Next time you're enjoying some Parmigiano-Reggiano cheese, you can impress your friends with your new knowledge of tyrosine.
Many people think those crunchy bits in hard cheeses like Parmesan are leftover salt, but that isn't true; salt is soluble and dissolves in the cheesemaking process. Unless something has been added during production, such as nuts or dried fruit, the answer to what those crunchy bits are is very simple: tyrosine, or calcium lactate. The name tyrosine comes from the Greek word for cheese, tyros.
Oh, wait, need more of an explanation? The breakdown of proteins is called proteolysis. When cheese ages, the protein chains break down. Those protein chains are made up of amino acids, and one of the amino acids present in casein (aka milk protein) is tyrosine. When the tyrosine is freed up as the chains break down, it collects into tiny crystals about the size of a grain of kosher salt. So the majority of the crystals you see in cheeses like Grana Padano, Parmigiano-Reggiano and aged Cheddars and Goudas are predominantly clusters of leftover tyrosine. Dairy scientists can replicate the formation of these crystals in controlled experiments, but they still aren't sure why it happens; they simply know there is a strong connection between the formation of tyrosine and the use of the starter culture Lactobacillus helveticus in cheesemaking.
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