Processed cheese is made by grinding natural cheese, mixing it with an emulsifying salt like sodium citrate, and heating the blend until it forms a smooth, uniform mass that stays stable as it cools. The emulsifying salt is the key ingredient that separates processed cheese from simply melting regular cheese. You can replicate this process at home with just three ingredients, or understand how factories scale it up to produce the slices and spreads you find in stores.
Why Regular Cheese Won’t Do the Same Thing
When you melt natural cheese, the fat and protein tend to separate. You get an oily puddle on top and a rubbery clump underneath. That happens because calcium acts like a glue holding the protein molecules tightly together in a rigid network, squeezing out the fat as the cheese heats up.
Emulsifying salts, most commonly sodium citrate or sodium phosphate, solve this problem by pulling calcium away from the protein. Once freed from that rigid structure, the proteins loosen up and spread out, wrapping around tiny droplets of fat and holding them in suspension. The result is a smooth, creamy emulsion where fat and water coexist peacefully instead of splitting apart. This is the entire basis of processed cheese, and it’s been the core technique since 1911, when two Swiss researchers named Walter Gerber and Fritz Stettler first shredded Emmentaler cheese, heated it with sodium citrate, and discovered it set into a firm, shelf-stable product on cooling.
How Factories Make It
Commercial production follows a straightforward sequence, though each step is tightly controlled for consistency.
Cheese selection and grinding. Manufacturers start by selecting and blending natural cheeses of different ages. Young cheese contributes body and firmness, while aged cheese adds flavor. The cheese is trimmed and ground into small, uniform pieces. This grinding step increases surface area so the cheese blends more efficiently and heats more evenly.
Ingredient blending. The ground cheese goes into a processing vessel first. Emulsifying salts are added early, followed by any liquid ingredients like water or milk. Dry ingredients go in last to prevent clumping. Factories may also add colorants like annatto (a plant-based pigment that gives cheese its yellow-to-orange hue), preservatives, and dairy ingredients like whey or milk powder to adjust texture and moisture.
Heating and mixing. The mixture is heated to between 70 and 85°C (158 to 185°F) with continuous agitation. This melts the cheese, activates the emulsifying salts, and pasteurizes the product for safety. Constant stirring prevents hot spots and creates the signature smooth, uniform texture. The whole heating phase typically takes only 4 to 8 minutes.
Forming and cooling. The hot, molten cheese is then poured into molds, extruded into slices, or pumped into jars and tubes. For sliced products, the cheese is formed into blocks and cooled before slicing. The product firms up as it cools, but retains its meltability when reheated, which is the whole point.
The Differences Between Processed Cheese Types
Not every product labeled “processed cheese” is the same. U.S. federal standards define three distinct categories based on moisture and fat content, and they behave quite differently in the kitchen.
- Pasteurized process cheese is the firmest type, with no more than 43% moisture and at least 47% fat in its solids. This is the classic “American cheese” you’d find in deli slices. It melts smoothly but holds its shape when cold.
- Pasteurized process cheese food allows up to 44% moisture and requires at least 23% fat overall. The higher moisture and lower fat requirement means it’s softer and less intensely cheesy. Velveeta is the most recognizable example.
- Pasteurized process cheese spread has between 44% and 60% moisture with at least 20% milk fat. This is the softest category, spreadable at room temperature, and includes jarred cheese products.
The more moisture a product contains, the softer and more spreadable it becomes. Manufacturers shift between these categories by adjusting how much water, milk, or whey they add to the blend.
How to Make It at Home
You don’t need industrial equipment. A saucepan, a whisk, and sodium citrate powder (available online or at specialty food stores) are all it takes. The basic ratio is simple: 1 cup of whole milk, 2 teaspoons of sodium citrate, and 8 ounces of shredded cheese.
Start by warming the milk in a saucepan over medium heat. Whisk in the sodium citrate until it fully dissolves. Then add the shredded cheese a handful at a time, stirring continuously until each addition melts completely before adding more. Softer cheeses like cheddar and Colby Jack work best because they melt more readily, but you can use almost any natural cheese. Harder, aged cheeses like Parmesan will need more liquid to compensate for their lower moisture content.
Within a few minutes of stirring, you’ll have a perfectly smooth, glossy cheese sauce. Pour it into a container lined with plastic wrap, press it flat, and refrigerate it. After a few hours it will firm up into a sliceable block that melts beautifully on burgers, sandwiches, or anything else. Left as a sauce, it works for nachos or mac and cheese without the graininess you get from melting regular cheese.
Adjusting Texture and Flavor
The ratio of liquid to cheese controls whether you end up with a firm block or a pourable sauce. Less milk produces a firmer product closer to deli-style slices. More milk gives you a fondue-like consistency. You can also swap some of the milk for beer, broth, or cream to change the flavor profile.
Blending cheeses is where things get interesting. A mix of sharp cheddar for flavor and mild mozzarella for stretch creates something close to a classic American slice. A combination of Gruyère and fontina makes an upscale version with more complex flavor. The sodium citrate doesn’t care what cheese you use. It will emulsify anything.
If you find the texture too soft, reduce the liquid slightly in your next batch. If it’s too firm or rubbery, you likely overcooked it or used too little liquid. The sweet spot for heating is just until everything is melted and homogeneous. There’s no benefit to cooking it longer, and extended heat can make the texture gummy.
Why It Lasts So Long
One of the original motivations for inventing processed cheese was shelf life. Natural cheese continues to age, growing sharper and eventually spoiling. The heating step in processed cheese pasteurizes it, killing bacteria and enzymes that drive aging. The emulsified structure also creates a more uniform product with fewer air pockets and less exposed surface area where mold can take hold. Commercially produced processed cheese, sealed in airtight packaging, can last months in the refrigerator and even longer unopened at room temperature, depending on the product. Homemade versions, without preservatives, will keep in the fridge for about a week.