WO2024029460A1

WO2024029460A1 - Galvanic taste stimulation device and galvanic taste stimulation method

Info

Publication number: WO2024029460A1
Application number: PCT/JP2023/027751
Authority: WO
Inventors: 一真青山; 中村裕美青山; 智浩雨宮; 純一暦本
Original assignee: 国立大学法人東京大学
Priority date: 2022-08-03
Filing date: 2023-07-28
Publication date: 2024-02-08

Abstract

Provided are a galvanic taste stimulation device and a galvanic taste stimulation method that are capable of taste adjustment by using anode GTS.　The galvanic taste stimulation device 20 comprises: an anode 24 provided on the lower jaw of a person, a cathode 26 provided on the back side of the neck of the person, and a signal output unit 22 that outputs an electrical signal between the anode and the cathode.

Description

Taste electric stimulation device and taste electric stimulation method

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2022-124101 filed on August 3, 2022, and the content thereof is hereby incorporated by reference.

The present disclosure relates to a taste electrical stimulation device and a taste electrical stimulation method.

Galvanic taste stimulation (GTS) is a technology used to change taste through electrical stimulation, and can adjust taste without changing the concentration of taste components in food. For example, by using the taste-enhancing effect of electrical stimulation to intensify the taste of food, even if the concentration of salt, which is an example of a taste component, is low, humans can create the illusion that the food is richly seasoned. It can help you eat healthy and delicious food.
GTS is divided into two types, an anode GTS and a cathode GTS, depending on the position of each electrode. A GTS with an anode mounted in or near the mouth is called an anode GTS, and a GTS with a cathode mounted in or near the mouth is called a cathode GTS.

JP2018-42991A

Previous research has shown that anodal GTS induces an electric or metallic taste during stimulation (Non-Patent Document 1). Because of this concern about electrical taste, no electrical taste stimulation device using anode GTS has been developed. On the other hand, cathode GTS is known to have the characteristic that almost no electric taste is perceived compared to anode GTS, and a taste electrical stimulation device using cathode GTS has been developed.

Patent Document 1 discloses a taste electric stimulation device that uses cathode GTS to enable continuous taste enhancement over a longer period of time than conventional techniques. However, cathodic GTS requires the use of a continuous square wave signal to enable continuous taste enhancement over a longer period of time than the prior art.

Therefore, an object of the present disclosure is to provide a taste electrical stimulation device and a taste electrical stimulation method that can perform taste adjustment using anode GTS.

A taste electric stimulation device according to one aspect of the present disclosure includes an anode installed on the lower jaw of a person, a cathode installed on the back side of the neck of the person, and a signal output that outputs an electric signal between the anode and the cathode. It is equipped with a section. According to this aspect, the taste electric stimulation device can perform taste adjustment using the anode GTS. The anode GTS allows taste adjustment using a single square wave signal.

In the electrical taste stimulation device, the electrical signal may be a single rectangular wave signal. According to this aspect, the taste electric stimulation device can perform continuous taste adjustment using a single rectangular wave signal.

The taste electrical stimulation device may further include a signal control unit that sets the current amount and/or duration of the electrical signal. According to this aspect, the electrical taste stimulation device can set the optimum current amount and/or duration depending on the usage situation.

In the electrical taste stimulation device, the electrical signal may be output while the person is ingesting the taste substance orally. According to this aspect, the taste electric stimulation device can provide a more excellent meal experience in fields such as medical care and nursing care where certain dietary restrictions are required.

In the above taste electric stimulation device, the taste substance may include a taste substance that does not ionize. According to this aspect, the electrical taste stimulation device can be expected to have an enhancing effect even on sweet substances that are not ionized, for example.

In the electrical taste stimulation device, the taste substance may include a taste substance that is ionized. According to this aspect, the electrical taste stimulation device can be expected to have an enhancing effect on, for example, ionized umami substances.

In a method according to another aspect of the present disclosure, a taste electric stimulation device including an anode installed on the lower jaw of a person and a cathode installed on the back side of the neck of the person outputs an output between the anode and the cathode. The steps include setting the amount of current of the electric signal and outputting the electric signal between the anode and the cathode, the electric signal being a single rectangular wave signal.

According to the present disclosure, it is possible to provide a taste electrical stimulation device and a taste electrical stimulation method that can perform taste adjustment using anode GTS.

FIG. 1 is a configuration diagram of a taste electric stimulation device according to an embodiment. (a) is a waveform diagram of a single-shot rectangular wave signal, and (b) is a waveform diagram of a continuous rectangular wave signal. FIG. 3 is a diagram showing the final concentration of the adjusted sample under each condition. It is a figure showing the taste enhancement effect of each condition as a magnification. FIG. 3 is a diagram showing the final concentration of the adjusted sample under each condition. It is a figure showing the taste enhancement effect of each condition as a magnification.

Embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following embodiments are provided to facilitate understanding of the present invention, and are not intended to be interpreted as limiting the present invention. Further, the present invention can be modified in various ways without departing from the gist thereof. Furthermore, those skilled in the art can adopt embodiments in which each element described below is replaced with an equivalent one, and such embodiments are also included in the scope of the present invention.

(overview)
An overview of the present disclosure will be described using FIG. 1. FIG. 1 is a configuration diagram of a taste electric stimulation device according to an embodiment. The taste electrical stimulation device 20 is a device that electrically stimulates nerves from the body surface (skin) of the subject 1, and includes a signal control section 21 and a signal output section 22.

The signal control unit 21 sets the amount of current and duration of the electrical signal output from the signal output unit 22, which will be described later. The signal output section 22 outputs an electric signal between the anode electrode 24 and the cathode electrode 26 based on the settings of the signal control section 21 .

A conducting wire 23 is connected to the positive terminal of the signal output section 22, and an anode electrode 24 is provided at the tip thereof. The anode electrode 24 can be installed at a suitable location on the body part of the subject 1, but in FIG. 1, the anode electrode 24 is installed at the center of the chin of the lower jaw. Further, a conductive wire 25 is connected to the negative terminal of the signal output section 22, and a cathode electrode 26 is provided at the tip of the conductive wire 25. The cathode electrode 26 can be installed at a suitable location on the body part of the subject 1, but in FIG. 1, the cathode electrode 26 is installed on the dorsal side of the neck.

(1) Experiment 1: Confirmation of the existence of the taste enhancement effect of the taste electric stimulation device (1-1) Experimental method Procedure 1: First, subject 1 was asked to drink distilled water and a 20% NaCl aqueous solution to increase the taste. I asked him to check his strength.
Step 2: Subject 1 was instructed to put 30 mL of NaCl aqueous solution of one of four concentrations (1%, 2%, 4%, and 8%) in his mouth as a test sample without informing him of the concentration. did.
Step 3: While subject 1 is being electrically stimulated by the electrical taste stimulation device 20, subject 1 holds 30 mL of the NaCl aqueous solution with the same concentration as the test sample in step 2 in his mouth, and asks him to memorize the strength of the salty taste. instructed.
Step 4: Prepare 30 mL of NaCl aqueous solution with the same concentration as the test sample as an adjusted sample, and use distilled water and 20% NaCl aqueous solution to compare the taste intensity of the adjusted sample with the taste intensity memorized in Step 3. Subject 1 was instructed to make adjustments so that they were equal.

In this embodiment, the taste electric stimulation device 20 uses a single-shot rectangular wave signal as shown in FIG. 2(a). Note that the taste electric stimulation device 20 uses a single rectangular wave signal with three current amounts (1.0 mA, 2.0 mA, or 3.0 mA), and in Experiment 1, four types of salt concentrations and three currents were used. A total of 24 tests were conducted for each subject, two times for each dose combination (4 x 3). The participants in the experiment were nine adults, and they were thoroughly explained to the participants before the experiment that electricity would be passed through their bodies, and the participants agreed to the experiment.

The maximum duration of electrical stimulation was 10 seconds, and the current was applied to the subject after instructions from the experimenter, and then the current was stopped when the subject memorized the intensity of the taste and received an instruction to stop the current. .

(1-2) Method for calculating the concentration of the adjusted sample In Experiment 1, in order to adjust the taste intensity of the adjusted sample, distilled water and a NaCl aqueous solution with a concentration of 20% were prepared. The initial weight of each 20% NaCl aqueous solution was measured. In this embodiment, subject 1 may add distilled water or a 20% NaCl aqueous solution any number of times in order to adjust the taste intensity of the prepared sample. Then, in order to confirm the strength of the taste of the prepared sample, 2 mL of the NaCl aqueous solution from the prepared sample was transferred to Subject 1's mouth using a dropper.

The weight of 2 mL of NaCl aqueous solution for adjusting the taste intensity of the adjusted sample was determined using the following formula.

Here, W is the weight of 2 mL of NaCl aqueous solution with a concentration of c [%]. Using each concentration of NaCl aqueous solution (1%, 2%, 4%, and 8%) and the corresponding weight of 2 mL of the same aqueous solution, the slope k and the intercept b are each 0.016 using a linear approximation using the least squares method in advance. It was calculated as 2.054. Note that since W is the weight of 2 mL of aqueous solution, when c=0, b should be the same as 2.0. This difference is thought to be due to measurement errors in the use of the dropper and electronic balance.

