{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,26]],"date-time":"2026-06-26T20:33:19Z","timestamp":1782505999298,"version":"3.54.5"},"reference-count":32,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2016,1,25]],"date-time":"2016-01-25T00:00:00Z","timestamp":1453680000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["81001646"],"award-info":[{"award-number":["81001646"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"TCM Administration of Henan Province","award":["2014ZY02066"],"award-info":[{"award-number":["2014ZY02066"]}]},{"name":"Excellent Youth Cultivation Project by Henan University of TCM","award":["2014KYYWF-YQ01"],"award-info":[{"award-number":["2014KYYWF-YQ01"]}]},{"name":"Tianjiang Pharmaceutical","award":["XZ2011030042"],"award-info":[{"award-number":["XZ2011030042"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>To accurately, safely, and efficiently evaluate the bitterness of Traditional Chinese Medicines (TCMs), a robust predictor was developed using robust partial least squares (RPLS) regression method based on data obtained from an electronic tongue (e-tongue) system. The data quality was verified by the Grubb\u2019s test. Moreover, potential outliers were detected based on both the standardized residual and score distance calculated for each sample. The performance of RPLS on the dataset before and after outlier detection was compared to other state-of-the-art methods including multivariate linear regression, least squares support vector machine, and the plain partial least squares regression. Both R2 and root-mean-squares error (RMSE) of cross-validation (CV) were recorded for each model. With four latent variables, a robust RMSECV value of 0.3916 with bitterness values ranging from 0.63 to 4.78 were obtained for the RPLS model that was constructed based on the dataset including outliers. Meanwhile, the RMSECV, which was calculated using the models constructed by other methods, was larger than that of the RPLS model. After six outliers were excluded, the performance of all benchmark methods markedly improved, but the difference between the RPLS model constructed before and after outlier exclusion was negligible. In conclusion, the bitterness of TCM decoctions can be accurately evaluated with the RPLS model constructed using e-tongue data.<\/jats:p>","DOI":"10.3390\/s16020151","type":"journal-article","created":{"date-parts":[[2016,1,25]],"date-time":"2016-01-25T10:03:06Z","timestamp":1453716186000},"page":"151","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":23,"title":["Evaluation of the Bitterness of Traditional Chinese Medicines using an E-Tongue Coupled with a Robust Partial Least Squares Regression Method"],"prefix":"10.3390","volume":"16","author":[{"given":"Zhaozhou","family":"Lin","sequence":"first","affiliation":[{"name":"Institute of Clinical Pharmacy, Beijing Municipal Health Bureau, Beijing 100035, China"},{"name":"School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100102, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiao","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100102, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruixin","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, The First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou 450000, China"},{"name":"The Level Three Laboratory of Chinese Traditional Medical Preparation of State Administration of TCM, Zhengzhou 450000, China"},{"name":"Key Laboratory of Viral Diseases Prevention and Treatment of TCM of Henan Province, Zhengzhou 450000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaojie","family":"Gao","sequence":"additional","affiliation":[{"name":"School of pharmacy, Henan University of Traditional Chinese Medicine, Zhengzhou 450008, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lu","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, The First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou 450000, China"},{"name":"The Level Three Laboratory of Chinese Traditional Medical Preparation of State Administration of TCM, Zhengzhou 450000, China"},{"name":"Key Laboratory of Viral Diseases Prevention and Treatment of TCM of Henan Province, Zhengzhou 450000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bingya","family":"Kang","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, The First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou 450000, China"},{"name":"The Level Three Laboratory of Chinese Traditional Medical Preparation of State Administration of TCM, Zhengzhou 450000, China"},{"name":"Key Laboratory of Viral Diseases Prevention and Treatment of TCM of Henan Province, Zhengzhou 450000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junhan","family":"Shi","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, The First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou 