Natural Antimicrobial Strategies

Originally Published: November 10, 2017
Last Updated: February 9, 2021
Lactic acid starter cultures in fermented foods have natural antimicrobial properties.

November 10, 2017 – Jairus R. David, Ph.D., Natural Antimicrobial Program, Research & Innovation, ConAgra Foods, Inc., began his presentation on a positive note. He affirmed that a dialogue about clean labeling is exactly what is needed; the focus of his speech was on preservatives, antimicrobials and options for clean labels.

“None of us may have all the answers,” suggested David, “but by connecting, we can try to understand what ‘clean label’ and this movement mean and how we can achieve the desired results.”

The application of preservatives and antimicrobials is complex and requires due diligence. “Preservatives are good, and they have played a big role in protecting food for centuries,” David stated. “Without preservatives, there would be more food spoilage and public health issues due to food-borne pathogens.”

For example, sorbates, benzoates and propionates are antimicrobials that specifically control the growth of spoilage and pathogens, and they need to be used in a prudent and judicious manner—not to mask poor practices. Lactates and diacetates are examples of antimicrobials used in meat to limit growth of Listeria monocytogenes and are especially important in refrigerated RTEs and perishable meats. Producers and consumers want to be assured of a certain retail shelflife and do not want spoilage or returned products.

“Food manufacturers should monitor the microbial load at all stages in the conversion of raw materials to end food products,” he stated. The finished product will not be better than the starting material. The key is a kill or control step, which could be sterilization or pasteurization, for example. Consumers also play a role in food safety: in how they handle, store, cook and reheat food. There is definitely a case for use of preservatives.

When using an antimicrobial, the first question is, does it work? “Usually,” advised David, “the answer is ‘yes, but…’”

Each product needs customization and, in clean labeling, cost is a big deal. Margins are very low. Developers need to understand the efficacy, sensory impact and regulatory limits of the antimicrobial. Especially with naturals, taste can be impacted in a good or bad way. Usually, the sensory threshold is lower than the efficacy level. Also note that the regulatory limit for antimicrobials is usually well-defined and cannot be exceeded.

“There is nothing wrong with chemical preservatives,” David emphasized, “but today, consumers want a clean label.” When looking at a new natural antimicrobial ingredient, due diligence pays off. Antimicrobials are a big challenge; for example, there are not a lot of natural options for Gram-negative pathogens like Salmonella.

David offered tips for application of natural antimicrobials: Look early at the sensory impact and efficacy. At least a two log reduction in microbiological media and model foods (either orange juice or sterilized milk) is needed, or it will not work in food. The next question is whether it will function after scale-up and how the cost impacts the product. And, natural, clean label antimicrobials are not inexpensive. Who is going to pay for it? Lastly, unanticipated issues often occur during development, scale-up and plant trials. Therefore, the key is to persevere.

To cover all bases, David suggests use of an antimicrobial toolbox to maintain sanity (see chart “Antimicrobial Toolbox”), and he challenges vendors to come up with more options for Gram-negative bacterial pathogens and spore formers, in particular.

“Natural Antimicrobials: Strategies & Considerations for Their Use in Food,” Jairus David, Ph.D., Natural Antimicrobial Program, Research & Innovation, ConAgra Foods, Inc.

This presentation was given at the 2016 Clean Label Conference. To download presentations from this event, go to

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