Maintaining a “clean label” is an important goal for many food processors, yet they can’t let quality suffer in pursuit of that goal. Fortunately, when it comes to the shelf life extenders used in clean-label processed food, nature has created a treasure trove of options.
Plant extracts, fermentation metabolites, enzymes and combinations of natural ingredients help food processors counteract nearly every enemy of shelf life, from oxidation to spoilage to staling.
“Shelf life can be extended in a number of ways, protecting a product from taste or texture degradation, spoilage or inhibiting the growth of pathogens,” says Brian Nevin, vice president of product management, food protection & preservation for Kerry. “Many naturally occurring, everyday ingredients contain functional components such as proteins, salts or acids that inhibit bacterial growth, for example through pH and water activity impact.”
Natural antimicrobials
Many processed foods face microbial challenges. Soups, sauces, alternative proteins and many other products are routinely bombarded by pathogens that destroy flavor and texture and may create serious health risks. Common synthetic preservatives used to protect food from microbes are benzoates, sorbates, propionates and nitrites ... but processors seeking a clean label shun those products.
Instead, they turn to natural ingredients, particularly those created through fermentation, such as vinegar. Durafresh is a line of buffered vinegars and other fermentates available from Kerry. As anybody who has made pickles knows, vinegar is an effective preservative. Food processors can add buffered vinegar (buffering maintains a constant pH in the vinegar) to a product and label the additive “vinegar,” because the buffering agent, such as sodium bicarbonate, is considered a processing aid, not an ingredient.
Another commercially available shelf life extender that includes buffered vinegar (and/or cultured dextrose, depending on the blend) is Durashield Natural Food Protection Blends, a product introduced in March 2021 by Kalsec.
“The buffered vinegar has no negative impact on color or flavor,” notes Andrew Lee, senior R&D manager of food protection for Kalsec. “And the end product provides a nice antimicrobial effect.”
Another commercially available shelf life extender that includes buffered vinegar is Durashield Natural Food Protection Blends, a product introduced in March 2021 by Kalsec.
How does a product of fermentation kill microbes in processed food? It’s the acid in the ingredient that does the trick. Buffered vinegar, for example, contains acetic acid, which penetrates the cell wall of the microbes and lowers the pH.
“When it reduces the pH inside the cell, the microorganism has a very intense response trying to pump it out, and it kind of exhausts itself and can’t reproduce,” explains Zeev Ben-Oni, president of Mezzoni Foods, which makes clean-label antimicrobial ingredients from cultured (fermented) wheat, dextrose, brown rice and whey.
Ben-Oni adds that his company’s cultured products all have the same anti-microbial efficacy regardless of the base ingredient, but certain customers prefer one over the others.
“All of them work the same, but some customers prefer, say, ‘brown rice’ because it has a premium sound to it,” he says. “If you make bread, you might not want to say ‘cultured dextrose’ on the label because of the association with sugar, so you use cultured wheat instead.”
IFF also makes a range of fermentates from wheat, dextrose and dry milk. The company’s MicroGard and Natamax lines are natural antimicrobials used in bakery applications, explains David Guilfoyle, group manager bakery, fats and oils at IFF.
IFF makes a range of fermentates from wheat, dextrose and dry milk. The company’s MicroGard and Natamax lines are natural antimicrobials used in bakery applications.
“The MicroGard fermentates inhibit molds and yeasts in bakery products and provide similar antimicrobial coverage like the synthetic counterparts such as calcium propionate,” Guilfoyle says. “Natamax is another part of the fermentation that creates a fungistat, which kills molds and yeasts on contact. So the best use of Natamax is surface application to the outside of bakery products.”
Newly Weds Foods has a number of natural shelf life extenders in its IsoStat Products Group, which is somewhat optimized for meat products.
NatureGuard is rosemary extract that addresses lipid oxidation in a wide range of fat-containing foods and edible oils. It's manufactured using a proprietary supercritical fluid extraction process in which carbon dioxide is used in place of organic solvents to extract the functional elements. "This procedure results in a cleaner, higher purity product with more consistent quality," says the company website.
The NatureIn Line offers all the benefits of chemical sounding inhibitors, yet is based on either vinegar or a combination of lemon juice and vinegar. Low levels extend shelf life and high levels inhibit Listeria Monocytogenes.
AdvanStat Blends include antimicrobials and antioxidants plus other functional products and/or flavors. In addition to shelf life extension, they stabilize colors, inhibit pathogens and can provide other benefits based on customized formulation has a number of natural shelf life extenders in its IsoStat Products Group, somewhat optimized for meat products.
Natural antioxidants
Oxidation is another enemy of shelf life. When many food products – particularly those containing fats -- are exposed to oxygen, their chemical composition changes over time, and they become rancid. Nobody buys rancid food, so preventing oxidation is a key element of extending shelf life.
The most popular synthetic antioxidants are butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). These chemicals work, but nobody seeking a clean label product likes to see BHA and BHT among the ingredients.
