Environmental Testing: Sponge That!
All environmental monitoring begins with a collection tool and there are a wide range of options. There are different mechanisms, sponge materials, bags and more. Let's do a quick run down:
Environmental collection sponges typically have a stick to hold onto but not always. For some collection spots, it is easier to use a pair of gloves and a free sponge. The collection sticks also have different mechanisms. These don't impact usage of the sponge but some operators have strong preferences! Options include:
- The clip mechanism pictured here
- The twist off
- The bend and break
Sponge Material & Buffer
There a quite a few different sponge and buffer combinations and what makes sense for you may depend on sampling conditions, plant conventions and regulatory requirements. Let's start with the sponge material:
The two primary materials for environmental sampling are cellulose and polyurethane. Cellulose, a natural material, can have some variability in size, thickness and ruggedness. Some users also complain that when using cellulose sponges, the material rips and frays on rough surfaces. Polyurethane is a manufactured product and therefore has a high level of consistency. In addition, polyurenthane has a higher tensile strength and has more of a tendency to stretch rather than rip. This may make it easier to use on rough surfaces. All sponges sold for environmental testing are sterilized so there is no risk of contamination from the sponge to the surface or your sample.
There are four buffers typically used in environmental sampling: Letheen, DE, Neutralizing Buffer and Buffered Peptone.
- Letheen neutralizes surface disinfectants, chlorine and flourides which may be food on recently cleaned surfaces.
- DE was developed to neutralize a broad spectrum of disinfectants and preservative antimicrobial chemicals, including quaternary ammonium compounds, phenolics, iodine, chlorine preparations, mercurials, formaldehyde, and glutaraldehyde.
- Neutralizing buffer is specifically designed to neutralize quarternary ammonium.
- Buffered Peptone is typically used as a pre-enrichment for Salmonella samples.
Different buffers can have different impact on both the target bacteria and the diagnostic so check with your supplier or lab before making a change.
It's in the Bag
And last but not least, let's look at the bag or outside packaging for the sponge. A few things to consider here.
- Bag Size: If you are running an enrichment based test, you will need a larger bag so that enrichment can be added directly to the bag.
- Moisture Barrier: Many sponges are sold with the buffer inside the bag. It is important that the bag provide a good moisture barrier so that liquid does not evaporate. Some suppliers have a foil overwrap around either the sponge or a group of sponges.
- Closure mechanism: Many bags have a twist tie mechanism to close the bag. This is critical if you are further processing in your collection bag.
What works for you
Find what works for you! Our development team did a deep dive on sponges last year to find that best combination of sponge, mechanism, bag and buffer for Listeria and for our diagnostic. Our pick for DETECT/L is the World Bioproducts EZ-10LET-PUR, from their EZ Reach line. Whatever you choose, the right tools can make all the difference!
Together, we can make food safer.