Effect of Yoghurt Starter Culture and Pasteurization on Some Pathogenic Microorganisms in Domestic Soft Cheese

Abstract

The study was conducted to detect the contamination of some dairy products (cheese, butter, yukurt, cream, milk) in the local markets of Tikrit city. The results detected of micro-pollutantion in dairy products revealed to presence of aerobic bacteria in milk samples and in numbers reached. (3.1 × 101 and 0.7 × 101) (c.f.u /gm), with the total number of Bacterial Count (2.7 × 101 to 1.81 × 102) (c.f.u/gm). The study showed that the milk samples were free from the Coliform, psychrophilic and Thermoduric Bacteria . Yeast and mold were found in the milk samples in numbers ranging from 1.03 × 101 to 3.6 × 101(c.f.u/gm). The result of the detection of microbial pollutants in cheese revealed the presence of aerobic and Coliform Bacteria except for Ch5, the Coliform and the thermoduric Bacteria in the cheese samples were 35.1 × 101, 1.06 × 101 and 2.75 × 101. (c.f.u/gm). However this study showed the absence of Thermoduric Bacteria in the cheese models of Ch 5 and Ch2, as well as the absence of all samples of cheese from the psychrophilic Bacteria. Yeasts and molds in the cheese models ranged from 1.03 × 101 to 3.6 × 101 (c.f.u/gm). The results of the detection of the microbial contaminants in Yogurt showed that the Yogurt samples of the Yo4 and the Yo2 were absent from the Coliform Bacteria, and the samples of Yo5 and Yo2 were found to be absent from psychrophilic Bacteria. It has been observed through the results, that absence of all cream samples from Coliform Bacteria, as well as the psychrophilic Bacteria and the Thermoduric Bacteria. while the yeast and molds ranged from 3.3 × 101 to 0.55 × 101 (c.f.u/gm). The results of the detection of microbial pollutants in butter revealed the presence of aerobic bacteria in the butter samples and the absence of all butter samples from the Coliform Bacteria, while the Thermoduric Bacteria ranged from 2.25×101 to 0.4 × 101 (c.f.u/gm). The psychrophilic Bacteria in the butter samples were ranged from 0.45 × 101 to 0.9 × 101 (c.f.u/gm).