O uso de Bifidobacterium spp. e/ou Lactobacillus acidophilus em leites fermentados tornou-se popular no final da década de 70, como resultado dos avanços científicos na área de taxonomia e ecologia das bifidobacté-rias. Sua popularidade também aumentou devido a sua característica de baixa capacidade de acidificação durante a estocagem. Muitas patentes surgiram principalmente devido aos desenvolvimentos ocorridos na produção de fermentos e de novos produtos [7].VINDEROLA, BAILO & REINHEIMER [21] afirmaram que a adição de bactérias probióticas ao leite fermentado é prática amplamente adotada pelos laticíni-os. Contudo, fatores como acidez do iogurte, oxigênio dissolvido, interações entre espécies, práticas de inoculação e condições de estocagem podem condicionar a sobrevivência da microbiota probiótica em produtos lác-teos fermentados [20,21]

Time-dependent structural decay (h) of four different spreadable cheeses was established using a Wells-Brookfield cone and plate viscometer. The h values were determined at constant values of shear rate, (10 set-l to 200 set-'). The products studied were two samples of commercial Neufchatel cheese (one plain and one chocolate flavored) and two different saqples of cheese prepared using the Maubois, Mocquot and Vassal (MMV) method, which utilizes milk concentrated by ultrafiltration. All samples presented a structural decay characterizable by two different rate constants. Yield stress for Neufchatel cheese was observed to be one-third of the values obtained for MMV cheeses.

Sensory evaluation and analysis of pH, titratable acidity and microbial counts after 1, 7, 14 and 21 days of storage of five combinations of lyophilized Bifidobacterium longum and/or Lactobacillus acidophilus added to milk fermented with Streptococcus thermophilus were studied during storage at 4ºC. The taste and acidity sensory attributes were significantly (P<0.05) perceived as the storage time increased. Favourite combinations contained, initially, Bif. longum and L. acidophilus (10 8 and 10 7 cfu/mL, respectively) and Bif. longum only (10 8 cfu/mL). These combinations did not differ significantly among them and neither from the standard fermented milk. The lowest sensory scores and highest titratable acidity values were obtained for fermented milk added of L. acidophilus (10 8 cfu/mL initial concentration). During the 21 days of storage at 4ºC the viable cell counts of: Str. thermophilus did not change. Bif. longum viable cells counts kept constant or reduced 1 logarithmic cycle and L. acidophilus reduced 1 or 2 logarithmic cycle. We did not observe inhibition of over-acidification caused by the presence of bifidobacteria or L. acidophilus.