Each time Subject 1 checked the taste intensity, the weight of the distilled water and 20% NaCl aqueous solution used for adjustment was measured. Using the measured weights, the amounts of distilled water and 20% NaCl aqueous solution to be added were estimated. Finally, the final concentration of the prepared sample was calculated using the number of times the taste intensity of the prepared sample was confirmed, the initial weight of the prepared sample, and the amounts of distilled water and 20% NaCl aqueous solution added.

(1-3) Experimental Results Figure 3 shows the final concentration of the adjusted sample under each condition. In FIG. 3, the horizontal axis shows the concentration of the test sample, and the vertical axis shows the final concentration of the adjusted sample. The plot in the figure is the average value between subjects, and the error bar indicates the standard error. Figure 3 shows that the higher the concentration of the test sample, the higher the final concentration of the adjusted sample.

FIG. 4 is a diagram showing the taste enhancement effect as a magnification of the current amount and concentration of the test sample. The fold factor was defined as the ratio of the final concentration of the adjusted sample to the initial concentration of the adjusted sample, ie the concentration of the test sample. In FIG. 4, the horizontal axis shows the concentration of the test sample, and the vertical axis shows the magnification of the concentration of the adjustment sample relative to the test sample. The plot in the figure is the average value between subjects, and the error bar indicates the standard error.

Applicants used MATLAB R2019b to calculate magnification factors based on three current conditions (1.0 mA, 2.0 mA, and 3.0 mA) and four concentration conditions (1%, 2%, 4%, and 8%). A two-way analysis of variance (ANOVA) was performed on The ANOVA results showed a significant main effect of current (F (2, 96) = 4.87, p < 0.05) and test sample concentration (F (3, 96) = 13.24, p < 0.05); There was no significant interaction (F (6, 96)=0.67, p=0.674). Asterisks in the figure indicate significant differences (p<0.05) due to multiple comparisons of concentrations (Scheffe method).

Experiment 1 showed that anodic GTS using a single square wave signal enhanced the salty taste of an aqueous NaCl solution. The figures and statistical results showed that the magnification in low concentration NaCl aqueous solution was higher than that in high concentration NaCl aqueous solution. Additionally, multiple comparisons (Scheffe's method) for current conditions showed significant differences between 1.0 and 3.0 mA. This means that high current stimulation strongly enhances salty taste.

(2) Experiment 2: Comparison of taste enhancement effects between anode GTS and cathode GTS (2-1) Experiment method Preparation: For each subject, the amount of current that gave the strongest sense of salty taste was determined. Specifically, the amount of current was adjusted from 0.0 mA to 3.0 mA in 0.1 mA increments, and the amount of current at which each subject felt the strongest salty taste was determined.
Procedure 1: Subject 1 was instructed to drink distilled water and a 20% NaCl aqueous solution to check the strength of the taste.
Step 2: Subject 1 was instructed to put 30 mL of NaCl aqueous solution of one of four concentrations (1%, 2%, 4%, and 8%) in his mouth as a test sample without informing him of the concentration. did.
Step 3: While applying electrical stimulation to Subject 1 using either anode GTS or cathode GTS, hold 30 mL of NaCl aqueous solution with the same concentration as the test sample in Step 2 in the mouth and memorize the strength of its salty taste. Subject 1 was instructed to:
Step 4: Prepare 30 mL of NaCl aqueous solution with the same concentration as the test sample as an adjusted sample, and use distilled water and 20% NaCl aqueous solution to compare the taste intensity of the adjusted sample with the taste intensity memorized in Step 3. Subject 1 was instructed to make adjustments so that they were equal.

In the anode GTS, a taste electric stimulation device 20 using a single-shot rectangular wave signal as shown in FIG. 2(a) was used. For cathodal GTS, a cathodal taste electrical stimulator (not shown) using a continuous square wave signal as shown in FIG. 2(b) was used. In cathodal GTS, electric stimulation has a suppressing effect on taste, and this suppressing effect causes a unique taste enhancement effect to be seen after the electrical stimulation is stopped.In order to obtain a sustained enhancement effect, continuous rectangular It uses wave signals.

Note that both the taste electric stimulation device 20 and the cathode taste electric stimulation device use electric signals with the amount of current obtained in advance preparation, and in Experiment 2, anode GTS and cathode GTS (4× Tests 2) and 2) were conducted twice for each subject, for a total of 16 tests. The participants in the experiment were six adults, and they were thoroughly explained to the participants before the experiment that electricity would be passed through their bodies, and the participants agreed to the experiment.

(2-2) Method for calculating the concentration of the adjusted sample The method for calculating the concentration of the adjusted sample is the same as in Experiment 1, so it will be omitted.

