New research on pathogens in low-moisture foods is coming soon

Consumers and government entities expect commercially prepared foods to be safe. Accurate water activity measurements are helping ensure they are.

Most people understand how important it is to cook raw chicken thoroughly. Consumers also know that they should examine fresh fruits and vegetables to reduce their risk of foodborne illnesses. But most people don’t think to – and aren’t able to – check commercially prepared convenience foods for contamination. 

This makes Dr. Jennifer Acuff’s job that much more critical. Acuff, a food scientist and researcher at the University of Arkansas, focuses most of her research on low-moisture foods (or, more accurately, “low-water-activity foods”). Contrary to popular perception, these food products can host potentially dangerous microbes.

“I really like eating low-moisture foods,” Acuff says. “They’re not often suspected as risky, but outbreaks and recalls aren’t necessarily uncommon anymore. There have been quite a few high-profile outbreaks, even recently.”

In 2022, a product recall on infant powder formula created a nationwide shortage. 

“These are foods that we’re feeding to our kids,” Acuff says. “They’re convenience foods. They’re things that have long shelf lives, and so we really are expecting them to be perfectly safe. Consumers are very disappointed when they learn that that may not always be true.”

A $200,000 Grant to Fund Research

Research from people like Acuff and accurate water activity measurement tools are helping to combat these potential health risks. The United States Department of Agriculture’s National Institute of Food and Agriculture recently awarded Acuff a $200,000 seed grant to help her get foundational information and data that will, she hopes, lead to more multidisciplinary collaborative grants in the future. 

Acuff and her team are conducting experiments to determine how well foodborne pathogens can survive in low-moisture food environments. 

“In these experiments, we’re checking the impacts of specific amounts of water and storage conditions on what we’re calling ‘low-moisture food persistent bacterial populations,’” Acuff says. “We’re also going to look at how different types of food or nutrients can impact their survival and what might happen to them when moisture is reintroduced.”

Water Activity Measurements

Measuring water activity strengthens Acuff’s research.

“Water activity gives you a really good read into what amount of water is available, obviously, and not currently bound by something else,” Acuff says. “So it tells us how much is available for bacteria to use. That’s a good indicator of whether or not you can expect the growth of bacteria.”

Especially in low-moisture foods, measuring water activity can inform countless aspects of food production and safety. 

“Water activity [measurements] can be used for many other things, but it’s our key measurement when we’re trying to target certain levels,” Acuff says. “We’ve seen an increase in thermal resistance from bacteria as you decrease the water activity. Whenever you’re looking through publications in this field, you’re always going to be asking, ‘Okay, so that was the thermal line activation rate, but what was the water activity?’ Because that’s one of the key measurements now that we use to compare different commodities.”

Preventing Widespread Outbreaks

A wide variety of foods fit into the “low-water-activity food” category. This makes their safety especially important since low-water-activity foods are often used as ingredients in other food products. 

“Because of the nature of low-water-activity foods and what they’re used for, they’re oftentimes sent into many other products,” Acuff says. “Things like flour are going to be added to baking mixes, things like peanuts and peanut products are going to be added to granola bars and other food items. We see that when a recall or an outbreak happens with a low-water-activity food, it’s so often very far-reaching.”

Outbreaks in low-water-activity foods are hugely consequential partly because of their wide usage. In some cases, the scope of a recall can also be more extensive with low-water-activity foods because many low-moisture food processes don’t involve frequent cleaning and testing. 

“Sometimes [the scope of a recall] has to do with when was the last time you had some kind of cleaning and a negative pathogen test,” Acuff says. “For a low-moisture food, they might be processing for a long time before they’re having a totally clean break. Sometimes that can mean your recall is just humongous. It’s very different from a produce packing house where they have clean breaks every day.”

These wide-reaching outbreaks involving low-water-activity foods can cost companies millions of dollars. 

“It really depends on what their issue is,” Acuff says. “But it can cost a company hundreds of thousands depending on how bad the outbreak is. If there’s an outbreak involved, recalls will cost a certain amount, but outbreaks can cost exponentially more because you have other aspects, like litigation and things like that. It could be up to millions of dollars. It’s astronomical, the consequences of an outbreak.”

Food Safety Modernization Act

In 2011, the United States passed legislation that aimed to decrease the number of foodborne illnesses, increase the overall safety of food products, and save companies millions of dollars in recalls and litigation. The Food Safety Modernization Act sets out requirements for food producers—requirements that food scientists like Acuff can help companies meet. 

The Act, Acuff says, requires food producers to have a preventative-controls-qualified individual who can help them communicate necessary information in their preventive controls plan and food safety analyses.

“Every plant is totally different,” Acuff says. “Their design, the personnel, the product that they’re making. So there’s not one single set of training that is going to make perfect sense to every group. Even within a company, their plants are going to be different.”

But something that isn’t different from place to place and food to food? Water activity measurements and the value they provide to food scientists, producers, and consumers.

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