Cavitation effects of sonication on microbial load and physicochemical properties of orange juice

Strong interest of consumers in acquiring minimally processed foods that conserve the different micronutrients has raised the need to study the effect of food processing methods on quality attributes. The aim of thisstudy was to determine the effect ultrasound treatment (for 5, 10, 15 min at 37 and 80 kHz frequency) on physicochemical properties (titratable acidity, pH, oBrix, browning index, opacity), color attributes and microbial load (total microbial population, yeast and mold, and coliforms) of orange juice. Results showed non-significant changes for titratable acidity, °Brix, and pH in sonicated samples compared to control (p>0.05). The difference between browning and opacity indexes of the sonicated samples and heating treatment sample was significant (p<0.05) and the sonication caused to decrease thebrowning and opacity indexes of orange juices. The color parameters investigation of orange juice samples showed that the decreasing of frequency sonication and increasing the time of treatment leads to increase the lightness (L*), and decrease of the redness (a*) of orange juice samples. Significant reductions in the microbial load corresponding to sonication time were also recorded (p<0.05). 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, sensorial and nutritional quality.