Novel supramolecular deep eutectic solvent-enabled in-situ lignin protection for full valorization of all components of wheat straw

[Display omitted] •A novel supramolecular DES for efficient in-situ lignin protection is first developed.•The supramolecular DES strategy shows superior lignin protection and sugar liberation.•β-CD has excellent adsorption ability toward lignin due to its “host–guest” inclusion.•The adsorption process of β-CD fits with pseudo-first-order and Langmuir model.•The supramolecular DES pretreatment realizes valorization of all biomass components. Lignin is usually deemed as an inhibitor to enzymatic hydrolysis of cellulose due to its physical barrier, non-productive adsorption, and steric hindrance. Herein, a novel supramolecular deep eutectic solvent (SUPRADES), comprising ethylene glycol and citric acid in 5:1 M ratio, and β-cyclodextrin (β-CD) in a concentration of 3.5% (w/w), was developed to be efficient for pretreating wheat straw. The delignification rate, cellulose enzymatic digestibility, and hemicellulose removal reached 90.45%, 97.36% and 87.24%, respectively, which may be attributed to the introduction of β-CD with superior ability of both adsorption and in-situ lignin protection to efficiently remove lignin with intact structure from cellulose surface. The mechanisms of high-efficiency lignin extraction/protection were systematically illustrated by adsorption kinetics. Moreover, Trichosporon cutaneum grown on the hemicellulose and cellulose fractions after pretreatment afforded 8.8 g total lipids from 100 g wheat straw. The green SUPARDES pretreatment strategy offers a new avenue for upgrading lignocellulose to biofuels.