{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T16:49:19Z","timestamp":1786121359371,"version":"build-2736575974"},"reference-count":40,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T00:00:00Z","timestamp":1785801600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>European oak (Quercus robur L. and Quercus petraea (Matt.) Liebl.) is widely used for decorative veneers, but natural color heterogeneity complicates package matching and industrial sorting. This exploratory study characterized one processed veneer package from each of eight commercial provenance labels: Szczecin, Krotoszyn, Zielona G\u00f3ra, Wroc\u0142aw, Katowice, Krosno, and Lublin (Poland), and Wittenberg (Germany). Each package was assessed visually and by ten CIELAB measurement points, while package-level subsamples were analyzed for ethanol-soluble extractives, cellulose, lignin, and X-ray diffraction characteristics. Package means differed most strongly in lightness (L* = 59.4\u201369.7); however, within-package L* ranges reached 10.7 units and overlapped the differences among package means, showing that package means alone are insufficient to demonstrate provenance-based sorting. Exploratory correlations based on eight packages indicated that higher extractive content was associated with lower lightness (Pearson r = \u22120.80, p = 0.017; Spearman \u03c1 = \u22120.75, p = 0.033), and the association remained negative in all leave-one-package-out recalculations (r = \u22120.96 to \u22120.72). In contrast, apparent Pearson lignin\/color associations were weak in rank analysis and changed sign after exclusion of P5. Associations of the Segal crystallinity index with color were directional but not statistically conclusive at n = 8. All diffractograms showed cellulose I reflections near 15\u201317\u00b0 and 22\u201323\u00b0 2\u03b8; approximate CrI values ranged from 48.0% to 66.2%. The results support combined colorimetric and chemical characterization for package-level quality control, but independent replication across multiple packages per region is required before any geographic origin classifier can be validated.<\/jats:p>","DOI":"10.3390\/molecules31152712","type":"journal-article","created":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T13:42:36Z","timestamp":1785850956000},"page":"2712","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Color Variability of European Oak Veneer Packages: An Exploratory Colorimetric, Chemical, and X-Ray Diffraction Study"],"prefix":"10.3390","volume":"31","author":[{"given":"Edmund","family":"Smolarek","sequence":"first","affiliation":[{"name":"Balti Spoon O\u00dc, Kupu K\u00fcla, 74610 Kuusalu Vald, Harju Maakond, Estonia"},{"name":"Department Mechanical Wood Technology, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, Wojska Polskiego 28, 60-637 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1909-9111","authenticated-orcid":false,"given":"Kinga","family":"Szentner","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Faculty of Forestry and Wood Technology, Poznan University of Life Sciences, 60-637 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6339-0796","authenticated-orcid":false,"given":"Jaros\u0142aw","family":"Jakubowicz","sequence":"additional","affiliation":[{"name":"Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9832-9274","authenticated-orcid":false,"given":"Maciej","family":"Jarz\u0119bski","sequence":"additional","affiliation":[{"name":"Department of Physics and Biophysics, Faculty of Food Science and Nutrition, Pozna\u0144 University of Life Sciences, Wojska Polskiego 38\/42, 60-637 Poznan, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4867-195X","authenticated-orcid":false,"given":"Marek","family":"Wieruszewski","sequence":"additional","affiliation":[{"name":"Balti Spoon O\u00dc, Kupu K\u00fcla, 74610 Kuusalu Vald, Harju Maakond, Estonia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1080\/17480270600687026","article-title":"The new journal Wood Material Science and Engineering","volume":"1","author":"Walinder","year":"2006","journal-title":"Wood Mater. Sci. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1051\/forest\/2009088","article-title":"Wood color variation in sapwood and heartwood of young trees of Tectona grandis and its relationship with plantation characteristics, site, and decay resistance","volume":"67","author":"Moya","year":"2010","journal-title":"Ann. For. