Have you ever seen or added liquid in your environmental sampling devices and questioned what is it, why is it there, or if all the liquid is the same? I know when I began in food manufacturing and took my first samples, these were questions that arose for me and how these factors were impacting the results. The simple answer is that this liquid is called neutralizing broth and there are multiple types that act differently to protect the sample taken.
There are two main jobs that neutralizing broths preform:
- First, as the name describes the broth will work to neutralize any residual sanitizers that may have been concentrated on the sampling device during collection. Many of the cells of bacteria collected are stressed but may survive in the facility. When the cells are exposed to concentrated sanitizer there is the risk to return a negative result when the target organism is actually present.
- Second, the neutralizing broths offer nutrients to maintain the viability of microorganisms until they can be grown to a detectable level in the lab.
While the end goal of all neutralizing broths is closely the same, the components and effectiveness varies among four main types as highlighted in the remainder of this blog.
- Interferes with several diagnostic tests and is not recommended for use with 3M Petrifilm™
- Little capacity to neutralize peroxide-based or acid sanitizers
- Does not have sufficient buffering capacity to overcome high acid sanitizers
- Weakest to neutralize quaternary ammonium compound (“quat”) sanitizers
- Minimal neutralizing activity against peroxide-based sanitizers and limited buffering capacity with low pH sanitizers
D/E neutralizing broth
- Strongest neutralizing activities against the commonly used sanitizers
- Unstable, pH degradation if stored above refrigerated temperatures
- Not compatible with 3M Petrifilm ™
HiCap neutralizing broth
- Excellent neutralizing capability for commonly used sanitizers
- Formulated using only components that are accepted for use in foods and are non-allergenic
- Compatible with 3M Petrifilm ™
- Stored between 2 and 30˚C
Be sure to look at your collection devices to see which broth is used to make sure you are pairing it with the best media and diagnostics test.
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