{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T15:42:53Z","timestamp":1773070973167,"version":"3.50.1"},"reference-count":29,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2016,2,15]],"date-time":"2016-02-15T00:00:00Z","timestamp":1455494400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A taste sensor that uses lipid\/polymer membranes can evaluate aftertastes felt by humans using Change in membrane Potential caused by Adsorption (CPA) measurements. The sensor membrane for evaluating bitterness, which is caused by acidic bitter substances such as iso-alpha acid contained in beer, needs an immersion process in monosodium glutamate (MSG) solution, called \u201cMSG preconditioning\u201d. However, what happens to the lipid\/polymer membrane during MSG preconditioning is not clear. Therefore, we carried out three experiments to investigate the changes in the lipid\/polymer membrane caused by the MSG preconditioning, i.e., measurements of the taste sensor, measurements of the amount of the bitterness substance adsorbed onto the membrane and measurements of the contact angle of the membrane surface. The CPA values increased as the preconditioning process progressed, and became stable after 3 d of preconditioning. The response potentials to the reference solution showed the same tendency of the CPA value change during the preconditioning period. The contact angle of the lipid\/polymer membrane surface decreased after 7 d of MSG preconditioning; in short, the surface of the lipid\/polymer membrane became hydrophilic during MSG preconditioning. The amount of adsorbed iso-alpha acid was increased until 5 d preconditioning, and then it decreased. In this study, we revealed that the CPA values increased with the progress of MSG preconditioning in spite of the decrease of the amount of iso-alpha acid adsorbed onto the lipid\/polymer membrane, and it was indicated that the CPA values increase because the sensor sensitivity was improved by the MSG preconditioning.<\/jats:p>","DOI":"10.3390\/s16020230","type":"journal-article","created":{"date-parts":[[2016,2,15]],"date-time":"2016-02-15T06:23:07Z","timestamp":1455517387000},"page":"230","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Research on the Changes to the Lipid\/Polymer Membrane Used in the Acidic Bitterness Sensor Caused by Preconditioning"],"prefix":"10.3390","volume":"16","author":[{"given":"Yuhei","family":"Harada","sequence":"first","affiliation":[{"name":"Graduate School of Information Science and Electrical Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Junpei","family":"Noda","sequence":"additional","affiliation":[{"name":"Graduate School of Information Science and Electrical Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rui","family":"Yatabe","sequence":"additional","affiliation":[{"name":"Research and Development Center for Taste and Odor Sensing, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hidekazu","family":"Ikezaki","sequence":"additional","affiliation":[{"name":"Intelligent Sensor Technology, Inc., 5-1-1 Onna, Atsugi-shi, Kanagawa 243-0032, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kiyoshi","family":"Toko","sequence":"additional","affiliation":[{"name":"Graduate School of Information Science and Electrical Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan"},{"name":"Research and Development Center for Taste and Odor Sensing, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,2,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"288","DOI":"10.1038\/nature05401","article-title":"The receptors and cells for mammalian taste","volume":"444","author":"Chandrashekar","year":"2006","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2481","DOI":"10.1039\/c0an00292e","article-title":"Recent advances in electronic tongues","volume":"135","author":"Riul","year":"2010","journal-title":"Analyst"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"S18","DOI":"10.1038\/486S18a","article-title":"Technology: The taste of things to come","volume":"486","author":"Savage","year":"2012","journal-title":"Nature"},{"key":"ref_4","unstructured":"Toko, K. (2013). Biochemical Sensors: Mimicking Gustatory and Olfactory Senses, Pan Stanford Publishing."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Toko, K. (2000). Biomimetic Sensor Technology, Cambridge University Press.","DOI":"10.1017\/CBO9780511541179"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3411","DOI":"10.3390\/s100403411","article-title":"Advanced taste sensors based on artificial lipids with global selectivity to basic taste qualities and high correlation to sensory scores","volume":"10","author":"Kobayashi","year":"2010","journal-title":"Sensors"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"3001","DOI":"10.1109\/JSEN.2013.2263125","article-title":"Electronic tongues\u2014A review","volume":"13","author":"Tahara","year":"2013","journal-title":"IEEE Sens. J."},{"key":"ref_8","unstructured":"Habara, M., and Toko, K. (2006). Encyclopedia of Sensors, American Scientific Publishers."},{"key":"ref_9","first-page":"1","article-title":"Relationship between taste sensor response and amount of quinine adsorbed on lipid\/polymer membrane","volume":"2","author":"Fukagawa","year":"2012","journal-title":"J. Innov. Electron. Commun."