The appearance of this amino acid in the ham (it is also very characteristic of long-aged cheese) it is simply the result of natural chemical processes that take place inside the piece and it is capable of transforming raw meat into one of the most appreciated foods in the world of gastronomy.
The existence of tyrosine crystals does not mean that the product is not edible or that is has bad or low quality. They have nothing to do with mold neither, they are not harmful. They are simply related to the natural and microbiological process that occurs during a long, slow and natural curing process.
He same thing happens with some long-aged cheeses. You can clearly feel them when eating an authentic Italian Parmegiano Reggiano. You can eat the jamón or the cheese with these dots, actually you may even want to count your lucky crystals and celebrate.
We’re all pretty happy about this because it is said that the crunchiness improves mouthfeel and is an evidence of a natural and not manipulated or forced aging process. As far as taste goes, interestingly tyrosine has been variously described as adding umami flavor or no flavor at all, depending on the product.
The primary reason tyrosine is considered a sign of quality is because it is an evidence of a long and deliberate, and, dare we say, natural, aging process.