Determination of Shelf Life of Locally Produced Soymilk

The study was carried out to access the shelf life of soymilk and soymilk yogurt sold in Onitsha Urban to assess the public health implication of these drinks visa vies food safety and health of the populace. The microbial analysis was carried out in the Project Laboratory of Chukwuemeka Odumuegwu Ojukwu University, Uli, Anambra State. Fifty (50) samples of soymilk bought from different markets from 50 different soymilk vendors and one laboratory prepared soy milk and was used for the study. The laboratory prepared samples were used as control. The shelf life of soymilk was evaluated; samples were stored at various temperatures for 7days. Sensory evaluation of the samples was taken. Standard microbiological methods were utilized to isolate the microorganisms involved, biochemical analysis was used to identify the isolates. Results revealed the presence of E. coli, and members of the genera Staphylococcus, Streptococcus, Klebsiella, Bacillus, Salmonella, Pseudomonas sp. , and fungi isolates of the genera Aspergillus, Candida, Rhizopus, Penicillum sp. , and Saccharomyces cerevisiae. Almost all the samples obtained from different markets were contaminated with E. coli, coliform and Staphylococcus sp. , Bacteria counts of days 0, 3 and 7 are 0.9 x 103 7.7 x 103, 1.1 x 103 - 8.0 x 103 and 4.6 x 103 - 0.8 x 103cfu/ml respectively. Samples prepared under aseptic condition showed no growth of microorganisms on the day zero, but on day 3 there was growth of Streptococcus sp. in one sample ranging from 1.3 x 103- 2.0 x 103 cfu/ml, on day 7, Streptococcus sp. was seen in all the samples ranging from 2.0 x 103 - 3.6 x 103. Bacillus was isolated in soymilk stored at room temperature. The study shows that the use of sterile processed water and pasteurization of the end product extends the keeping quality. Soymilks were only stable for 5days. The microbial load of ready-to- drink yogurt sold in our local markets is very high, their keeping quality is matter of hours, this subjects the populace to multiplicity of adverse health implications which includes salmonellosis, diarrhea and other diseases caused by Staphylococcus, Pseudomonas, Bacillus, Salmonella and Aspergillus. Soymilk vendors should be educated on the effect of food poisoning on human health and importance of producing their products hygienically.