P3-15 Rapid Quantitative Enumeration of Yeasts and Molds

Wednesday, July 31, 2013
Exhibit Hall (Charlotte Convention Center)
Sailaja Chandrapati, 3M Food Safety, Maplewood, MN
Tera Nordby, 3M Food Safety, St. Paul, MN
Introduction: Yeast and Molds are ubiquitous food spoilage agents that can grow at a wide range of temperatures, pH values and more importantly at reduced water activities (Aw) thus having the potential for substantial economic losses to the food industry. These organisms have become important indicators for monitoring food quality but the 5-7 day incubation required by traditional enumeration methods poses a burden on food producers. A novel dehydrated film medium was developed to address the need for rapid (48-60 hours) detection of yeasts and molds and the detection technology was optimized to overcome the inherent limitations of yeast and mold appearance and interpretation on dehydrated media.

Purpose: This study was performed to demonstrate comparative enumeration of yeast and molds using a new dehydrated film medium and reference methodology as described in FDA/BAM and ISO21527:2008 (parts 1 and 2).

Methods: The method comparison was conducted using a variety of naturally contaminated food matrices (n = 75) with the new dehydrated film test method and a reference method (FDA/BAM and ISO21527:2008, parts A and B). Each food sample was serially diluted in 0.1% peptone water. The new dehydrated film medium was hydrated with 1ml of the sample and 100 micro-liters were spread plated on DRBC or DG-18 media in replicate.  

Results: Results were statistically comparable between the new dehydrated film method at 48-60 h to DRBC and DG-18 at 5 days with no significant differences as indicated by the P-values (> 0.05) and regression analysis.

Significance: Rapid quantitative detection of yeasts and molds using the new dehydrated film method was evaluated using a large number (n = 75) of naturally contaminated foods. The new method was found to be reliable and have improved interpretation thus providing end users with actionable results in a shorter time frame.