EFFECT OF Pseudomonas fragi ON THE COLOR OF BEEF

Growth of Pseudomonas fragi had a significant (P > 0.05) effect on the color of beef stored at 1°± 1°C. Beef color was measured with a Hunter Color/Difference Meter and percentages of myoglobin (Mb), oxymyoglobin (O 2 Mb), and metmyoglobin (MMb) on meat surfaces were determined using a Beckman DU Spectrophotometer with a reflectance attachment. As surface growth of P. fragi increased from log 2.2 to 7.2/cm 2 during 20 days storage at 1°± l°C, the pH increased from 5.5 to 6.6, free fatty acid values (FFA) increased from 0.62 to 2.60 and percent O 2 Mb decreased from 100% to 0%. Data indicated that proteolytic and lipolytic degradation products of P. fragi may be important in decreasing the color stability of beef stored at 1°± 1°C.