{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,1]],"date-time":"2026-08-01T04:58:32Z","timestamp":1785560312965,"version":"3.56.0"},"reference-count":46,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T00:00:00Z","timestamp":1785369600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003451","name":"University of the Basque Country","doi-asserted-by":"crossref","award":["PA24\/03"],"award-info":[{"award-number":["PA24\/03"]}],"id":[{"id":"10.13039\/501100003451","id-type":"DOI","asserted-by":"crossref"}]},{"award":["PA24\/03"],"award-info":[{"award-number":["PA24\/03"]}],"id":[{"id":"https:\/\/ror.org\/000xsnr85","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Apple pomace is an abundant agro-industrial residue rich in oligosaccharides, whose efficient and sustainable extraction remains challenging. To overcome these limitations, this study delivers a novel biorefinery strategy by coupling ultrasound-assisted extraction pretreatment with optimised microwave-assisted hydrolysis. Through response surface methodology, the optimal microwave hydrolysis extraction conditions were achieved at 20 min and 120 \u00b0C. The obtained oligosaccharides presented a molecular-weight of 191,071 Da, a polydispersity index of 2.19 and a high content of galacturonyl groups (9.95 g\/L) and arabino substituents (7.27 g\/L). Furthermore, a biphasic system was applied at the optimal point obtained for the monophasic system in order to examine its potential for selective oligosaccharide fractionation. In this case, the galacturonic acid did not form part of the obtained oligosaccharides, and instead they were predominantly formed by galactose and arabinose (6.55 and 4.48 g\/L respectively). Moreover, this biphasic setup yielded fewer polydisperse fractions with a lower content of degradation products. Overall, this work highlights the promise of optimised microwave-assisted hydrolysis as a sustainable strategy for oligosaccharide valorisation from apple pomace while demonstrating that the extension to a biphasic system represents a promising alternative for improving process selectivity.<\/jats:p>","DOI":"10.3390\/molecules31152654","type":"journal-article","created":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T08:09:42Z","timestamp":1785398982000},"page":"2654","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Transforming Apple Pomace into Functional Oligosaccharides via Microwave Optimisation"],"prefix":"10.3390","volume":"31","author":[{"given":"Itsasne","family":"Beitia","sequence":"first","affiliation":[{"name":"Biorefinery Processes Research Group, Department of Chemical and Environmental Engineering, University of the Basque Country EHU, Plaza Europa, 1, 20018 San Sebasti\u00e1n, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8395-703X","authenticated-orcid":false,"given":"Leyre","family":"Sillero","sequence":"additional","affiliation":[{"name":"Biorefinery Processes Research Group, Department of Chemical and Environmental Engineering, University of the Basque Country EHU, Nieves Cano, 12, 01006 Vitoria-Gasteiz, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2122-4439","authenticated-orcid":false,"given":"Itziar","family":"Eg\u00fc\u00e9s","sequence":"additional","affiliation":[{"name":"Biorefinery Processes Research Group, Department of Chemical and Environmental Engineering, University of the Basque Country EHU, Plaza Europa, 1, 20018 San Sebasti\u00e1n, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Izaskun","family":"D\u00e1vila-Rodr\u00edguez","sequence":"additional","affiliation":[{"name":"Biorefinery Processes Research Group, Department of Chemical and Environmental Engineering, University of the Basque Country EHU, Plaza Rafael Moreno \u201cPitxitxi\u201d 2, 48013 Bilbao, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"108358","DOI":"10.1016\/j.jece.2022.108358","article-title":"Apple Pomace Biorefinery: Integrated Approaches for the Production of Bioenergy, Biochemicals, and Value-Added Products\u2013An Updated Review","volume":"10","author":"Costa","year":"2022","journal-title":"J. Environ. Chem. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Eg\u00fc\u00e9s, I., Hernandez-Ramos, F., Rivilla, I., and Labidi, J. (2021). Optimization of Ultrasound Assisted Extraction of Bioactive Compounds from Apple Pomace. Molecules, 26.","DOI":"10.3390\/molecules26133783"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"132570","DOI":"10.1016\/j.biortech.2025.132570","article-title":"Whole Yeast Cell Synthesis of 5-Hydroxymethylfurfural-Derivatives from Apple Waste Processed by Green Technologies","volume":"430","author":"Martins","year":"2025","journal-title":"Bioresour. