Populations of Lactobacillus delbrueckii ssp bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus and Bifidobacterium species in Australian yoghurts

Fifty commercial yoghurts, representing 16 Australian manufacturers, and claiming to contain the probiotic bacteria, Lactobacillus acidophilus and Bifidobacterium species, were examined for the viable population of these species as well as the yoghurt culture species, Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. The viable populations of L. delbrueckii ssp bulgaricus and S. thermophilus exceeded 10 7 cfu/g in 54% and 68% of the samples, respectively. The viable populations of L. acidophilus and Bifidobacterium species exceeded 10 6 cfu/g only in 24% and 14% of the samples, respectively. Yoghurts possessing high populations of L. delbrueckii ssp bulgaricus tended to be more acid (pH < 4) and contained L. acidophilus and/or Bifidobacterium species at populations less than 10 6 cfu/g.