Poor survival of probiotic bacteria in yogurt has been recorded. Growth of
a probiotic yeast, Saccharomyces boulardii, in association with the bio-yog
urt microflora, by incorporating the yeast into commercial bio-yogurt, has
been suggested to stimulate the growth of the probiotic organisms and to as
sure their survival during shelflife. Therefore, the ability of growth and
survival of the probiotic yeast itself in diary products, namely bio-yogurt
, UHT yogurt and UHT milk were investigated. S. boulardii was incorporated
into the dairy products and stored at 4 degreesC over a 4-week period. pH,
Lactose utilisation and the production of organic acids were monitored at e
ach interval. Based on the results in this study, the probiotic yeast speci
es, S. boulardii, has the ability to grow in bio-yogurt reaching maximum co
unts exceeding 10(7) cfu/g. The number of yeast populations was substantial
ly higher in the fruit based yogurt, mainly due to the presence of proporti
ons of sucrose and fructose derived from the fruit. Despite the inability o
f S. boulardii to utilize lactose, the yeast species utilized available org
anic acids, galactose and glucose derived from bacterial metabolism of the
milk sugar lactose present in the dairy products. Excessive gas and alcohol
production by the yeast species proved, however, to be major constraints f
or incorporating this yeast into bio-yogurt. (C) 2001 Elsevier Science Ltd.
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