Sonication at mild temperatures enhances bioactive compounds and microbiological quality of orange juice

Freshly squeezed orange juice was sonicated (for 1, 10, 20 and 30 min at 24 kHz frequency) to evaluate its impact on selected physico-chemical and antioxidant properties, such as total phenolics, flavonoids, DPPH radical scavenging activity, total carotenoids, ascorbic acid, pH, °Brix and color attributes. Additionally, the effects of sonication treatments on the microbial load (aerobic mesophilic, yeast and mold) were also evaluated. Sonication of juice samples for 10, 20 and 30 min during which the temperature rose to 43-45 °C showed enhancement in most of the bioactive compounds compared to samples treated for 1 min and control samples (untreated). Significant reductions in the microbial load corresponding to sonication time were also recorded. Results of the present study indicate that sonication coupled with mild temperatures may be employed as a suitable technique for orange juice processing, and may be applied to improve its safety and nutritional quality.