Valorization of brewer's spent grains through cascaded protein recovery and fast pyrolysis of its residues

Yingyuan Wei; Kaya Goossens; Diederik P L Rousseau; Katleen Raes; Marcella Fernandes de Souza; Jianqiang Chen; Peng Gao; Di Wu; Frederik Ronsse; Stef Ghysels

doi:10.1016/j.wasman.2026.115538

Valorization of brewer's spent grains through cascaded protein recovery and fast pyrolysis of its residues

Waste Manag. 2026 May 30:218:115538. doi: 10.1016/j.wasman.2026.115538. Epub 2026 Apr 15.

Authors

Affiliations

¹ Thermochemical Conversion of Biomass Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium; Centre for Green Chemistry Environmental Biotechnology, Ghent University Global Campus, Incheon 21985, the Republic of Korea.
² Thermochemical Conversion of Biomass Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
³ Laboratory for Industrial Water and Ecotechnology (LIWET), Department of Green Chemistry and Technology, Ghent University Campus Kortrijk, Graaf Karel de Goedelaan 46, Kortrijk B-8500, Belgium.
⁴ Laboratory for Bioresource Recovery (RE-Source), Department of Green Chemistry and Technology, Ghent University, 9000 Ghent, Belgium.
⁵ Research Unit VEG-i-TEC, Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Campus Kortrijk, Sint-Martens-Latemlaan 2B, 8500 Kortrijk, Belgium.
⁶ Laboratory of Advanced Environmental & Energy Materials, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, China.
⁷ Centre for Green Chemistry Environmental Biotechnology, Ghent University Global Campus, Incheon 21985, the Republic of Korea; Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.
⁸ Thermochemical Conversion of Biomass Research Group, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium. Electronic address: Stef.Ghysels@UGent.be.

PMID: 41990413
DOI: 10.1016/j.wasman.2026.115538

Abstract

This study investigates value creation from brewer's spent grains (BSG) through cascaded protein removal and pyrolysis. More specifically, fast pyrolysis of BSG and its formation of pyrolysis liquids as a source of biorefinery intermediates was investigated and compared with BSG that underwent water leaching and protein extraction prior to pyrolysis (PWBSG). After protein extraction of BSG (N content of 4.42 wt%), a crude protein fraction was obtained with a nitrogen content of 9.17 wt%, corresponding to a nitrogen yield of 28.72%. Thermogravimetric analyses showed that the protein removal step using sodium hydroxide (NaOH) altered the physicochemical properties of PWBSG, resulting in a smaller relative peak area for levoglucosan while also having a reduced peak area for protein-derived N-containing compounds. Performing fast pyrolysis in a 250 g·h^-1 continuous fast pyrolysis set up resulted in bio-oil yields of 47.27 ± 0.55 wt% and 53.45 ± 1.97 wt% for BSG and PWBSG, respectively. Upon fractionation of the bio-oil in an aqueous and organic phase (EtOAc), a desired decomplexation of the bio-oil was observed, retaining valuable biorefinery chemicals such as phenol and 2-furanmethanol, among others. This renders these bio-oil fractions good streams for further downstream processing.

Keywords: Bio-oil; Brewers’spentgrains; Protein extraction; Protein quantification; Washing; py-GC–MS/FID.

MeSH terms

Biofuels* / analysis
Edible Grain* / chemistry
Plant Oils
Plant Proteins* / chemistry
Polyphenols
Pyrolysis
Thermogravimetry

Substances

Biofuels
Bio-Oil
Plant Proteins
Plant Oils
Polyphenols