EFFECTS OF FREEZING AND THAWING ON THE MICROBIOLOGICAL AND PHYSICOCHEMICAL QUALITIES OF FROZEN PORK
Umoafia G. E.* and Okoro C. U.
This study was designed to establish the roles played by freezing and subsequent thawing of meat on the microbiological and physicochemical qualities of frozen pork. Initial microbiological and physicochemical assay of fresh pork bought from Marian market Calabar – Nigeria was carried out. A 10g sample of the meat was frozen for two weeks and later thawed and analyzed for pathogens and nutrient composition. The total microbial load of fresh pork ranged between 1.20x106cfu/g to 4.9x104cfu/g. Total coliforms was between 2.0x105cfu/g to 6.1x106cfu/g and total fungal count was between 1.96x105cfu/g to 5.7x106cfu/g. Total microbial load for freeze-thawed pork ranged between 5.0x104cfu/g to 2.6x106cfu/g. Total coliform was 3.2x106cfu/g to 7.8x104cfu/g. A total of 18 isolates including the following genera Pseudomonas, Salmonella, Staphylococcus, Escherichia, Enterobacter, Serretia, Penicillium and Aspergillus were prominent in fresh sample. There was a drastic disappearance of some of these organisms in the freeze-thawed sample as only Salmonella and Pseudomonas sp. survived. Decrease in nutrients especially the water soluble vitamins. It is worthy of note that freezing does not bring about sterility of frozen meat. Microbial load and types were reduced while some physicochemical qualities like tenderness, colour and vitamin content were negatively affected. However, freezing, safe thawing, proper cooking and hygiene can greatly reduce the microbial load to as low as 1x102 cfu/g which is the acceptable level of microorganisms in food by the World Health Organization.[Full Text Article]