Microencapsulation of red onion (Allium cepa L.) extracts by spray and freeze drying: Chemical characterization and release behavior during in vitro digestion

Microencapsulation of red onion (Allium cepa L.) extracts by spray and freeze drying: Chemical characterization and release behavior during in vitro digestion | 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 Microencapsulation of red onion (Allium cepa L.) extracts by spray and freeze drying: Chemical characterization and release behavior during in vitro digestion Bahtınur Taşcı, Saranya Selvaraj, İlkay Koca This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7157234/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 3 You are reading this latest preprint version Abstract Red onions ( Allium cepa L.) are rich in polyphenols, particularly quercetin. This study focused on the extraction, drying, and microencapsulation of red onion polyphenols via spray- and freeze-drying using maltodextrin (MD) and gum arabic (GA) as encapsulating agents. The extraction process was optimized using response surface methodology, with optimal conditions being 20°C, 15 min, and 60% ethanol, yielding 1716.43 ± 57.44 mg/kg total phenolics, 349.5 ± 21.06 mg/kg flavonoids, and 29.16 ± 1.11 mg/kg anthocyanins. The obtained extracts were spray-dried, achieving the highest bioactive content with a 1:1 MD:GA ratio at 170°C. Powdered extracts were microencapsulated using MD or MD:GA through both spray- and freeze-drying, and the resulting microcapsules were characterized to assess their physicochemical properties. Microencapsulated extracts retained over 90% of their bioactive content compared to the free extract and exhibited improved in vitro bioaccessibility of flavonoids, with notable resistance to degradation under simulated gastric conditions. Thermal stability tests confirmed that encapsulation significantly improved resistance to heat degradation, maintaining over 92% of polyphenols at 80°C for 1 hour. In vitro digestion studies further revealed a controlled release of flavonoids, with minimal degradation in the gastric phase and enhanced bioaccessibility in the intestinal phase. Spray-drying with an MD:GA ratio of 1:1 at 170°C was identified as the most effective and economical encapsulation method, suggesting its suitability for developing functional food formulations enriched with bioactive onion compounds. microencapsulation red onion in vitro bioaccessibility phenolic compounds flavonoids Full Text Supplementary Files SupplementaryFile.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers invited by journal 25 Feb, 2026 Editor assigned by journal 21 Jul, 2025 First submitted to journal 18 Jul, 2025 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. 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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-7157234","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":597190980,"identity":"0b4e3ddf-0378-46d2-8b2b-c264aaa5c2ef","order_by":0,"name":"Bahtınur Taşcı","email":"","orcid":"","institution":"Ondokuz Mayis Universitesi","correspondingAuthor":false,"prefix":"","firstName":"Bahtınur","middleName":"","lastName":"Taşcı","suffix":""},{"id":597190981,"identity":"2efd9471-20f0-44b7-8966-bddee90962b9","order_by":1,"name":"Saranya Selvaraj","email":"data:image/png;base64,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","orcid":"https://orcid.org/0009-0000-2146-2915","institution":"University of Sri Jayewardenepura Faculty of Applied Sciences","correspondingAuthor":true,"prefix":"","firstName":"Saranya","middleName":"","lastName":"Selvaraj","suffix":""},{"id":597190982,"identity":"2e936af4-92b8-4977-8019-d9e911486bc2","order_by":2,"name":"İlkay Koca","email":"","orcid":"","institution":"Ondokuz Mayis Universitesi","correspondingAuthor":false,"prefix":"","firstName":"İlkay","middleName":"","lastName":"Koca","suffix":""}],"badges":[],"createdAt":"2025-07-18 11:33:51","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7157234/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7157234/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104835172,"identity":"269796f0-d01c-4573-a39d-f85cbd1a6df5","added_by":"auto","created_at":"2026-03-17 17:41:33","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2006130,"visible":true,"origin":"","legend":"","description":"","filename":"FinalManuscript18.7.2025.