WET CLASSIFICATION OF STARCH - A PHYSICAL POSSIBILITY TO INFLUENCE THE TECHNOLOGICALLY IMPORTANT PROPERTIES OF STARCH

The requirements on the sharp classification of starch are not totally fulfilled by known methods. A classification process was developed by countercurrent separation in the centrifugal field. With this techniq ue, narrow starch grain size distributions can be produced. These prod uct fractions are different in their grain size, viscous properties, t heir composition (ash, protein, grease) and other relevant starch qual ities. The grain size at which the separation is carried out can be ch anged by a variation of the operating parameters (through-put and cent rifugal field of the centrifuge) and determined by means of a given eq uation. The quality of the classification process depends on the starc h properties (starch and protein contents in the suspension) and opera ting parameters (water through-put). A typical result of the classific ation (coarse fraction: 3%<10 mu m; fine fraction: 70%<10 mu m) is pre sented. But also the influence of the operating parameters on the sepa ration efficiency curve and the properties of the product fractions ar e discussed.