Evaluation of Chemical and Microbiological Properties of Concentrated " Tuluq" and " Torba" Yoghurts during Storage

Tuluq and Torba bag yoghurt are the traditional concentrated yoghurt that is produced in some parts of Iran such as Azerbaijan. In this study, traditional concentrated yoghurt was produced in four methods, Tuluq and Torba bags, packed in polyethylene containers and was evaluated with control yoghurt during storage time. The chemical properties were included pH, acidity, total solid, fat and protein content. Also samples were evaluated of the Starter cultures such as Streptococcus salivarius ssp. Thermophilus, Lactobacillus delbrueckii ssp. Bulgaricus count, post contamination microbes such as coliform, psychrotrophic bacteria, mold and yeast count and pathogenic microbes such as Staphylococcus aureus and E. coli count. In analysied samples yoghurt, pH were (3.89-4.56), acidity (0.94-1.70 g/100 g), total solid (12.5-37.5%), fat (2.9-17.9%) and protein content (3.7-12.5%). Starter cultures decreased during storage time. Streptococcus Thermophilus count was more than Lactobacillus Bulgaricus count during storage time. Psychrotrophic bacteria mold and yeast count increased during storage time but the coliform, staphylococcus aureus and E. coli bacteria did not change. The results revealed that Tuluq yoghurt not only has high nutritional quality and microbiological properties but also has long shelf-life and it can be introduced as a valuable dairy product.