Peptone Water: What Plant Managers Need to Know

This blog post is a 16 minute read

For those in the meat processing industry, food safety and microbial control are consistently top-of-mind issues. Using buffered peptone water (BPW) for microbial testing in poultry is an industry-standard practice, and now the USDA Food Safety Inspection Service (FSIS) has switched to neutralizing buffered peptone water (nBPW) because of improved recovery of pathogens, Salmonella and Campylobacter.

How is buffered peptone water used, and why? What is the difference between the two types of buffered peptone water—and, are there pros and cons of using one over the other? What is the reasoning behind the FSIS’s decision to move exclusively to using nBPW?

These are important questions to investigate in light of the changes made to food safety laws under the Food Safety Modernization Act. The primary intent of FSMA is to shift to a preventative mindset, identifying sanitation problems and remediating them quickly, before a foodborne illness outbreak can occur.

What is Buffered Peptone Water?

Peptone water is a buffered solution generally containing peptone—a soluble protein—which is then buffered to a neutral pH (approximately 7.0) using a base disodium phosphate. According to the FDA’s Bacteriological Analytical Manual (BAM), it contains peptone, sodium chloride, two forms of phosphate (disodium and mono-potassium), and distilled water.

400 mL Sterile Water

16.4 g nBPW Powder for rehydration into 400 mL H2O

Premade nBPW in 10 mL and 25 mL sizes

Buffered peptone water is used for the detection of microorganisms and it improves the detection of bacteria from raw ingredients, finished product, and samples taken from the food processing environment. This solution is an ideal medium in which to retain microbial viability and promote growth, particularly with samples taken from surfaces and carcasses such as those in poultry processing plants.

Buffered peptone water enables samples that are taken from hostile environments with injured microorganisms (like a previously sanitized food contact surface) to develop. BPW is also used for the dilution of a raw ingredient or finished product samples that may contain high levels of bacteria, providing quantitative levels of bacteria in colony forming units per gram (CFU/g) or mL of product.

How is Neutralizing Buffered Peptone Water Different?

Raw poultry is known to naturally contain high levels of Salmonella and Campylobacter bacteria. Because of these known pathogens, a range of steps is taken during the processing of poultry to control and address the presence of pathogens to minimize consumer exposure. A number of these processing steps incorporate strong sanitizers and acid rinses.

Significant amounts of these acids and sanitizers can pool in parts and carcasses and make their way into the buffered solutions used for microbial sampling and detection of microorganisms. The presence of these chemical residuals in microbial sampling buffers like BPW solutions can potentially lead to additional microbial lethality to the test sample and inaccurate detection and recovery of pathogens.

Buffered Peptone Water

Neutralizing buffered peptone water is similar to buffered peptone water, but it includes sodium thiosulfate and lecithin as additional agents that act to “neutralize” acids and sanitizers.

It is for this reason that nBPW is now required to be used by the FSIS inspectors for official sampling to monitor levels of Salmonella and Campylobacter in chicken and turkeys.

How Does the Difference Between BPW and nBPW Affect a Testing Program?

An important thing to note is that the FSIS now exclusively uses nBPW—the neutralizing buffered peptone water—for its testing. If the industry wants its required indicator and pathogen test results to align with the FSIS’s results, using nBPW is how to get there.

However, the industry has been slow to adopt nBPW for several reasons. First, the price of nBPW is higher than BPW and it has a shorter shelf life. Second, there are a limited number of suppliers of nBPW. Third, the preparation of nBPW from bulk media is a time-consuming and complicated process—and, it is labor-intensive. Fourth and finally, there is a long dissolve time for nBPW, which matters when you are frequently testing for the presence of Salmonella and other microorganisms.

Buffered Peptone Water

Taking all of these factors into account, it is unsurprising that industry has been slow to adopt nBPW—despite the fact that aligning a plant’s internal testing processes with the FSIS makes the most sense for trusted results and reducing the number of required samples.

The poultry industry must also use OMA-validated testing methods. If switching to nBPW, they should align with indicator methods that have been validated for use with that buffer. For example, a commonly used film test for detecting aerobic and Enterobacteriaceae indicators instructs not to use buffers containing thiosulfate.

Charm is Addressing Industry Concerns

Charm Sciences has developed an nBPW testing solution that is lower in cost, shelf stable, quick-to-dissolve, and simple-to-use that addresses the industry concerns that have been slowing adoption of nBPW.

A premeasured pouch of powdered nBPW is added to sterile water and shaken for 20 seconds. The powder is quick-dissolving and shelf stable—and the sterile water can be provided by either the end user or from Charm.

Buffered Peptone Water

Additionally, AOAC-OMA validated nBPW solution with Charm’s Peel Plate® EB Microbial Tests. Samples can be easily tested, aligning samples taken for indicators and pathogens with those samples taken by federal regulators.

If you are interested in seeing how easy it could be to align your plant testing using the industry-standard solution, contact us. We’d be happy to speak with you about your current poultry testing situation and needs, and send you an nBPW sampling buffer to try.

About Charm Sciences

Established in 1978 in Greater Boston, Charm Sciences helps protect consumers, manufacturers, and global brands from a variety of issues through the development of food safety, water quality, and environmental diagnostics tests and equipment. Selling directly and through its network of distributors, Charm’s products serve the dairy, feed and grain, food and beverage, water, healthcare, environmental, and industrial markets in more than 100 countries around the globe.