In cheesemaking, milk selection is essential, affecting the flavour, texture, and safety of the final product. While raw, pasteurized, and ultrapasteurized milk are widely used, thermized milk offers a balanced approach between safety and flavour complexity, making it popular with artisanal cheesemakers. Here’s a breakdown of how thermized milk compares to other types and examples of cheeses crafted with each.
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What is thermized milk?
Thermizing milk involves heating it to temperatures between 57°C and 68°C (135°F–154°F) for about 15 to 20 seconds. This gentle process reduces bacterial levels without fully sterilizing the milk. Thus, it preserves many of the milk’s natural enzymes and beneficial microbes.
The thermizing process requires precise temperature control to ensure consistency and avoid overprocessing the milk. Typically, cheesemakers use specialized equipment like plate heat exchangers, which allow milk to flow over heated plates. This allows even heating and helps maintain the integrity of the milk’s proteins, fats and other components that contribute to flavour and texture.
After heating, the milk is quickly cooled to prevent further changes in its composition, keeping it as close to raw as possible while reducing harmful bacteria.
Equipment needed for thermization
Thermizing milk requires specialized equipment to carefully control temperature, ensuring the milk is gently heated without fully pasteurizing it. Here’s a look at the key tools used in this process and how they work together.
1. Plate heat exchangers
First and foremost, plate heat exchangers are the most commonly used equipment for thermization. These exchangers contain metal plates that allow milk to flow in thin layers while heated water flows on the opposite side. As a result, the milk is quickly warmed to the perfect temperature range (57°C–68°C / 135°F–154°F) without staying hot for too long.
After heating, the milk moves through a cooling section, where it’s rapidly cooled back down. This way, the milk’s natural flavour and structure are preserved, ready for the next steps in cheesemaking.
2. Tubular heat exchangers
Another option, especially for smaller, artisanal operations, is the tubular heat exchanger. This equipment works similarly to plate exchangers but uses a series of tubes instead of plates.
In tubular exchangers, milk flows through these tubes while steam or hot water heats the outside. Though tubular exchangers are less efficient for large-scale production, they are often preferred for small-batch cheesemaking, as they handle milk gently and preserve its quality.
3. Temperature control systems
Furthermore, precise temperature control is crucial for effective thermization. Automated temperature control systems monitor and adjust the milk’s temperature in real-time, ensuring it stays within the exact range needed for thermization without crossing into pasteurization levels.
Many systems use sensors throughout the heat exchanger to keep heating consistent, which is essential for creating safe and flavourful cheese.
4. Holding and cooling tanks
After thermization, the milk needs to be cooled down quickly to prevent further heating. This is where holding and cooling tanks come in.
These tanks maintain the milk at a stable, safe temperature until it’s ready for the cheesemaking process. Additionally, some systems include cooling jackets around the tanks to ensure the milk stays at the right temperature, which helps preserve its quality and flavour.
5. Sanitation and filtration systems
Finally, maintaining clean equipment is crucial in the cheesemaking process. Many thermization systems are equipped with built-in cleaning functions or Clean-in-Place (CIP) systems. These systems flush the equipment with specialized detergents and water, ensuring that everything is sanitized between uses.
Additionally, some systems include filters to remove any impurities from the milk before it’s thermized, contributing to the purity and quality of the final product.
Together, this equipment allows cheesemakers to handle thermization with precision. Each tool plays an important role, ensuring that the milk is heated gently and consistently to reduce bacteria levels while preserving its natural qualities.
Cheeses made with thermized milk
Thermizing milk provides a way to enhance safety while preserving more of the milk’s natural complexity. This makes it ideal for cheesemakers who want to balance traditional methods with modern food safety standards, giving cheeses made from thermized milk a distinct flavour and texture profile.
These are three great examples of cheeses made using thermized milk.
1608 from Charlevoix
Originating from Quebec, Canada, 1608 is a semi-hard cheese made from thermized milk. It has a buttery, nutty flavour with an earthy aroma. The cheese’s unique character comes from the preservation of beneficial bacteria in thermized milk, creating a rich, complex taste with a smooth, dense texture.
Livarot
Livarot is a soft, washed rind cheese from Normandy, France, known for its bold, pungent aroma and orange-hued rind. Thermized milk enhances its depth, creating a full-bodied flavour with earthy and nutty notes.
Often called “The Colonel” due to the stripes around its rind, Livarot’s texture is supple and creamy.
Chaource
Hailing from the Champagne region of France, Chaource is a soft, creamy cheese with a bloomy rind. Made from thermized milk, this cheese has a delicate, buttery flavour with slight tanginess.
Chaource’s rich, creamy interior becomes denser as it ages, while the thermization process preserves subtle nuances in its flavour profile.
Other types of milk used in cheesemaking
Raw milk
Raw milk, untreated and packed with natural bacteria, produces cheeses that reflect their regional terroir.
However, it carries a higher pathogen risk, so raw milk cheeses often require a minimum 60-day ageing period in the USA and Australia. Famous examples include Roquefort, Comté and Parmigiano Reggiano, each showcasing complex, evolving flavours.
Pasteurized milk
Pasteurized milk, heated to 72°C (161°F) for 15 seconds, eliminates most bacteria, improving safety but sacrificing some complexity. Cheesemakers add starter cultures to replace lost bacteria, resulting in milder flavour.
Commercial Cheddar, Brie and Gouda are classic examples, loved for their balanced taste and accessibility.
Ultrapasteurized milk
Ultrapasteurized milk, heated to 135°C (275°F) for a few seconds, has a long shelf life but altered proteins, making it harder to form curds. Rare in traditional cheesemaking, it’s used for mild, creamy cheeses like Fromager d’Affinois, known for its smooth texture but gentler flavour.
Thermized cheese: a middle ground
Because thermization doesn’t strip away the milk’s unique bacteria as pasteurization does, it allows the cheese to retain its local character. Terroir—the unique combination of climate, soil, animal diet, and regional bacteria—remains vibrant in thermized milk cheeses, which are more complex in flavour than pasteurized options.
Effectively, thermization captures these regional nuances without requiring the cheeses to be aged for extended periods, making them more versatile for a range of textures and styles.
As a result, thermized milk is a perfect compromise for artisan producers who seek safety without compromising flavour. It provides a practical way to create cheeses that reflect their origin while meeting modern food safety standards, allowing cheesemakers to bring the best of tradition into today’s market.
Conclusion
Milk selection shapes the character of each cheese. Raw milk brings robust, regional flavours; pasteurized milk offers safety and consistency; and ultrapasteurized milk suits mild, creamy varieties.
Thermized cheese, however, stands out as a balanced option, providing cheesemakers with complexity and improved safety. This careful choice highlights the art and science of cheesemaking, allowing each cheese to tell a story through the milk’s treatment.
Jonah is a a hipster, eco-warrior and slow food afficionado. Coming from a scientific background, Jonah has a particular interest in cheese science. And yes, he loves a good cheese pun!
