Optimization of ohmic heating of whey based drink using response surface methodology

Experiments were conducted according to Box Behnken Design for optimization of ohmic heating (OH) for pasteurization of whey based drink (sugar : 5 % litchi juice : 8 % ; pectin : 0.7% ; Potassium meta bisulphate : 1.5%). The three OH process variables were processing time, applied voltage and height of ohmic heater. Optimum conditions obtained by numerical optimization were processing time - 7.6  min, applied voltage – 49.5 V and thickness – 40 mm  to achieve optimum conditions (maximum desirability = 0.863) with  the predicted value for temperature was 73.80 o C,  cell viability 20.53 X10 3 cfu /m L,   color  index  54.83 and sensory score 7.55.