acidophilus NCFM AP24534 cell line (P < 0.05), although no statistically significant difference (P > 0.05), was noticed in the whole yoghurts fermented by the same probiotic strain. According to Varghese and Mishra (2008), the buffering capacity is directly proportional to the total solids (TS) content of the fermented product, which can lead to longer fermentation time. This observation, which is certainly valid for TS increasing with milk derivatives, does not seem to be applicable to TS increase induced by passion fruit peel powder addition that in some cases even accelerated the fermentation (Table 1). On the other hand, Almeida, Tamime, and

Oliveira (2009) ascribed the different acidification profiles of different LABs to their peculiar capacity to assimilate nutritive compounds of the milk, which could explain the differences in the kinetic parameters observed amongst the various yoghurts. According to McCann, Fabre, and Day (2011), the carrot cell wall addition was clearly the responsible for the reduction in

1 h of the fermentation time of yoghurt fermented by St and Lb. However, in the present study, the correlation analyses indicates that multiple factors, such as the lipid content of the milk, the culture composition and the presence of PFPP can affect the acidification parameters of probiotic yoghurts. The results of post-acidification (pH) and titratable acidity during the shelf-life of the yogurts are presented in Table 2. After one day of cold storage, the pH of yoghurts ranged from 4.37 to 4.50, Etoposide research buy and the largest differences between the yoghurts with passion fruit peel powder and the controls were detected in skim yoghurts fermented by L. acidophilus L10 (4.42 PFPP yoghurt and 4.50 control) and B. lactis Bl04 (4.42 PFPP yoghurt and 4.48 control) (P < 0.05). Titratable acidity varied from 0.64 to 0.74 mg lactic acid g−1 in whole yoghurts and from 0.87 to 1.07 mg lactic

acid g−1 in skim yoghurts. The increase in this parameter induced by the addition of passion fruit peel powder was statistically significant in all yoghurts (P < 0.05), but the whole ones co-fermented by B. lactis strains. After 14 days of shelf-life the pH of all yoghurts decreased significantly (P < 0.05) and ranged from 4.21 to 4.38 amongst the whole yoghurts and from 4.26 to 4.38 amongst the skim clonidine ones. On the other hand, after 28 days, it was observed a slight but significant increase in the average pH of control whole yoghurts co-fermented by L. acidophilus NCFM and B. lactis strains and PFPP whole yoghurts co-fermented by L. acidophilus strains and B. lactis Bl04 (P < 0.05). Surprisingly all the whole yoghurts with passion fruit peel powder showed higher pH than their respective controls (P < 0.05). However, such a scenario did in not happen within the skim yoghurts group. In this case the fiber did in fact promote a significant decrease in the pH of all yoghurts, except that co-fermented by B. lactis Bl04.