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Steam explosion (SE) is a versatile tool for the pretreatment of lignocellulosic plant 27 materials and the further separation of their main constitutive components, i.e. cellulose, 28 hemicellulose, lignin, etc. In this study, we propose to evaluate the effects of SE 29 treatment on the recovery of secondary metabolites. As a case study, the well-known 30 grape pomace phenolic compounds were considered. Our results demonstrate that the 31 efficiency of the steam explosion in term of yield (900 mg polyphenols per kg of dry 32 grape pomace) was relatively similar to conventional maceration methods in alcoholic 33 media (800 mg/kg). Advantages of SE compared to maceration were highlighted: the 34 process is organic solvent free, destabilize the biomass structure and release insoluble 35 bound phenolic compounds. In addition, it offers the possibility to modulate distinct 36 polyphenols profiles by modifying the process conditions.

High-purity cellulose nanofibers were isolated from wheat straw through an environmentally friendly, multistep treatment process that combined steam explosion, microwave-assisted hydrolysis, and microfluidization. The cellulose content of the processed nanofibers increased from 44.81% to 94.23%, whereas the hemicellulose and lignin contents significantly decreased. Scanning electron microscopy revealed the effects of the isolation treatments on fiber morphology and width. Atomic force microscopy was used to observe the changes in the components, surface roughness, and crystallinity of the fibers. Transmission electron microscopy showed long, loose nanofiber bundles that were 10–40 nm wide with an average individual diameter of 5.42 nm. Fourier transform infrared spectroscopy showed that noncellulosic components were effectively removed. X-ray diffraction analysis revealed the improved crystallinity of the processed fibers, as well as the partial crystalline transformation of cellulose I to cellulose II. T...

Steam explosion is a thermo-mechanicochemical pretreatment which allows the breakdown of lignocellulosic structural components by the action of heating, formation of organic acids during the process, and shearing forces resulting in the expansion of the moisture. Two distinct stages compose the steam-explosion process: vapocracking and explosive decompression which include modification of the material components: hydrolysis of hemicellulosic components (mono- and oligosaccharides released), modification of the chemical structure of lignin, and modification of the cellulose crystallinity index, etc. These effects allow the opening of lignocellulosic structures and influence the enzymatic hydrolysis yield of the material.