[Case report: tyrosine deposits]

Whitish precipitations in three samples of raw cured ham, which appeared in the stereomicroscope as piles of crystals, were confirmed as tyrosine crystals. Tyrosine is readily soluble in nitric acid (yellowish discoloration) and, after addition of potash lye, it precipitates as yellow-orange picrate. Factors that influence the formation of tyrosine crystals are largely unknown. In raw cured ham of Parma experience has shown that tyrosine crystals are found in ham stored for a very long time.