{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,5]],"date-time":"2025-11-05T06:18:53Z","timestamp":1762323533323,"version":"build-2065373602"},"reference-count":30,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2012,7,23]],"date-time":"2012-07-23T00:00:00Z","timestamp":1343001600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Effects of the moisture content (MC) of tea on diffuse reflectance spectroscopy were investigated by integrated wavelet transform and multivariate analysis. A total of 738 representative samples, including fresh tea leaves, manufactured tea and partially processed tea were collected for spectral measurement in the 325\u20131,075 nm range with a field portable spectroradiometer. Then wavelet transform (WT) and multivariate analysis were adopted for quantitative determination of the relationship between MC and spectral data. Three feature extraction methods including WT, principal component analysis (PCA) and kernel principal component analysis (KPCA) were used to explore the internal structure of spectral data. Comparison of those three methods indicated that the variables generated by WT could efficiently discover structural information of spectral data. Calibration involving seeking the relationship between MC and spectral data was executed by using regression analysis, including partial least squares regression, multiple linear regression and least square support vector machine. Results showed that there was a significant correlation between MC and spectral data (r = 0.991, RMSEP = 0.034). Moreover, the effective wavelengths for MC measurement were detected at range of 888\u20131,007 nm by wavelet transform. The results indicated that the diffuse reflectance spectroscopy of tea is highly correlated with MC.<\/jats:p>","DOI":"10.3390\/s120709847","type":"journal-article","created":{"date-parts":[[2012,7,23]],"date-time":"2012-07-23T11:11:45Z","timestamp":1343041905000},"page":"9847-9861","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":32,"title":["Characterizing the Moisture Content of Tea with Diffuse Reflectance Spectroscopy Using Wavelet Transform and Multivariate Analysis"],"prefix":"10.3390","volume":"12","author":[{"given":"Xiaoli","family":"Li","sequence":"first","affiliation":[{"name":"College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China"},{"name":"Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chuanqi","family":"Xie","sequence":"additional","affiliation":[{"name":"College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6752-1757","authenticated-orcid":false,"given":"Yong","family":"He","sequence":"additional","affiliation":[{"name":"College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China"},{"name":"Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhengjun","family":"Qiu","sequence":"additional","affiliation":[{"name":"College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yanchao","family":"Zhang","sequence":"additional","affiliation":[{"name":"College of Biosystems Engineering and Food Science, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2012,7,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1023\/A:1010120826266","article-title":"Microwave technology for moisture measurement","volume":"1","author":"Okamura","year":"2000","journal-title":"Subsurf. Sens. Technol. Appl."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/j.jhydrol.2010.07.014","article-title":"Characterizing surface soil water with field portable diffuse reflectance spectroscopy","volume":"391","author":"Zhu","year":"2010","journal-title":"J. Hydrol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1016\/j.tifs.2006.09.003","article-title":"Theory and application of near infrared reflectance spectroscopy in determination of food quality","volume":"18","author":"Cen","year":"2007","journal-title":"Trends Food Sci. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1016\/S0308-8146(02)00583-6","article-title":"Analysis of water in food by near infrared spectroscopy","volume":"82","year":"2003","journal-title":"Food Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1016\/j.biosystemseng.2007.03.020","article-title":"Near infrared reflectance spectroscopy as a tool for the in-line determination of the moisture concentration in extruded semolina pasta","volume":"97","author":"Temmerman","year":"2007","journal-title":"Biosyst. Eng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.agrformet.2004.01.004","article-title":"Estimation of foliage moisture content using near infrared reflectance spectroscopy","volume":"124","author":"Gillon","year":"2004","journal-title":"Agric. For. Meteorol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1016\/j.rse.2004.12.007","article-title":"Spectral sensing of foliar water conditions in two co-occurring conifer species: Pinus edulis and Juniperus monosperma","volume":"96","author":"Stimson","year":"2005","journal-title":"Remote Sens. Environ."},{"key":"ref_8","first-page":"1","article-title":"Foliage moisture content estimation from one-dimensional and two-dimensional spectroradiometry for fire danger assessment","volume":"111","author":"Vaughan","year":"2006","journal-title":"J. Geophys. Res."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1016\/0308-8146(88)90036-2","article-title":"Near-infrared reflectance prediction of quality, theaflavin content and moisture content of black tea","volume":"27","author":"Hall","year":"1988","journal-title":"Food Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"136","DOI":"10.1007\/s11947-008-0149-8","article-title":"FTNIR spectroscopic method for determination of moisture content in green tea granules","volume":"4","author":"Sinija","year":"2011","journal-title":"Food Bioprocess Technol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"669","DOI":"10.1016\/j.foodchem.2006.05.057","article-title":"Chemical and near-infrared determination of moisture, fat and protein in tuna fishes","volume":"102","author":"Khodabux","year":"2007","journal-title":"Food Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5200","DOI":"10.1016\/j.biortech.2011.01.087","article-title":"Prediction of moisture, calorific value, ash and carbon content of two dedicated bioenergy crops using near-infrared spectroscopy","volume":"102","author":"Fagan","year":"2011","journal-title":"Bioresour. