Evaluation of Microbial Contamination of Dried Black Curd (Gharahghorut) Produced in Iran

Dried Black Curd (DBC), also known as Gharahghorut (Persian), is a dairy product produced from curd of yogurt or doogh. The aim of this study was to evaluate microbial contamination of industrially and traditionally produced DBC in Iran.

Four DBC brands holding certification of the Institute of Standards and Industrial Research of Iran (ISIRI), Iran Ministry of Health and Medical Education (IMHME) and ISO were purchased from a market in Tehran, Iran. Microbial monitoring for presence of coliform, Escherichia coli, coagulase-positive Staphylococcus aureus, mold and yeast was performed using different basic, enriched, selective and differential media including peptone water agar, MacCankey agar, blood agar and brain heart infusion agar, etc. according to the ISIRI standards (No.13299).

None of the tested samples had microbial contamination. However, in one traditional DBC sample, the population of mold and yeast was higher than the acceptable level defined by the ISIRI standard.

We found no contamination with coagulase-positive S. aureus, E. coli and coliforms in four brands of traditionally and industrially produced DBC in Iran. This indicates that the hygienic practices designated by the IMHME are well-implemented in the industrial sector. However, the mold and yeast contamination in traditionally produced DBC should be prevented by applying hygienic practices during the process of manufacturing and distribution.