Modeling the buffer capacity of ingredients in salad dressing products

Authors: LONGTIN, MADYSON - North Carolina State University; Price, Robert; MISHRA, RITU - North Carolina State University; Breidt, Frederick

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2019
Publication Date: 4/1/2020
Citation: Longtin, M., Price, R.E., Mishra, R., Breidt, F. 2020. Modeling the buffer capacity of ingredients in salad dressing products. Journal of Food Science. 85(4):910-917. https://doi.org/10.1111/1750-3841.15018.
DOI: https://doi.org/10.1111/1750-3841.15018

Interpretive Summary: Buffer capacity is a critical factor for determining how pH may change with the addition of ingredients to acid or acidified foods. However, there is little or no data in the scientific literature to aid industry or FDA about the buffer capacity of typical ingredients in acidic products, or easily applicable methods to allow pH prediction following the addition of ingredients with high pH (around neutral). To fill this scientific void, we have developed a mathematical model and methods for the analysis of food ingredients to allow pH predictions in acidic foods such as salad dressing products. Using this model, we analyzed a series of acid and neutral pH ingredients typical of dressings to validate the model. By cataloguing the buffering of each ingredient, pH changes with ingredient addition could be accurately estimated. With the addition of most ingredients selected salad dressing products, including ranch, blue cheese and vinaigrette, the ingredient buffering was minimal compared to the vinegar added, so pH did not change significantly. The models may useful for both food producers and regulatory agencies in determining the how pH may change as ingredients are added to acidic foods, for both food safety and product development purposes.

Technical Abstract: The pH of most acid food products depends on undefined and complex buffering of ingredients but is critically important for regulatory purposes and food safety. Our objective was to define the buffer capacity (BC) of ingredients in salad dressing products. Ingredients of salad dressings were titrated individually and in combination using concentrations typical of dressing products. Titration curves from pH 2 to 12 were generated with sodium hydroxide and hydrochloric acid, which were then used to generate BC curves. A matrix of concentration and pK values for a series of monoprotic buffers approximated the pH of each ingredient. Some buffer series required anion or cation corrections for accurate pH prediction, possibly due to the presence of salts of acid or bases. Most buffers had BC values less than 10-fold the BC of acetic acid (0.25 ß) typically in dressing formulations and had little influence on the final product pH of the dressings tested. Unexpectedly, we found that sugars in dressing formulations, including sucrose or corn syrup, exhibited buffering at pH values greater than 11 (0.035 ß and 0.059 ß, respectively), which was likely due to weakly acidic hydroxyl groups on the sugar molecules. However, the concentration and pK for buffers above pH 11 or below pH 2 were difficult to quantify due to the BC of water. The BC data may help to quantify the effects of salad dressing ingredients on the final product pH and benefit regulatory agencies and manufacturers in assessing product pH and safety.