Food Safety
search
cart
facebook twitter linkedin
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Food Safety
  • NEWS
    • Latest News
    • White Papers
  • PRODUCTS
  • TOPICS
    • Contamination Control
    • Food Types
    • Management
    • Process Control
    • Regulatory
    • Sanitation
    • Supply Chain
    • Testing and Analysis
  • PODCAST
  • EXCLUSIVES
    • Food Safety Five Newsreel
    • eBooks
    • FSM Distinguished Service Award
    • Interactive Product Spotlights
    • Videos
  • BUYER'S GUIDE
  • MORE
    • ENEWSLETTER >
      • Archive Issues
      • Subscribe to eNews
    • Store
    • Sponsor Insights
  • WEBINARS
  • FOOD SAFETY SUMMIT
  • EMAG
    • eMagazine
    • Archive Issues
    • Editorial Advisory Board
    • Contact
    • Advertise
  • SIGN UP!
White Papers

Streamlined Microbiological Workflows for the Detection of Listeria monocytogenes in Food

September 8, 2014

Listeriosis, which is caused by eating food contaminated with the bacterium Listeria monocytogenes, is an important public health concern in the U.S. The U.S. Centers for Disease Control and Prevention (CDC) estimates that approximately 1,600 illnesses and 260 deaths occur annually due to listeriosis in the U.S.[1]

To ensure consumer safety, rapid detection methods of L. monocytogenes in food are critical. However, traditional methods for detection require an enrichment step that is time consuming and labor intensive.

This article describes a solution designed to simplify and shorten the workflow of pathogen enrichment. Readybag® Half Fraser Broth comprises aluminum pouches filled with preweighed and gamma-irradiated granulated culture media, eliminating the need for upfront media preparation. Readybag Half Fraser Broth is compliant with ISO standard formulation.

The article will evaluate the application of the enrichment media in Readybag pouches for the detection of pathogens in wiener sausages, cream cheese, cantaloupe melon and cooked prawns. The article will provide the workflow and data for L. monocytogenes detection according to ISO 11290-1 in detail. Traditional preparation of Half Fraser Broth was used as the reference method.

Materials and Equipment
Culture media:

• Readybag Half Fraser Broth 12.5 g (1.02449.0060)

• FRASER Listeria Selective Enrichment Broth (base) (1.10398.0500)

• FRASER Listeria Ammonium iron(III) Supplement (1.00092.0010)

• FRASER Listeria Selective Supplement (1.00093.0010)

• Chromocult® Listeria Selective Agar (base) (1.00427.0500)

• Chromocult Listeria Agar Selective Supplement (1.00432.0010)

• Chromocult Listeria Agar Enrichment Supplement (1.00439.0017)

• PALCAM Listeria Selective Agar (Base) (1.11755.0500)

• PALCAM Listeria Selective Supplement (1.12122.0010)

PCR test kits:

• Foodproof® StarPrep II Kit (S 400 08, Biotecon Diagnostics GmbH, Postsdam)

• Foodproof Listeria monocytogenes Detection Kit (R 302 23, Biotecon)

Test strains:

• L. monocytogenes, St 26/1/II/03

• L. monocytogenes, W29/1/II B 2002

• L. monocytogenes, Frd. Nr.594

• L. monocytogenes, W 07/13

Methods
The workflow for the food trials was based on ISO 11290-1 (Figure 1). Four food types were investigated: wiener sausages, cream cheese, cantaloupe melon and cooked prawns. Each sample of mentioned foods was portioned aseptically to 25 g, and the samples were added into sterile stomacher bags. All food samples were inoculated at low levels with 1 mL L. monocytogenes suspension (inoculation level of 1–5 cfu/25 g sample). Negative controls were used without inoculation.

For the traditional workflow, Half Fraser Broth was prepared by weighing, dissolving, autoclaving and aseptic addition of supplements (Figure 1). Half Fraser Broth (225 mL) was added to each food sample.

For the Readybag workflow, the preweighed and sterile content of one Readybag pouch was added directly to the food sample followed by the addition of sterile, demineralized water dispensed from an Elix® Advantage Water Purification System (Figure 1).

All samples were homogenized in a paddle blender for 1 minute.

The stomacher bags were incubated at 30 °C for 24 hours.

After 24 hours of incubation the Half Fraser Broth was streaked to Chromocult Listeria Agar and Palcam Agar; 0.1 mL of the culture was transferred to 10 mL Fraser Broth.

Chromocult Listeria Agar and Palcam Agar were incubated at 37 °C and read out after 24 hours and—if necessary—after an additional 24 hours to check for the presence of characteristic colonies.

Fraser Broth was incubated at 37 °C for 48 hours and streaked to Chromocult Listeria Agar and Palcam Agar. Both agar media were incubated at 37 °C and checked for characteristic colonies after 24 and 48 hours.

Characteristic colonies from the plates were confirmed by real-time PCR.

Results
All spiked samples of wiener sausage, cream cheese, cantaloupe melon and cooked prawns showed positive results with both the traditional and Readybag workflows. There were no false-negative results (Table 1).

All negative controls without spiking showed no characteristic colonies on the agar plates. There were no false-positive samples with either of the workflows. Additionally, testing of Salmonella with Readybag Buffered Peptone Water against the traditional autoclaved media according to ISO 6579:2002 led to comparable results (data not shown; workflow is similar to that of Half Fraser Broth).

Conclusion
Food trials with the enrichment of L. monocytogenes demonstrate that the Readybag Half Fraser Broth workflow provides results identical to the traditional workflow with media preparation in an autoclave.

