4. Conclusions
In this study, the continuous ultrasound treatment reduced the
microbial counts in the blueberry juice with increasing juice flow
rate and sonication amplitude. For example, the juice treated with
US 93.5 mL/min/100A had the highest microbial reduction than the
US 24 mL/min/40A, US 24 mL/min/80A, US 24 mL/min/100A, US
93.5 mL/min/40A and US 93.5 mL/min/80A. Continuous US treatments
did not affect the TAC content of the blueberry juice.
Moreover, continuous US treated juices did not exhibit significant
changes in L* or a* color values, however, it slightly effected the hue
angle and chroma values of the juice. Regardless of the sonications
conditions, the continuous flow sonication processing preserved
the anthocyanins and juice color while still providing significant
reduction in microbial counts of APC, TC, yeast and mold. The study
demonstrated that continuous flow sonication may be an alternative
to thermal pasteurization which might result in a higher
quality juice.