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1172","DOI":"10.1166\/sl.2014.3182","article-title":"Examination of amount of astringent substances adsorbed onto lipid\/polymer membrane used in taste sensor","volume":"12","author":"Hara","year":"2014","journal-title":"Sens. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"16274","DOI":"10.3390\/s140916274","article-title":"Relationship between the amount of bitter substances adsorbed onto lipid\/polymer membrane and the electric response of taste sensors","volume":"14","author":"Toko","year":"2014","journal-title":"Sensors"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"6241","DOI":"10.3390\/s150306241","article-title":"Study of the relationship between taste sensor response and the amount of epigallocatechin gallate adsorbed onto a lipid-polymer membrane","volume":"15","author":"Harada","year":"2015","journal-title":"Sensors"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"257","DOI":"10.1016\/j.drudis.2007.01.010","article-title":"The latest trends in the taste assessment of pharmaceuticals","volume":"12","author":"Anand","year":"2007","journal-title":"Drug Discov. Today"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1007\/s00604-007-0929-2","article-title":"Voltammetric electronic tongues\u2014Basic principles and applications","volume":"163","author":"Winquist","year":"2008","journal-title":"Microchim. Acta"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1965","DOI":"10.1351\/pac200577111965","article-title":"Nonspecific sensor arrays (\u201celectronic tongue\u201d) for chemical analysis of liquids","volume":"77","author":"Vlasov","year":"2005","journal-title":"Pure Appl. Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"963","DOI":"10.1039\/b705107g","article-title":"Sensor arrays for liquid sensing-electronic tongue systems","volume":"132","author":"Ciosek","year":"2007","journal-title":"Analyst"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1016\/S0925-4005(97)00167-6","article-title":"Tasting of beverages using an electronic tongue","volume":"44","author":"Legin","year":"1997","journal-title":"Sens. Actuators B Chem."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"3965","DOI":"10.1021\/ac086073z","article-title":"Smart taste sensors","volume":"80","author":"Citterio","year":"2008","journal-title":"Anal. Chem."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"i258","DOI":"10.1093\/chemse\/bjh213","article-title":"A voltammetric electronic tongue","volume":"30","author":"Ivarsson","year":"2005","journal-title":"Chem. Sens."},{"key":"ref_20","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_21","doi-asserted-by":"crossref","first-page":"1059","DOI":"10.1016\/0039-9140(94)00124-3","article-title":"Chalcogenide glass chemical sensors: Research and analytical applications","volume":"41","author":"Vlasov","year":"1994","journal-title":"Talanta"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"532","DOI":"10.1016\/S0925-4005(97)00241-4","article-title":"Cross-sensitivity evaluation of chemical sensors for electronic tongue: Determination of heavy metal ions","volume":"44","author":"Vlasov","year":"1997","journal-title":"Sens. Actuators B Chem."},{"key":"ref_23","unstructured":"Insent, Inc. (2007). Highly Durable and Rapidly Measurable Taste Sensor for Quality Control of Products Using Artificial Lipid\/Polymer Membrane, Japan Science and Technology Agency. Report of Risk-Taking Fund for Technology Development."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"22439","DOI":"10.3390\/s150922439","article-title":"Analysis of a lipid\/polymer membrane for bitterness sensing with a preconditioning process","volume":"15","author":"Yatabe","year":"2015","journal-title":"Sensors"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1021\/j100620a020","article-title":"Effective fixed charge density governing membrane phenomena V. A reduced expression of permselectivity","volume":"77","author":"Kamo","year":"1973","journal-title":"J. Phys. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/0301-4622(96)00026-9","article-title":"Theory of electric characteristics of the lipid\/PVC\/DOPP membrane and PVC\/DOPP membrane in response to taste stimuli","volume":"61","author":"Oohira","year":"1996","journal-title":"Biophys. Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/0021-9797(74)90027-7","article-title":"Interpretation of asymmetric membrane potential","volume":"46","author":"Kamo","year":"1974","journal-title":"J. Colloid Interface Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/j.talanta.2003.10.006","article-title":"The phase-boundary potential model","volume":"63","author":"Eric","year":"2004","journal-title":"Talanta"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"329","DOI":"10.1021\/cr068100w","article-title":"Potentiometric Ion Sensors","volume":"108","author":"Johan","year":"2008","journal-title":"Chem. Rev."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/2\/230\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T19:19:09Z","timestamp":1760210349000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/16\/2\/230"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2016,2,15]]},"references-count":29,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2016,2]]}},"alternative-id":["s16020230"],"URL":"https:\/\/doi.org\/10.3390\/s16020230","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2016,2,15]]}}}