Occurrence
Reported found in white bread, macaroni, egg noodles, corn flakes, corn grits, oatmeal, wheat bran, wheat
flakes, shredded wheat, barley brown rice, rye flour, whole grain wheat flour, buttermilk, blue cheese, cheddar cheese, cottage cheese,
cream cheese, parmesan cheese, bacon, cured ham, frankfurters, pork sausage, canned red kidney beans, canned sweet corn, canned
peas, canned lima beans, canned potatoes, almonds, cashews, peanuts, dates, beef, lamb, veal, chicken and turkey.
Purification Methods
Likely impurities are L-cysteine and the ammonium salt. L-Tyrosine is dissolved in dilute ammonia, then crystallised by adding dilute acetic acid to pH 5. Also, crystallise it from H2O or EtOH/H2O, and dry it at room temperature in a vacuum over P2O5. It sublimes at 235-240o/0.03mm with 99.2% recovery and unracemised [Gross & Gradsky J Am Chem Soc 77 1678 1955]. [Albert Biochem J 50 690 1952, Greenstein & Winitz The Chemistry of the Amino Acids J. Wiley, Vol 3 pp 2348-2366 1961, Beilstein 14 IV 2264.]