Tuesday, July 11, 2017
Exhibit Hall (Tampa Convention Center)
Mara Celt
, 3M Food Safety
, St. Paul
, MN
Adam Stanenas
, 3M Food Safety
, St. Paul
, MN
Robert Jechorek
, 3M Food Safety
, St. Paul
, MN
John David
, 3M Food Safety
, St. Paul
, MN
Cari Lingle
, 3M Food Safety
, St. Paul
, MN
Introduction: Lactic acid bacteria (LAB) are an essential component for fermented foods, and these organisms have been known to benefit the human digestive systems as a probiotic. However, they can be key spoilage organisms in foods causing off flavors, discoloration, and bloating. There are numerous traditional agar methods for this large group of microorganisms including ISO 15214 and several methods in the Compendium of
Methods for the Microbiological Examination of Foods. These agar reference methods are laborious, and may require anaerobic chambers for the most efficient growth environment. To increase efficiency of LAB testing by eliminating agar preparation, a new rehydratable film method has been developed with a self-contained anaerobic environment. The new rehydratable film method can also distinguish between homofermentative and heterofermentative LAB.
Purpose: This study compared two agar reference methods to a new rehydratable media method for the detection and enumeration of LAB.
Methods: Test portions from 17 matrices were prepared by adding 11 g of each matrix to 99 mL of diluent. Samples were homogenized before serial dilutions were performed. One mL of diluted sample was plated, in duplicate, onto Petri dishes and the new rehydratable film method, 3M™ Petrifilm™ Lactic Acid Bacteria Count Plates. Tempered MRS agar was added to samples in Petri dishes and allowed to solidify at room temperature. If specified in the reference method, agar plates were placed in anaerobic jars with gas packs. Agar plates were incubated at the appropriate temperature, as outlined in the reference method. The rehydratable media method was incubated at 28°C and 37°C.
Results: The rehydratable media method was not statistically different (Mean Log Difference ≤ 0.5 logs) from the two reference methods tested.
Significance: The new rehydratable film method is an acceptable alternative to the most commonly used LAB agar methods.