(2-3) Experimental Results Figure 5 shows the final concentration of the adjusted sample under each condition. In FIG. 5, the horizontal axis shows the concentration of the test sample, and the vertical axis shows the final concentration of the adjusted sample. The plot in the figure is the average value between subjects, and the error bar indicates the standard error. Figure 5 shows that for both anodic and cathodic GTS, the final concentration of the conditioned sample is higher than that of the test sample.

FIG. 6 is a diagram showing the taste enhancement effect as a magnification under different stimulation conditions and concentrations. The fold factor was defined as the ratio of the final concentration of the adjusted sample to the initial concentration of the adjusted sample, ie the concentration of the test sample. In FIG. 4, the horizontal axis shows the concentration of the test sample, and the vertical axis shows the magnification of the concentration of the adjustment sample relative to the test sample. The plot in the figure is the average value between subjects, and the error bar indicates the standard error.

Applicants used MATLAB R2019b to conduct a two-way ANOVA on fold factors based on two stimulation conditions (anodal GTS and cathodal GTS) and four concentration conditions (1%, 2%, 4%, and 8%). did. The ANOVA results showed a significant main effect of sample concentration (F (3, 40)=0.37, p<0.05), but a significant main effect of stimulation condition (F (1, 40)=3.08, p=0.0868) and no significant interaction (F (3, 40)=0.67, p=0.574). Asterisks in the figure indicate significant differences (p<0.05) due to multiple comparisons (Scheffe method).

(3) Discussion In Experiment 1, it was shown that anode GTS using a single square wave signal enhanced the salty taste of the NaCl aqueous solution. In addition, the enhancement effect (magnification) was more pronounced in a low-concentration NaCl aqueous solution compared to a high-concentration NaCl aqueous solution, and a maximum of 3 times the enhancement was shown when a 1% NaCl aqueous solution was used. .

Experiment 2 showed that the enhancement effect of anodal GTS was stronger compared to the enhancement effect of cathodal GTS, but no significant difference between the two was shown. However, it has been shown that the enhancement effect of anode GTS is at least as good as that of cathode GTS.

Although it was shown through

Experiments

1 and 2 that anode GTS enhances the salty taste of NaCl aqueous solution, the mechanism of this enhancement effect is not clear. Regarding this mechanism, two hypotheses are possible. The first hypothesis is that the Na + ions that induce the salty taste move downwards according to the direction of the current. This increases the Na+ concentration around the tongue. According to this hypothesis, if a taste substance is ionized, it can be expected to have an enhancing effect on tastes other than salty.

The second hypothesis is that anodal GTS stimulates all the receptors for various tastes such as salty, sour, and umami, and that of all tastes, the salty taste induced by NaCl aqueous solution is more strongly enhanced. be. According to this hypothesis, it can be expected that even tastants that do not ionize will have an enhancing effect on tastes other than salty.

As described above, according to the present embodiment, the taste electric stimulation device 20 can perform taste adjustment by anode GTS using a single rectangular wave signal.

Furthermore, in this embodiment, taste adjustment can be performed by anode GTS, so according to the second hypothesis, it can be expected that even taste substances that are not ionized will have an enhancing effect on tastes other than salty.

By enabling continuous taste adjustment through anode GTS using a single-shot square wave signal, it is possible to provide a superior dining experience in fields such as medical care and nursing care where certain dietary restrictions are required. It is also expected to be used to support human eating experiences in virtual reality and the Metaverse.

Note that in this embodiment, taste adjustment was performed by anode GTS using a single-shot rectangular wave signal, but the waveform of the signal is not limited to the single-shot rectangular wave, and signals with other waveforms may be used.

1... Subject, 20... Taste electric stimulation device, 21... Signal control unit, 22... Signal output unit, 23... Conductive wire, 24... Anode electrode (anode), 25... Conductive wire, 26... Cathode electrode (cathode)

Claims

an anode placed on a person's lower jaw;
a cathode installed on the dorsal side of the neck of the person;
A signal output section that outputs an electric signal between the anode and the cathode. A taste electrical stimulation device.
The electrical taste stimulation device according to claim 1, wherein the electrical signal is a single rectangular wave signal.
The taste electrical stimulation device according to claim 1, further comprising a signal control unit that sets the current amount and/or duration of the electrical signal.
The electrical taste stimulation device according to claim 1, wherein the electrical signal is output while the person is ingesting the taste substance orally.
The taste electric stimulation device according to claim 4, wherein the taste substance includes a taste substance that does not ionize.
The electrical taste stimulation device according to claim 4, wherein the taste substance includes a taste substance that ionizes.
A taste electric stimulation device comprising an anode installed on the lower jaw of a person and a cathode installed on the dorsal side of the neck of the person,
setting the amount of current of an electric signal output between the anode and the cathode;
A method comprising: outputting the electrical signal between the anode and the cathode, the electrical signal being a single-shot rectangular wave signal.