Emergency Response Validation of the Soleris® Direct Yeast and Mold Method for Detection of Yeast and Mold in Dried...

Soleris® Direct Yeast and Mold (DYM) is a growth-based, automated method for detection of yeast and mold in select foods and other sample types including nutraceuticals and cosmetics. The Soleris method is used in a "dilute-to-specification" or threshold manner in which a result is scored as positive or negative around a predetermined cutoff (in CFU/g) established by the dilution and volume of sample homogenate tested.

The objective of this study was to validate the method for testing of dried cannabis flower. The validation was conducted under the Emergency Response Validation program of the AOAC Research Institute.

The study included inclusivity and exclusivity testing, in particular testing of yeast and mold species associated with cannabis, and a matrix study in which Soleris method presumptive results were compared with Soleris confirmed results using Dichloran Rose-Bengal Chloramphenicol (DRBC) agar for confirmation. Samples at four different levels of natural yeast and mold contamination were tested at two test thresholds.

In inclusivity testing, all 63 yeast and mold strains tested produced positive results within the specified test duration of 72 h. In exclusivity testing, 36 of 37 strains tested produced no detection within 72 h. In matrix testing, there were no significant differences between Soleris presumptive and confirmed results for any contamination level or test threshold as determined by probability of detection analysis.

Results indicate that the Soleris method is an effective procedure for detection of yeast and mold in dried cannabis flower.

With the Soleris method, results are available within 72 h compared with the 5-7 days required for microbiological culture methods.