Purpose: A study was conducted comparing the growth and recovery of Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus in the two different neutralizing media using aseptic milk chocolate beverages and puddings compared to the same inoculum in a dark chocolate version of the same brand.
Methods: Challenge studies were performed by inoculating 10 ml of the milk or dark chocolate product. The study included two brands each of a low acid aseptic beverage drink and two brand types of aseptic pudding. Samples were inoculated at target levels of 10 CFU per 10 ml product volume. Challenge studies were performed in triplicate to establish reproducibility. Culture confirmation and biochemical identification were performed on 1 sample of each triplicate set.
Results: Inoculated studies with the different brand and product types of milk chocolate did not display any significant delay in growth or detection with all organisms detected within 24 + 2 hours regardless of the bottle type. However, depending on the specific product type, inoculated studies with the dark chocolate did demonstrate delayed growth for Staphylococcus aureus in the charcoal bottle often requiring 33 - 41 hours for detection. The same Staphylococcus aureus inoculated sample could be detected within 24 + 2 hours with the use of BacT/ALERT iFA Plus medium containing adsorbent polymeric beads for added neutralization.
Significance: Staphylococcus aureus was the most effected by the dark chocolate product with delayed growth and detection. The detection of Staphylococcus was improved by as much as 16 hours by the use of the new iFA Plus neutralizing medium.