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"651","DOI":"10.1007\/s11947-008-0101-y","article-title":"Evaluation of least squares support vector machine regression and other multivariate calibrations in determination of internal attributes of tea beverages","volume":"3","author":"Li","year":"2010","journal-title":"Food Bioprocess Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3498","DOI":"10.3390\/s120303498","article-title":"A non-destructive distinctive method for discrimination of automobile lubricant variety by visible and short-wave infrared spectroscopy","volume":"12","author":"Jiang","year":"2012","journal-title":"Sensors"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"4602","DOI":"10.3390\/s100504602","article-title":"Intelligent gearbox diagnosis methods based on SVM, wavelet Lifting and RBR","volume":"10","author":"Gao","year":"2010","journal-title":"Sensors"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"240","DOI":"10.1016\/S0165-9936(02)00404-1","article-title":"NIR spectroscopy: A rapid-response analytical tool","volume":"21","author":"Blanco","year":"2002","journal-title":"Trac-Trend. Anal. Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"5994","DOI":"10.3390\/s100605994","article-title":"Wavelet analysis for wind fields estimation","volume":"10","author":"Leite","year":"2010","journal-title":"Sensors"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"11149","DOI":"10.1016\/j.eswa.2011.02.160","article-title":"Using wavelet transform and multi-class least square support vector machine in multi-spectral imaging classification of Chinese famous tea","volume":"38","author":"Li","year":"2011","journal-title":"Expert Syst. Appl."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1193","DOI":"10.13031\/2013.21719","article-title":"Wavelet incorporated spectral analysis for soil property determination","volume":"49","author":"Ge","year":"2006","journal-title":"Trans. ASABE"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/j.geoderma.2009.12.025","article-title":"Using data mining to model and interpret soil diffuse reflectance spectra","volume":"158","author":"Behrens","year":"2010","journal-title":"Geoderma"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4217","DOI":"10.1039\/c1an15222j","article-title":"Wavelet unfolded partial least squares for near-infrared spectral quantitative analysis of blood and tobacco powder samples","volume":"136","author":"Zhang","year":"2011","journal-title":"Analyst"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1016\/j.chemolab.2009.09.006","article-title":"Multiblock partial least squares regression based on wavelet transform for quantitative analysis of near infrared spectra","volume":"100","author":"Jing","year":"2010","journal-title":"Chemometr. Intell. Lab. Syst."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"303","DOI":"10.13031\/2013.22394","article-title":"A new perspective to near-infrared reflectance spectroscopy: A wavelet approach","volume":"50","author":"Ge","year":"2007","journal-title":"Trans. ASABE"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"615","DOI":"10.1109\/TGRS.2004.841476","article-title":"Wavelet domain statistical hyperspectral soil texture classification","volume":"43","author":"Zhang","year":"2005","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1299","DOI":"10.1162\/089976698300017467","article-title":"Nonlinear component analysis as a kernel eigenvalue problem","volume":"10","author":"Smola","year":"1998","journal-title":"Neural Comput."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Suykens, J.A.K., De Brabanter, J., Van Gestel, T., De Moor, B., and Vandewalle, J. (2002). Least Squares Support Vector Machines, World Scientific Publishing Co.","DOI":"10.1142\/5089"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1016\/j.jfoodeng.2005.06.036","article-title":"Nondestructive measurement of acidity, soluble solids and firmness of Satsuma mandarin using Vis\/NIR-spectroscopy technique","volume":"77","author":"Gomez","year":"2006","journal-title":"J. Food Eng."},{"key":"ref_28","unstructured":"Chen, Z.M. (2008). Chinese Tea Dictionary, China Light Industry Press. (In Chinese)."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1016\/j.aca.2005.02.075","article-title":"Classification of bread wheat flours in different quality categories by a wavelet-based feature selection\/classification algorithm on NIR spectra","volume":"544","author":"Cocchi","year":"2005","journal-title":"Anal. Chim. Acta"},{"key":"ref_30","unstructured":"Pelckmans, K., Suykens, J.A.K., Gestel, T.V., Brabanter, J.D., Lukas, L., Hamers, B., Moor, B.D., and Vandewalle, J. (2003). LS-SVMlab Toolbox User's Guide Version 1.5, Katholieke University Leuven. ESAT-SCD-SISTA Technical Report 02-145."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/12\/7\/9847\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:51:22Z","timestamp":1760219482000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/12\/7\/9847"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2012,7,23]]},"references-count":30,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2012,7]]}},"alternative-id":["s120709847"],"URL":"https:\/\/doi.org\/10.3390\/s120709847","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2012,7,23]]}}}