USE OF NISAPLIN(TM) TO INHIBIT SPOILAGE BACTERIA IN BUTTERMILK RANCH DRESSING

Nine commercial salad dressings (spoonable and pourable) were sampled for microbial flora, pH, and total acidity. Bacterial populations rang ed from 10(2) to 10(4) CFU/g in the salad dressings, but yeasts and mo lds were largely undetected (<1 x 10(2) CFU/g). The range of pH (3.3 t o 4.1) and titratable acidities (0.63 to 1.34% as acetic acid) indicat es that such differences in formulation may lead to varying shelf live s among the dressings, especially in regard to aciduric microorganisms . Nisaplin(TM), a commercial antimicrobial food additive and shelf-lif e extender, inhibited 27 of 30 bacterial isolates obtained from 6 sala d dressings. Nisaplin (200 ppm) was used as a preservative in a shelf- life study with a spoonable buttermilk ranch dressing at pH 3.8, 4.0, and 4.2, challenged with Lactobacillus brevis subsp. lindneri, a ranch dressing spoilage isolate, and maintained at 26 degrees C. In control samples at pH 4.2, both the added Lactobacillus and the indigenous fl ora increased starting at day 6 to a maximum at 30 days. However, in b uttermilk ranch dressing (pH 4.2) containing Nisaplin, initial levels of added inoculum were quickly reduced and no significant growth occur red during the 90-day shelf-life period. The data indicate that the na tural preservative Nisaplin may be an effective spoilage inhibitor for spoilage-sensitive refrigerated salad dressings.