STRESZCZENIE
Analizy mikrobiologiczne 61 próbek kefiru i 92 próbek jogurtu wytwarzanych przez różne zakłady mleczarskie i dostarczanych na rynek warszawski w roku 1995 i 2001 wykazały znaczną poprawę jakości obu napojów w badanym okresie. Nastąpiło znaczne zwiększenie odsetka próbek nie zawierających bakterii z grupy coli, Escherichia coli, Bacillus cereus oraz pleśni i drożdży. Jedynie część próbek kefiru nie spełniała wymagań FAO/WHO co do liczby drożdży.

ABSTRACT
The microbiological quality of kefir (61samples) and yoghurt (92 samples) purchased in retail network in Warsaw in the years 1995 and 2001 has been examined. The total number of bacteria in at least 90% of yoghurt and 73% of kefir was in the range 107 - 109 c.f.u. in 1g. The dominating group of bacteria in kefir were mesophilic lactic acid streptococci and in yoghurt (analysed in the year 2001) - S. thermophilus. The number of L. delbrueckii subsp. bulgaricus in 40% of samples was < 107 - in 1g. The increment of microbiological quality of the examined fermented milks has been observed. More than 86% of kefir and 97% of yoghurt analyzed in 2001 were free from coliform bacteria, most of them free from B. cereus, moulds and yoghurt - also from yeasts. About 48% of kefir samples did not fulfill the FAO/WHO requirements concerning the number of yeasts.