Effect of the autohydrolytic treatment of Miscanthus sacchariflorus Andersson on the yield of the reducing substances during the subsequent fermentolysis

Abstract

The effect of the autohydrolytic treatment of Miscanthus sacchariflorus Andersson on the yield of the reducing substances during the subsequent fermentolysis has been determined. It was established that a change in the conditions of the auto-hydrolytic treatment of Miscanthus sacchariflorus Andersson induces a formation of solid fractions containing cellulose, lignin, hemicellulose and mineral substances, the ratio of which depends on the severity factor, i.e. temperature and processing time. It was shown that at the severity factor of 5.67, almost complete hydrolysis of hemicellulose occurs, however, there is an increase in the lignin content in the solid fraction (up to 46.0 %) relative to the lignin content in the feedstock (20.8 %), which is due to lignin condensation with a consequent formation of pseudo lignin. The highest content of cellulose in the solid phase is observed as a result of hydrolytic processing of raw materials with a severity factor of 4.17 to 4.39, a temperature of 160 о С and a processing time of 25 min. At an increased temperature, an increase in the acidity of the medium catalyzes the hydrolysis of cellulose and reduces its content in the solid fraction to 60 % at a severity factor of 5.67. During the auto-hydrolytic treatment of Miscanthus sacchariflorus Andersson, an increase in the ash content in the solid fraction is observed. The solid fractions obtained after treatment with Miscanthus sacchariflorus Andersson were used as a substrate and were subjected to enzymatic hydrolysis with the enzyme preparations “Cellolux-A” and “BrewZime BGX” at an initial substrate concentration of 33 g/l. The increase in the yield of reducing substances has shown a steady increase with the removal of hemicelluloses and reached its maximum value (45.1 %) with an increase in the treatment severity factor to 4.48. The availability of the cellulose surface for the action of enzymes has decreased with an increase in the stiffness factor beyond a value of 4.48 due to the accumulation of lignin in the solid phase, as evidenced by a decrease in the yield of reducing substances in the enzyme to 31.8 %.