Influence of Cardboard Pretreatment on the Determination of Starch Content by the Enzymatic Method

We determined the amount of starch by the enzymatic method in different samples of corrugated cardboard, including the sample produced of primary semi-finished products and corrugated cardboard made of 100 % waste paper. For starch enzymatic degradation, it is necessary to extract it from the corrugated board structure, since the processes of compression and keratinization of pulp fibers reduce the availability of starch for extraction. Enzymatic treatment requires the use of a complex amylolytic preparation for complete hydrolysis of starch to glucose. We were able to determine, respectively, 70 and 84 % of starch obtained from primary semi-finished products by mechanical methods, such as defibrillation in water and degradation in a liquid nitrogen medium, and added at the production stage of corrugated cardboard. It was shown that extraction with alkaline agents was necessary for more complete extraction of starch from corrugated cardboard. The influence of alkaline treatment on the characteristics of fibers of waste paper fractions obtained at the Sukhonsky Cardboard and Paper Mill has been analyzed. The fibers swell in alkali, resulting in an increase in fiber width and its shortening, as well as a decrease in crystallinity, which can be a positive opportunity for more complete starch extraction. Fiber swelling and crystallinity reduction are more intensive for the short fiber fraction compared to the long fiber fraction. When determining starch in corrugated cardboard using the standard method SCAN-P 91:09 SСAN-W 13:09 it was not possible to detect all the starch added at the production stage of corrugated cardboard from primary semi-finished products. Also the processing conditions of this methodology lead to degradation of the partially hydrolyzed starch. The most complete extraction of starch from corrugated cardboard was achieved by two stages of alkaline extraction under the following conditions: 5 % NaOH, temperature of 20 °C, the duration of each extraction – 2 h. Under these processing conditions it was possible to determine all the starch (22.8 kg/t) in the corrugated cardboard produced of primary semi-finished products with known consumption of starch; the starch content in the corrugated cardboard produced of 100 % waste paper was 48.2 kg/t. For citation: Khadyko I.A., Novozhilov E.V., Chukhchin D.G. Influence of Cardboard Pretreatment on the Determination of Starch Content by the Enzymatic Method. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 150–162. DOI: 10.37482/0536-1036-2021-5-150-162