The mean doubling time (hours) of each of the two probiotic strains and of SYNBIO® combination grown in whole milk at the presence of 2%, 4% and 6% of each of buckwheat flour and oat bran, is shown in Table 4. Mean doubling time was used as measure of the effectiveness of the two vegetable substances in modulating growth rate. In general, doubling time of the tested probiotics strains grown with buckwheat flour and oat bran decreased as compared with the control. Mean doubling times were significantly lower (P b 0.05) for all cultures containing 4% and 6% buckwheat flour and oat bran respectively. A very long generation time (3.53 h) which significantly decreased in the presence of buckwheat flour and oat bran was observed for L. paracasei IMC 502®, as expected by its well-known difficulty to metabolize disaccharides (Desai et al., 2004). The mean doubling time of the two probiotic strains tested were remarkably lower in the combination (SYNBIO®) at the presence of both buckwheat flour and oat bran.