Without understanding the chemistry of cheese and other core foods in our diets, what we eat would have never become a science people can use to look their best and live their best lives.

What Chemical Process Turns Milk into Cheese?

Cheese comes from milk. “Traditional” cheese comes from cow’s milk. Cheeses from the milk of goats, sheep, yak, reindeer, and buffalo are also popular in certain places around the world. While the globalized food market allows for any geographic area to produce any type of cheese, the traditional origins of each type of cheese always point back to a specific geographic area.

The choice of animal milk was not out of experimentation, but rather a result of the proximity to resources. Today’s cheesemakers, though, have the luxury of experimenting with all types of bases to make their cheese.

The basic chemical process for turning milk into cheese happens naturally in your fridge when the milk goes past its expiration date. Bacteria grow rapidly in expired milk, feeding on the sugar in the milk known as lactose. This produces lactic acid as a byproduct, which causes the protein casein to lump together. We call this curdling.

Cheesemakers just initiate this process in a sanitized facility and at a much larger scale. The curdles are turned into cheese through the removal of whey, which is the liquid solution that typically has around 5% lactose content. The curdles are then molded and aged depending on the cheese variety.

What is the Primary Chemical Makeup of Cheese?

The rough chemical makeup of the standard piece of hard cheddar cheese breaks down to 37% water, 33% fat, 23% protein, 3.5% carbohydrates, and 3.5% minerals and other compounds. These 5 categories are present in all of the types of cheeses, but each type has a unique percentage combination of these categories.

That, along with the type of bacteria used to culture the milk base and the type of milk itself, is what separates one type of cheese from another. The “other compounds” category can get quite interesting. For example, casein turns into casomorphins when digested. This chemical affects opioid receptors in the brain, so it can be argued that eating cheese could release the same feel-good chemicals.

Chemicals that act on the opioid receptors are actually fairly common throughout nature. Maeng Da kratom, for example, contains the alkaloid mitragynine, which also works on the opioid receptors. It is not approved by the FDA for human consumption, though.

Many people wonder if different cheeses have unique chemical compositions. The answer is yes, and that unique composition often depends on the “starter” bacteria used as a culture to induce the curdling process. For example, blue cheeses get their characteristic blueness from the addition of Penicillium roqueforti. The ripening agent in camembert cheese is Penicillium camemberti and it is unique because it ripens the curds from the outside to the inside.

There are several other types of bacterium that all perform the same basic function, but cause quite a distinct level of aromatic variety.

When it comes to smell and taste, it boils down to casein, milk fats, and lactose. Several compounds can be byproducts as these three things break down.

Casein creates ammonia, ethanoic acid, aldehydes, alcohols, carboxylic acid, and sulfur compounds. Milk fats create carboxylic acid, beta-hydroxy acids, beta-keto acids, methyl ketones, and lactones. Finally, lactose creates butanedione, ethanal, ethanol, and ethanoic acid.

All of these compounds present in unique combinations is what gives each type of cheese its distinct aroma and flavor.

Conclusion

Now that you have read this article, hopefully you have a deeper appreciation for the chemistry of cheese. Understanding how cheese is made and the processes that lead to the hundreds and hundreds of cheese varieties will make you appreciate its role in your diet.