Marijuana Business Magazine July 2019

Marijuana Business Magazine | July 2019 88 6 Dilute Samples After the media is added and the sample is homogenized (i.e., mixed for uniformity), the sample is taken in the biosafety cabinet for Total Yeast and Mold (TYAM) plating. This is the first part of the biocontaminant test. An analyst uses a pipette to take an aliquot, or a portion, of the sample to dilute it with more media for yeast and mold testing. The sample should be diluted before it is plated, because even after Step 4—the introduction of media to the sample— the sample could be too concentrated for analysts to count individual colonies of contaminants after plating. The dilution allows analysts to more accurately detect and calculate the contaminants. 7 Pipette Samples Onto Petrifilm and Store The diluted sample aliquot is placed on TYAM 3M Petrifilm, which is a newer and more sustainable plating technology commonly used in the food and environmental testing industries. Once the sample aliquot is pipetted in the shallow reservoir of the Petrifilm, it forms a gel-like substance on the film, which contains nutrients that promote the growth of fungi and antibiotics that prevent the growth of bacteria. Pressure should be applied evenly to distribute the sample and fill the reservoir. Any sample media pressed outside the reservoir will not be included in the test analysis. After about 60 seconds, the gel solidifies and then is stored in a temperature-controlled incubator for 60-72 hours. That amount of time allows colony-forming units (CFU) of present contaminants to grow.