Protecting 40 pound cheese blocks against Listeria contamination

Phageguard L (PGL) has been successfully implemented by a U.S.-based cheese company to protect 40-pound mozzarella blocks from Listeria contamination during processing. Before full-scale implementation, a one-month trial period was conducted, focusing on two key assessments: the impact of Phageguard L bacteriophages on the company’s starter cultures and the efficacy of Phageguard L in controlling Listeria on 40-pound mozzarella blocks and preventing cross-contamination in subsequent processing stages.

Sensory evaluation of Phageguard L bacteriophage across more than 100 dairy starter cultures

Starter cultures are a crucial component of cheese-making, initiating the fermentation process by converting lactose into lactic acid, which lowers the milk’s pH. These cultures are essential for acidifying milk and developing the distinct flavors and textures of cheese. Bacteriophages, naturally occurring microorganisms (viruses), play a role in maintaining the balance of bacterial populations across various environments. Due to the high density of bacteria in starter cultures, preventive measures are necessary to avoid bacteriophages that target bacterial hosts such as Lactococcus, Streptococcus, and Lactobacillus, which can pose challenges to cheese production. The key from challenge to solution is the precise targeting ability, as each bacteriophage has its own specific bacterial host targeting range.

The bacteriophages in Phageguard L specifically target L. monocytogenes and L. innocua, leaving other bacterial populations unaffected. To confirm the host specificity of Phageguard L, a sensory study was conducted with over 100 different starter cultures from the cheese company. Phageguard L bacteriophages were directly added to the starter cultures using a spot assay to visualize their effect. The outcomes underscored the precision of Phageguard L bacteriophages, confirming their selective mode of action. Phageguard L effectively binds to and inactivates Listeria while preserving the microbial cultures critical to cheese-making.

Protecting 40-pound mozzarella blocks against Listeria contamination

Phageguard L was applied to protect 40-pound mozzarella blocks from Listeria contamination and mitigate cross-contamination risks during subsequent processing stages, such as shredding. To validate its efficacy, a one-month trial was conducted using a spray application to distribute the bacteriophage solution on the cheese blocks. Following the trial, data comparisons demonstrated significant reductions in Listeria contamination, with Listeria counts falling below detection levels on the shredded mozzarella samples. The results not only highlight Phageguard L’s effectiveness in inactivating Listeria on mozzarella blocks but also its protective effect on critical control points after application.

Listeria prevalence in cheese processing

Listeria is a known challenge to a wide range of food sectors, which is further acknowledged by the R&D director of the dairy company on the west coast, “Every cheese plant in the country will find Listeria if they look; it’s part of the ecology.” This underscores the need for reliable interventions ensuring product safety without compromising production efficiency or cheese quality.

The successful implementation of Phageguard L in controlling Listeria during mozzarella production underscores its value in enhancing Listeria protection across cheese operations. Given the sensitivity of the bacterial flora involved in cheese-making, natural and organic interventions like Phageguard L play a crucial role in advancing food safety within the cheese industry.