2009 Volume 26 Issue 4 Pages 202-207
In order to establish a rapid screening method for yeast and mold in food, the PCR-based QUALIBAXTM System (BAX Method) was compared to a conventional culture method using Potato Dextrose Agar (PDA Method) for detecting yeast and mold in margarine, filling and frozen dough. A spiked study on margarine used known strains of organisms often detected in the target food types: C. parapsilosis, C. sphaerospermum, P. aurantiogriseum, Mucor spp., A. versicolor and W. sebi. The correlation between 5-day results for the samples plated onto PDA and 48-hour results for the samples processed by the BAX Method was very high. Both methods demonstrated lower sensitivity for W. sebi. To improve the detection of W. sebi, the enrichment medium was modified by adding glycerol, glucose or sodium chloride to the broth. Results showed improved sensitivity rates for W. sebi when glycerol or glucose was added. An additional study compared the BAX Method with standard enrichment to the PDA Method on 110 unspiked samples: 75 were naturally contaminated and 35 were artificially contaminated through exposure to highly contaminated environments. Both methods demonstrated the same high levels of sensitivity in detecting yeast and mold. These studies suggest that the BAX Method can be used by food processors for rapid and highly sensitive screening when investigating yeast and mold contamination.