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"117149","DOI":"10.1016\/j.foodres.2025.117149","article-title":"Sustainable Utilization of Apple Pomace: Technological Aspects and Emerging Applications","volume":"220","author":"Thomas","year":"2025","journal-title":"Food Res. Int."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Zaky, A.A., Witrowa-Rajchert, D., and Nowacka, M. (2024). Turning Apple Pomace into Value: Sustainable Recycling in Food Production\u2014A Narrative Review. Sustainability, 16.","DOI":"10.3390\/su16167001"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"112091","DOI":"10.1016\/j.foodhyd.2025.112091","article-title":"Hydrothermal-Assisted Co-Recovery of Pectin, Phenolics, and Sugars from Apple Pomace Coupled with Understanding Dietary Fibre Development via Compositional, Structural, and Physicochemical Modulations","volume":"172","author":"Goonathilaka","year":"2026","journal-title":"Food Hydrocoll."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1016\/j.renene.2021.07.031","article-title":"A Sustainable Biorefinery Strategy: Conversion and Fractionation in a Facile Biphasic System towards Integrated Lignocellulose Valorizations","volume":"179","author":"Zhang","year":"2021","journal-title":"Renew. Energy"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1016\/j.fbp.2024.11.024","article-title":"Sweet-Sour Fate of Saccharides During Sequential Processing from Apple Pomace Through Acidic Extraction and Hydrolysis","volume":"149","author":"Korzeniowski","year":"2025","journal-title":"Food Bioprod. Process."},{"key":"ref_9","first-page":"1352","article-title":"Oligosaccharides: Sources, Biological Activities and Health Benefits in Animals and Humans","volume":"15","author":"Anyimadu","year":"2026","journal-title":"Int. J. Agric. Biosci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"100394","DOI":"10.1016\/j.foohum.2024.100394","article-title":"Extracting Bioactive Compounds from Apple Pomace for Sustainable Waste Reduction","volume":"3","author":"Aslam","year":"2024","journal-title":"Food Humanit."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"100598","DOI":"10.1016\/j.focha.2023.100598","article-title":"Apple Pomace, a Bioresource of Functional and Nutritional Components with Potential of Utilization in Different Food Formulations: A Review","volume":"4","author":"Kauser","year":"2024","journal-title":"Food Chem. Adv."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"242","DOI":"10.1007\/s00203-025-04446-5","article-title":"Oligosaccharides: A Comprehensive Review of Various Types, Biological Activities and Emerging Health Benefits","volume":"207","author":"Kumari","year":"2025","journal-title":"Arch. Microbiol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"4078","DOI":"10.1021\/acsfoodscitech.5c00914","article-title":"Upcycling Agro-Industrial Biomass into Bioactive Oligosaccharides for the Circular Bioeconomy: Beyond the Prebiotic Effects with a Focus on Receptor Interactions","volume":"5","author":"Prado","year":"2025","journal-title":"ACS Food Sci. Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"115560","DOI":"10.1016\/j.intimp.2025.115560","article-title":"Targeting Neurodegenerative Diseases with Bioactive Oligosaccharides: Mechanisms and Prospects","volume":"166","author":"Ni","year":"2025","journal-title":"Int. Immunopharmacol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Wilkowska, A., Nowak, A., Motyl, I., and Oracz, J. (2025). The Molecular Weight of Enzymatically Modified Pectic Oligosaccharides from Apple Pomace as a Determinant for Biological and Prebiotic Activity. Molecules, 30.","DOI":"10.3390\/molecules30010046"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1016\/j.fuproc.2017.03.027","article-title":"Development of a Chromatographic Methodology for the Separation and Quantification of V, Ni and S Compounds in Petroleum Products","volume":"162","author":"Vargas","year":"2017","journal-title":"Fuel Process. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1093\/fqs\/fyx004","article-title":"Recent Advances in Extraction of Antioxidants from Plant By-Products Processing Industries","volume":"1","author":"Selvamuthukumaran","year":"2017","journal-title":"Food Qual. Saf."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"111324","DOI":"10.1016\/j.foodhyd.2025.111324","article-title":"Optimization of Microwave-Assisted Hydrothermal Extraction of Homogalacturonan-Rich, Low Methoxyl Pectin from Discarded Garlic Peels: Comparative Macromolecular and Functional Analysis with Conventional Extraction","volume":"166","author":"Benmebarek","year":"2025","journal-title":"Food Hydrocoll."