Readybag pouches offer significant time savings compared to the traditional method of sample preparation. In the case of Listeria enrichment with Half Fraser Broth, using Readybag pouches reduced workflow time (media preparation to incubation) from 24 to 8 minutes.

Rolf Ossmer is head of applied microbiology, Volker Lanz is product manager, dehydrated culture media, and Andreas Bubert is head of global marketing, food & beverage segments, at Merck Millipore/BioMonitoring in Darmstadt, Germany.

References
1. www.cdc.gov/listeria/statistics.html

 

 

 


Author(s): Rolf Ossmer, Volker Lanz and Andreas Bubert

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • people holding baby chicks

    Serovar Differences Matter: Utility of Deep Serotyping in Broiler Production and Processing

    This article discusses the significance of Salmonella in...
    Food Type
    By: Nikki Shariat Ph.D.
  • woman washing hands

    Building a Culture of Hygiene in the Food Processing Plant

    Everyone entering a food processing facility needs to...
    Food Prep/Handling
    By: Richard F. Stier, M.S.
  • graphical representation of earth over dirt

    Climate Change and Emerging Risks to Food Safety: Building Climate Resilience

    This article examines the multifaceted threats to food...
    International
    By: Maria Cristina Tirado Ph.D., D.V.M. and Shamini Albert Raj M.A.
Manage My Account
  • eMagazine Subscription
  • Subscribe to eNewsletter
  • Manage My Preferences
  • Website Registration
  • Subscription Customer Service

More Videos

Sponsored Content

Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the Food Safety Magazine audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of Food Safety Magazine or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

close
  • mold
    Sponsored byIFC

    Tackling Mold Remediation in Food Processing Plants

  • a worker in a food processing plant
    Sponsored byLPS® DETEX®

    How a Beverage Facility Improved Food Safety and Compliance with Detectable Packaging Solutions

  • Two men standing in a produce storage facility having a discussion.
    Sponsored byOrkin Commercial

    Staying Compliant With FSMA

Popular Stories

sunflower oil

Louisiana Passes ‘MAHA’ Bill Targeting More Than 40 Ingredients, Including Seed Oils, Dyes, Sweeteners

smoked salmon in oil

Study Shows Food Type Significantly Affects Listeria’s Ability to Survive Digestion, Cause Sickness

Justin Ransom and Denise Eblen

USDA-FSIS Announces Dr. Justin Ransom as New Administrator

Events

July 15, 2025

Hygienic Design Risk Management: Industry Challenges and Global Insights

Live: July 15, 2025 at 11:00 am EDT: From this webinar, attendees will learn the importance of hygienic design to ensure food safety and sanitation effectiveness.

July 22, 2025

Beyond the Binder: Digital Management of Food Safety

Live: July 22, 2025 at 3:00 pm EDT: During this webinar, attendees will learn best practices for the use of digital food safety management systems across industry and regulatory agencies.

August 7, 2025

Achieve Active Managerial Control of Major Risk Factors Using a Food Safety Management System

Live: August 7, 2025 at 2:00 pm EDT: From this webinar, attendees will learn about changes to the FDA Food Code, which now includes a requirement for FSMS. 

View All

Products

Global Food Safety Microbial Interventions and Molecular Advancements

Global Food Safety Microbial Interventions and Molecular Advancements

See More Products
Environmental Monitoring Excellence eBook

Related Articles

  • QIAGEN Achieves AOAC Certification of Automated Workflows for Detection of Listeria Pathogens in Common Foods

    See More
  • rod shaped bacteria possibly listeria

    Scientists Detect Low Levels of Listeria in Food Within Eight Hours Using Streamlined Workflow

    See More
  • Development of a Detection Method for Listeria spp. in Food and Environmental Samples on the Atlas™ System

    See More

Related Products

See More Products
  • 1119053595.jpg

    Food Safety for the 21st Century: Managing HACCP and Food Safety throughout the Global Supply Chain, 2E

  • 9781138070912.jpg

    Trends in Food Safety and Protection

  • 1119160553.jpg

    Food Safety: Innovative Analytical Tools for Safety Assessment

See More Products

Events

View AllSubmit An Event
  • October 24, 2024

    The Future of Metal and X-Ray Detection in Plastics

    On Demand: From this webinar, attendees will learn how to enhance safety and compliance in their F&B operations.
View AllSubmit An Event

Related Directories

  • Anritsu - Product Inspection & Detection

    Anritsu manufactures product inspection and detection equipment for food and pharma industries. Part of the Product Quality Assurance division of Anritsu Corp., we advance quality control programs with high-performing and reliable solutions. Our X-Ray Systems, Checkweighers, Metal Detectors, Combo Systems, Rejectors, and QuiCCA Software provide a superior ROI and ensure compliance with stringent quality control programs while protecting your brand. Our local branches in the US, Europe, Brazil, and Mexico are equipped with in-house service & parts dept., we deliver, install, and maintain in record time. With over 200,000 installations, we are the brand that is trusted to protect the safety and security of your customers.
  • KLEANZ Food Safety Technologies

    KLEANZ Food Safety Technologies is proud to be the leader in software and services for the Food and Beverage industry. For over 30 years, we have ensured that our clients’ Food Safety, Sanitation Management, and Maintenance needs are satisfied and streamlined. We pride ourselves in helping our clients mitigate risk.
×

Never miss the latest news and trends driving the food safety industry

eNewsletter | Website | eMagazine

JOIN TODAY!
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
  • SIGN UP TODAY
    • Create Account
    • eMagazine
    • eNewsletter
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • Instagram
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing