults great harm. Humans are infected with Listeria only via ingestion and typically in the consumption of contaminated food or water. Second, only to Salmonella in the number of cases of illness in the United States due to foodborne contaminants, it is no wonder that L. monocytogenes is considered a significant public health concern. The U.S. Department of Agriculture has announced the bacterium an adulterant in RTE meats and adopted a zero-tolerance policy for its proximity in these products.

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Pasteurization can be used to kill Listeria, but in larger packages of RTE foods, the desired temperature is not always reached throughout the product, allowing some bacteria to persist. In addition, after pasteurization, some foods are mixed with unpasteurized ingredients that can introduce contamination. Equipment, countertops, and any other surfaces that contact the food (gloves, etc.) can also be sources of contamination if not properly cleaned and sanitized. That can be challenging to accomplish in older processing plants that have walls and ceilings constructed with angled steel, i-beams, concrete block, interlocking metal and fiberglass panels, double-t ceilings, and tiles with concrete grout, which serve as excellent places for standing water and the build-up of dust, dirt, mold, and bacteria, including ListeriaEscherichia Coli, and Salmonella. Often the cracks, pits, and seams present in these plants provide surfaces for bacterial growth, notwithstanding aggressive power washing and chemical sanitation techniques. In addition, Listeria continues to grow at low temperatures; it can aerosolize and attach to equipment and people and is therefore difficult to control in the processing environment.

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It should also be noted that in older plants, other sources of contaminants are of real concern, such as chipping paint and spalled and cracked concrete. The aggressive cleaning protocols used in food processing plants only hasten damage to coatings and other surfaces, leading to frequent maintenance and repainting and or complete replacement. Not only is this approach labor-intensive and very costly, in some cases, but plant shutdowns are also required, having a further negative impact on profitability.

Today, with access to advanced food-grade polyurea coatings from ArmorThane, many companies have achieved full rehabilitation of the walls and ceilings in food processing plants, often during planned maintenance weekends. Using a patented process including structural rehabilitation, precise surface preparation, retrofit design modifications, ArmorThane’s food-grade protective polyurea coatings deliver a monolithic liner that eliminates all current chips, seams, and gaps, according to CEO Garry Froese. He also remarks that as part of this process, space is “reshaped” so that only smooth, curved lines remain and areas where water, dirt, grime, and pathogens can accrue, are eliminated.

The fast-curing pure polyurea coating from ArmorThane, specifically formulated for use by food processing plants, is a key component of the rehabilitation system. Froese notes that the material is spray applied, which means it can be applied quickly by trained applicators, built up to any required thickness, and shaped into the modified wall and ceiling design. “Therefore, a one-coating system can be used to create a monolithic surface, minimizing plant downtime rapidly. Most other coatings take one to four days to cure, which is too long if you need to get the plant back online. 

Polyurea sets up and can be returned to service within minutes,” he adds. A custom polyurea topcoat provides a smooth surface that resists standing water and prevents dust, dirt, and bacteria from taking hold. ArmorThane has worked closely with countless organizations and plants to adjust the polyurea cure time, gel time, and topcoat properties to meet their specific needs for the food processing industry.

Rehabilitation Process

The rehabilitation process starts with repairing any areas with spalled or cracked concrete, chipping and peeling paint, or heavy corrosion. Intensive cleaning removes grease and grime, and other surface contaminants are then performed using specially approved wash-down solutions and self-contained high-powered water-blasting techniques. Holes, voids, seams, and penetrations are then filled, and any reshaping is completed using, for example, a combination of concrete and molded foam materials to transition any flat surfaces from 90° to 45° to prevent standing water from accumulating. According to Froese, every piece of equipment, pipe, flooring, and other exposed areas is wrapped in plastic or covered before spraying the polyurea coating, which is completed carefully and evenly to provide a nice, clean look.

Often this approach—complete interior wall and ceiling rehabilitation—is the quickest and most cost-effective way for food processors with aging facilities to break the cycle of constant deterioration and ongoing repair while also minimizing the risk of the pathogen-based product.

If you would like to know more, contact ArmorThane today!

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