June 23, 2014
From the Mail Bag: Differences Between Environmental and Food Sampling
- Food Safety
By Lauren Bambusch
My small ingredients manufacturing company has been doing pathogen testing on our batches for over a year now. I’d like to start testing our equipment and surfaces between batches as part of an expansion to our HACCP plan. However, I’m concerned that the protocol would be difficult and give my quality control manager just another thing to learn.
Zack W., New York City, NY
I can’t speak to every protocol out there, but I can tell you that the InstantLabs’ Food Safety Testing Kits are specifically designed to be simple to use, and that includes moving back and forth from food to environmental samples. In fact, both types of protocols are identical after the enrichment preparation step.
So here’s how it works: when testing a food product, you’ll mix a sample of the food or ingredient (typically 25+ grams) with the enrichment media in a filtered enrichment bag such as a Whirl-Pak bag. Sound familiar yet? Well, after mixing the media and the product, you’ll put the filtered enrichment bag into the incubator and let it sit there for a while. When the incubation period is over, you’ll take a small sample of that enrichment, do a simple one-step DNA extraction, mix it with PCR reagents, and insert it into the Hunter®. Then voila: results.
Testing your equipment, surfaces, or other environmental samples is almost identical. The only change is instead of mixing a food sample with the enrichment broth, you’ll take a pre-moistened swab or sponge and wipe a square in a double zig-zag pattern. From there, you’ll put the sponge or swab into the enrichment media, and continue on just as if it were a food sample.
Whether or not you use a sponge or a swab depends on what surface you’re testing—items like stainless steel equipment and table tops often sample a larger surface area (4” x 4” or larger) and require a sponge like this one, while sealed concrete surfaces like the floor or possibly the walls test a smaller 1” x 1” surface area and require a swab like this. Both are available pre-moistened, so all you need to do is swab, enrich, and go.
Again, I can’t speak to the protocol for the process you’re using now, but I can tell you that with InstantLabs, your quality control manager would have no problem adapting your current testing schedule and protocols to include the environmental samples.
Lauren Bambusch is a microbiologist by trade as well as a writer and baker by hobby. She lives in Baltimore with her husband, three cats, a super-sized mutt, and a school of fish, all of whom root for her Alma mater, Michigan State. Go Green!