An Investigation of Microbial Contamination of Animal Butter at the Market Level in Zanjan

Background: Butter is one of the oldest dairy products known in the world and plays an important role in human nutrition. The aim of this study was evaluating of the microbial quality of traditional   and industrial butter marketed in Zanjan. Methods: In this descriptive cross-sectional study, a total of 29 samples of butter were investigated in 2 groups which 24 samples were of traditionally producedl butter and 5 industrially produced butter samples, randomly collected from the market in Zanjan, Iran. All samples were evaluated for total bacterial count, Staphylococci, coliform, fungi and mold. Results: Fourteen samples of traditional butter had higher coliform load than allowed in standards. Eighteen samples were contaminated with Staphylococcus, and mold was found in 8 samples. Also, fifteen samples were contaminated with Escherichia coli. Among the industrial samples, one was contaminated with Staphylococcus aureus but no contamination by coliform, Escherichia coli and mold and mold was observed. Conclusion: 58.33%, 75%, 33.33% and 62.5% of the traditional butter samples had higher coliform, Staphylococcus, mold and E. coli contamination, respectively than standard limit.  One of the industrial samples was contaminated with Staphylococcus. It is recommended that higher supervision on the production and distribution of these products is applied.