FAQ: Bacteriophage in cheesemaking

To prevent bacteriophage in cheesemaking, your culture management needs to excel on six critical points. It must include good manufacturing practice, excellent sanitation and disinfection, phage-resistant cheese cultures, an appropriate culture rotation program, proactive monitoring and strong phage support from your culture supplier. Falling short on any one of these increases your risk of bacteriophage attacks.

Your questions answered

To help you reduce that risk and take your phage management to the next level, we’ve put together answers to some of the most common questions we hear from our customers about bacteriophages.

1. Why do phage attacks cause slow acidification in cheesemaking?

Milk acidification is fundamental to both structure and flavor development in cheese. Lactic acid bacteria are essential for milk acidification. Bacteriophages (phages) infect and destroy these bacteria. By compromising these cultures, phages slow acid development and can even cause it to fail entirely.

2. What are the impacts of phage activity in cheesemaking?

Phages directly impact key cheesemaking process steps, leading to process inconsistency. Poor phage management can lead to poor coagulation, moisture control, texture, yield and overall product quality. It can also increase waste and production downtime. It can even lead to batch loss. Managing phage risks is therefore critical to both operational efficiency and profitability in your cheese plant.

3. Why are sanitation and disinfection critical to preventing phages in cheesemaking?

Phages are commonly introduced in cheese plants through the environment. Sources can include the air, water, drains and soil on the floor. Phages can also be present in raw materials including milk and milk-derived products such as whey, cream, concentrated milk and protein powders. And production staff can unknowingly spread phages throughout the plant as they move from one location to another. So effective phage management needs well-defined sanitation and disinfection protocols, both for standard operating conditions and for when your plant is on phage alert.

4. How can good manufacturing practice help prevent bacteriophage in cheesemaking?

Once phages are introduced to your cheese plant, they can spread rapidly. Good manufacturing practice plays a key role in preventing this. To ensure staff don’t spread phages, implement hand and foot disinfection before entering production areas. And ensure staff have clothes appropriate to each area of the cheese plant, for example hairnets and blouses for upstream processes or production areas. Flow management is also essential to prevent cross-contamination. By carefully controlling how raw materials and byproducts, such as whey, move through your plant, as well as managing the flow of air, water and people, you can maintain a “forward march” in production. That prevents the risk of “feedback loops,” where contamination can circulate back into the process.

5. What is a phage-resistant cheese culture?

While no cheese starter culture is entirely resistant to phages, some are more robust than others. Phage-robust cultures are composed of lactic acid bacteria strains selected and/or designed for multiple phage defense mechanisms. This robustness leads to more stable acidification, improved production consistency, and reduced risk of batch failures.

6. How do culture rotation programs help prevent bacteriophage in cheesemaking?

Phages are highly specific, typically infecting only certain bacterial strains. If a cheese plant uses the same culture continuously, the phages that infect that strain quickly multiply. Those same phages will lose effectiveness when a new culture is introduced. A culture rotation program is a structured way of introducing new cultures. It allows you to alternate starter cultures over time and keep your process one step ahead of phage build-up.

7. Why do I need to minimize the number of cultures in my rotation program?

Even two very similar cultures will perform slightly differently. That leads to process variability, which impacts yields. So an effective phage rotation program alternates as few starter cultures as possible in a controlled rotation.

8. Why should I avoid sourcing my cultures from more than one supplier?

While phages are very specific, some bacterial strains are similar enough that the same phage can infect them. These strains are called “phage-related”. The goal should always be to have only phage-unrelated strains in your rotation program. As one supplier won’t know the composition of another’s cultures, mixing suppliers may lead to phage-related strains in your rotation program. And for the same reason, it’s impossible for one supplier to recommend the right phage-rotation program for another supplier’s cultures. So recommended best practice is to stick to one culture supplier for your cheese plant.

9. Does starter culture dose impact the risk of phages?

Dosing lower than your supplier’s recommendation slows down acidification, which increases vulnerability to phages. That’s because phages multiply so much more rapidly than the bacteria they infect; up to 100-fold for every two-fold increase in bacterial count. So the goal is to reach final pH and cell concentration as quickly as possible, before phages can overwhelm your starter cultures. A lower dose is a false economy, as it allows phages to multiply, ultimately impacting productivity, recipe cost, end-product quality and shelf-life. That’s why you should always follow your supplier’s dosing recommendations.

10. How can proactive monitoring help reduce the risk of phages?

Proactive monitoring of phages enables early detection and informed decision-making. By taking and analyzing samples on a regular basis, you can track phage levels over time. This proactive monitoring provides data-driven insights to help you build a picture of phage pressure in your cheese plant. Combined with expert analysis and review, it helps you identify and make the adjustments needed to your manufacturing practice and/or culture strategies before phages can disrupt fermentation in your plant. Proactive monitoring combined with training allows you to implement continuous improvements in your plant and helps your team to respond quickly and effectively to emerging risks.

11. How can phage support from my culture supplier help reduce the risk of phages?

Strong phage support from your culture supplier helps you identify, monitor and manage phage risks more effectively than relying on internal measures alone. This support should include expert guidance on culture rotation and application, systematic phage monitoring and analysis, risk assessments tailored to your production setup and training and technical support for your team. The right supplier will also support you with proactive monitoring services that reduce phage risk through continuous, digital monitoring that delivers data-driven insights.