The Development of Aerobic Spoilage Flora on Meat Stored at Chill Temperatures

Abstract

In meat juice medium, aerobic spoilage bacteria utilized the following substrates in the order shown: Pseudomonos, glucose, amino acids, lactic acid; Acinetobacter, amino acids, lactic acid: Enterobacter, glucose, glucose‐6‐phosphate, amino acids; Microbacterium thermosphactum, glucose, glutamate. All the bacteria grew at their maximum rate utilizing the first and second substrates, but the growth rates declined when these were exhausted. The growth rate of Acinetobacter was reduced at pH 5·7 and below. All other species grew at their maximum rate within the pH range 5·5–7·0. On meat pseudomonads grew faster than the other species at all temperatures between 2° and 15°C. Interactions between any two species were observed only when one organism had attained its maximum cell density. Substrate exhaustion at the meat surface did not limit bacterial growth and it is suggested that the maximum cell density of aerobic spoilage cultures is determined by oxygen limitation of growth.

Development and evaluation of time-temperature integrator formonitoring high temperature thawing of frozen buffalo meat

“…The significant (P < 0.05) increase in FAA content of treatment samples was due to increased breakdown of meat proteins by bacterial proteases. This was supported by the finding that meat with higher Pseudomonas count always produces a higher level of free amino acids (26). The TVBN content of severely thawed buffalo meat nearly reaches the upper limit of sensorial rejection, which is 16.5 mg of volatile nitrogen per 100 g of beef (27).…”

“…The significant decrease (P < 0.05) in D-glucose concentration recorded for treatment and control samples in the present study was due to the growth of glucose utilizing bacterial microflora. Low concentration of D-glucose in spoiled samples suggested the possible involvement of pseudomonads, since fresh meat spoilage under aerobic conditions was usually initiated by exhausting the available glucose in meat (26).…”

Acquisition of iron by the non-siderophore-producing Pseudomonas fragi

“…In its natural environment, mainly meat and milk products (Gill & Newton, 1977;Molin & Ternstrom, 1982;Ternstrom e t al., 1993), P. fragi grows well and should, therefore, compete successfully with the other bacterial species, such as fluorescent pseudomonads, which also participate in meat spoilage (Molin & Ternstrom, 1982). As demonstrated here, P.fragi strains are well equipped to acquire iron even if they do not apparently produce siderophores themselves.…”

“…How these strains meet their iron requirements is not understood at all. Of these species, P. fragi is of particular interest since its natural environment includes meat or milk products (Gill & Newton, 1977 ;Molin & Ternstrom, 1982 ;Ternstrom et al, 1993). In such environments iron is tightly bound to proteins like transferrin, ferritin, lactoferrin and haemoglobin, and should, therefore, be more difficult to access by bacteria as compared to other natural environments where iron is available as iron salts or iron hydroxides.…”

Microbiological, physical and chemical studies on fresh red meats packaged under different modified gas atmospheres

“…They grow the fastest and utilize glucose at refrigerated temperatures, and hence, possess the capacity to outcompete members of other genera (Gill and Newton, 1977). Brochotrix thermosphacta also utilizes glucose but because of its slower growth rate, it is a poor competitor to the pseudomonads .…”