Fortunately, natural alternatives exist for them, too. Perhaps the most popular is the herb rosemary.
“We have three decades of experience extracting rosemary’s active compounds, carnosic acid and carnosol,” says Jane Quartel, executive director of product management – food protection, for Kalsec Inc. “Those are the antioxidant compounds in rosemary.”
Kalsec’s new Durashield product includes rosemary, making it effective as an antioxidant as well as an antimicrobial. Not only does the rosemary add antioxidant properties, but it also has a synergistic effect with the antimicrobials in the product, improving the antimicrobial effect, Lee says. Thus Durashield is a “one-stop shopping” ingredient for food processors concerned about microbial issues and oxidation.
Another natural antioxidant is tea extract. Tea contains polyphenols, which are known to be antioxidants, though their antioxidant mechanism is unclear. IFF’s Guardian product includes both rosemary extract and tea extract.
“Oxidation inhibition is an often overlooked part of shelf life extension, but it is key to improving overall shelf life extension, especially in high-fat formulations,” Guilfoyle notes.
Another plant-based antioxidant is sorghum. “Sorghum has high antioxidant levels, specifically phenolic compounds that may enable it to be a viable shelf life extender,” says Doug Bice, Sorghum Checkoff market development director and spokesperson for Simply Sorghum.
Sorghum’s effectiveness as an antioxidant on frozen meat was evaluated in a 2016 study at Texas A&M University. “Both varieties of sorghum bran retarded lipid oxidation equal to BHA/BHT but was significantly more effective than rosemary extract in cooked pork crumbles and chicken patties without negatively affecting sensory attributes,” the study concluded.
Preventing staling
The bane of bakery product manufacturers is staling. Nobody wants to buy stale bread! Staling occurs when moisture migrates from the starch granules in bread to the interstitial spaces, which causes the starch to re-crystallize and get hard.
Staling is typically prevented with the addition synthetic antioxidants, crumb softeners or emulsifiers.
Another staleness-preventing ingredient is enzymes. Enzymes, which are proteins and are considered clean-label ingredients, interrupt and slow the staling process in breads. Furthermore, in many applications enzymes are considered processing aids and do not need to be included on the ingredient label.
Ben-Oni says his company has created an antimicrobial product that also includes enzymes to prevent staling. “This way people can get softness plus extended shelf life,” he says.
Do they work as well?
An important question food processors must ask about natural alternatives to synthetic preservatives is how effective they are. The replies vary. Some report that, at least in some applications, the natural alternatives are essentially equal.
“They are pretty much comparable,” Lee says. “It depends on the application. We have been testing against synthetic antimicrobials, and we are seeing Durashield can replace those in different applications. It’s a clean-label replacement for those products.”
Others say natural preservatives are not quite as effective as the synthetics. Basically, it comes down to the application and the quantity. The more of the natural ingredient that can be included in a recipe, the more effective it is. But if the ingredient affects taste or texture, there are limits to its usage.
“I have customers test it to find the upper limit of the ingredient in terms of taste, and then they can run it at that limit or one or two points below,” Ben-Oni says. “They figure out how much they need based on their application.”
A related question is: Do the natural preservatives affect the flavor of a product? Again the answer to that question varies, and it greatly depends on quantity.
“My answer to that question is that even water has taste,” Ben-Oni says. “We tell customers to test it.”
Quartel from Kalsec says taste is an important factor that needs to be considered. “We’ve been very careful with that,” she says. “I think cultured dextrose has a history of tasting not so great, and buffered vinegar, too. So we work closely with a professional sensory panel to make sure whatever application we put these ingredients in will delight the customers.”
In some cases the natural preservatives could be flavor enhancers. Lee notes that Durashield can add a savory note when it’s used in a high concentration, which may be desirable in food products such as meat substitutes.
Cost comparison
One disadvantage of clean-label shelf life extending ingredients is cost. The high-quality natural ingredients and intensive processing required to create these ingredients are costly.
“It’s more expensive, which is pretty typical of natural products,” Quartel says. “Cultured dextrose is made with microorganisms that need to be fermented; rosemary is a crop that needs to be put in the ground. Those factors make it significantly more expensive than a synthetic.”
However, with clean-label becoming a more and more important marketing characteristic, the extra cost of using a natural preservative is more often seen as worthwhile today. And given that the preservative generally makes up only 1 percent or less of a product’s volume, the cost of the preservative might not be a major issue.
“Cost used to be a big ‘make it or break it’ point, but now people understand that if they want natural, it’s more costly,” Ben-Oni says.
Quartel concurs: “The industry is aware that there is a cost differential and they have the expectation for that. When companies are ready to make the switch, they’re also ready to make the switch from a price perspective. If someone expects the same price, that’s not realistic.”
The bottom line is that the demand for clean-label preservatives is strong and likely to continue to grow.
“We’ve been talking about clean labels for 20 years, but those trends continue,” Quartel says. “There is a lot of opportunity in the market.”
