processed cheese slices for cheese burgers

The Science Behind Processed Cheese

Do you like cheese on top of your (vegetarian) burger? If so, what type? A slice of ‘regular’ cheese? Or a special pre-packaged slice of ‘hamburger cheese’?

If you chose the second option, most likely, you’ve chosen processed cheese. It’s not ‘real’ cheese, but a modified version that’s not just cheaper to make, but also has some unique properties. One of them is its excellent heat resistance, making it perfect for topping a hot sandwich!

Processed cheese still contains cheese. But also contains several other ingredients that aren’t allowed in cheese. Let’s have a closer look at what these are and how they give processed cheese its special properties.

What is processed cheese?

Processed cheese starts its life as regular cheese, which is made by curdling animal milk. To transform this cheese into processed cheese, they are blended together, with a few other ingredients. Emulsifying salts are crucial in this process. Aside from cheese and emulsifying salts, manufacturers may also add several other ingredients to achieve the desired consistency.

Processed cheese can go by many names. Some may refer to it as American cheese, prepared cheese, cheese spread, cheese product or even plastic cheese. What’s interesting is that we can’t seem to agree on what processed cheese really is. Whereas there is an FAO definition of cheese, there isn’t one for processed cheese. The different countries around the world simply could not agree on one.

Why processed cheese?

Processed cheese was likely developed at first to use up left over cheese. Nowadays, it can be used for a variety of reasons. Whether or not you’ll decide to use it will depend on what you’re using the cheese for. Is it used to top a burger, or eaten as is, with a glass of wine? That will likely result in a different choice.

Processed cheese is cheaper

First of, generally speaking, processed cheese is cheaper than regular cheese. As you’ll see below, the process is quite simple and fast. Whereas most cheeses need to be ripened for some time, processed cheese is ready immediately. Also, you can often revert to cheaper ingredients.

An added (cost) benefit is that processed cheese can use up left over batches of cheese that can’t be sold as is, but are still safe to eat. They can still be processed to be made into processed cheese.

It behaves different

Processed cheese behaves differently than many ‘regular’ kinds of cheese. For one thing, it melts very differently. If you need a cheese that stretches well when melted, your best bet would be a processed cheese. Also, processed cheeses work very well on top of hot sandwiches, again because of their great melting behavior.

A unique, consistent and stable flavor & texture

Want to add funky flavors or make new textures? Processed cheese allows for a lot more variation than ‘regular’ cheese does. Spreadable cheese, cheese in a tub, and string cheese are most likely all processed cheeses.

If you want to make the exact same product over and over again, processsed cheese is your best bet. In regular cheese manufacturing there can be some variation between different batches of cheese. For some, this is part of a great cheese, for others, it’s a logistical nightmare. Processed cheese is consistent.

Some processed cheeses can be stored for months, outside of refrigeration. Thus, these products are very stable over time and don’t spoil easily.

Analogue vs. processed cheese

Aside from cheese and processed cheese, there is yet another category of ‘cheese’: analogue cheese. You generally won’t be able to buy these cheeses as a consumer. Instead, they’re used in a range of manufactured foods such as frozen pizzas. Analogue cheeses aren’t made with cheese, they don’t even have to contain any dairy ingredients. They’re made to look and behave like cheese, but they aren’t.

The ingredients

Processed cheese starts with cheese

Processed cheese starts out as regular cheese, most often, it’s made of a mix of different cheeses. Some cheeses might have ripened for some time and have quite a strong flavor. Others have not ripened at all and have quite a bland taste. The cheeses are the starting point of processed cheese and choosing the right ones is a major decision factor when making processed cheese.

Maturity impacts quality

Most cheeses are ripened in some way (with the exception of a few fresh cheeses such as paneer). During ripening, which is simply storage of the cheese under controlled conditions, enzymes break down a range of molecules. This results in the formation of a lot of flavor molecules.

The advantage of using cheese that has been ripened for a longer period of time in processed cheese is its added flavor. Also, it becomes easier to make processed cheese with a smoother, maybe even spreadable consistency. Unripened cheese on the other hand has less flavor and will give a stiffer texture, but, it is a lot cheaper to use.

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Cheese type impacts behavior

If you’ve ever tried to make cheese fondue, or tried to melt cheese, you will have know that cheese isn’t very stable at high temperatures. It’s prone to splitting, with the fat separating out. The lower the water content, the warmer the cheese needs to be to melt. Also, the texture might become very stringy. This is because of a structure formed by the casein proteins. Cheeses that have been aged for long don’t tend to form these stringy textures, the enzymes have broken down essential connections during ripening.