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"121203","DOI":"10.1016\/j.indcrop.2025.121203","article-title":"Apple Pomace Valorisation into Antioxidant Polyphenols: Multi-Criteria Process Design","volume":"231","author":"Celeiro","year":"2025","journal-title":"Ind. Crops Prod."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"114149","DOI":"10.1016\/j.microc.2025.114149","article-title":"Ultrasound-Assisted Extraction of Polyphenols from Apple Pomace Using Choline Chloride-Oxalic Acid Deep Eutectic Solvent: Characterization, Reusability, and Molecular Dynamics Simulation","volume":"214","author":"Wang","year":"2025","journal-title":"Microchem. J."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"100637","DOI":"10.1016\/j.foohum.2025.100637","article-title":"Valorization of Black Carrot Pomace by Using Microwave-Assisted Hydrothermal Extraction Method: An Optimization and Comparison Research on Pectin Extraction","volume":"4","author":"Demir","year":"2025","journal-title":"Food Humanit."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"101384","DOI":"10.1016\/j.fbio.2021.101384","article-title":"Valorization of Bioactive Compounds in Fruit Pomace from Agro-Fruit Industries: Present Insights and Future Challenges","volume":"44","author":"Iqbal","year":"2021","journal-title":"Food Biosci."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Nour, A.H., Oluwaseun, A.R., Nour, A.H., Omer, M.S., and Ahmed, N. (2021). Microwave-Assisted Extraction of Bioactive Compounds (Review). Microwave Heating-Electromagnetic Fields Causing Thermal and Non-Thermal Effects, IntechOpen.","DOI":"10.5772\/intechopen.96092"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"120364","DOI":"10.1016\/j.carbpol.2022.120364","article-title":"Microwave-Assisted Extraction of Hemicellulosic Oligosaccharides and Phenolics from Robinia Pseudoacacia Wood","volume":"301","author":"Garrote","year":"2023","journal-title":"Carbohydr. Polym."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"20751","DOI":"10.1007\/s13399-023-05244-z","article-title":"Microwave-Assisted Hydrothermal Processing of Pine Nut Shells for Oligosaccharide Production","volume":"14","author":"Torrado","year":"2024","journal-title":"Biomass Convers. Biorefin."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"105325","DOI":"10.1016\/j.ultsonch.2020.105325","article-title":"Ultrasound Assisted Extraction (UAE) of Bioactive Compounds from Fruit and Vegetable Processing by-Products: A Review","volume":"70","author":"Kumar","year":"2021","journal-title":"Ultrason. Sonochem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"108100","DOI":"10.1016\/j.cep.2020.108100","article-title":"Simultaneous Microwave-Ultrasound Assisted Extraction of Bioactive Compounds from Bark","volume":"156","author":"Sillero","year":"2020","journal-title":"Chem. Eng. Process. Process Intensif."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"100435","DOI":"10.1016\/j.cogsc.2020.100435","article-title":"Biphasic Reaction Systems for Lignocellulosic Biomass Revalorisation","volume":"28","author":"Labidi","year":"2021","journal-title":"Curr. Opin. Green Sustain. Chem."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"130221","DOI":"10.1016\/j.seppur.2024.130221","article-title":"Streamlined Fractionation for Recovery of High-Yield Xylo-Oligosaccharides, Pure Lignin and Ethanol from Poplar Using Short-Chain Organic Acid\/Pentanol Biphasic System","volume":"358","author":"Liao","year":"2025","journal-title":"Sep. Purif. Technol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"107694","DOI":"10.1016\/j.biombioe.2025.107694","article-title":"Oxidative Depolymerization of Lignin Through Biphasic System for Enhanced Monomer Yields and Improved Valorization","volume":"194","author":"Zhao","year":"2025","journal-title":"Biomass Bioenergy"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"330","DOI":"10.1016\/j.carbpol.2019.03.103","article-title":"Optimum Alkaline Treatment Parameters for the Extraction of Cellulose and Production of Cellulose Nanocrystals from Apple Pomace","volume":"215","author":"Bilek","year":"2019","journal-title":"Carbohydr. Polym."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"102638","DOI":"10.1016\/j.biteb.2026.102638","article-title":"Integrated Biorefinery Scheme for Apple Pomace: Synergistic Extraction and Fermentation for Dual Recovery of Pectin and 2,3-Butanediol","volume":"34","author":"Lozano","year":"2026","journal-title":"Bioresour. Technol. Rep."