Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop Enzymatic pulping of lignocellulosic biomass Xuejiao Lin a,1 , Zhengmei Wu a,1 , Chenyuan Zhang a,d , Shijie Liu a,c , Shuangxi Nie a,b,d, ⁎ a College of Light Industry and Food Engineering, Guangxi University, Nanning, 530004, China b State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510640, China c Department of Paper and Bioprocess Engineering, SUNY College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY, 13210, United States d Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control, Nanning, 530004, China ARTICLE INFO Keywords: Lignocellulosic biomass Enzymes Biobleaching Dissolving pulp Enzymatic pulp refining ABSTRACT With advances in biotechnology, enzyme technologies have been increasingly applied to pretreat lignocellulosic biomass before the production of pulp. There are several driving forces, which include decreasing environmental impact from the traditional pulp and paper manufacturing processes, decreasing the overall production cost, and improving the product properties. This paper reviews recent developments in the area, particularly, related to the production of bleached pulp, dissolving pulp and pulp refining. This paper focuses on the mechanism and influencing factors of enzymatically assisted pulp bleaching to reduce adsorbable organic halide (AOX) forma- tion and dissolving pulp production and focuses on saving energy in pulp refining. The enzyme technology is in the marketplace of the pulp and paper processes, and it is expected to gain more importance in the future. 1. Introduction Green technology/practice has been in high demand, particular for the traditional manufacturing industry, such as pulp and paper industry (Balea et al., 2017; He et al., 2016). For this reason, enzyme technol- ogies and their applications to the pulp and paper manufacturing pro- cesses have been a hot topic in the research community (Ma et al., 2017; Menezes et al., 2016). With significant advances in enzymes production technology, the market price of enzymes have fallen, which allows the use of enzymes, e.g., xylanase and cellulases, in related processes. For example, biobleaching has become a preferred method for pulp bleaching, and the use of enzymes can be extended to the production of dissolving pulp and mechanical pulp (Sindhu et al., 2016). The great potential for enzyme technology has been demon- strated in reducing environmental pollution and improving pulp prop- erties as well as the comprehensive utilization of lignocellulosic bio- mass (Meighan et al., 2017). Lignocellulosic biomass primarily consists of cellulose, hemi- cellulose, lignin and extracts (Kim et al., 2016; Liu, 2010; Mosier et al., 2005; Song et al., 2016a; Yao et al., 2015b; Zhang et al., 2012). At present, three types of enzymes, namely, cellulases, hemicellulases and ligninases, are used in the lignocellulosic biomass treatment process (Demuner et al., 2011; Nie et al., 2018). Cellulases can be used to im- prove the performance of dissolved pulp (Duan et al., 2017) and reduce the energy consumption of pulp refining (Singh et al., 2015). Hemicellulases are primarily used to assist in pulp bleaching for the reduction of environmental pollution load (Maan and Dutt, 2017; Nie et al., 2015). The major ligninases, such as laccase, can be used to treat the lignocellulosic biomass, which can also reduce pollution (Gonçalves et al., 2015; Pei et al., 2016; Wang et al., 2014b). Dissolving pulp is a type of high-purity chemical pulp that is re- garded as an important raw material for producing cellulose deriva- tives, such as regenerated cellulose fiber, cellulose rayon, acetate fiber and cellulose ethers (Duan et al., 2017; Tian et al., 2014; Wang et al., 2015c). Utilization of lignocellulosic biomass to prepare highly reactive dissolving pulp is now facing shortcomings in terms of low pulp purity and poor fiber reactivity. The enzymatically assisted preparation of dissolving pulp can hydrolyze or oxidize the non-cellulose components, based on the specificity and high efficiency of the enzymes. Therefore, the pulp purity and fiber reactivity can be improved, and the fiber viscosity can be reduced. The technology of pulp bleaching assisted by enzymes is a reliable and green technology (Aracri and Vidal, 2011). Xylanase is the most commonly used enzymes in pulp bleaching. Xy- lanase can hydrolyze hexenuronic acid (HexA), formed during cooking, and xylan in fiber, thereby enhancing the permeability of the pulp (Saleem et al., 2012). To activate and relax the fiber surface to promote the water absorption and fibrillation of the fiber, enzymatic pretreat- ment with high activity cellulases or hemicellulases was employed, thereby improving pulping performance and reducing energy con- sumption of pulp refining (Cebreiros et al., 2017; Yang et al., 2011). https://doi.org/10.1016/j.indcrop.2018.04.033 Received 30 November 2017; Received in revised form 8 April 2018; Accepted 15 April 2018 ⁎ Corresponding author at: College of Light Industry and Food Engineering, Guangxi University, Nanning, 530004, China. 1 These authors contributed equally to this work. E-mail address: nieshuangxi@gxu.edu.cn (S. Nie). Industrial Crops & Products 120 (2018) 16–24 0926-6690/ © 2018 Elsevier B.V. All rights reserved. T