CASE-REPORT - TYROSINE CRYSTALS

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