INFLUENCE OF HYDROLYTIC TREATMENT ON THE CONTENT OF REDUCING SUBSTANCES IN NEUTRAL-SULPHITE ALKALI

Abstract

The aim of this work is to develop a technology for the preparation of neutral-sulfite liquors formed during the production of fibrous semi-finished products - cellulose from birch wood - for subsequent use as a nutrient medium for the cultivation of microorganisms. Acid hydrolysis was carried out at a temperature of 100 °С at a ratio of a 10% sulfuric acid solution to a liquor sample of 1 : 1. Enzymatic hydrolysis of neutral sulfite liquors was carried out with the enzyme preparations Accellerase XY and Accellerase XC at 50±2 °C and 60±2 °C. The end of hydrolysis was determined by the cessation of the increase in the content of reducing substances (RS) in the hydrolyzate. The original neutral sulphite lye contained 9.4% dry matter, 21.7 g/l of reducing substances, pH 5.3±0.2. It has been shown that as a result of enzymatic hydrolysis, the content of insoluble dry residue in the hydrolyzate decreases to 8.32% and 8.41%, respectively, and during acid hydrolysis – to 7.8%. The content of RS in neutral sulfite lye after acid hydrolysis increases by an average of 3 times, while after enzymatic hydrolysis - a maximum of 2 times. It was found by gas-liquid chromatography that pentoses predominate in the obtained hydrolysates. Microbiological processing of media with a similar carbohydrate composition is possible by a number of strains of microorganisms capable of assimilating pentoses, for example, yeast-like fungi of the Saccharomycetaceae family and bacteria of the Enterobacteriaceae family.