Yogurt is one of the most popular types of fermented milk almost all over the world particularly the Middle East. Although cow’s milk is considered the main source for large scale yogurt production, many nomads in Khorasan, North East Iran rear sheep and goats for milk and meat production. Ewe’s milk is especially suitable for yogurt production because of its high protein and total solids content and as a result it is largely attracted consumer acceptance. However, due to poor sanitary conditions of milking practices and storage equipments as well as improper heat treatment of milk before culture inoculation, a wide spectrum of microorganisms with pathogenic importance could be present in the final product and cause illness. The aim of this study was to examine traditionally produced yogurt samples for presence of microorganisms of sanitary importance. Samples of traditionally produced yogurt by three main nomads of Khorasan Province were collected on site right after production taking in to account the way of heat treatment. These samples were kept in sterilized bottles in cold container and were transferred to the laboratory immediately for microbial examination. The viable count of coliform (indicative of unsanitary conditions), E.coli, Staphylococcus aureus (coagulase positive), and yeast and mould were determined. Most probable number (MPN) technique showed that only yogurt samples prepared with milk exposed to low heat treatment (40 C) were contaminated with 102 × 2.4 CFU/g coliform. No E.coli and Staphylococcus aureus (coagulase positive) were found in all examined samples which indicate that the environmental conditions of milk after fermentation do not support the growth of such microorganisms. Yeast and molds were found with different count in all samples revealing the unsatisfactory post production sanitation. Therefore, it is concluded that traditional yoghurt supplied by nomads in Khorasan constitutes no high risk hazard to consumers. However, hygienic and technological measures should be performed properly to safeguard the consumer health.

Keywords