Optimizing monosaccharide production from liquid hot water pretreatment and enzymatic hydrolysis of grass-clover press cake

Nicolai Sundgaard Bekker; Saqib Sohail Toor; Kamaldeep Sharma; Thomas Helmer Pedersen; Lars Haastrup Pedersen

doi:10.1016/j.heliyon.2023.e18448

Optimizing monosaccharide production from liquid hot water pretreatment and enzymatic hydrolysis of grass-clover press cake

Heliyon. 2023 Jul 19;9(8):e18448. doi: 10.1016/j.heliyon.2023.e18448. eCollection 2023 Aug.

Authors

Nicolai Sundgaard Bekker¹, Saqib Sohail Toor², Kamaldeep Sharma², Thomas Helmer Pedersen², Lars Haastrup Pedersen¹

Affiliations

¹ Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark.
² Department of Energy, Aalborg University, Pontoppidanstræde 111, 9220 Aalborg, Denmark.

Abstract

In the present study, clover-grass press cake was treated by liquid hot water at temperatures of 180-200 °C for a reaction time of 5-10 min. Evaluation of pretreatments was based on the monosaccharide yield after enzymatic hydrolysis of the pretreated slurry and solid fraction, respectively. Extraction of up to 48% hemicellulose and 4% cellulose was observed during pretreatment. The optimal pretreatment conditions were identified as 190 °C and 10 min resulting in monosaccharide yields of 90% and 73% of the theoretical maximum by slurry and solid conversion, respectively. At optimal conditions, the C6 monosaccharide yield (83-90%) was fairly equal compared to the C5 monosaccharide yield (56-89%), which increased by slurry conversion due to near-complete monomerization of soluble xylo-oligosaccharides. In this study, we showed that clover-grass press cake possesses considerable potential as feedstock for production of fermentable sugars in a biorefinery context.

Keywords: Agro-industrial residues; Enzymatic hydrolysis; Grass pulp; Green biorefinery; Liquid hot water; Monosaccharides.