Acid Tolerant Microorganisms Involved in the Spoilage of Salad Dressings.

Microbiological spoilage of salad dressings and similar products generally results from the growth of a select group of microorganisms. Although frequently isolated these organisms have not been well characterized. Several isolates from spoiled products were examined. Data indicated that spoilage resulted from growth of lactobacilli, similar to the previously described Lactobacillus fructivorans , and yeasts, similar to Saccharomyces bailii . In addition to their acid tolerance, these organisms shared one other common characteristic, rapid fermentation of fructose. Addition of this carbohydrate to enumeration media resulted in improved recovery of both lactobacilli and yeasts.