Metmyoglobin Conversion to Red Myoglobin Derivatives and Citrate Utilization by Bacteria Obtained from Meat Products and Pickles for Curing

Abstract

Bacteria (119 isolates) from fermented salami, beef jerky and model pickle submerged pork cuts were examined for conversion of metmvoglobin to desirable red mvoglobin derivatives. In nine isolates (SY-1B-SY-9B) from beef jerky and seven isolates (MH-1-MH-7) from model pickle, metmyoglobin was found to undergo conversion to red myoglobin derivatives. Isolates MH-5 and MH-7 were identified as Staphylococcus carnosus and Staphylococcus caseolyticus, respectively. S. caseolyticus MH-7 utilized citrate to produce diacetyl/acetoin. All isolates from beef jerky produced oxymyoglobin. Heme-moiety solution extracted from each MRS broth culture inoculated with strains MH-5-MH-7 showed one peak at 399nm in Soret's band. The red MRS culture quickly underwent discoloration on removing cells via centrifugation (10, 000×g, 5min). Acetone (75%) extraction from pork cuts submerged in each MRS broth culture inoculated with strains MH-5 and MH-7 showed absorption peaks at 415, 541 and 583nm. The red myoglobin derivative could not be identified but it was neither oxymyoglobin nor nitrosomyoglobin. The three peaks were virtually the same as those from Parma ham, a traditional meat product in Italy. The results indicate bacteria obtained from meat during curing to possibly contribute to its color and flavor.