| dc.description.abstract | Pasteurization is a means of increasing the shelflife
of milk. This study focused on identifying
thermoduric bacteria that decrease the shelf-life
of pasteurized milk and finding a solution to
minimize their presence in pasteurized milk. The
study was carried on site of MILCO dairy factory
in Sri Lanka. Aseptically collected milk samples
were used for the determination of total colony
count of bacteria in silo, balance tank where milk
was sampled just before pasteurization and just
after passing pasteurization unit at different
times of the day to check the possibility of
process line contaminations between silo tanks
and pasteurization unit and the effect on the
efficiency of pasteurization. Staphylococcus aureus,
Staphylococcus epidermidis and Bacillus cereus were
identified as resistant bacteria to pasteurization.
Since bacteria under stress are more tolerant to
harsh environmental conditions, it was assumed
that providing bacteria with more favourable
conditions would make them more vulnerable to
pasteurization. Based on this assumption, a new
pasteurization process is proposed where milk is
held at 300 C for 17-20 min prior to pasteurization.
The shelf-life of milk, pasteurized by simulating
these conditions in the laboratory, was increased
up to eight days in comparison to five days with
regular process. This process is yet to be tested
for its practicability, by setting a plate system
for heating the raw milk up to 300 C after the silo
and store milk at 300 C in the balance tank for the
desired time. | en_US |