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1230","DOI":"10.1021\/jf011007i","article-title":"Structural Characterization of Oligosaccharides and Polysaccharides from Apple Juices Produced by Enzymatic Pomace Liquefaction","volume":"50","author":"Dietrich","year":"2002","journal-title":"J. Agric. Food Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"101180","DOI":"10.1016\/j.ijoes.2025.101180","article-title":"Microwave-Assisted Extraction Optimization of Hedysarum Polybotys Polysaccharide and Study of Their Electrochemical Fingerprint Characteristics","volume":"20","author":"Hao","year":"2025","journal-title":"Int. J. Electrochem. Sci."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"739","DOI":"10.1007\/s11947-021-02603-4","article-title":"Kinetics of Pectin Reactions in Apple Pomace During Hydrothermal Treatment","volume":"14","author":"Eblaghi","year":"2021","journal-title":"Food Bioprocess Technol."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Zong, X., Lei, N., Yin, J., He, W., Nie, S., and Xie, M. (2024). Exploration and Improvement of Acid Hydrolysis Conditions for Inulin-Type Fructans Monosaccharide Composition Analysis: Monosaccharide Recovery and By-Product Identification. Foods, 13.","DOI":"10.3390\/foods13081241"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Fernandes, P.A.R., Ferreira, S.S., Bastos, R., Ferreira, I., Cruz, M.T., Pinto, A., Coelho, E., Passos, C.P., Coimbra, M.A., and Cardoso, S.M. (2019). Apple Pomace Extract as a Sustainable Food Ingredient. Antioxidants, 8.","DOI":"10.3390\/antiox8060189"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"123896","DOI":"10.1016\/j.biortech.2020.123896","article-title":"Multiproduct Biorefinery Based on Almond Shells: Impact of the Delignification Stage on the Manufacture of Valuable Products","volume":"315","author":"Morales","year":"2020","journal-title":"Bioresour. Technol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"4094","DOI":"10.1039\/D4GC05977H","article-title":"Harnessing the Potential of Biphasic Solvent Systems in Lignocellulosic Biomass Fractionation Through Computational Insights","volume":"27","author":"Saleknezhad","year":"2025","journal-title":"Green Chem."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1384","DOI":"10.1016\/j.gee.2023.11.005","article-title":"Advances in Selective Conversion of Carbohydrates into 5-Hydroxymethylfurfural","volume":"9","author":"Liang","year":"2024","journal-title":"Green Energy Environ."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"5638","DOI":"10.1021\/cr2000042","article-title":"Synthesis of Sugars by Hydrolysis of Hemicelluloses\u2014A Review","volume":"111","author":"Salmi","year":"2011","journal-title":"Chem. Rev."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"4607","DOI":"10.1039\/C8GC01031E","article-title":"Catalytic Lignocellulose Biorefining in n -Butanol\/Water: A One-Pot Approach toward Phenolics, Polyols, and Cellulose","volume":"20","author":"Renders","year":"2018","journal-title":"Green Chem."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"11069","DOI":"10.1021\/acssuschemeng.8b05841","article-title":"Versatility of a Dilute Acid\/Butanol Pretreatment Investigated on Various Lignocellulosic Biomasses to Produce Lignin, Monosaccharides and Cellulose in Distinct Phases","volume":"7","author":"Schmetz","year":"2019","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_44","unstructured":"(2008). Determination of Extractives in Biomass: Laboratory Analytical Procedure (LAP) (Standard No. NREL\/TP-510-42619)."},{"key":"ref_45","unstructured":"(2012). Determination of Structural Carbohydrates and Lignin in Biomass (Standard No. NREL\/TP-510-426-18)."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"636","DOI":"10.1016\/j.biortech.2016.03.153","article-title":"Assessment of suitability of vine shoots for hemicellulosic oligosaccharides production through aqueous processing","volume":"211","author":"Gordobil","year":"2016","journal-title":"Bioresour. Technol."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/15\/2654\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,1]],"date-time":"2026-08-01T04:19:22Z","timestamp":1785557962000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/15\/2654"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,30]]},"references-count":46,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["molecules31152654"],"URL":"https:\/\/doi.org\/10.3390\/molecules31152654","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,30]]}}}