Untreated, thermally pasteurized, ultrasound and
ultrasound-UV irradiated juices were stored at refrigeration temperature of 4 C for 10 weeks after processing. Sample of juice
was withdrawn at regular intervals for analysis of the shelf life of
the processed juice. During the analysis of the shelf life, the growth
of microorganisms was monitored as an indicator of the shelf life.
Colony forming unit measurements were used as the
micro-organism count method. By serial dilution technique, colony
forming unit per milliliter was established. Spread plate count
technique (SPCT) and streak plate method was used to obtain the
isolated colonies from the mixed cultures at the end of 24 h and
it was sub-cultured on nutrient broth and nutrient agar plates.
The number of individual colonies on an agar plate was counted
by visual observation in light. The actual CFU/ml of juice was then
calculated using the following equation: