tirosina-del-jamon

White dots in the ham: Tyrosine

We’ve practically heard it all when it comes to explaining these white dots that appear in the cut of ham, from “it’s due to the acorns that the pig ate” to “the muscles were stiff from walking in the fields”. It’s neither one nor the other. It’s not even salt that hasn’t dissolved properly as some people say. These white dots that appear inside the meat are tyrosine crystals.

So what is tyrosine? This is a non-essential amino acid (chemical units of the body that are formed by proteins) in mammals that is produced from another amino acid called phenylalanine. It was discovered by the German chemist Justus Von Liebig working with the casein protein, found in cheese, providing its name that comes from the Greek word tyros, meaning cheese. This is an important amino acid for the general metabolism as it is a precursor for adrenaline and dopamine that regulate mood. It should not be confused with thyroxine, a hormone secreted by the thyroid gland.

Why does it appear in ham? Proteolysis (deterioration of proteins in the meat) takes place during the curing process, facilitating the formation of free amino acids that end up crystallising in these hard, white formations appearing on the inside, both in ham from Iberian pigs and light-skinned pigs. Traditionally, the appearance of these structures has been associated with slow, drawn-out curing, which would facilitate crystallisation of free amino acids. However, tyrosine is also spotted in fast-curing hams, telling us that different factors might bring about the appearance of these white marks. Its formation is encouraged by a drop in the quantity of salt (as aspect the sector is working on in general), an increase in drying temperature or even a high pH. In addition, an almost excessive proliferation of tyrosine crystals has been seen in hams with previously frozen raw material.

Can it be eaten? The answer is yes. It is true that the crystals are occasionally a size that might be noticed when chewing, due to their hardness, but they are not a health risk. Tyrosine is also behind the appearance of a white veil, visible on the surface of the cut of meat, and just like its crystallised version, it is not a sign of poor quality or a defect in the piece.

In short, the appearance of tyrosine crystals in the ham (as in processed meat or cured cheese) is simply the result of a series of natural chemical processes that take place inside the piece that are capable of transforming raw meat into one of the most appreciated foodstuffs in world of gastronomy.

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