Quality Assessment of Raw and Treated Milk Samples Collected From Food and Drink Establishments and Milk Distribution Centers of Jimma City, Southwest Ethiopia

Abstract

Background: Milk is an important source of nutrition but is also highly susceptible to microbial contamination and adulteration if not handled with hygiene. In Ethiopia, raw milk has been studied extensively, but little is known about the microbial safety of treated milk (boiled or steamed) consumed in urban establishments such as cafes and hotels. Objective: To assess the quality of raw and treated milk samples collected from food and drink establishments and milk distribution centers of Jimma city, southwest Ethiopia. Method: A cross-sectional study was conducted among 201 milk samples collected from food and drink establishments and milk distribution centers from September to October 2024. Stratified systematic random sampling was used, with one milk sample collected per establishment. Laboratory analyses assessed total bacterial count (TBC), total coliform count (TCC) and specific gravity for adulteration. Structured questionnaires and observational checklists captured milk handling practices. Quality assurance included negative controls (uninoculated media, sterile water) were performed. Data were analyzed using Kruskal-Wallis tests, logistic regression and adjusted odds ratios (AOR). Result: A total of 15 raw, 68 boiled, and 118 steamed milk samples were analyzed. Both raw and treated milk frequently exceeded Ethiopian Standards for TBC and TCC, with Staphylococcus aureus and Escherichia coli as dominant isolates. Adulteration was detected in >40% of samples, particularly from steamed milk establishments. Hygiene practices were poor: none of the handlers used personal protective equipment (PPE) and only 22.9% had received training. Observed hygiene did not always align with self-reported practices. Multivariate analysis identified milk adulteration and cooler temperature management as significant predictors of poor milk quality. Conclusion and recommendation: Milk sold in Jimma City is compromised by microbial contamination and adulteration due to poor milk handling practice. Strengthened regulatory enforcement, improved cold chain infrastructure and mandatory handler training are recommended to safeguard consumer health.