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1007\/s00468-003-0290-y","article-title":"Color of larch heartwood and relationships to extractives and brown-rot decay resistance","volume":"18","author":"Gierlinger","year":"2004","journal-title":"Trees"},{"key":"ref_4","unstructured":"Kreber, B. (1994). Understanding Wood Discoloration Helps Maximize Wood Profits, Western Dry Kiln Association."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2074","DOI":"10.15376\/biores.8.2.2074-2083","article-title":"The effect of moisture content and drying temperature on the color of two poplars and Robinia wood","volume":"8","author":"Nemeth","year":"2013","journal-title":"BioResources"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Wiedenbeck, J., Wiemann, M., Alderman, D., Baumgras, J., and Luppold, W. (2003). Defining Hardwood Veneer Log Quality Attributes.","DOI":"10.2737\/NE-GTR-313"},{"key":"ref_7","first-page":"413","article-title":"Using color in machine vision systems for wood processing","volume":"22","author":"Brunner","year":"1990","journal-title":"Wood Fiber Sci."},{"key":"ref_8","unstructured":"Ozarska, B. (2003). A manual for decorative wood veneering technology. Project No. PN01.1600, Prepared for the Forest and Wood Products Research and Development Corporation and Funded by the Australian Government, Forest and Wood Products Australia."},{"key":"ref_9","unstructured":"Lutz, J.F. (1977). Wood Veneer: Log Selection, Cutting, and Drying, Technical Bulletin 1577."},{"key":"ref_10","unstructured":"Venet, J., and Keller, R. (1986). Identification et Classement des Bois Francais, ENGREF. [2nd ed.]."},{"key":"ref_11","unstructured":"Hon, D.N.S., and Shiraishi, N. (1991). Wood and Cellulose Chemistry, Marcel Dekker."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"403s","DOI":"10.1051\/forest:19930746","article-title":"The influences of age, extractive content and soil water on wood color in oak: The possible genetic determination of wood color","volume":"50","author":"Klumpers","year":"1993","journal-title":"Ann. For. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1093\/forestry\/69.2.111","article-title":"Genetic control of wood color, density and heartwood ellagitannin concentration in European oak (Quercus petraea and Q. Robur)","volume":"69","author":"Mosedale","year":"1996","journal-title":"Forestry"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1051\/forest:19870405","article-title":"Mesure de la couleur du bois; Int\u00e9r\u00eat forestier et industriel","volume":"44","author":"Janin","year":"1987","journal-title":"Ann. For. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1051\/forest:2002074","article-title":"Cons\u00e9quences du vieillissement du bois de ch\u00eane sessile (Quercus petraea (Matt.) Liebl.) sur sa perception esth\u00e9tique par les utilisateurs","volume":"60","author":"Zanetti","year":"2003","journal-title":"Ann. For. Sci."},{"key":"ref_16","unstructured":"Hoffmann, P. (1987). Mesure de la Variabilite de la Couleur du Bois: M\u00e9thodologie et Influence de L\u2019anatomie du Plan Ligneux et de la Variation Angulaire du Debit, DEA Sciences du bois, Universite de Nancy I, Station de Recherches sur la Qualite des Bois, INRA-CRF."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1051\/forest:19930202","article-title":"Modifications de la couleur du bois de chenes europeens expose a la lumiere solaire","volume":"50","author":"Mazet","year":"1993","journal-title":"Ann. For. Sci."},{"key":"ref_18","first-page":"177","article-title":"Color alteration and chemistry changes in oak wood (Quercus pedunculata (Ehrh)) during plain vacuum drying","volume":"46","author":"Jomaa","year":"2010","journal-title":"Wood Sci. Technol."},{"key":"ref_19","first-page":"13","article-title":"The color of wood from white oak","volume":"1","author":"Resch","year":"2000","journal-title":"Forsch.-Entwickl."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"5051","DOI":"10.15376\/biores.8.4.5051-5066","article-title":"A revaluation of Turkey oak wood (Quercus cerris (L.)) through combined steaming and thermo-vacuum treatments","volume":"8","author":"Ferrari","year":"2013","journal-title":"BioResources"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1718","DOI":"10.15376\/biores.8.2.1718-1730","article-title":"Effect of combined steam and heat treatments on extractives and lignin in sapwood and heartwood of Turkey oak (Quercus cerris (L.)) Wood","volume":"8","author":"Todaro","year":"2013","journal-title":"BioResources"},{"key":"ref_22","unstructured":"Mitisor, A., and Istrate, V. (1982). Technology of Veneers, Plywood and Fibreboards (In Romanian: Tehnologia Furnirelor, Placajelor si Placilor din Fibre de Lemn), Technical Publishing House."