Malcond Valladares, Ph.D., Food Scientist, The National Food Lab (NFL), systematically covered the process necessary to meet clean label salad dressing safety standards for one popular application at Global Food Forums’ 2022 Clean Label Conference. His presentation, titled “Considerations for Selecting and Evaluating Clean-Label Antimicrobial Ingredients for Dressings,” reviewed four key steps that must be taken when formulating clean label non-thermally processed salad dressings (and other acidified foods).
FDA’s Title 21CFR117 provides regulations for hazard analysis, risk-based preventative controls and good manufacturing practices (GMPs). Begin by defining the regulatory space for your product, advised Valladares. He then focused on salad dressings classified as acidified foods made from high- and low-acid ingredients. Acidified foods are shelf-stable, have a pH of less than 4.6 and water activity (aw) over 0.85.
Valladares stressed the importance of allowing particulates to reach equilibrium with the rest of the formula before testing to ensure a pH is less than 4.6. Equilibrium can take up to 24 hours to occur.
Possible sources of microbial risk include ingredients, the production environment, processing and storage, and recontamination.
Pathogens, such as E. coli 0157:H7, Listeria Monocytogenes and Salmonella enterica, and spoilage microorganisms, like lactic acid bacteria, yeast and mold, are of concern. “This is especially true when the manufacturing process does not include a kill step process or treatment to mitigate the microbial risks associated with these products,” Valladares emphasized. “There’s a high chance that mold can grow over time, and mold can shift the pH, allowing pathogen growth, as well,” he added.
“A clean label system must deliver a validated pathogen kill step of 5-log reduction for pathogens of concern,” Valladares said. This system depends on a specific combination of formula and process, as does inhibiting spoilage microorganisms for improved shelflife. The goal is to assess the robustness of the formula to environmental contamination during processing, as well as secondary growth after opening and storage.
Screening Formulation Options
Standardized formulation parameters for salad dressings can be found in 21CFR169. The International Commission on Microbiological Specifications for Foods (ICMSF) established specific ranges of certain ingredients. Usage of acetic acid at 0.5-1.5% will keep the pH well below the 4.6 threshold, advised Valladares. The ICMSF also recommended salt concentrations of 1-4% and sugar concentrations of 1-30%. Even so, these parameters result in an aw of 0.95, which is above the threshold for the growth of pathogens and microbes, thereby requiring preservative ingredients. (See chart titled “Clean Label Antimicrobials,” which provides a list of clean label ingredients used to control microbial risk.)
Various tests are required to ensure the viability and stability of the product. Flavor stability should be checked throughout the shelf life, as should the visual quality of your product.
Once a formulation is developed, the 5-log kill step for pathogens must be documented. The processing authority may need to review the formula and process and determine if FDA filing is required. The pathogenic kill step is validated via a microbial challenge study in triplicate per sampling time. This study determines the time needed to achieve a 5-log reduction under storage conditions. Data generated from the microbial challenge study must be robust enough to support a food safety plan.
Finally, shelflife studies assess the product’s robustness during storage and test for recontamination over time. Valladares recommends running a spoilage challenge study that is 1.5 times the desired shelflife target under relevant storage conditions. He concluded by emphasizing that the spoilage challenge study cannot predict shelflife past the time indicated in the microbial challenge study.
“Considerations for Selecting and Evaluating Clean-Label Antimicrobial Ingredients for Dressings,” Malcond Valladares, Ph.D., Food Scientist, The National Food Lab
To view this presentation in pdf form, go to “Meeting Food Safety Standards in Clean Label Dressings” in Global Food Forums’ R&D Academy.
