ZIMBABWE – A recent study conducted by the Zimbabwe Ministry of Health and Childcare’s Department of Food and Microbiology has shed light on the on-farm hygiene characteristics that affect milk contamination produced at informal dairy farms in Zimbabwe.

This research aimed to understand the microbiological safety level profiles (MSLPs) of dairy workers’ hands and milking containers and the influence of hygiene and handling practices on the MSLPs of raw and cultured milk from six informal dairy farms in Zimbabwe.

The study involved interviews and direct observations to evaluate hygiene and handling practices. A total of 192 environmental swabs and milk samples were taken and analyzed for microbial presence.

Researchers focused on raw milk, cultured milk, dairy workers’ hands, and milking containers, assessing total bacterial and coliform counts, Escherichia coli, Salmonella, Listeria monocytogenes, and Klebsiella pneumoniae.

None of the six farms received maximum MSLP scores due to factors such as the use of plastic containers, reliance on unsafe water sources like wells, milking in open areas with bare hands, lack of cold storage facilities, and the absence of established food safety management systems (FSMS).

Microbiological assessment findings

The analysis revealed that raw milk from all six farms contained unacceptably high total bacterial and coliform counts, exceeding legal limits.

The milk’s poor microbial quality was largely attributed to inadequate sanitation and hygiene practices related to the farm environment, milking, and storage equipment, as well as the personal hygiene of the dairy workers.

E.coli levels in raw milk were a concern at four farms, indicating fecal contamination. Despite regulations prohibiting the sale of milk contaminated by E. coli, the raw milk from these farms continued to be sold to consumers, underscoring the necessity of milk pasteurization.

Cultured milk also exhibited high microbial loads, with samples from all farms except one receiving low MSLP scores. This type of milk is produced through natural fermentation under rudimentary and uncontrolled conditions.

Although the acidic environment of cultured milk, with a recorded pH ranging from 4.6 to 4.9, should inhibit bacterial growth, it still allowed the survival of many microbes, including E. coli.

Positive observations

Despite the overall findings, there were positive observations. Salmonella and Listeria monocytogenes were not detected in any samples or swabs, suggesting that some hygiene procedures were effective in controlling these pathogens.

Additionally, no indicator organisms or pathogens were found on the hands of dairy workers or in milking containers.

However, the total bacterial count on dairy workers’ hands ranged from 2.0 to log 6.1 colony-forming units per square centimeter (CFU/cm²), and milking containers ranged from 2.3 to log 4.3 CFU/cm².

These levels exceeded the acceptable total bacterial count of less than log 2 CFU/cm² for hands and surfaces that come into contact with food. This high bacterial count was attributed to inadequate personal hygiene, the use of unsafe well water, and milking in open spaces with bare hands.

Best practices identified

The farm with the highest MSLP score managed to mitigate the risk of milk contamination through several best practices, including cleaning the milking parlor with detergents after each milking session, using municipal water, storing milk in stainless steel cans in a cold room, and minimizing the storage time to less than 30 minutes.

This farm also maintained documentation of a food safety program, although its implementation did not fully meet globally accepted FSMS standards (ISO 22000).

The risk factors identified in this study provide a foundation for developing microbial contamination prevention strategies in Zimbabwe’s informal dairy sector.

Infrastructure development and training are crucial to improving the quality of milk and milk products produced and marketed through this value chain. Implementing these measures can enhance food safety and public health, ensuring safer dairy products for consumers in Zimbabwe.

The study was conducted in collaboration with Midlands State University, the University of Venda, and the National Food Institute at the Technical University of Denmark.

Subscribe to our food and agriculture industry email newsletters that provide busy executives like you with the latest news insights and trends from Africa and the World. SUBSCRIBE HERE