Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • harvard-cite-them-right
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Starch and protein recovery from brewer's spent grain using hydrothermal pretreatment and their conversion to edible filamentous fungi – A brewery biorefinery concept
University of Borås, Faculty of Textiles, Engineering and Business.ORCID iD: 0000-0002-1214-8614
University of Borås, Faculty of Textiles, Engineering and Business.
University of Borås, Faculty of Textiles, Engineering and Business.ORCID iD: 0000-0003-4887-2433
2021 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 337, article id 125409Article in journal (Refereed) Published
Sustainable development
According to the author(s), the content of this publication falls within the area of sustainable development.
Abstract [en]

This study aimed at recovering a highly concentrated starch and protein stream from the brewer's spent grain (BSG). The effect of pretreatment temperature and retention time on the solubilization of starch and protein; and the generation of fermentation inhibitors were studied. Then, the application of recovered streams for fungal cultivation was evaluated using different edible fungi Aspergillus oryzae, Neurospora intermedia, and Rhizopus delemar. The hydrothermal pretreatment resulted in the highest solubilized starch concentration, 43 g/L, corresponding to 83% solubilization of initial BSG starch content. The highest protein concentration was 27 g/L (48% solubilization of initial BSG protein content). Cultivation with Neurospora intermedia on the recovered streams from the two best pretreatment conditions, 140 ℃ for 4 h and 180 ℃ for 30 min, resulted in pure fungal biomass with the highest protein content 59.62% and 50.42% w/w, respectively. Finally, a brewery biorefinery was proposed for the valorization of BSG. 

Place, publisher, year, edition, pages
Elsevier, 2021. Vol. 337, article id 125409
Keywords [en]
Biorefinery, Brewer's spent grain, Hydrothermal pretreatment, Protein recovery, Starch recovery, Aspergillus, Bioconversion, Fermentation, Recovery, Refining, Solubility, Starch, Biorefineries, Biorefinery concept, Brewers spent grains, Filamentous fungus, Intermedia, Neurospora, Solubilisation, Proteins, Aspergillus oryzae, Neurospora intermedia, Rhizopus oryzae
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
URN: urn:nbn:se:hb:diva-25803DOI: 10.1016/j.biortech.2021.125409ISI: 000677956400001Scopus ID: 2-s2.0-85108262270OAI: oai:DiVA.org:hb-25803DiVA, id: diva2:1578421
Available from: 2021-07-06 Created: 2021-07-06 Last updated: 2023-05-04
In thesis
1. Unlocking the Potential of Brewer’s Spent Grain: Sustainable Biorefinery Approach and Value-Added Product Generation
Open this publication in new window or tab >>Unlocking the Potential of Brewer’s Spent Grain: Sustainable Biorefinery Approach and Value-Added Product Generation
2023 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Brewer’s spent grain (BSG) constitutes 85% of brewing byproducts and 30% of initial malt. In 2021, BSG production reached approximately 37.2 million tons. Owing to its high moisture and nutritional content, BSG is prone to biological deterioration, causing environmental issues when discarded as waste. It has limited application as low-quality animal feed owing to its high fiber and low protein content, making landfilling the primary disposal method. However, BSG's abundance of starch, cellulose, hemicellulose, lignin, and protein make it ideal for value-added product generation in a biorefinery. The aim of this research was to investigate BSG fractionation and identify valuable products from each fraction, ultimately establishing a BSG-based biorefinery for sustainable valorization. 

Fungal cultivation, anaerobic digestion, hydrothermal, and organosolv pretreatments were employed to establish a BSG-based biorefinery. Edible filamentous fungi (Aspergillus oryzae, Neurospora intermedia, and Rhizopus delemar) were cultivated on crude BSG to produce food and feed-grade biomass. Fungal growth increased the protein content of the BSG by up to 47%. However, entangled solids with fungal filaments negatively affected product digestibility, limiting its incorporation in food and feed. This problem was resolved by recovering a solid-free, starch- and protein-rich stream from BSG via hydrothermal pretreatment. 

Hydrothermal pretreatment effectively separated BSG's starch and protein components, with solubilizations reaching 82% and 48% of the initial content, respectively. Fungal assimilation of the liquid stream produced pure, high-protein biomass and high ethanol yield. However, most of the BSG cellulose and lignin remained in the solid fraction. Organosolv pretreatment was applied to further separate BSG polymers into valorizable fractions efficiently, yielding a cellulose-rich solid stream, polysaccharide-rich organosolv liquor, and high-purity lignin (~95%). This pure lignin product can enhance the biorefinery’s economy and be sold or converted into platform chemicals. 

Direct fungal cultivation on cellulose-rich pulp and liquor fractions from organosolv revealed that the liquor fraction was suitable for producing pure, high-protein fungal biomass, while the pulp fraction required further processing. Moreover, anaerobic digestion was employed to produce a diverse array of products improving the product flexibility of the biorefinery. Organosolv liquor produced biohydrogen and volatile fatty acids (VFAs) without methanogen inhibition, while BSG and BSG organosolv solid fractions generated biogas. Inhibiting methanogens shifted the BSG process towards VFAs production, while organosolv solid fractions showed limited potential for VFAs generation. 

These results illustrate that BSG can serve as the foundation for a multi-product biorefinery that generates food-grade fungal biomass and valuable co-products, including high-purity lignin, bioethanol, biogas, biohydrogen, and VFAs. This flexibility allows the biorefinery to adapt to market changes and ensure its economic viability. 

Place, publisher, year, edition, pages
Borås: Högskolan i Borås, 2023
Series
Skrifter från Högskolan i Borås, ISSN 0280-381X ; 136
Keywords
Brewer's spent grain, Hydrothermal pretreatment, Organosolv pretreatment, Edible filamentous fungi, Anaerobic digestion, Biorefinery
National Category
Biochemistry and Molecular Biology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-29573 (URN)978-91-89271-90-6 (ISBN)978-91-89271-91-3 (ISBN)
Public defence
2023-06-02, C203, Allégatan 1, Borås, 10:00 (English)
Opponent
Supervisors
Available from: 2023-05-04 Created: 2023-03-28 Last updated: 2023-08-02Bibliographically approved

Open Access in DiVA

fulltext(2393 kB)233 downloads
File information
File name FULLTEXT01.pdfFile size 2393 kBChecksum SHA-512
e5f336bb999b90f3060b27af63546587b078206f379af66d5cd2b338c9aab232060676a3434d7ecc8b45aca599e86c60d10282c000a207cf3ca9008edb4d5441
Type fulltextMimetype application/pdf

Other links

Publisher's full textScopus

Authority records

Parchami, MohsenFerreira, JorgeTaherzadeh, Mohammad J

Search in DiVA

By author/editor
Parchami, MohsenFerreira, JorgeTaherzadeh, Mohammad J
By organisation
Faculty of Textiles, Engineering and Business
In the same journal
Bioresource Technology
Industrial Biotechnology

Search outside of DiVA

GoogleGoogle Scholar
Total: 233 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 419 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • harvard-cite-them-right
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf