Comparative evaluation of the bacteria isolated from decomposing cow milk and soybean milk

Abstract

A comparative evaluation of the bacteria isolated from decomposing cow milk and soybean milk were investigated. Six (6) bacterial species Bacillus circulans, Bacillus pumilus, Bacillus subtilis, Micrococcus luteus, Streptococcus faecalis and Streptococcus lactis were isolated from decomposing cow milk, while four (4) bacterial species namely Bacillus brevis, Bacillus licheniformis, Lactobacillus casei and Staphylococcus epidermidis were isolated from decomposing soybean milk stored at ambient temperature (30 + 10C). The initial bacterial load was found to be log 3.18 cfu/ml and log 3.70 cfu/ml in the decomposing cow milk and soybean milk respectively. The counts increased to log 9.99cfu/ml and 8.96 cfu/ml, in cow milk and soybean milk respectively, when the experiment was terminated. There was an increase from 40.0 to 90.0% occurrence of the bacterial isolates between day zero and day 4. Fresh cow milk contained 4.70% crude protein, 18.94% total solids and 0.0141% acidity; this values increased to 5.12 crude protein, 18.97% total solids and 0.1172% acidity in the spoilt sample while, fresh soybean milk contained 3.40% crude protein, 11.73% total solids and 0.0522% acidity, which also increased to 3.49% crude protein, 11.74% total solids and 0.0798% acidity in the spoilt sample on day 7. However, fresh cow milk was recorded to contain 9.75% soluble solids, 36.5mg/ml total sugar, and pH of 6.4; these values decreased to 7.67 soluble solids, 17.6mg/ml total sugar and pH of 3.9 in the spoilt sample while, fresh soybean milk was recorded to contain 9.60% soluble solids, 40.8%mg/ml total sugar and pH 6.2; this values also decreased to 5.69 soluble solids, 19.2mg/ml total sugar and pH 4.4 respectively on day 7, when the experiment was terminated. The 1.00 and 0.50% total ash with 3.50 and 2.75% crude fat recorded for the fresh cow milk and fresh soybean milk did not change in the spoilt samples throughout the study period.

JARD Vol. 4 (2) 2005: pp. 122-138