Role of Bacteria in the Oxidation of Myoglobin

Abstract

The addition to steaks of cell suspensions of a number of aerobic bacteria and of Saccharomyces cerevisiae greatly increased the rate of discoloration. Low inocula resulted in the more rapid appearance of the brown color of metmyoglobin, whereas high cell populations quickly produced the purple color of myoglobin. Sonically treated suspensions of Pseudomonas geniculata produced similar changes in surface color but less rapidly. No such effect was observed with Lactobacillus plantarum . The visible changes in color were found to be associated with the oxygen demand of the surface tissue including, of course, the demand of any contaminating microorganisms. Inhibitors of respiratory activity inhibited the rate of discoloration under normal atmospheric conditions. However, when the oxygen level in the atmosphere was reduced, the inhibitors had no significant effect. In an oxygen-free atmosphere, the steak surfaces were the purple color of myoglobin; at 10 mm oxygen pressure, the pigment was oxidized to metmyoglobin and the surface was brown in color. No bacterial activity was necessary for pigment oxidation under low oxygen pressures. Addition of dilute solutions of glucose oxidase resulted in rapid oxidation of the meat pigment to metmyoglobin both in extracts and on steak surfaces. More concentrated solutions resulted in further oxidation as evidenced by the appearance of a green color. Horseradish extract with a high peroxidase activity added with H 2 O 2 resulted in rapid oxidation of the pigment but neither were very effective alone, although H 2 O 2 did result in a browning reaction in aged steaks. It is concluded that the primary role of the bacteria in meat discoloration is in the reduction of the oxygen tension in the surface tissue. The implications of the data are discussed and a possible mechanism of myoglobin oxidation is proposed.

Effect of Freezing and Microbial Growth on Myoglobin Derivatives of Beef

“…A number of factors have been shown to cause the oxidation of myoglobin in prepackaged beef (Renerre, 1990;Madhavi and Carpenter, 1993). These include the type of muscle (Ledward, 1971;Hood, 1980;Renerre, 1984), storage temperature (Walters, 1975), oxygen pressure and modified atmosphere packaging (Bartkowski, et al, 1982;Okayoma, 1987;Young et al, 1988;Lamine, 1991;Luno et al, 1998) bacterial contamination (Robach and Costilow, 1961;Bala et al, 1977a,b;Ben Abdallah, 1992), packaging film permeability to gases (Pirko and Ayres, 1957;Ben Abdallah, 1992), and lipid oxidation (Greene, 1969;LaBrake and Fung, 1992;Gatellier et al, 1995;Chan et al, 1997).…”

Spectral Changes of Atlantic Salmon (Salmo salar L.) Muscle during Cold Storage As Affected by the Oxidation State of Heme

“…Air storage leads to heme oxidation, whereas most heme under O 2 limited conditions is converted to its deoxy form. , In addition, the number of spoilage bacteria such as Pseudomonas spp. and Shewanella putrefaciens increases rapidly in air-stored salmon. , The growing microorganisms may promote heme oxidation by reducing the oxygen partial pressure through oxygen consumption and the formation of a biofilm on the sample surface. , After prolonged air storage resulting in profound spoilage, several psychrophilic bacteria convert metMb into deoxyMb and red-colored heme derivatives. As a result, metMb content can decrease at late storage and the cessation of autoxidation may be observed spectroscopically. ,− …”

“…49,50 The growing microorganisms may promote heme oxidation by reducing the oxygen partial pressure through oxygen consumption and the formation of a biofilm on the sample surface. 51,52 After prolonged air storage resulting in profound spoilage, several psychrophilic bacteria convert metMb into deoxyMb and red-colored heme derivatives. As a result, metMb content can decrease at late storage and the cessation of autoxidation may be observed spectroscopically.…”