Microbial Contamination of Commercial and Traditional Doogh Dairy Products in Lorestan Province of Iran

Background: Doogh is a popular dairy beverage in Iran which its main ingredient is yogurt. The aim of this study was evaluation of bacterial and fungal contamination of this product marketed in Lorestan province, West of Iran. Methods: A total of 200 doogh samples consisted of 150 commercial samples, including five different brands and also 50 homemade samples were purchased randomly from markets. Coliforms, Escherichia coli, Staphylococcus aureus, mold, and yeasts counts were performed according to Iranian national standard protocols. Results: E. coli and S. aureus counts were negative for all doogh samples. Coliform enumerations of all samples were less than the acceptable range declared from Iranian national standard. Out of 200 samples, 56 (28%) were unacceptable due to mold and yeast counts more than the maximum acceptable level stated by national standard of Iran (≤100 CFU/ml). Overall, 45 samples (90%) of traditional as well as 11 samples (7.3%) of commercial doogh were microbiologically unacceptable. Conclusion: Attempts have to be made to standardize the processing of Iranian traditional doogh manufacturing, and public health authorities should control the hygienic quality of both traditional and commercial doogh in Lorestan province, routinely.