Seward Stomacher® Contributes to Environmental Listeria Contamination Study

‘Free Range’ Listeria processed by Stomacher 400 Circulator

Worthing, UK- Seward Limited, manufacturer and developer of the world leading, patented Stomacher® Laboratory Paddle Blender range, has announced that its Stomacher 400 Circulator has been used in a recent study(1) to evaluate environmental contamination by Listeria species. The increased interest in animal welfare and free range methods, such as pasture reared poultry, has made it important that there is a greater understanding of the ecology and epidemiology of Listeria in these systems.


Listeria species are naturally present in the environment and can be isolated from pasture, fruit and vegetable crops. The extent to which farm animals reared in a free range environment are exposed and contaminated by these sources has been evaluated by a team from the Universities of Arkansas and Ithaca.

The methodology developed by this team was intended to evaluate the level of contamination of the pasture by Listeria species occupied by free range poultry(1). Samples of grass and soil were collected from the pasture, both before and after introduction of the poultry, and processed using the Stomacher 400 Circulator to extract, culture and isolate the Listeria species present.


The environmental samples collected after introduction of poultry were significantly more likely to contain Listeria (P < 0.001). PCR tests found that both L. monocytogenes and L. innocua, including hemolytic L. innocua, were recovered from cecal, grass and soil samples. This has serious implications for the rate of contamination of free range poultry exposed to untreated pastures.


Stomacher® 400 Circulator is the Gold Standard of sample preparation in the food industry, but the same characteristics of performance, reproducibility and strength has diverse applications beyond the food microbiology laboratory. Soil, turf, faeces and clay have all been successfully processed. Seward can find references for diverse applications from their archives of 1000s of methods to support their customers.


For more information, see This release is also available online at:



[1] Listeria monocytogenes and hemolytic Listeria innocua in poultry. S. R. Milillo, J. C. Stout, I. B. Hanning, A. Clement, E. D. Fortes, H. C. den Bakker, H .Wiedmann and S. C. Ricke. Poultry Science, 2012 91:2158-2163

About Seward Limited -

Seward manufactures the world leading range of Stomacher® paddle blenders and Stomacher® accessories used in sample preparation for microbiological analyses. The company has been manufacturing and developing the world renown and patented Stomacher® Lab Blender for 40 years. The original and still regarded as the best, over 8 million food samples a day are prepared on Stomacher® 400 paddle blender units around the world.

In addition to sample preparation for food safety analyses, within the bioscience market the new developments of the Stomacher® 80 and micro 80 are proving invaluable for safe and efficient sample processing. The Stomacher® 3500 has established itself as the instrument of choice for preparing samples for the new pathogen test protocols requiring jumbo size samples.

The company is based in Worthing, West Sussex, UK with subsidiaries in Port Saint Lucie, Florida, USA and Singapore. All Seward machine products are manufactured within the UK and 1 of its 3 worldwide Stomacher® bag manufacturing operations is also UK-based. This ensures control of quality and price to deliver excellent value to global trading partners and laboratory customers.

Seward Limited continues to develop the product range, now with 3 patents to its credit.  Stomacher® is the most highly referenced brand name in food safety and life science sample preparation in scientific publications. The company also assists customers with method development through reference searches and sample evaluations within its own development laboratory.

Seward contact details:

Europe and ROW: +44 (0) 1903 823077;

US Canada: +1 772 621 8220;

Asia, Pacific and Middle East: +65 67447811;

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