OPTIMIZATION OF ULTRASONIC AND HIGH HYDROSTATIC PRESSURE CONDITIONS ON QUALITY PARAMETERS OF MULBERRY (MORUS MORACEAE) JUICE USING RESPONSE SURFACE METHODOLOGY

The Box-Behnken design response surface method was employed to analyze the synergistic effects of manosonication on some quality parameters of mulberry juice. Activity of polyphenol oxidase (PPO) was significantly affected by the linear terms of ultrasonic frequency and pressure, as well as the interaction between ultrasonic frequency and pressurizing time. Peroxidase (POD) was significantly affected by the interaction between ultrasonic time and pressurizing time as well as the quadratic term of ultrasonic time. Yeast and bacteria were inactivated to levels beyond detection. Model desirability prediction at 95% confidence gave optimal manosonication levels as 25.00kHz, 15.35min, 376.36MPa and 10.01min for ultrasound frequency, ultrasound time, pressure and pressurizing time, respectively. At these optimum levels, the predicted % anthocyanin retained activities of PPO and POD, color brightness, hue angle and chroma were 83.08%, 45.55%, 53.93%, 7.59, 112.09 degrees and 11.74, respectively. The overall desirability index was 0.639.