Purpose: The purpose of this study was to develop and assess the performance of a device for the rapid detection of aciduric microorganisms in high-acid food products in the juice and beverage industries.
Methods: Experiments were performed to select the optimal growth medium and semi-permeable matrix indicator chemistries that would produce the most rapid detection of aciduric microorganisms in the new vial. Orange Serum Broth (Acumedia) was selected as the growth medium. This medium was optimized for growth of the target organisms. Inclusivity studies were performed using a panel of the target organisms at levels of <100 CFU/ml. In addition, the detection time in the instrument and growth of low inoculum levels of the organisms in food matrices was examined.
Results: The inclusivity test panel of twenty-one organisms consisted of bacteria including Lactobacillus, Leuconostoc and Alicyclobacillus, yeasts and molds. The instrument detection times in juice products were as low as 20 hours for an inoculum level of 3 CFU/ml for Leuconostoc mesenteroides, 33 hours for an inoculum level of 9 CFU/ml for Aspergillus niger and 16 hours for an inoculum level of 39 CFU/ml for Candida krusei. The majority of the other target organisms containing < 100 CFU/ml detected in < 48 hours. The acidic food matrices tested did not interfere with the vial test.
Significance: The new Orange Serum vial provides a system for the rapid detection of aciduric microorganisms in many high-acid food products in < 48 hours compared to the standard incubation time of 5 days for agar plates.