Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2025
Publication Date: 7/16/2025
Citation: Anthony, A.M., Skinner, C.R., Katare, N., Guydan, D., Johanningsmeier, S.D., Breidt, F. 2025. Development of a synthetic medium to investigate the role of buffer capacity and metabolites on the fermentation chemistry of cucumber juice. Journal of Food Protection. https://doi.org/10.1016/j.jfp.2025.100580.
DOI: https://doi.org/10.1016/j.jfp.2025.100580

Interpretive Summary: A novel technique called buffer modeling has been developed that can be used to determine how the pH or sourness of an acidic food product will change as food ingredients are added to the product during manufacture. To adapt this technology to food fermentation studies, an artificial bacterial growth medium was developed that can be fermented with similar results as natural vegetable fermentations, resulting in similar acid levels and biochemical changes. The ability to use an artificial medium to investigate a natural fermentation is important because studies with this medium showed how medium components influence acidity changes. The results showed that specific chemical constituents of cucumber fermentation brines, including malic acid naturally present in cucumbers, can strongly influence biochemistry and safety. This study demonstrated that buffer modeling technique works and can be used for future food safety studies that can help predict die-off of disease causing bacterial in acid and acidified foods.

Technical Abstract: The objective of this study was to investigate the role of buffer capacity on fermentation biochemistry in a model cucumber fermentation system. To this end, synthetic media were prepared that had similar fermentation properties to cucumber juice (CJ). While synthetic media are commonly used, matching the buffer capacity of a natural microbial fermentation with a synthetic medium has not been attempted. Buffer modeling technology has recently been shown to be an effective means to link pH and weak acid concentration in acid and acidified foods. Our hypothesis was that an artificial cucumber juice medium (ACJ) with similar buffering and nutrients to CJ would result in similar metabolite and pH changes during fermentation by Lactobacillus pentosus LA445 (a commercial cucumber fermentation isolate). ACJ formulations (N=27) were prepared based on the composition of 10 independent CJ preparations. Selected ACJ formulations that had similar buffer capacities to CJ preparations in the pH 2 to pH 7 range were fermented under anaerobic conditions. Malic acid was found to be the principal buffer in this pH range and the initial concentration correlated with sugar utilization and final medium pH. The data showed that media with similar buffer capacity resulted in similar sugar utilization patterns (p > 0.05) following 72 hours of fermentation. The data indicate that artificial media developed with buffer modeling technology may be useful for the study of a variety of food and other fermentations in which pH evolution and acid production influence quality and safety.