Abstract

The ability of microorganisms to survive in freezer temperatures and cause spoilage of foods during thawing was examined. Cooked foodstuffs used for the study were; vegetable soup, jollof rice, and steamed beef. All were freshly prepared and allowed to cool down before freezing for three (3) days at a temperature of 21ºC after which they were brought out of the freezer and allowed to thawing for three (3) hours at 21ºC. Samples were analyzed for bacteria populations and spoilage pathogens by standard microbiological methods. Total heterotrophic bacterial mean counts for vegetable soup, jollof rice sample, and steamed beef samples were 5.90 x 10⁴CFU/g, 6.61x 10⁴CFU/g, and 6.43 x 10⁴CFU/g respectively. Four bacterial isolates identified and their percentage occurrence from vegetable soup were; Bacillus cereus (10%), Listeria monocytogenes (10%) Staphylococcus aureus (10%) and Streptococcus spp (10%).  Three isolates from jollof rice were Bacillus cereus (10%), Micrococcus spp (10%). and Salmonella spp (10%) while three isolates from steamed beef were Pseudomonas spp (10%)., Escherichia coli (10%) and Listeria monocytogenes (10%). Bacillus cereus, occurred in the soup and jollof rice while Listeria monocytogenes occurred in the soup and steamed beef. Percentage occurrences of bacteria in the various samples were vegetable soup, 40%, jollof rice and steamed beef, 30% each. The bacteria isolates in this study are known potential pathogens. Their presence in these foodstuffs samples analyzed is of public health significance. There is need for awareness to be created and caution taken concerning foodstuffs stored in the freezer. When trying to thaw the food, rapid thawing is required or thawing in the refrigerator to avoid further contamination.