Manufacturing processed cheese can sometimes seem more like a trial-and-error approach rather than a scientifically calculated undertaking.
There are many physico-chemical reactions taking place during processed cheese manufacture, but there are a few tricks of the trade that can help manufacturers to get the results they desire on a more consistent basis.
When armed with a few key formulas and a basic understanding of the chemistry at play, manufacturers will find that the secret behind great processed cheese is as simple as measuring the correct components.
The role of emulsifying salts
Understanding the basic properties of emulsifying salts is perhaps the most important step in creating a desirable processed cheese. Knowing the upper limits of solubility and noting the many key roles that emulsifying salts play in the chemistry of processed cheese will allow manufacturers to create a consistent product.
Emulsifying salts are best known for their ability to aid in emulsification; that is, facilitating the coverage of fat released during the heating/mixing step with solubilized caseins. Additionally, some types of emulsifying salts, such as pyrophosphates, can form crosslinks between proteins, creating a firmer, less meltable cheese.
Emulsifying salts also directly modify the pH of cheese; often, mixtures of emulsifying salts are added to attain the desired final pH value. Given the critical impact that these emulsifying salts can have on the end product, it’s imperative that manufacturers use the correct type(s) and amount(s) of these ingredients. In order to determine this, many manufacturers rely on intact casein tests or simple trial and error only, when in fact, knowing the level of bound calcium is equally important.
The intact casein test
Measuring intact casein is perhaps the most common method used in selecting the ideal type/age of natural cheese for a batch of processed cheese. The intact casein test tells manufacturers how much enzymatic breakdown of the protein has occurred during cheese aging. This information gives the cheesemaker clues regarding how the end product will perform. However, it does not measure the amount of protein that is cross-linked (bound) by calcium phosphate, which changes during aging and is a key structural component.
Cheese manufacturing methods (acidification profile) alter the amount of calcium cross-linking. More acid early in the process causes a larger reduction in bound calcium. It is very easy to have two cheese samples that have the same age and same measured level of intact casein but very different levels of bound calcium.
This difference in bound calcium will cause the cheeses to behave very differently when converted into processed cheese. Thus, if cheesemakers use the intact casein test alone, it can be difficult for cheesemakers to consistently control and predict processed cheese functionality when using different sources of natural cheeses with unknown pH histories.
Additionally, it is important to understand that in processed cheesemaking, the added emulsifying salts have a strong affinity for calcium, pulling it away from cheese proteins. This calcium exchange reaction helps to disperse the insoluble natural cheese network into a pumpable fluid mixture during the cooking of processed cheese. These dispersed proteins associate (stick back together) during the cooling process and reform into a new type of gel network.
Higher concentrations of emulsifying salts cause an even greater breakdown in the original cheese structure and the dispersed proteins form a finer and less meltable structure once they cool. Therefore, it is just as important for manufacturers to measure the calcium loss as it is for them to measure protein breakdown.
Manufacturers can benchmark their existing cheese supply, or retest it if there is some significant change in the cheesemaking process, to better determine the amount/type of emulsifying salts needed to yield a desirable and consistent end product.
In the end, creating a consistent processed cheese is not an exercise in trial and error but instead an opportunity to use the chemistry of processed cheese to your benefit. By harnessing the knowledge gained by measuring intact casein and bound calcium, a cheesemaker can better determine the texture and performance of the end product. Truly, science and a basic understanding of processed cheese chemistry, is the secret of the trade.