Investigating the chemical and microbial characteristics of some local yogurt samples prepared from traditional dairy products stores in Tuyserkan city

Author
nooshin noshirvani
Assistant Professor, Department of Food Science and Technology, Tuyserkan Faculty of Engineering & Natural Resources, Bu-Ali Sina University, Hamedan, Iran
10.22034/FSCT.21.156.63
Abstract
Considering the great desire of concumers to consume traditional dairy products and their reluctance to use factory products, this study was conducted with the aim of investigating different chemical and microbial characteristics of traditional youghurt samples offered in Tuyserkan city and compare it with pasteurized yoghurt. The chamical characteristics inclusing percentage of dry matters, moisture content, acidity, pH and fat and microbial characteristisc including total bacterial count, coliforms, mold and yeasts, and Staphylococcus aureus were investigated and compared with the pasteurized sample as a control. The moisture and dry matter content of the samples varied from 87.7-84.33% and from 12.62 to 15.25%, respectively. The fat content of the yogurts produced was between 2.5-2.9 and thus within the range of semi-fat yogurts according to the national standard. No significant difference was observed between different samples in terms of moisture, dry matter and fat (P>0.05). The acidity (percentage by weight in terms of lactic acid) and pH value of various samples ranged from 0.87-1.81 and 3.68-47.4, respectively and were therefore fully in line with the national standard (at least 0.7). Different samples showed a significant difference in terms of pH and acidity (P < 0.05). The results of microbial characteristics indicate the presence of mold and yeast in all samples (100%), coliform in 83.33% and Staphylococcus aureus in 50% of the samples. Regarding microbial characteristics, a significant difference was observed between traditional and industrial samples. Thus, the industrial sample showed the lowest microbial load compared to the traditional yogurt samples (P < 0.05). Therefore, it is strongly recommended to control the incoming raw milk and observe the sanitary conditions during production, packaging and supply in the production of traditional products.
Keywords
Yogurt
traditional dairy
national standard
Chemical properties
Microbial properties

Subjects

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