Survivability of Escherichia Coli in Commercial Powder Goat Milk during Four Months Storage at Two Different Temperatures
Bacteria in low moisture environments are not favorable for growth, but can survive and cause a possible food safety risk for consumers. A study was conducted to evaluate survivability of Escherichia coli and storage stability of commercial powdered goat milk (PGM) products. Three batches of whole milk PGM samples were purchased at a local outlet, and divided into two halves to assign non-inoculated control and E. coli inoculated groups, then stored at 4 and 22°C for 0, 2, and 4 months. Results showed that significant reduction (P<0.05) in E. coli counts occurred at 22°C treatment group by more than 2 log CFU/g at 2 months storage, then further decreased by an additional 0.37 log CFU/g at 4 months storage. The survival of E. coli was significantly higher at 4°C, suggesting that E. coli could survive better at 4°C by extending a longer latent period than at higher temperature (22°C) under the low water activity condition. E. coli counts had negative correlations with water activity at both temperature treatments for all three storage periods except for 0 and 2 months at 22°C, indicating that the survivability of the E. coli would decrease in powdered whole goat milk for 4 months of storage because of decrease in water activity. It was concluded that Escherichia coli survival and storage stability of the commercial PGM products were significantly (P<0.05) affected by storage temperature and time.
Yogurt has deep roots in Ethiopia, particularly for pastoral communities, and now its handling is facing deep scrutiny from a research team at Addis Ababa University (AAU). Led by Dr. Kebede Amenu, the team is using bacterial counts to compare the safety of yogurt stored in aluminum containers versus traditional yogurt containers that women treat with a smoking process for sanitation. The team carried out a lab-based experiment to assess the effect of smoking of containers using different tree species on the microbial load of milk and yogurt kept in smoked containers. Building its case, the milk safety project collected milk and feces from 217 cows and camels in May and completed microbiological analysis for E.coli O157 and Salmonella. Comparing the results of this analysis to that on microbes present in the containers will help to determine the efficiency of the sanitation process. Ultimately, Dr. Amenu hopes to improve the sanitation of dairy products in remote parts of Ethiopia. The project, as summarized in this blog post, supports women and families to overcome food insecurity. It also funds three master’s students.
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