Abstract:
Untreated milk cannot be kept for long time due to
microbial spoilage. The spore-formers are major contaminants as
it significantly affects the shelf-life, quality, and wholesomeness
of milk, which is treated with heat at different levels. Mesophilic
and thermophilic spores can survive even post treatment. The comparison between the spore counts under different heating methods
was performed on samples of different suppliers. 110 samples from
six points were collected to analyze the effect of thermized and
ultra-high temperature (UHT) on the spores. Samples were heated
at 80 0C for 10 minutes to inactivate the vegetative cells. Plate
Count Agar (PCA) was formulated and mesophilic spores were
incubated at 30°C for 48 hours, while the Petri dishes for counting
thermophilic spores were incubated at 55°C for 48 hours. Incubated
culture plates were enumerated for spore-forming bacterial colonies.
High heat resistant spores (Sporothermodurans) were not detected
on milk of four suppliers. A significant difference (p<.0.05) was
found to be among the spore counts of both thermophilic and
mesophilic of raw, thermized and UHT milk. The reduction of
spore-formers after thermization was higher on thermophilic than
mesophilic. The study revealed that the most effective method for
reduction of spore-forming bacteria was UHT
