concentrating pathogens in foods and beverages


Rapid microbiological analytical methods off great potential for increasing the reliability of pathogen detection in foods while reducing labor costs and product hold times; however, small analysis volumes limit the use fulness of these methods. Pre-enrichment is often used to overcome this limitation, but the significant time advantage of these methods is then lost. In an effort to fill this void, InnovaPrep has developed a rapid ‘mechanical concentration’ approach using a single-use membrane filter tip and a novel elution process to allow for straightforward, user-friendly concentration of pathogens


·         Campylobacter jejuni

·         Clostridium perfringens

·         Salmonella spp.

·         Escherichia coli O157:H7

·         Bacillus cereus

·         Escherichia coli

·         Listeria monocytogenes

·         Shigella spp.

·         Staphylococcus aureus

The concentration process uses microfiltration to capture organisms within a porous membrane filter within the Concentrating Pipette’s single-use tip. After the sample has been trapped, InnovaPrep’s patented Wet Foam Elution™ process is employed to wash the organisms off of the membrane surface into a very small liquid volume to better match the input volumes of rapid detection methods such as immunoassay, PCR etc., thus, enabling detection at previously undetectable levels. The one-pass method provides rapid sample volume reduction and simultaneous clean buffer exchange. Nowhere is this more important than for trace analysis of foodborne contaminants. Liquid food and beverage samples can be concentrated in minutes allowing concentration factors of several orders of magnitude for direct detection by allowing analysis of the entire sample. This method eliminates the need for enrichment.

Examples include: Wine, beer and soda (degassed), electrolyte drinks, tea, apple juice, sports drinks, rinses from food processing equipment, food preparation surface samples, etc.

Some more-difficult matrices can be first diluted, prefiltered, and then concentrated for direct detection.

Examples include: honey; spices; condiments; baby food; oils; and fish, seafood, poultry, hot dogs, nuts, and produce rinses.

Solid samples that cannot be diluted can be pulverized, prefiltered, then added to an enrichment broth (with or without enzymatic pretreatment) and incubated for reduced periods (3 to 6 hours) prior to concentration.

Example included: Beef, eggs, dog food, cereals, nuts, and nut butters.

InnovaPrep has demonstrated the ability to concentrate bacteria, viruses, molds and parasites from samples with various levels of organic and non-organic material loading using the concentrating Pipette. The device is robust; however, to reduce membrane blinding it is often necessary to prefilter samples. InnovaPrep offers prefilter products including Mesh Pipette Filter Sleeves and 1 Micron Prefilter Bags shown below.

The sleeves prevent large particulates from blinding the filter within the Concentrating Pipette tip while processing liquids. Half of the sleeve is made of a polyethylene mesh filter with pore sized holes 330 microns in diameter, and the other half is soli d 3.0 mil (0.075 mm) polyethylene. The pipette tip slides into the sterile sleeve and is inserted into the sample fluid to be tested. The liquid will pass through the filter, while screening out the larger debris.

For very high particulate loads large samples can be prefiltered by pouring through a depth filter bag. These are made from 10 inched glazed polypropylene felt rated for 1 micron filtration. 

The pipette tips also can be user-modified to accommodate the luer fitting on common disk-type filters such as PA LL 11 μm filters as shown above. This can serve as an eve n more effective pre-filter than the mesh pipette filter sleeve during sample processing. After the sample is pulled into the concentrating pipette tip, the user simply removes the filter disk (or sleeve), prior to elution of the sample.


Our Microbiology Sample Preparation Specialists will help develop methods for your particular application to save you time and money. We know that when it comes to microbiology, sample matrices are unique. If you would like InnovaPrep to provide testing/method development with your sample types using the Concentrating Pipette prior to purchasing, please contact us.