Processed cheese is made by blending natural cheese with emulsifying salts, then heating and stirring the mixture until it forms a smooth, uniform mass. The process transforms the crumbly protein structure of natural cheese into a creamy, meltable product with a much longer shelf life. What seems like a simple idea actually involves some clever chemistry, and the details of each step explain why processed cheese behaves so differently from the natural cheese it starts as.
The Base: Natural Cheese
Every batch of processed cheese begins with real cheese. In the U.S. and Canada, the base is usually cheddar or cheddar-type cheese, often a blend of young and aged varieties averaging about three months old. Younger cheese contributes moisture and a mild flavor, while older cheese adds sharpness and body. Manufacturers can also use colby, Swiss, gruyere, or other varieties depending on the desired final product.
Most cheese destined for processing is made specifically for that purpose, typically a stirred-curd cheddar or a cheese base produced through ultrafiltration. Trimmings and lower-grade natural cheese can also go into the mix, but these represent only a small portion of total processed cheese production.
The Key Ingredient: Emulsifying Salts
Natural cheese doesn’t melt smoothly on its own. When you heat it, the fat separates from the protein and pools into greasy puddles. Emulsifying salts solve this problem, and they’re the ingredient that makes processed cheese possible.
The most common emulsifying salts are sodium phosphates (both mono- and polyphosphates) and sodium citrates. These salts work by pulling calcium out of the cheese’s protein network. In natural cheese, calcium acts like glue holding protein molecules together in tight clusters. Emulsifying salts swap out that calcium for sodium, which loosens the protein structure and lets the proteins absorb water. Once hydrated, these proteins can interact with fat, coating individual fat droplets and holding them in a stable suspension throughout the cheese. The result is a homogeneous emulsion where fat and water coexist peacefully instead of separating.
The degree of calcium removal matters. More calcium sequestration means more protein dispersion, which creates a smoother, more emulsified product. Different emulsifying salts also influence the final texture and pH through their buffering capacity, so manufacturers adjust the salt blend to achieve specific melting properties and firmness.
The Cooking Process
Once the natural cheese is selected and shredded or ground, it goes into a large heated cooker along with the emulsifying salts, water, and any other ingredients. The mixture is heated to around 70 to 85°C (roughly 160 to 185°F) under constant stirring. Most systems also apply a partial vacuum, which removes air bubbles and helps create a dense, even texture.
During the initial heating stage, fat separates from the cheese just as it would in your kitchen. But as the emulsifying salts do their work, the freed proteins re-emulsify that fat, wrapping around the fat globules like a membrane. The continuous stirring ensures everything blends evenly. Within minutes, the chunky cheese mixture transforms into a flowing, molten mass.
The heating also pasteurizes the product, killing bacteria and enzymes that would otherwise continue aging (and eventually spoiling) the cheese. This is why processed cheese lasts so much longer than the natural cheese it came from. Without active enzymes breaking down proteins and fats, the flavor and texture stay stable for months.
Additional Ingredients
Beyond cheese and emulsifying salts, manufacturers often add other dairy ingredients like whey, cream, milk, or butter to adjust the fat and moisture content. Salt enhances flavor, and colorings give the product its familiar look. Annatto extract, a plant-derived yellow-orange pigment, is the most traditional cheese colorant, though some products use beta-carotene or synthetic dyes like FD&C Yellow No. 5 or No. 6 to achieve a more uniform or vivid color.
Preservatives such as sorbic acid or nisin may be added to extend shelf life further, particularly in products sold at room temperature. Flavoring agents, spices, or inclusions like jalapeños or smoked flavoring round out the ingredient list for specialty varieties.
Shaping and Packaging
While still hot and fluid, the processed cheese is poured into its final form. For individually wrapped slices, the molten cheese is spread into a thin sheet, cooled, and cut. For blocks and loaves, it’s poured into molds. Cheese spreads go directly into jars or tubs. The product sets as it cools, with the emulsified protein network firming into either a sliceable solid or a spreadable paste depending on the formulation.
The hot-fill process also helps with preservation. Filling containers while the cheese is still at pasteurization temperature reduces the chance of contamination, contributing to the product’s famously long shelf life.
Different Categories of Processed Cheese
Not all processed cheese is the same product, and U.S. federal regulations draw clear lines between categories based on composition. Pasteurized process cheese has the strictest requirements: no more than 43% moisture and at least 47% fat in the solid portion. It must be made primarily from natural cheese.
Pasteurized process cheese food allows more flexibility, with moisture up to 44% and fat as low as 23%. This category can include more non-cheese dairy ingredients like whey and milk. Products labeled “cheese product” or “cheese spread” have even more latitude with moisture, fat, and added ingredients, which is why their texture tends to be softer and their flavor milder.
These distinctions matter at the grocery store. If a package says “pasteurized process cheese,” it contains more actual cheese and less added dairy filler than one labeled “cheese product.”
Why Processed Cheese Is Higher in Sodium
One notable nutritional difference between processed and natural cheese is sodium content. Processed cheese averages about 1,242 mg of sodium per 100 grams, roughly double the 615 mg per 100 grams found in natural cheddar. The emulsifying salts are the main reason, since they’re sodium-based compounds added on top of whatever salt was already in the natural cheese. Across different brands, processed cheese sodium levels range widely, from about 936 to 1,590 mg per 100 grams, so checking labels is worthwhile if you’re watching your intake.
A Century-Old Invention
James L. Kraft began producing processed cheese in 1915, packing it into small tins. His method was novel enough to earn a patent in 1916, and by 1917 the U.S. government was buying Kraft’s tinned cheese to feed troops in World War I. The product solved a real problem: natural cheese spoiled quickly, especially in the field. Processed cheese, sealed in tins and free of active enzymes, could survive shipping and storage in conditions that would ruin ordinary cheddar. That same basic principle, using heat and emulsifying salts to create a stable, long-lasting product, remains the foundation of processed cheese manufacturing today.