Pilot-scale production of xylo-oligosaccharides and fermentable sugars from Miscanthus using steam explosion pretreatment

Rakesh Bhatia,Ana Winters,David N Bryant,Maurice Bosch,John Clifton-Brown,David Leak,Joe Gallagher

doi:10.1016/j.biortech.2019.122285

Rakesh Bhatia, Ana Winters + Show 5 more

Open Access

https://doi.org/10.1016/j.biortech.2019.122285

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Abstract

This study investigated pilot-scale production of xylo-oligosaccharides (XOS) and fermentable sugars from Miscanthus using steam explosion (SE) pretreatment. SE conditions (200 °C; 15 bar; 10 min) led to XOS yields up to 52 % (w/w of initial xylan) in the hydrolysate. Liquid chromatography-mass spectrometry demonstrated that the solubilised XOS contained bound acetyl- and hydroxycinnamate residues, physicochemical properties known for high prebiotic effects and anti-oxidant activity in nutraceutical foods. Enzymatic hydrolysis of XOS-rich hydrolysate with commercial endo-xylanases resulted in xylobiose yields of 380 to 500 g/kg of initial xylan in the biomass after only 4 h, equivalent to ~74 to 90 % conversion of XOS into xylobiose. Fermentable glucose yields from enzymatic hydrolysis of solid residues were 8 to 9-fold higher than for untreated material. In view of an integrated biorefinery, we demonstrate the potential for efficient utilisation of Miscanthus for the production of renewable sources, including biochemicals and biofuels.

Highlights

The European Union (EU) is committed to a reduction of > 40 % in greenhouse gas (GHG) emissions and a 25 % increase in the total European transportation fuels from biofuels by 2030 to meet and potentially exceed the objectives of the Paris Agreement for long-term decarbonisation of the EU energy system
A higher acetyl-group content has previously been demonstrated advantageous for efficient auto-hydrolysis of sugarcane bagasse and for the production of XOS (Zhang et al, 2018)
The biomass composition of Mxg used in this study was comparable to other previously reported studies (Chen et al, 2014; Ji et al, 2015), though it may differ depending on plant growth conditions including climate, soil and use of fertiliser (Lewandowski et al, 2016)

Summary

Introduction

The European Union (EU) is committed to a reduction of > 40 % in greenhouse gas (GHG) emissions and a 25 % increase in the total European transportation fuels from biofuels by 2030 to meet and potentially exceed the objectives of the Paris Agreement for long-term decarbonisation of the EU energy system. Such goals are driven in part by the transition from fossil-based fuels to carbon-neutral plant biomass-based renewable energy sources (European Commission, 2018). More readily up-scalable high biomass yielding and seed-based hybrids of Miscanthus are being developed and are expected to be market-ready by around 2022, to contribute more to renewable energy and GHG mitigation targets, and for expansion of the European bio-economy (Clifton-Brown et al, 2019)

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