بررسي مقايسه اي محيطهاي كشت مختلف براي شمارش كشت هاي آغازگر در ماست

A comparative study on suitability of culture media for yoghurt starter culture

Starter cultures are one of the most important factors affecting yoghurt quality .Thc qualitative and quantitative assessment of yoghurt starter bacteria (Streptocoeeu thermophilus and Lactobacillus delbrukti subsp bidgarieus) is valuable because some countries have proposed standards of quality yoghurt which may include the requirement that a minimum number of viable yoghurt organisms must be present at the time of the sale. Also, the proportion of two yoghurt bacteria is believed to K important in determining the quality of yoghurt. In the current study, nine different types of general and differential media were compared for the growth and differentiation of yoghurt bacteria. It was noted that although many media have been proposed for enumeration of yoghurt bacteria, only few of them proved to be reliable. M17 and acidified MRS (AMRS) performed as expected, but itʹ using one mediurn is preferred. Tryptone Protease Peptone Yeast Extract agar (TPPY) and Reinforced Clostridia] Prussian Blue agar (RCPB) are media of choice.