Effects of two different enzyme treatments on the microstructure of outer surface of wheat straw

The outer surface of wheat straw (WS) plays a critical role for the penetration of chemicals in the pulping production. In this study, we characterized the changes of outer surface before and after enzyme treatment. The results showed that neutral cellulase and lipase had different effects on the microscopic morphology of the outer surface of WS. Both enzyme treatments reduced the silicon content on the outer surface of WS, and the effects of neutral cellulase treatment were more obvious. Neutral cellulase mainly destroyed the vascular bundles on the outer surface of WS, degraded part of the cellulose, and then promoted the shedding of the siliceous layer connected to the cellulose, while lipase mainly destroyed the cuticle on the outer surface of WS. Furthermore, neutral cellulase promoted the dissolution of various sugar components, especially the dissolution of glucose. The dissolution of glucose had increased by 7 times with the addition of neutral cellulase. Therefore, adding a process of enzyme treatment before pulping production could destroy the microstructure of the outer surface of WS, provide favorable conditions for the penetration of chemicals in the subsequent pulping process, and reduce the use of chemicals.Graphical abstractThe wheat straw was treated with neutral cellulase and lipase, and the membrane on the outer surface of the wheat straw was destroyed, which provided favorable conditions for the chemical soaking in the subsequent pulping process.