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7157234/v1_covered_7d7f6610-5c57-4e6a-bd21-996ec61f28b2.pdf"},{"id":103762147,"identity":"6eb32611-c056-4300-b3c4-1f6b1c5d92be","added_by":"auto","created_at":"2026-03-02 15:21:21","extension":"docx","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":30106,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFile.docx","url":"https://assets-eu.researchsquare.com/files/rs-7157234/v1/427d50e4c1ad190a71cd50da.docx"}],"financialInterests":"","formattedTitle":"Microencapsulation of red onion (Allium cepa L.) extracts by spray and freeze drying: Chemical characterization and release behavior during in vitro digestion","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"chemical-papers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"chpa","sideBox":"Learn more about [Chemical Papers](http://link.springer.com/journal/11696)","snPcode":"11696","submissionUrl":"https://www.editorialmanager.com/CHPA/default.aspx","title":"Chemical Papers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"microencapsulation, red onion, in vitro bioaccessibility, phenolic compounds, flavonoids","lastPublishedDoi":"10.21203/rs.3.rs-7157234/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7157234/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eRed onions (\u003cem\u003eAllium cepa\u003c/em\u003e L.) are rich in polyphenols, particularly quercetin. This study focused on the extraction, drying, and microencapsulation of red onion polyphenols via spray- and freeze-drying using maltodextrin (MD) and gum arabic (GA) as encapsulating agents. The extraction process was optimized using response surface methodology, with optimal conditions being 20\u0026deg;C, 15 min, and 60% ethanol, yielding 1716.43\u0026thinsp;\u0026plusmn;\u0026thinsp;57.44 mg/kg total phenolics, 349.5\u0026thinsp;\u0026plusmn;\u0026thinsp;21.06 mg/kg flavonoids, and 29.16\u0026thinsp;\u0026plusmn;\u0026thinsp;1.11 mg/kg anthocyanins. The obtained extracts were spray-dried, achieving the highest bioactive content with a 1:1 MD:GA ratio at 170\u0026deg;C. Powdered extracts were microencapsulated using MD or MD:GA through both spray- and freeze-drying, and the resulting microcapsules were characterized to assess their physicochemical properties. Microencapsulated extracts retained over 90% of their bioactive content compared to the free extract and exhibited improved in vitro bioaccessibility of flavonoids, with notable resistance to degradation under simulated gastric conditions. Thermal stability tests confirmed that encapsulation significantly improved resistance to heat degradation, maintaining over 92% of polyphenols at 80\u0026deg;C for 1 hour. In vitro digestion studies further revealed a controlled release of flavonoids, with minimal degradation in the gastric phase and enhanced bioaccessibility in the intestinal phase. Spray-drying with an MD:GA ratio of 1:1 at 170\u0026deg;C was identified as the most effective and economical encapsulation method, suggesting its suitability for developing functional food formulations enriched with bioactive onion compounds.\u003c/p\u003e","manuscriptTitle":"Microencapsulation of red onion (Allium cepa L.) extracts by spray and freeze drying: Chemical characterization and release behavior during in vitro digestion","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-02 15:21:12","doi":"10.21203/rs.3.rs-7157234/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewersInvited","content":"","date":"2026-02-25T23:13:16+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-21T09:21:35+00:00","index":"","fulltext":""},{"type":"submitted","content":"Chemical Papers","date":"2025-07-18T07:33:35+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"chemical-papers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"chpa","sideBox":"Learn more about [Chemical Papers](http://link.springer.com/journal/11696)","snPcode":"11696","submissionUrl":"https://www.editorialmanager.com/CHPA/default.aspx","title":"Chemical Papers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"3444c961-5a07-4ae1-b31b-b74d379fc2d3","owner":[],"postedDate":"March 2nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-02T15:21:12+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-02 15:21:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7157234","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7157234","identity":"rs-7157234","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}