Compared to the RS gruel, the addition of passion fruit fiber to the RS gruel had no significant influence on averages of the maximum acidification rate (Vmax) but increased the time to reach Vmax in the RSPF gruels fermented by ALAB, probiotic strains (except L.casei) and by all co-cultures, indicating a longer time of adaptation of the bacteria to the RSPF matrix (Table 1). This finding indicates that all strains took, in general, longer time to adapt to the presence of passion fruit fiber. Notwithstanding, the fiber reduced in about 2 h the fermentation time of the RSPF gruels fermented by L. plantarum and B. lactis and in about 5 h the RSPF gruel fermented by L. casei, but increased in 3 h the fermentation time of the same gruel fermented by L. fermentum (P b 0.05). Although the passion fruit fiber had influenced significantly the fermentation time of the RSPF fermented by the single cultures (except L. acidophilus), it had no effect when the gruel was fermented by cocultures (Table 1).