Pasteurization became the foremost step in keeping dairy products safe more than a century ago. Even so, a multitude of other courses of action and best practices applied by dairy processors today go into further safeguarding the milk, cheese, butter, ice cream and other milk-derived products that feed people domestically and abroad.

Dairy manufacturing in the United States, of course, involves adherence to the requirements set forth in the Pasteurized Milk Ordinance (PMO), which not only outlines time and temperature specifications, but also how dairy facilities must be constructed, equipped, cleaned and sanitized. Plus, the PMO delineates parameters for how milk is handled, stored and shipped.

This baseline standard of quality assurance helps make dairy one of the safest foods people can consume – per data from the US Food and Drug Administration, for every 2 billion servings of pasteurized milk or milk products consumed in the US, less than one person gets sick.

Food safety and quality experts in the US dairy industry also learned through the years how to best protect products to an even greater extent.

“Preventing post-pasteurization cross-contamination from the environment is critical to making safe dairy products,” said Chad Galer, vice president of product research and food safety at Dairy Management Inc., Rosemont, Ill. “The key to accomplishing this is having a strong food safety and quality program that is backed up by a strong food safety culture.”

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Contaminants in question

Collaboration within the US dairy industry to optimize quality assurance long has benefited processors and consumers alike. That’s the type of work that professionals who are part of the Innovation Center for US Dairy routinely address.

With the help of experts in the field, the center published a guidance for the US dairy industry titled, “Controlling Pathogens in Dairy Processing Environments.” The document’s authors pointed out that in most cases, “only a few pathogens of concern” originate in a production environment. While listeria monocytogenes and salmonella subspecies are well-established perpetrators, more recently, cronobacter sakazakii led to powdered infant formula recalls and shortages in 2022.

Industry contributors to the center’s guidance noted that pathogens typically enter a dairy processing environment by the means of raw materials or people that come into a facility. Furthermore, the document warns that once pathogens are present, they may make their way into an environment that sustains growth and remain there for years – if proper controls are not in place.

The Innovation Center for US Dairy’s document draws attention to the threat of listeria monocytogenes, warning that it “grows at refrigeration temperatures and can tolerate a higher salt environment than other bacteria,” Within a facility, the experts said, listeria monocytogenes may pop up in cool, wet areas where pasteurized products are handled and stored.

Conversely, dry dairy powder and production operations are associated with the potential for salmonella and cronobacter sakazakii. Industry specialists cautioned that cronobacter sakazakii becomes an even bigger concern when it originates in dry dairy powder that is intended to be used without further heat treatment. Such contaminated products made for infant nutrition or immune-compromised adults, experts forewarned, can lead to blood infection, meningitis or, in some cases, death.

While there have been recalls in the dairy industry through the years, Galer wouldn’t describe them as frequent or typical. He considers it good news that post-pasteurization cross-contamination instances are rare enough that there aren’t truly common examples of quality assurance gone wrong.

“The dairy industry, and the food manufacturers in general, following best practices are always trying to prevent those instances of process cross-contamination,” he said.

Graphic: Innovation Center for US Dairy

The pathogen control equation

Galer, who serves on the Innovation Center for US Dairy’s food safety committee, persistently references a simple, informative guidance the organization created to outline key principles that collectively create an effective food safety culture. It’s called the pathogen control equation.

“There are several elements that keep products and consumers safe,” Galer said.

A shorthand mechanism that covers an extensive scope of actions, the equation recommends six principles in a dairy processing facility: the separation of raw from ready-to-eat areas; ensuring good manufacturing practices are followed; controlled conditions, with a well-maintained infrastructure appropriate for products; sanitary facility and equipment design; effective cleaning and sanitation procedures and controls; and robust environmental pathogen monitoring.

The center points out to dairy processors that it’s more likely for pathogens or “spoilage organisms” to be located in uncontrolled or raw manufacturing areas, and less likely for them to pop up in a facility’s controlled production or ready-to-eat (RTE) areas. That’s why its equation calls for managing the flow of not only personnel, but also supplies, equipment and air, to reduce the potential for cross-contamination.

