Background
and Objective: Lactobacilli are one of the
major microorganisms in the probiotic yoghurt. The therapeutic potentials of
these microorganisms are due to their variations and rates of survival during
the shelf life
of probiotic yoghurt. This study aimed to assess the total colony counts of
lactobacillus strains in some examples of typical commercial probiotic yoghurt.   Materials
and Methods: In this cross-sectional survey,
50 samples of
probiotic yoghurts
(10
samples derived
from 5 dairy brands)
were
collected and
coded.
The variations of all lactobacilli strains were counted after the preparation
of surface cultures in 2 stages (1: Mid–day of shelf-life, and 2: 1 day before
the expiration date of yoghurt) additionally, the pH of all samples was
measured in the latter stage. Data were analyzed using the SPSS program.   Results: The average lactobacilli colony count was lower in the second
culture as compared to the first one in 4 out of 5 probiotic yoghurt brands (p≤
0.002). Amongst
all estimated
samples,
the highest
number of colony counts was less than the minimum recommended dose
(2.9×105
vs. 106, p < 0.0001). The mean pH of samples was significantly
lower than the optimum pH at the end of the shelf life (p < 0.0001).   Conclusion: Underrated total colony
counts of lactobacilli strains during shelf life, and increased acidity of
samples at the end of storage period would exacerbate the potential efficacy
and clinical merits of evaluated commercial probiotic yoghurts. Implementing
regular quality controls in accordance with national standardized protocols, as
well as further extended research are warranted.