Ready-to-use culture media bags in food microbiology: Advantages, disadvantages, and supplier selection

Since the early 2000s, several culture media suppliers have been offering food microbiology laboratories a highly convenient format: the ready-to-use (RTU) media bag.

According to our survey, 23% of SuperMicrobiologists use these ready-to-use bags.

In this article, we’ll explore the advantages and disadvantages of this culture media format. We’ll also share some tips to help you choose the right supplier for your culture media pouch.

Content :

• What is a RTU culture media bag ?
• Advantages
• Disadvantages
• 5 Tips to Choose the Best Enrichment Broth Bags Supplier

What is a RTU culture media bag ?

It is a plastic bag filled with sterile liquid culture media (an enrichment broth). Most suppliers offer two sizes: 3 liters and 5 liters.

The most commonly used culture media in this format are Buffered Peptone Water (BPW) and Fraser broth (used for Listeria detection).

These bags are typically connected to a gravimetric dilutor for use in the first step of sample preparation: weighing and diluting the stock solution.

Advantages of Enrichment Broths in Bags

• Ready-to-use: No preparation time needed. If you arrive at the lab at 8 a.m., you can start the first dilutions at 8:01 a.m.
  
• ISO 11133 compliance: Defining a batch is much simpler (compared to a media preparator). If storage space is available, you can order a large batch, reducing the number of performance tests required.

For more on media preparators, check out this very interesting article: Tips for Choosing the Best Media Preparator.

Disadvantages of Enrichment Broths in Bags

• Price: The cost per liter for ready-to-use flexible bags is higher than purchasing powdered media!
  
• Transport: Bags primarily consist of water, which takes up space in trucks, increases shipping costs, and isn’t exactly eco-“friendly.”
  
• Handling: If you use large quantities of bags daily, the required handling, from pallet to the lab (and sometimes via the incubator for preheating). This greatly increases the risk of musculoskeletal disorders (MSDs).

5 Tips to Choose the Best Enrichment Broth Bags Supplier

Here are some tips to help you select the right culture media bags for your food microbiology laboratory:

1 – Culture Media Quality

There are significant quality differences between suppliers. Depending on the matrices you need to analyze (e.g., acidic samples, 375g samples, etc.), it may be wise to test multiple culture media options.

2 – Single Batch

To avoid performing multiple performance tests (ISO 11133), it’s best to request delivery of a single batch. Make sure your suppliers can accommodate this.

3 – Transport Boxes

It May Seem Simple, But moving a heavy box without proper handles can be a challenge. Some suppliers offer more practical solutions, such as boxes with built-in “handles” for easier handling.

4 – Logistics

Suppliers typically operate on a schedule with subscription-based deliveries. But what happens if you need to perform more analyses than usual? Can the supplier provide emergency deliveries?

Ask about their production location and buffer stock volume to ensure they can meet unexpected demands.

5 – Eyelets

Diluent bags are typically hung on a stand, allowing the dispensing nozzle to face downward. Some suppliers offer bags with one or two eyelets (small holes) for hanging. This is practical, but it’s up to you to decide what works best for your needs.

Also, check that the bag’s plastic is sturdy enough to hold up on the eyelets. A 5-liter bag weighs 5 kilograms, and after several hours, the strain on the eyelets could tear the bag.

Conclusion on Ready-to-Use Bags

In conclusion, ready-to-use bags (RTU) provide a convenient and time-efficient solution for food microbiology laboratories. Their ease of use, requiring no preparation, saves time and enhances analysis efficiency. However, their higher cost compared to powdered media and the ecological impact of transporting large amounts of water are factors to consider.

To select the most suitable RTU bag supplier for your lab, prioritize the quality of the culture media, confirm the possibility of receiving a single batch to avoid redundant performance tests, and assess the supplier’s logistics to meet specific needs.

Ultimately, the choice between different culture media formats will depend on the unique requirements and constraints of each laboratory. By carefully weighing the pros and cons, you can make an informed decision. Regardless of the choice, the primary goal remains the same: to ensure reliable, high-quality analyses for food safety.