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Food Ingredients

The long road to all-natural preservatives

Consumers want clean labels, but ensuring food safety and shelf life without synthetics is a challenge

by Melody M. Bomgardner
July 25, 2017 | A version of this story appeared in Volume 95, Issue 31

The hot dog and deli meat aisle of a grocery store.
Credit: Melody Bomgardner/C&EN
Consumers navigate a variety of clean label claims for hot dogs and deli meats.

The official hot dog of summer received a makeover this year. Oscar Mayer wieners now boast no added nitrates, nitrites, or other artificial preservatives. The move, by parent company Kraft Heinz, shows that the clean-label food trend has gone fully mainstream.

“Oscar Mayer is America’s most iconic hot dog brand, and, as the equity leader, we felt it was time to take a stand for the love of a better hot dog,” said Greg Guidotti, the brand’s head of marketing, in announcing the change.

Guidotti stressed that the new dogs have the same great taste and the same price as the former versions. The announcement punned that Oscar Mayer went to “great lengths” in its product development, which took more than a year of recipe testing and tinkering.

But the recipe could change again. Careful label readers will learn that the frankfurters contain celery juice­—a natural source of nitrites—to replace the sodium nitrite preservative that was added. In the U.S., labeling rules allow celery juice to be listed as a natural flavor but require a disclaimer noting the use of natural nitrite sources.

For now, celery juice is an attractive alternative for meat producers because it sounds more like a food and less like a chemical.

These days, both food companies and shoppers want to see “recognizable names on labels,” says Anieke Wierenga, senior director of food innovation at the Dutch ingredients firm Corbion. “As a food industry, we don’t have the full trust of our consumers. They want to check us and know what’s in there.”

A mixed bag

Food makers are using a combination of natural and synthetic preservatives.

This chart shows the proportion of deli and cured meats and bread and buns that contain natural and synthetic preservatives.
Source: Label Insight
 Note: Ingredients listed as "natural flavors" may also serve as preservatives.

Food giants including Kraft Heinz, General Mills, and Nestlé have spent the past few years aggressively reworking their recipe books to remove artificial colors and flavors in a bid to provide more natural fare. Changing up preservatives carries much higher stakes because no one wants to play a guessing game with food safety. The industry is evaluating plant-based ingredients, but it could be years before it has a natural solution for every food preservation problem.

It’s not possible to manufacture food in a way that keeps out every microbe, industry experts stress. And although not all organisms are harmful, some can produce deadly enterotoxins, aflatoxins, and botulism toxins.

That’s why the industry has long relied on synthetic antimicrobials—sodium nitrate, sodium benzoate, propionate, and the like—to kill a range of bacteria, yeast, and other fungi. They are inexpensive, are used in tiny amounts, and have a long track record.

And the preservative universe goes beyond antimicrobials. There are antioxidants to keep fats and oils from going rancid, acidulants that lower the pH of foods to prevent microbes from multiplying, and ingredients that maintain color, flavor, and moisture during the product’s shelf life.

Creating a label that looks “clean” to the consumer while covering all the bases for food safety and shelf life is a tall order, ingredient makers say. “The challenges of eliminating synthetic preservatives in favor of natural ones is huge,” says Kantha Shelke, food scientist at the food consultancy Corvus Blue. “The food industry is not there yet, though they are doing a lot of work.”

To meet clean-label requirements, Corbion has accelerated its product development efforts. “Before clean label we could offer just one or two products to meet a need,” Wierenga says. “Now the amount of launches to customers is more like tens per year.”

In some cases, an ingredient maker can develop natural ingredients only to see preferences shift again. For example, Corbion is an innovator in lactic acid ingredients from fermentation to control Listeriain meat products. But recently, food companies found that lactates didn’t meet the “found in the pantry” criteria of some consumers. They wanted to use acetic acid—labeled as vinegar—instead.

The catch is that unlike vinegar, lactates have a mild taste, so both the vinegar and food recipes had to be revamped.

“Now our customers come to us earlier in the food formulation process with the expectation that we can help them,” Wierenga says. Corbion’s R&D team has developed custom vinegars—some with fermented dextrose—for different food recipes to provide the right sensory profile and optimize Listeriacontrol, she says.

Meat is a particularly thorny challenge. Ingredients that Corbion uses with vinegar for preserving meat products include jasmine tea extract—an antioxidant—and citrus powder, which prevents moisture migration out of the product.

If consumers should frown on nitrite sources such as celery juice in hot dogs and other cured meat products, manufacturers will be in for a tough time. Health researchers have flagged the use of nitrites in cured meats because they can form cancer-causing nitrosamines when heated. The health effect is the same regardless of where the nitrites come from.

“Replacing nitrites—that’s a difficult one,” Wierenga admits, given that they perform an important role in preventing botulism growth. “The industry is quite far away from a solution.”

One strategy for getting closer to consumers’ clean-label desires is to replace some chemical preservatives with natural ingredients while keeping one or two of the old standbys in place.

“You might expect to see a decline in the use of synthetically produced preservatives in favor of naturally derived preservatives, but we have not seen that with our own products,” says Paul Hogan, a vice president at Emerald Kalama Chemical, a maker of benzoate-based preservatives.

Hogan points to market research showing that from 2012 to 2016, the number of new food products that contain sodium benzoate increased by 86% even as all-natural claims grew by 69%. Because the claim “all natural” on a food label is not legally defined in the U.S., decisions about naturalness are left to the food brand. In contrast, using synthetics for the purpose of preservation is not allowed in foods certified as organic.

Condiments, which tend to linger in consumers’ kitchens for months, if not years, benefit from the mixed approach, Hogan says. Mustard often contains both vinegar and sodium benzoate because “vinegar alone does not provide the level of microbial control needed to prevent spoilage at the levels it would typically be used,” he says.