450000, China"},{"name":"The Level Three Laboratory of Chinese Traditional Medical Preparation of State Administration of TCM, Zhengzhou 450000, China"},{"name":"Key Laboratory of Viral Diseases Prevention and Treatment of TCM of Henan Province, Zhengzhou 450000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zidan","family":"Wu","sequence":"additional","affiliation":[{"name":"School of pharmacy, Henan University of Traditional Chinese Medicine, Zhengzhou 450008, China"},{"name":"Department of Computer Science and Statistics, University of Rhode Island, Kingston, RI 02881, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinjing","family":"Gui","sequence":"additional","affiliation":[{"name":"School of pharmacy, Henan University of Traditional Chinese Medicine, Zhengzhou 450008, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuelin","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, The First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou 450000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2016,1,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"82","DOI":"10.2174\/187221110789957309","article-title":"E-tongue: A tool for taste evaluation","volume":"4","author":"Gupta","year":"2010","journal-title":"Recent Pat. Drug Deliv. Formul."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2723","DOI":"10.1002\/jps.20900","article-title":"Utilization of a modified special-cubic design and an electronic tongue for bitterness masking formulation optimization","volume":"96","author":"Li","year":"2007","journal-title":"J. Pharm. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"943","DOI":"10.1248\/cpb.52.943","article-title":"Bitterness evaluation of medicines for pediatric use by a taste sensor","volume":"52","author":"Ishizaka","year":"2004","journal-title":"Chem. Pharm. Bull."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2947","DOI":"10.1016\/j.foodchem.2012.06.021","article-title":"Discrimination of mineral waters by electronic tongue, sensory evaluation and chemical analysis","volume":"135","author":"Sipos","year":"2012","journal-title":"Food Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1016\/j.ijpharm.2012.05.047","article-title":"Development and evaluation of taste-masked drug for paediatric medicines\u2014Application to acetaminophen","volume":"434","author":"Thi","year":"2012","journal-title":"Int. J. Pharm."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2595","DOI":"10.1021\/cr980102w","article-title":"Cross-Reactive Chemical Sensor Arrays","volume":"100","author":"Albert","year":"2000","journal-title":"Chem. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1016\/S0003-2670(97)00498-4","article-title":"An electronic tongue based on voltammetry","volume":"357","author":"Winquist","year":"1997","journal-title":"Anal. Chim. Acta."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2042","DOI":"10.1002\/jps.1155","article-title":"Quantification of suppression of bitterness using an electronic tongue","volume":"90","author":"Takagi","year":"2001","journal-title":"J. Pharm. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1016\/j.ijpharm.2012.11.047","article-title":"Bitterness prediction of H 1-antihistamines and prediction of masking effects of artificial sweeteners using an electronic tongue","volume":"441","author":"Ito","year":"2013","journal-title":"Int. J. Pharm."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"4744","DOI":"10.3390\/s110504744","article-title":"Electronic noses and tongues: Applications for the food and pharmaceutical industries","volume":"11","author":"Baldwin","year":"2011","journal-title":"Sensors"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1016\/j.talanta.2009.11.041","article-title":"Electronic tongue as a screening tool for rapid analysis of beer","volume":"81","author":"Polshin","year":"2010","journal-title":"Talanta"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/j.aca.2013.09.048","article-title":"On-line monitoring of food fermentation processes using electronic noses and electronic tongues: A review","volume":"804","author":"Peris","year":"2013","journal-title":"Anal. Chim. Acta."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"7799","DOI":"10.3390\/s110807799","article-title":"A biomimetic sensor for the classification of honeys of different floral origin and the detection of adulteration","volume":"11","author":"Zakaria","year":"2011","journal-title":"Sensors"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/j.aca.2010.03.017","article-title":"Review: Highlights in recent applications of electronic tongues in food analysis","volume":"665","author":"Peris","year":"2010","journal-title":"Anal. Chim. Acta."