Abstract

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 “MSG preconditioning”. 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.

Highlights

  • Human beings perceive saltiness, sourness, bitterness, umami and sweetness when they taste foods and beverages; these are called “five basic tastes”

  • The taste sensor comprises potentiometric sensor electrodes with lipid/polymer membranes, each of which respond selectively to each basic taste [4,5,6,7,8,9,10,11,12]

  • The study of the property changes of the lipid/polymer membrane used in the bitterness sensor C00 caused by monosodium glutamate (MSG) preconditioning is one of the approaches to clarify the mechanism of the taste sensor, and will be instrumental for the high functionality of the taste sensor

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Summary

Introduction

Sourness, bitterness, umami and sweetness when they taste foods and beverages; these are called “five basic tastes”. The tests might inflict stress on panelists Against this background, objective evaluations of taste using sensors have attracted considerable attention [2,3,4,5,6,7]. The taste sensor comprises potentiometric sensor electrodes with lipid/polymer membranes, each of which respond selectively to each basic taste [4,5,6,7,8,9,10,11,12]. The study of the property changes of the lipid/polymer membrane used in the bitterness sensor C00 caused by MSG preconditioning is one of the approaches to clarify the mechanism of the taste sensor, and will be instrumental for the high functionality of the taste sensor. We investigated the changes in the C00 sensor membrane caused by MSG preconditioning by performing three kinds of experiments which included the measurement of the amount of adsorption

Reagents
Measurement of Contact Angle
Measurement of Adsorbed
3.1.Results
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Conclusions

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