Short-shelf-life foods such as bread can also require significant intervention, according to Corbion’s Wierenga. “If you want to go beyond a couple of days, you need a mold solution,” she says.

Commercial bread smells different from bakery bread because it contains propionate, she says. “It’s a fairly benign ingredient, but a chemical.” If only a few days of shelf life are needed, some clean-label breads fend off fungi with fermented sugar ingredients.

Before bread gets moldy, it typically gets stale. Though shoppers are discouraged from squeezing bread in the bakery aisle, softness is generally correlated with freshness. The blame for staleness falls on the starch molecule, which recrystallizes and hardens over time, according to Wierenga. Clean-label bakers have adopted enzymes to keep starches stretchy.

A food scientist portions out bread dough.
Food scientists evaluate how preservative ingredients impact bread quality.

The clean-label reworking of breads also has to account for dough handling and baking. Commercial bakers speed up the process by conditioning their dough with ingredients such as diacetyl tartaric acid esters of mono- and diglycerides, known as DATEM, and partially hydrogenated vegetable oils. They produce a tall loaf in short order.

“On a real commercial bread you see a long list of ingredients, but there is continuous movement from our customers and companies like us to clean up the label,” Wierenga says.

Going through the spice cabinet is one way that food companies and their ingredient suppliers search for label-friendly preservatives. Label Insight, an ingredients database firm, lists a number of common herbs and spices that “may act as a preservative.” An analysis of ingredient labels on bakery goods and deli and cured meats shows manufacturers are looking to rosemary, garlic, ginger, cinnamon, and clove.

Food companies have known since the 1990s that more than a thousand plants are potential sources of antimicrobial compounds. Many also act as antioxidants.

At Kemin, an Iowa-based food ingredient maker, scientists look for natural preservatives by screening plants identified in the literature, including reports about Chinese herbal medicines, says William Schroeder, Kemin’s director of R&D for food technologies. The goal is to find functional plants that consumers can love and that are easy to grow. “We’d rule out a berry that grows only in Greenland,” Schroeder says.

If the team finds a plant substance that works as an antioxidant, it then tries to determine the method of action.

Schroeder says antioxidants can work in one of three ways: chelation, scavenging oxygen groups, or sequestering free radicals. A particular food may require one or more of these actions. Some, such as mayonnaise, require all three. “Mayo is an emulsion with water, oils, and an emulsifier. It’s a mess because you have to hit all those targets,” he says.

Once a promising plant has been discovered, it can take more than 10 years to develop a commercial food ingredient, Schroeder says. Kemin will try to identify the molecule or molecules responsible for the preservative action and create extracts that impart little or no flavor or odor to food. If the ingredient is not already generally recognized as safe by the U.S. Food & Drug Administration, the company can petition to obtain the status.

Rosemary, which provides the antioxidant compound carnosic acid, is an early success of this process, Schroeder says. Rosemary extract and tocopherols—familiar to consumers as vitamin E—are replacing synthetic antioxidants such as butylated hydroxyanisole (BHA) and tert-butylhydroquinone (TBHQ). A more recent example is green tea extracts, which contain antioxidant polyphenols as well as catechins that can inhibit the growth of bacteria.

As the food industry becomes more comfortable using plant extracts as preservatives, newcomers are carving out niches. Montreal-based Biosecur Lab was founded in 2000 but entered the food market only in 2011. It is commercializing natural alternatives made from citrus extracts, according to President Yves Methot. Last year the firm introduced FoodGard, an antimicrobial for fruit filling, pudding, and beverage applications.

“We found our timing was quite good—the product was just what the market asked for,” Methot says. He explains that the extracts get their antimicrobial power from bioflavonoids and polyphenols. When combined with a plant-derived glycerin carrier, the ingredient can be used in organic foods.

“Our vision is to replace [synthetic] chemicals, but we can do it only if the food processor wants to have a clean label,” Methot stresses. “If they only want something that sounds natural, it is not that cheap.”

The willingness of food companies to pay more for clean-label ingredients varies. “If the company is pioneering a new clean-label product, they may have flexibility to pay more,” Kemin’s Schroeder says. In contrast, the marketer of a grocery store stalwart may not be inclined to pay for new ingredients.


In some cases, clean-label replacements are worth the money and effort, says Lisa Y. Lefferts, a senior scientist at the consumer advocacy group Center for Science in the Public Interest. CSPI recommends food makers prioritize the removal of BHA, nitrites, nitrates, propyl gallate, and TBHQ, contending that they pose a small risk of adverse effects, including cancer. It also labels butylated hydroxytoluene (BHT) as a slight or possible health risk.

“There are plenty of ways to ensure food safety and shelf life without using preservatives that add a small or possible risk to the food supply,” Lefferts says. She suggests replacing antioxidant chemicals with vitamins C and E. “Freezing, nitrogen gas to replace air, and using dark glass instead of clear bottles are other possibilities,” she says. “Or they can just be left out.”

Shelke, the food scientist, warns that consumers may not be ready to adapt to all-natural products with shorter shelf lives. In addition, she is concerned that newer ingredients being tried now have yet to be proved. “Everyone has a special antimicrobial they are calling me about, and some of them are mystery mixtures,” she says. “I get nervous about it. Just because it’s natural or from a plant doesn’t mean it’s safe.”

Still, demand for clean-label ingredients is growing, experts agree. Courtney Schwartz, Kemin’s communications manager for food technologies, says she expects plant extracts to account for 60% of the firm’s sales in five years, up from about one-third today. “Clean label is something consumers are demanding,” she says, “not just from premium brands but now from value brands as well.”


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