Bentonite, temperature and pH effects on purification indexes of raw sugar beet juice to production of inverted liquid sugar

Abstract The present study deals with modeling of the effects of processing temperature (30–95 °C), concentration of Bentonite (Bent) (1–5 g/L) and pH (3.5–6) on color, turbidity, purity, ash and invert sugar content of purified raw sugar-beet juice. The used methodology was the face central composite design of response surface to optimize the key parameters (temperature of processing, concentration of Bent and pH) of the process. The main goal was to focus on the possibility to produce invert sugar directly from raw sugar-beet juice in conjunction with an alternative purification method and also comparison with the common conventional lime processing in the industry. In this way, second-order polynomial models were developed for dependent responses using least-square fit of regression analysis. The results of analysis of variance indicated that all three investigated independent parameters have significant influence on purity indexes of raw beet-juice. The optimum condition was a constant reaction time (30 min) at temperature of 75 °C, pH 4.47 and Bent concentration of 1.7 g/L which were determined on minimization of color, turbidity and ash content and maximization of invert sugar and purity. At this optimum point: color, turbidity, purity, ash and invert sugar content were found to be 1664 ICU 420 , 6.3 NTU, 93.9%, 0.55% and 1.6%, respectively. Also the clarified juice quality obtained by Bent method was improved greatly when compared with conventional limed–carbonated as the color and turbidity in clarified juice were removed by the rate of 35.55% and 76.09%, respectively.