Abstract:
As yoghurt is a very popular food item, assessment of quality of
commercialized yoghurt during storage in refrigerators is needed. Lack of
data on quality parameters of different brands of yoghurt in Sri Lanka poses
a risk on consumer safety. This study assessed the changes of physico chemical and microbiological parameters during the shelf life of some plain
set yoghurts sold in Matara municipal area of Sri Lanka.
Five different brands of plain set yoghurt with highest consumer preference
were selected for the present study. From each brand, fifteen samples were
collected and kept under refrigerated condition (4 C) for the analysis.
Those samples were analyzed for the physico-chemical properties (syneresis
effect, pH, titratable acidity, total protein content, calcium concentration)
and microbial composition (total plate count, total yeast and mould count)
by using three replicates of each sample at 4, 7, 14, 21 and 28 days intervals
from the production date and the results were compared with local and
international standards.
All microbiological parameters and total protein content of all the five
yoghurt brands were not within the permissible range for local and
international standards. Only the titratable acidity was in the permissible
range of local standards. Except calcium concentration, all the other
physico-chemical parameters and microbiological parameters of collected
yoghurt samples were changed with the storage time. Furthermore, this
study revealed that physicochemical and microbial parameters are varied
also among different brands of set yoghurt. The results of the study suggest
to introduce to quality standard for set yoghurts and producers should
motivate to follow standards.
