Purpose: A novel oxygen depletion technology, GreenLight, has been introduced to reduce the time to result for screening tests in dairy products. This technology uses the respiration of viable aerobic organisms to estimate microbial loads in food samples. A method was developed for introduction to dairy producers in Slovakia and the Czech Republic, with the goal of delivering good yeast/mold selectivity while minimizing sample preparation and reducing time-to-result versus the traditional microbial methods.
Methods: The study compared known fungal contaminants inoculated into fruit yoghurt, purchased at retail. Samples were tested on the rapid technology and compared to a traditional plate count method. Anti-microbials were introduced and evaluated for their improvement on selectivity of the target organisms. A customized broth was created to be used in further factory validation.
Results: Final laboratory verification results using customized broth produced 24 data pairs in triplicate for two target organisms. These indicate that the rapid system can enumerate Candida tropicalis at 10 CFU/ml in approximately 18 hours with correlation to plate count of 0.89 (Pearson Coefficient). This compares favorably to 5 days for the reference method. Geotrichum candidum was measured in approximately 22 hours (Pearson 0.96) at the same level.
Significance: The study predicts that a product release test for spoilage organisms can be designed that reduces time-to-result in packaged yoghurt products by over 100 hours, allowing early detection, recall and reduced waste.