Exploring the Potential of Residues from Industrial Tannins Extraction through Comprehensive Characterization

Exploring the Potential of Residues from Industrial Tannins Extraction through Comprehensive Characterization | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Exploring the Potential of Residues from Industrial Tannins Extraction through Comprehensive Characterization Youness Senhaji, Elsa Duret, Eduardo Robles, Rene Herrera, Nidal Del Valle Raydan, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8086676/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The industrial extraction of tannins from maritime pine (Pinus pinaster) bark generates multiple solid by-products at different stages, including the raw bark, partially extracted material, and final residue, whose valorization remains largely unexplored. This study presents a comprehensive chemical and structural characterization of these three materials using a multi-analytical approach, with the aim of assessing their potential for material recovery and sustainable reuse. Fourier-transform infrared spectroscopy (FTIR) revealed depletion of hydroxyl-rich phenolics and enrichment in aliphatic associated structures. Proximate analysis demonstrated increased volatile content and fixed carbon in the final residue, indicating improved suitability for thermochemical conversion. Despite successive extractions, the final residue retained significant levels of total phenolics (373.86 mg GAE/g), condensed tannins (116.8 mg CE/g), and strong antioxidant activity (up to 425 µg AAE/mg), confirming the presence of bioactive compounds. However, the Stiasny number remained below 40%, suggesting limited reactivity with formaldehyde. In terms of structural composition, the final residue was enriched in acid-insoluble lignin (≈ 80%) and showed a dramatic loss in cellulose and hemicellulose content (< 7%), highlighting extensive structural degradation. Solvent extractive tests (Soxhlet, TAPPI T 264) revealed unusually high solubility (up to 85%), linked to depolymerized fragments. Size exclusion chromatography confirmed a decrease in molecular weight, suggesting breakdown of macromolecules during processing. Overall, these residues exhibit promising characteristics for energy recovery and extraction of phenolic-rich fractions, supporting their integration into circular bioeconomy strategies. maritime pine bark tannin extraction industrial residues waste valorization circular bioeconomy Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8086676","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":589211215,"identity":"0ec6a129-7ab5-4b11-b925-66932799ffd2","order_by":0,"name":"Youness Senhaji","email":"","orcid":"","institution":"University of Pau and the Adour Region, CNRS, IPREM-UMR 5254","correspondingAuthor":false,"prefix":"","firstName":"Youness","middleName":"","lastName":"Senhaji","suffix":""},{"id":589211216,"identity":"b6ff6823-5cda-47c9-9f0c-dbb9085b7f57","order_by":1,"name":"Elsa Duret","email":"","orcid":"","institution":"University of Pau and the 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This study presents a comprehensive chemical and structural characterization of these three materials using a multi-analytical approach, with the aim of assessing their potential for material recovery and sustainable reuse. Fourier-transform infrared spectroscopy (FTIR) revealed depletion of hydroxyl-rich phenolics and enrichment in aliphatic associated structures. Proximate analysis demonstrated increased volatile content and fixed carbon in the final residue, indicating improved suitability for thermochemical conversion. Despite successive extractions, the final residue retained significant levels of total phenolics (373.86 mg GAE/g), condensed tannins (116.8 mg CE/g), and strong antioxidant activity (up to 425 \u0026micro;g AAE/mg), confirming the presence of bioactive compounds. However, the Stiasny number remained below 40%, suggesting limited reactivity with formaldehyde. In terms of structural composition, the final residue was enriched in acid-insoluble lignin (\u0026asymp;\u0026thinsp;80%) and showed a dramatic loss in cellulose and hemicellulose content (\u0026lt;\u0026thinsp;7%), highlighting extensive structural degradation. Solvent extractive tests (Soxhlet, TAPPI T 264) revealed unusually high solubility (up to 85%), linked to depolymerized fragments. Size exclusion chromatography confirmed a decrease in molecular weight, suggesting breakdown of macromolecules during processing. 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