Phenolic compounds present in the POE are able to interact with milk proteins; these may affect the functional properties of dairy products (O'Connell & Fox, 2001). During fermentation pH decreases as the lactic acid is produced by the starter culture d S. thermophilus and L. bulgaricus. The time taken for LF-yogurts to reach pH 4.6 was affected by the addition of POE (Fig. 1), and the multiplication of S. thermophilus and L. bulgaricus was slightly greater in yogurts supplemented (Table 2), specially in LF-yogurts B, C and D, which could have been the reason for the shorter incubation time needed to reach pH 4.6 for these samples. This may be explained due to the prebiotic effect of PO, as its contains dietary fiber represented by non-digestible carbohydrates like chitin, band a-glucans, xylans, mannans and galactans The ability of fiber to accelerate the acidification rate of milk in yogurt manufacturing has also been reported Studies have indicated that PO extracts assist probiotic bacteria growth rates and the symbiotic effect of the extract might be successful with some Lactobacillus strains