Listeria: How to win the war that never ends

Risk. It’s an inescapable part of life that’s always around us, invisible … until it’s not. In the food industry, safety risks, such as listeriosis – a pathogenic bacterial infection – can threaten the strongest of brands, people’s health and even their lives.

According to Food Standards Australia New Zealand, each year in Australia around 150 people are hospitalised with listeriosis and about 15 people die. Recent tragedy provides another reminder that the war against human pathogens goes on and on. Although the rate is declining, Australia has seen eight Listeria-related product recalls in the past 18 months.

The tactical warfare waged by the global food industry against food safety threats is multifaceted and grows increasingly sophisticated. Manufacturing facilities take ever-greater measures to ensure that equipment is as sterile as possible and pathogens don’t enter the processing stream. Molecular diagnostic pathogen test kits are getting shorter time to results. Packaging solutions such as antimicrobial sachets, films, coatings and high-pressure processing (HPP) also contribute to the cause. Foods are formulated to include antimicrobial ingredients that inhibit microbial outgrowth.

Food safety is complicated
“It’s difficult for manufacturers to know when the safety measures they’ve taken are truly sufficient,” said Andrew Pearce, ANZ country manager at Corbion, an ingredient solutions provider known for its expertise in food preservation. “When hygienic practices and ingredient solutions are in place, and no problems are detected, it’s easy to believe that there are no problems.”

Corbion works with food manufacturers to implement high-performance safety and shelf life solutions in a wide variety of applications, including bakery, meat, culinary, confectionery, dairy and beverage products. Although the company has been honing its expertise in this area for 80+ years, Pearce said finding the best solution to a given customer’s challenge is never a simple matter.

“Food safety may start with minimizing the microbial load in the raw materials and equipment used to process a food product,” Pearce said, “but then it comes down to the conditions in the product itself and whether those conditions support or inhibit the growth of pathogenic bacteria. It’s next to impossible to create a perfectly sterile product, so making sure you make it difficult for unwanted microbes to grow is crucial in food safety.”

The composition of the product is everything, Pearce explained. It’s not just that the right solution for a salad dressing is different than it is for a deli ham product; the best answer for a cured deli ham may be quite different from what’s needed in uncured deli shredded chicken. Protein and water quality, sodium content, and other ingredients all impact the chemistry of the food matrix. The lower the pH (i.e., higher acidity), the less hospitable the product is toward microorganisms. If the product’s storage temperature isn’t low enough, bacteria are better able to grow.

Listeria monocytogenes is a major concern for food regulators and manufacturers in part because it can grow even at refrigerated temperatures and in products with low water activity. While Listeria is inactivated at cooking temperatures, it can often re-enter the food supply following heat treatment.

Rising to the reformulation challenge
Adding another level of complexity to the challenge for manufacturers is the fact that incorporating a food safety solution has the potential to wreak havoc with important aspects of product quality and sensory appeal – things like flavor, texture, and shelf stability.

Thinking about what it takes to make consumers happy, in addition to keeping them safe, can also put limits on the kinds of ingredient solutions that can be considered. An increasing number of consumers check ingredient labels before purchasing foods in an effort to avoid ingredients they don’t understand or aren’t comfortable with. This challenges manufacturers to deliver the same product attributes (including safety) using more “natural” solutions they may never have worked with before.

“Reformulating food products is a complex undertaking because every part of a food matrix is connected to every other part,” Pearce said. “It takes an in-depth understanding of those interdependencies to be able to change one component of a formulation without losing important product characteristics.”

The process of reformulation is iterative, involving a sometimes lengthy series of sensory and microbial tests, each including small changes in dosages, ingredient composition and other factors. Corbion uses a combination of experience and advanced, data-driven modeling tools to quickly identify the optimal solution that meets the manufacturer’s food safety requirements while preserving the attributes of product quality that are so important to creating success in the marketplace. The Corbion Listeria Control Model, for one, leverages data from more than a decade of clinical studies, internal challenge studies, and external validation studies in real food matrices  to estimate the effectiveness of various pathogen control solutions, considering moisture level, pH, water activity, and levels of sodium, potassium and nitrite.

The right ally can make the difference
For food manufacturers, a dedication to achieving hygienic conditions within their own facilities and supply chains is an important part of what it takes to create foods that begin the journey to the consumer as microbiologically safe. But maintaining non-pathogenic integrity throughout that journey – including the product’s lifespan on the customer’s shelf – requires a level of know-how that can’t be taken for granted, even among ingredient suppliers, according to Pearce.

Having access to outside ingredient knowledge and microbiological expertise to complement in-house strengths can speed product development, result in a superior end product and dramatically reduce food safety risks that could threaten the public and the manufacturer’s brand. Choosing the right partner can improve outcomes by combining strengths in innovation, formulation, modeling, manufacturing, quality testing, market insights and other industry best practices.

Since producers prioritize their product safety programs, the outlook is good, Pearce said. “The food industry will never be able to stop fighting against Listeria and other pathogens, but with the help of food safety experts and state-of-the-art ingredient solutions, manufacturers – and consumers – can keep winning.”