In fact, Doyle emphasizes, “There have been several examples throughout the years where foods have become toxic or pathogens have grown because the antimicrobials have been removed [from product formulations].”
Some of the substitutes for standard antimicrobials are less potent and reliable, according to Doyle. He notes that vinegar, which contains acetic acid, is commonly used today as an alternative preservative.
“The acetic acid is what controls the pathogens, but it’s not nearly as effective as sorbate or benzoate in terms of broad activity against spoilage organisms and Salmonella and Listeria.”
Clean-label ingredient producers such as Amsterdam-based Corbion and Kemin Industries in Des Moines, Iowa, insist that their vinegar-based antimicrobials are highly effective, however.
Newly Weds Foods (www.newlywedsfoods.com) has a portfolio of natural food safety ingredients, most of them based on rosemary, vinegar and lemon juice. NatureIn, for example, are liquids based on buffered and reacted vinegar or in combination with lemon juice concentrate. It acts a general antimicrobial and is effective against listeria. It can be added directly to the product surface or in brines.
Kathleen Glass, associate director of the Food Research Institute at the University of Wisconsin, is just as enthusiastic as Doyle about traditional preservatives. However, as the clean label movement gained unstoppable momentum over the past 10 years, she and her colleagues have been working with ingredient companies to help them develop the safest and most effective natural solutions.
“The ingredient companies we work with have been working very, very hard over the past decade in trying to find what are going to be good alternatives,” she explains. “What are going to be things that do work, and what are the limitations along with them?
“What we have to do as scientists is look at what are the active components that are really providing that extra margin of safety and what can we find from a natural source that gives us the same kind of components.”
Among additives, sodium nitrite — used to combat harmful bacteria in processed and cured meats such as salami and ham — has long been the target of scrutiny. An increasing number of meat processing companies today are substituting celery juice for nitrites to produce so-called “uncured,” or “no nitrite-added” meat products.
“Celery extract is high in nitrate, which has to be converted to nitrite to be effective as an anti-botulinim,” Doyle explains. “When you use celery extract, you need a bacteria culture to convert the nitrate to nitrite.” He says that premature spoilage has occurred because of insufficient nitrite in uncured processed meat; the nitrite level is more difficult to precisely control when it’s produced bacteriologically rather than synthesized in a laboratory.
But Glass points out that over the years, clean label ingredient companies that use celery juice for sodium nitrite have “increased the efficacies” of the fermentation. “So we’re getting a higher concentration in every gram of celery powder. And as a result, you don’t have to add as much,” she says. “That results in lower costs, but also less of a flavor impact.”
Norbert Kaminski, a professor of pharmacology and toxicology at Michigan State University, agrees that obtaining the optimum amount of a naturally occurring antimicrobial can be problematic. Benzoic acid, for example, is a widely used antimicrobial preservative that’s found in tomatoes, apples, blueberries and many vegetables. “The problem is that you need to have an effective concentration for these antimicrobials to have any activity,” Kaminski says. “And you have to be able to produce them economically, which can be challenging if you’re trying to extract these [antimicrobial compounds] from natural products.”
One hallmark of the clean label movement is the widespread belief that “natural” equates to “safe,” Kaminski observes. “That is a wrong premise,” he insists. “Just because something is natural doesn’t mean it’s safe.” The large number of outbreaks of foodborne illness from fresh produce (both organic and non-organic) bears this out.
Many people who seek out “clean food” prefer organically grown produce in large part because they believe it is free of synthetic pesticide residue. But in the absence of applied pesticides, “plants produce natural toxins to defend themselves against various stressors out in the field, whether insects or microbiological pathogens,” Kaminski says. Some of these toxic compounds can be “very mutagenic,” he emphasizes.