ABSTRACTPeroxidase is one of the most heat resistant enzymes and may cause undesirable quality changes in thermally processed foods. Peroxidase activity and its resistance to thermal inactivation in fresh and pasteurized lump, claw and flake meat of both male and female blue crabs was determined spectrophotometrically. Male crabs usually exhibited a greater initial activity (ΔOD4 6 0/min/mg N) than did females of equal size. Heat inactivation curves indicated two straight line decreasing segments which varied by rate of descent. D values obtained for the enzyme based on the second straight line segment were D8 0=47 min, D1 1 0=18.2 min and D1 5 0= 11.2 min. A “z” value of 92°F was also obtained for the e