THE USAGE OF ENZYMATIC METHODS FOR STARCH DETERMINATION IN TECHNOLOGICAL FLOWS OF PAPER MILLS.

It is necessary to determine the amount of starch in order to find effective methods of controlling it in technological flows of paper mills. Enzymatic methods for starch determination based on the selective action of amylolytic enzymes on starch are promising. Water-soluble low molecular weight dextrins are formed when starch is treated with alpha-amylase. Dextrins are then hydrolyzed by glucoamylase to glucose, which is determined by various methods. Material pretreatment is necessary to increase starch availability for the action of enzymes. Two enzymatic methods were used in the research. The standard SCAN-P 91:09 SCAN-W 13:09 test-method and NArFU-test method (method is developed at the department of biology, ecology and biotechnology, Northern Arctic Federal University, Arkhangelsk, Russia). High-temperature short-term alkaline treatment of the material is necessary according to the SCAN-test method. Two hours alkaline treatment at room temperature is necessary according to the NArFU-test method for pulp, paper and cardboard. Boiling treatment at the initial pH of medium is necessary according to the NArFU-test method for white water. White water samples of the Sukhona pulp and paper mill (Sokol, Russia) were used. White water samples were also obtained in laboratory conditions. It was determined 9- 24 % less starch in the laboratory white water according to the SCAN-test method in comparison with the NArFU-test method and 70% less starch in the industrial whitewater. This is due to the destruction of partially destroyed starch in water under the high-temperature alkaline treatment using the SCAN-test method. The high content of starch remaining after previous production cycles was determined in the pulp fractions of waste paper used for cardboard production. It was determined 9 % less starch in the short-fibered pulp according to the SCAN-test method in comparison with the NArFU-test method, and 14% less starch in the long-fiber fraction. The pretreatment conditions according to the SCAN-test method lead to the determination of a lower starch content. NArFU-test method is recommended for starch determination in technological mediums of paper mills. [ABSTRACT FROM AUTHOR]