Blueberries have received considerable attention due to their content of health promoting compounds
such as polyphenols and anthocyanins. Thermal processing is known to cause degradation of anthocyanins
and juice color. The objectives of this research were to study the effect of continuous ultrasonication
processing on the microbiological, chemical and physical properties of blueberry juice (BJ).
Unpasteurized BJ was pumped at 24 mL/min or 93.5 mL/min to the continuous flow cell of an ultrasonic
processor, where it was sonicated at three treatment levels, 13.88 ± 2.45, 43.45 ± 4.12, and 73.60 ± 5.35
(J/mL) energy density. Sonicated and unsonicated juices were analyzed for coliforms, total aerobes, yeasts
and molds. Total anthocyanin content, total phenol content, antioxidant activity, Brix, titratable acidity,
pH and color were also determined for both sonicated and unsonicated juices. Continuous flow sonication
successfully reduced microbial counts. Sonication at higher intensities significantly (p < 0.05)
reduced microbial counts. The highest log reduction in total aerobes (1.36 log cycles) was achieved at
high flow rate (93.5 min/mL) with high intensity (100 amplitude) sonication condition compared to
untreated and control juice samples. Continuous flow sonication processing preserved the anthocyanins
and color of blueberry juice. This study demonstrated that ultrasonication can be an alternative
pasteurization treatment to thermal processing.