Microbiological examination of beef prepared by bacterial fermentation in brine containing papaya

Salt and papaya were used to brine-ferment fresh round beef pieces which were later smoked and dried (Ubbaonu, 1982). This study was undertaken to conduct microbial examinations which were performed to aid in the selection of an appropriate salt-papaya brine concentra-tion in Ubbaonu's study (1982) and to produce a product fit for human consumption. Identification of the microflora of the beef pieces was performed before fermentation, after fermentation, and after drying and storing the meat for 30 days. During the fermentation, beef pieces were separated and treated with 35 different brine solutions made of varying levels of NaCl (0% to 10% in 2% increments) in combination with varying levels of papaya (0% to 25% in 5% increments). At the end of the brine-fermentation, presumptive coliforms and anaerobes were reduced when 8% salt or more was used in the brine (P < 0.0001). Presumptive C. perfringens were not detected at salt concentrations higher than 6%. Salmonella was found at 2% and 8% salt. The increase of papaya in the brine decreased the meat's final pH (P < 0.0001). A 10% salt-10% papaya fermentation was selected as the best combination based on the results of this study and Ubbaonu's (1982) observations. A new batch of fresh beef round pieces was subjected to this treatment to collect bacterial isolates for identification. Fresh beef pieces had a microflora composed mainly of Micrococcus (95% on SMA and 87% on SMA plus 3% NaCl). Gram-positive heterofermentative lactics predominated in the APT agar microflora (33.3%). S. faecium (40.9%) and S. faecalis (36.3%) were the predominant microorganisms found on SPS anaerobic agar. Only Rhodotorula was found in malt extract agar. At the end of the fermentation, the contaminant P. fluorescens predominated among the bacteria isolated from SMA (78%), SMA plus 3% NaCl (68%) and APT agar (63.3%); Streptococcus formed 87% microaerophilic/anaerobic isolates. Malt extract agar showed no yeasts or molds. After drying, the homofermentative bacteria (Streptococcus and Pediococcus) formed the predominant fermented-dried meat microflora. Malt extract agar showed no yeasts or molds.