Good manufacturing practices (GMPs), industry food safety experts will tell you, are critical in the dairy industry for preventing contamination. The Innovation Center for US Dairy notes that GMPs apply to employees, as well as all production practices implemented. Because moisture may lead to “microbial harborage” and growth, the equation advises dairy production facilities to keep floors and surfaces dry, well-maintained and free of cracks. The guidance describes harborage points in a facility as “locations where pathogens may survive,” adding “they are usually difficult to reach with routine cleaning.”

Effective, efficient cleaning and sanitation within a facility are fortified when a sanitary design is carried out for all of the spaces and equipment in a plant. The Innovation Center for US Dairy informs dairy processing quality, food safety and engineering professionals that the importance of fully assessing cleanability and design should involve observing – or possibly taking part in – the sanitation process to ensure practical knowledge may be applied for various scenarios that may arise.

Even facilities that may lack strong sanitary designs can offset those shortcomings with effective sanitation procedures and controls, the center’s experts report. What’s more, the guidance highlights the seven steps many companies follow for both wet and dry cleaning. As a means of preventing cross-contamination, manual cleaning in a wet environment often involves pre-sanitation preparation, pre-rinse, soap scrub, post-rinse, inspection, sanitation, and reassembling/setup. The seven steps for manual cleaning and sanitation in dry environments require pre-sanitation preparation; securing, dismantling and inspecting equipment; pre-cleaning; detail cleaning; final cleaning; sanitation inspections; and final inspection and documentation.

The environmental monitoring of pathogens serves as both a crucial principle and a way to measure the success of a dairy processing facility’s pathogen control program, the center’s food safety specialists explain. An environmental monitoring program (EMP) assesses conditions during and after production within a plant. A strong EMP, experts apprise, verifies that a facility’s preventive controls, GMPs, controlled conditions, sanitary designs and cleaning programs are effective.

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Digging deeper

Emphasizing the all-encompassing commitment necessary within a dairy processing facility to maintain pristine conditions, Galer said the quality assurance steps tied to product safety call for an attention to details – before, during and after production.

“Reviewing data on a regular basis to ensure all employees are trained and to ensure any environmental monitoring positives [contaminants detected] are quickly addressed is an important and ongoing practice to ensure the food safety and quality program is effectively implemented,” he said.

Establishing and perpetuating an effective food safety and quality program is essential in the production of every single dairy product. Galer said no one product necessitates more steps and protocols, nor an additional level of scrutiny. The industry sets high standards all across the board.

“The risk of post-pasteurization cross-contamination increases with the amount of product exposure during manufacturing and/or packaging,” Galer said. “More potential exposure to the environment during these steps should require more attention to detail and robust protocols to protect the product.”

He also called attention to how part of the dairy industry’s food safety success relies upon unrelentingly adapting and advancing its quality assurance strategies. The Innovation Center for US Dairy’s food safety committee exists because industry experts volunteer their time and convene to share best practices.

“The dairy industry has always been a leader in driving continuous improvement in food safety,” he said. “This helps to ensure safe products for consumers and maintain trust in dairy products by working on food safety together as an industry.”

From Galer’s vantage point, the dairy industry remains vigilant in preventing cross-contamination in its processing facilities. He said some focus areas key to quality assurance are the niches and hard-to-reach spaces on equipment and infrastructure within a plant.

To prevent cross-contamination from impacting dairy products, he reiterated that a vigorous EMP is a prerequisite. And to achieve peak efficacy, food safety and quality assurance professionals need what Galer calls a “seek and destroy” approach.

It may seem counterintuitive to the uninitiated, but Galer explained that the best practices most dairy processors follow expect environmental monitoring to lead to at least a low percentage rate of detected organisms.

In fact, he said it isn’t good to have a 0% monitoring hit rate, and if a company presented to the Innovation Center for US Dairy that it was operating at that level, the experts would shed more light on the situation.

“No, you don’t have a perfect plan,” Galer said. “You need to dig deeper and focus on niches, hard-to-reach places.”

A monitoring approach firing on all cylinders will detect some low level of contamination – not on product contact surfaces, Galer made clear, but in areas adjacent to product contact surfaces, such as items above exposed product, package guides, equipment legs, control panels or aprons. RTE or high hygiene processing room floors, walls and surfaces, and tools in those spaces, also are likely to have a low percentage rate of identifiable contaminants.

“You want to be digging deep enough that you’re finding it,” Galer said.