Determination of effectiveness of ultrasonication on some chemical and microbiological properties of sourcherry juice by response surface methodology

In this study, effect of ultrasonication on some chemical and microbiological properties of sourcherry juice was determined by response surface methodology. Sourcherry juice was sonicated at varying amplitude levels (50-100 %), temperatures (20-40 °C) and treatment times of 2-10 minutes at a constant frequency of 20 kHz. A quadratic model for the changes of total monomeric anthocyanins (P<0.01), total phenolics (P<0.05), antioxidant activity (P<0.05), polymeric color (P<0.05) and visual color (P<0.05) was found significant. 2FI model determined for the inactivation of Escherichia coli O157:H7was found significant (P<0.01). The results showed that different ultrasonication amplitudes, temperatures and times had no significant effect on pH, °Bx and titratable acidity. A significant increase in total monomeric anthocyanins in sourcherry juice was observed as the amplitude level and temperature increased (P<0.01). Temperature had a significant effect on the levels of total phenolics content, an increase in the total phenolics was obtained as the tempearure increased (P<0.05). The effect of amplitude level on the increase in antioxidant activity of sourcherry juice was also found significant (P<0.05). Colour parameters (L*, a*, b*, C, h) generally increased by increasing temperature, amplitude and time. It was determined that E.coli O157:H7 significantly affected by ultrasonication temperature and time (P<0.05).