COMPARATIVE STUDIES ON THE MICROBIAL LOAD OF FLAVOURED AND UNFLAVOURED DRINKING YOGHURT

To assess the accuracy and helpfulness of plain and flavoured drinking yoghurt, one hundred and
fifty random samples (thirty each) of plain, strawberry, mango, banana and orange were collected from
different supermarkets in Cairo and Giza Governorates, Egypt. The examined samples were analyzed to
assess and compare the microbiological quality of plain and flavoured drinking yoghurt samples before
their expiry or sell-by date. The data obtained revealed that, aerobic spore former count were determined
in different types of examined plain, strawberry, mango, banana and orange samples with a mean values
of 6.4×103±1.1×102, 1.3×105±2.1×104, 3.2×106±4.3×105, 6.9×105±7.2×104 and 4.2×106±6.6×105, respectively.
Mould and yeast counts were detected in 30, 100, 100, 100 and 90% of the examined samples. Coliforms, Enterococci
and, Staphylococci were detected in different kinds of examined flavoured drinking yoghurt.
Pseudomonas and Aeromonas as well as Bacillus cereus were present in the examined samples with percentages
ranged from 23.3 to 66.7% and 0 to 36.6%, respectively. Salmonella and Yersinia were not detected
in all examined samples. The survival of Listeria monocytogenes in drinking yoghurt stored at refrigerator
for 30 days was investigated. The public health significance and economical importance of different
microbial groups as well as recommended hygienic measures were discussed