Separation Science and Technology, Vol.48, No.1, 113-121, 2013
Primary Clarification of Stevia Extract: A Comparison Between Centrifugation and Microfiltration
Two clarification processes, namely, centrifugation and microfiltration were used for primary clarification of crude stevia extract. The optimized condition (speed and time) of centrifugation was obtained using response surface methodology. Microfiltration was carried out using a 0.2 mu m pore size membrane at different operating pressures (138, 207, 276kPa) and stirring speeds (500, 1500, and 2500rpm). Clarified stevia extract was analyzed in terms of color, clarity, total solid, and stevioside content. The performance of both of these methods was compared based on the quality of clarified extract. 89.5% stevioside was recovered at 5334g centrifugation speed with 25.6 minutes of centrifugation. During microfiltration, severe flux decline was observed. At 138kPa and 500rpm, the flux decline was 87% within 5 minutes of filtration. This was more severe at higher transmembrane pressure drop and it was 89% at 276kPa under same stirring. Stirring speed increased the flux significantly. After 25 minutes, at 138kPa, 2.4 times flux enhancement occurred when the stirring speed increased from 500 to 2500rpm. Recovery of stevioside was more at lower operating pressure and about 89% recovery was attained at 138kPa.