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"569","DOI":"10.1016\/j.talanta.2011.04.025","article-title":"Rapid honey characterization and botanical classification by an electronic tongue","volume":"85","author":"Major","year":"2011","journal-title":"Talanta"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"12233","DOI":"10.3390\/s140712233","article-title":"A bio-inspired herbal tea flavour assessment technique","volume":"14","author":"Zakaria","year":"2014","journal-title":"Sensors"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"240","DOI":"10.1016\/j.aca.2011.02.013","article-title":"Use of the smart tongue to monitor mold growth and discriminate between four mold species grown in liquid media","volume":"690","author":"Zhao","year":"2011","journal-title":"Anal. Chim. Acta."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Xu, M., Yang, S., Peng, W., Liu, Y., Xie, D., Li, X., and Wu, C. (2015). A Novel Method for the Discrimination of Semen Arecae and Its Processed Products by Using Computer Vision, Electronic Nose, and Electronic Tongue. Evid. Based Complement. Alternat. Med., 2015.","DOI":"10.1155\/2015\/753942"},{"key":"ref_19","first-page":"48","article-title":"Research on distinguish of Chinese herbal medicine based on electronic tongue technology","volume":"31","author":"Wu","year":"2012","journal-title":"Transducer Microsyst. Technol."},{"key":"ref_20","first-page":"282","article-title":"The Prospect of Making the Characters and Odor of Chinese Materia Medica Express Objectivly Based on Electronic Nose and Electronic Tongue","volume":"31","author":"Li","year":"2009","journal-title":"Chin. Tradit. Patent Med."},{"key":"ref_21","first-page":"1041","article-title":"Connection of Stewing Rehmanniae Radix with Wine and Its \u201cTaste\u201d","volume":"37","author":"Zhong","year":"2015","journal-title":"Chin. Tradit. Patent Med."},{"key":"ref_22","first-page":"1532","article-title":"Study on Application of Electronic Tongue in the Evaluation of Taste-Masking Effect of Pharmaceutical Formulation","volume":"7","author":"Li","year":"2013","journal-title":"World Sci. Technol. Mod. Tradit. Chin. Med."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/j.fitote.2013.02.010","article-title":"Sensory Evaluation of the Taste of Berberine Hydrochloride Using an Electronic Tongue","volume":"86","author":"Wang","year":"2013","journal-title":"Fitoterapia"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"986","DOI":"10.1007\/s13197-011-0422-0","article-title":"Discrimination of different white chrysanthemum by electronic tongue","volume":"50","author":"Wang","year":"2013","journal-title":"J. Food Sci. Technol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/j.talanta.2014.03.036","article-title":"Correlation of sensory bitterness in dairy protein hydrolysates: Comparison of prediction models built using sensory, chromatographic and electronic tongue data","volume":"126","author":"Newman","year":"2014","journal-title":"Talanta"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"17770","DOI":"10.3390\/s140917770","article-title":"Voltammetric electronic tongue and support vector machines for identification of selected features in Mexican coffee","volume":"14","year":"2014","journal-title":"Sensors"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1696","DOI":"10.3892\/etm.2014.1614","article-title":"Bitterness intensity prediction of berberine hydrochloride using an electronic tongue and a GA-BP neural network","volume":"7","author":"Liu","year":"2014","journal-title":"Exp. Ther. Med."},{"key":"ref_28","first-page":"378","article-title":"Quality assessment of green tea taste by using electronic tongue","volume":"27","author":"Wu","year":"2011","journal-title":"Trans. Chin. Soc. Agric. Eng."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"509","DOI":"10.1002\/wics.96","article-title":"Matlab library LIBRA","volume":"2","author":"Verboven","year":"2010","journal-title":"Wiley Interdiscip. Rev. Comput. Stat."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/j.chemolab.2004.06.003","article-title":"LIBRA: A MATLAB library for robust analysis","volume":"75","author":"Verboven","year":"2005","journal-title":"Chemometr. Intell. Lab. Syst."},{"key":"ref_31","unstructured":"Leuven University, Leuven, Belgium, RSIMPLS Toolbox. Available online: http:\/\/wis.kuleuven.be\/stat\/robust\/LIBRA\/."},{"key":"ref_32","unstructured":"LS-SVMlab Toolbox. Available online: http:\/\/www.esat.kuleuven.be\/sista\/lssvmlab\/."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/2\/151\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:18:15Z","timestamp":1760210295000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/2\/151"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,1,25]]},"references-count":32,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2016,2]]}},"alternative-id":["s16020151"],"URL":"https:\/\/doi.org\/10.3390\/s16020151","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,1,25]]}}}