Abstract:
The study of protein separation from tamarind kernel powder (TKP) using the rotating filter can be categorized into three sections. As for the first section, the composition and particle size of TKP were studied. It was found that TKP was composed of polysaccharide, protein, fat, and others with the contents of 63.42-73.57, 15.36-16.54, 4.91-5.10, and 16.31-4.79% by weight, respectively. When dispersed in water, the particle size of TKP was approximately 22-23 micrometers. With the increasing of the concentration of the suspension, the viscosity of the suspension increased while the density was insignificantly changed. The corresponding viscosities and densities of the suspension at the suspension concentration of 20, 40, and 60 gram per litre were 2.42, 6.12, and 17.706 centipoises, respectively, and 1004.82, 1011.18, and 1014.52 kilogram per cubic meter, respectively. Concerning the second section, four types of the filters were studied in the filtration with wiper at the concentration of 10 gram per litre; three made of synthetic fiber and the other made of stainless steel. The procedure was started by the ultrasonic treatment for 5 minutes and then washing with pure water for four times. It was found that the second type of the filter gave the best results; 95.07% protein removal, 56.30% polysaccharide loss, and 12.34 micrometers of pore size. Regarding the third section, various factors affecting protein separation from TKP by using the rotating filter were investigated at the feed flow rate of 38 litre per hour. Those factors were the concentration of the suspension, the pressure across the filter, rotating speed, and the distance between the filter surface and the internal surface of the outer cylinder. It was found that rotating speed and pressure across the filter had a great influence on the separation at the low concentration of the suspension. With the increasing of the rotating speed, the optimal value of pressure across the filter was increasing likewise. In response to the optimal value, the filtrate flux, percentage protein removal, percentage polysaccharide loss were higher. On the other hand, at the high concentration of the suspension, the rotating speed was the only one that had an effect on the separation. As for the effects of the distance between the filter surface and the internal surface of the outer cylinder, it was found that the shear force occurring from Taylor's vortice was decreased with the higher and lower distance than 0.008 meters. That made the filtrate flux, percentage protein removal, and percentage polysaccharide loss decrease. In addition, The rotating filter can separate small particles by considering the particle size distributions of TKP in raw material, feed stream, and filtrate stream. At the optimal conditions for the filtration, the particle size distribution curve of TKP in raw material and that of TKP in feed stream separated, but shared the same average particle size of 22-23 micrometers. While the narrow curve particle size distribution of TKP in filtrate stream could be observed with the average particle size of 7-9 micrometers. The optimal conditions for the filtration of the TKP suspension by using the rotating filter were as follows; the suspension concentration of 20 gram per litre, the filter rotating speed of 1700 round per minute, the pressure across the filter of 0.16 bar, and the distance between the filter surface and the internal surface of the outer cylinder of 0.008 meters. (the Taylor number was 7596, the shear rate was 10704 per sec, and the axial Reynold number was 50). Consequently, the following results were obtained; the filtrate flux of 9354.41 litre per square meter per hour, protein removal of 74.36%, and polysaccharide loss of 40.31%, protein, polysaccharide and fat content in the product of 9.70%, 66.41% and 5.10% by weight, respectively and product yield of 29.03% by weight