},{"key":"ref_23","unstructured":"Morosanu, C. (2011). Study Regarding the Quality of Wood from European Oak and Sessile Oak Having as Destination Aesthetic Veneers. [Ph.D. Dissertation, Transilvania University of Brasov]."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"4298","DOI":"10.15376\/biores.8.3.4298-4311","article-title":"Valorization of wood resources for the cutting of decorative veneer in the context of sustainable development of Romanian forests","volume":"8","author":"Dumitrascu","year":"2013","journal-title":"BioResources"},{"key":"ref_25","first-page":"613","article-title":"Veneer recovery analysis of plantation eucalypt species using spindleless lathe technology","volume":"9","author":"McGavin","year":"2014","journal-title":"BioResources"},{"key":"ref_26","unstructured":"(2015, February 23). I.N.S. Available online: https:\/\/insse.ro\/cms\/ro\/content\/volumul-de-lemn-exploatat."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Smolarek, E., Kowalska, J., Pa\u0142ubicki, B., and Wieruszewski, M. (2025). The Habitats of European Oak (Quercus) in Poland and General Oak Wood Color Issues. Forests, 16.","DOI":"10.3390\/f16071063"},{"key":"ref_28","unstructured":"Scalbert, A., Monties, B., and Janin, G. (1987). Comparaison de M\u00e9thodes de Dosage des Tanins: Application \u00e0 des Bois de Diff\u00e9rentes Esp\u00e8ces, Actes du 2\u00e8me Colloque Sciences et Industries du Bois."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1515\/hfsg.1987.41.1.19","article-title":"Oak peroxydase: Relationship with polyphenoloxydase","volume":"41","author":"Stich","year":"1987","journal-title":"Holzforschung"},{"key":"ref_30","unstructured":"(2012). Hardwood Round Timber\u2014Qualitative Classification\u2014Part 1: Oak and Beech (Standard No. EN 1316-1:2012)."},{"key":"ref_31","unstructured":"(1984). Paints and Varnishes\u2014Colorimetry\u2014Part 2: Color Measurement (Standard No. ISO 7724-2:1984)."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1","DOI":"10.21164\/pomjlifesci.1228","article-title":"The use of oaks in cosmetology","volume":"72","author":"Szynal","year":"2026","journal-title":"Pomeranian J. Life Sci."},{"key":"ref_33","first-page":"387","article-title":"Radial distribution of heartwood extractives and lignin in mature European larch","volume":"36","year":"2004","journal-title":"Wood Fiber Sci."},{"key":"ref_34","first-page":"141","article-title":"Correlation between hue angle and lightness of wood species grown in Hungary","volume":"58","author":"Tolvaj","year":"2013","journal-title":"Wood Res."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Rowell, R.M. (2012). Handbook of Wood Chemistry and Wood Composites, CRC Press. [2nd ed.].","DOI":"10.1201\/b12487"},{"key":"ref_36","unstructured":"Fengel Dietrich, D., and Wegener Gerd, G. (1989). Wood: Chemistry, Ultrastructure, Reactions, Walter de Gruyter."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"483","DOI":"10.1007\/s00107-004-0520-z","article-title":"Application of Fourier Transform Near Infrared Spectroscopy (FT-NIR) to thermally modified wood","volume":"62","author":"Hinterstoisser","year":"2004","journal-title":"Eur. J. Wood Wood Prod."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"786","DOI":"10.1177\/004051755902901003","article-title":"An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer","volume":"29","author":"Segal","year":"1959","journal-title":"Text. Res. J."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1186\/1754-6834-3-10","article-title":"Cellulose crystallinity index: Measurement techniques and their impact on interpreting cellulase performance","volume":"3","author":"Park","year":"2010","journal-title":"Biotechnol. Biofuels"},{"key":"ref_40","unstructured":"TAPPI (2015). Acid-Insoluble Lignin in Wood and Pulp, Test Method T 222, TAPPI Press."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/15\/2712\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T04:13:10Z","timestamp":1786075990000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/15\/2712"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,4]]},"references-count":40,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["molecules31152712"],"URL":"https:\/\/doi.org\/10.3390\/molecules31152712","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,4]]}}}