Some additional proteins for structure

Aside from using cheese as a protein source, processors may add more proteins. Often, regular milk proteins are used such as whey and caseins. Despite you still needing milk to make these proteins, it may still be more cost-effective to use these ingredients than using milk and making that into cheese.

Whey proteins firm up cheese

Adding extra proteins such as whey proteins can make processed cheese firmer, but also make it less susceptible to melting. The proteins will form a large complex network within the processed cheese.

Fats for creaminess

Cheese naturally contains fat, but processed cheese will generally also contain another source of fat. This can be a fat from milk, but it can also be a vegetable fat. The amount and type of fat will have a big impact on the melting behavior of the cheese.

Emulsifying salts help it mix

In a lot of cheeses, the fat will split from the rest of the cheese once melted. If you’d cool the cheese back down, it will look quite different than it did before. To ensure that the fat doesn’t split from the proteins when making processed cheese, you need to add emulsifying salts. These salts help the cheese to remain homogeneous and they’re a crucial component of processed cheese. Without them, most processed cheese wouldn’t exist!

The most commonly used emulsifying salts are sodium citrate and phosphates.

Other ingredients

The protein, fat and emulsifying salts are crucial for making processed cheese, but there are a lot of other ingredients that may be added to achieve certain properties. For instance, colorants may be used to color the cheese. Flavors can be added as well.

Also, just about any processed cheese will contain salt, often in higher amounts than ‘regular’ cheese.

It depends on the country where the processed cheese is made and sold what is and what isn’t allowed to be used.

Hydrocolloids help thickening

To help firm up a processed cheese, manufacturers may are hydrocolloids. These are large bulky molecules that can help set processed cheese. Examples are carrageenan, and xanthan gum. Whether or not these are allowed to be used in processed cheese depends strongly on which type of processed cheese you’re making and in which country you’re based.

Starches lower costs

Proteins are expensive but are crucial for giving processed cheese a desirable texture. As an alternative, starches can be added. These can act as fillers in processed cheeses.

Mold inhibitors extend shelf life

The main way in which cheese spoils is through growth of molds. To slow down this growth and extend the processed cheese’s shelf life, manufacturers may add mold inhibitors such as potassium sorbate.

How processed cheese is made

Once you’ve chosen your cheeses and overall formulation, it’s time to get to work and make processed cheese. Whereas regular cheese making can be a long, complex process with a lot of process steps, making processed cheese is a lot simpler. Essentially, it’s all about mixing.

Melt and mix

To mix the cheeses together into processed cheese they are first shredded into smaller pieces. This makes it easier to mix everything together.

Next, the ingredients are melted and mixed. To do this, the mixture needs to be heated so all the fats in the cheese melt. Temperatures around 70-95°C are commonly used.

The mixing takes place in specialized ‘cookers’ that can heat and mix at the same time. The exact time, temperature and rate of mixing all impact the quality of the final processed cheese.

Don’t want it to turn brown

To maintain color it is important that the cheese does not contain too much sugar (lactose). The lactose might react with the proteins in the cheese, in a reaction called the Maillard reaction. This can cause the processed cheese mix to turn brown during procesing.

Cut and shape

Once the blend is complete, it’s a matter of cooling down the mixture in whichever form it needs to be. If it’s a spreadable product it will likely be filled in tubs. If it still needs to be sliced, it is shaped in a block and cooled down until it is firm enough to cut. Since processed cheese does not need to ripen, unless cheese, it’s a significantly shorter and thus cheaper production process.

Sources

Michigan Dairy Review, on the history of processed cheese. Very extensive scientific article discussing various aspects of processed cheese.

FDA, giving definitions for all the different cheese (products)

Regulation (EU) No 1169/2011 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on  the provision of food information to consumers, describes labelling of all food products, including cheese

Regulation 1333/2008 from the EU describes the allowed additives in food, also distinguishing between cheese and processed cheeses (look for the most recent consolidated version)

FAO, CODEX GENERAL STANDARD FOR CHEESE, Codex Standard 283-1978

Mamdouh El-Bakry, Bhavbhuti M. Mehta, Processed Cheese Science and Technology: Ingredients, Manufacture, Functionality, Quality, and Regulations, Woodhead Publishing 2002, chapter 1-4, link

*Here we’re limiting ourselves to cheeses made from animal milk. Plant-based cheeses have a very different science behind them seeing as how these plant-based ingredients generally don’t curdle.

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