Taste presentation device and taste presentation method

Abstract

To provide a taste sense presentation device which can express the modification effect of the taste sense so that a user can feel it while keeping a current value relatively small.SOLUTION: A taste sense presentation device includes: a first electrode and a second electrode which are provided so that an electrical circuit can be formed between food and drink taken by a user and the user's body; and electric stimulation generation means which supplies an electrical current to generate electric stimulation between the first electrode and the second electrode. The electric stimulation generation means is provided so as to start supply of the electric current in a state of cathode stimulation in which the second electrode becomes the cathode, and change the direction of the electric current so as to be switched to the state of anode stimulation in which the second electrode becomes the anode. In the cathode stimulation, the retention time Tx1 in which the electric current should be held at the setting value Is1 of the electric current in the cathode stimulation is set to be equal to or greater than 0.30 second.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a taste presentation device or the like for changing the taste perceived by a user by using electrical stimulation.

Background Art

[0002] For users who have to adopt a light diet with restricted salt and sugar due to health management or other reasons, as a method for enhancing the taste such as saltiness to improve satisfaction, a method has been proposed in which the taste of food and drink is modified and presented to suit the user's preference or the like by using electrical stimulation. For example, a taste presentation device has been proposed that supplies a rectangular wave current of a certain frequency between an anode that contacts a body part such as the user's neck muscle and a cathode that contacts food and drink to produce an enhancing effect on the user's taste (see Patent Document 1). A device has also been proposed that supplies a two-phase current to an electrode arranged to contact the user's tongue or the like to electrically stimulate the nerve branches that carry taste to the brain (see Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When attempting to modify taste, such as enhancing saltiness, using electrical stimulation, the user may feel discomfort or an electric taste. Discomfort refers to unnatural sensations that the user may feel, for example, due to the time difference between putting food or drink in the mouth and perceiving the modified taste, or unnatural sensations that may be felt in body parts close to the electrodes when an electric current is passed. Electric taste refers to a taste similar to that of metal or a sour taste felt when an electric current is passed. If the current value is decreased to avoid such inconveniences, the saltiness enhancement effect may be diminished accordingly, making it difficult for the user to perceive.

[0005] Therefore, an object of the present invention is to provide a taste presentation device and a taste presentation method capable of expressing a taste modification effect so that the user can feel it while keeping the current value relatively small.

Means for Solving the Problem

[0006] A taste presentation device according to an aspect of the present invention includes a first electrode and a second electrode provided so as to be able to form an electric circuit between food or drink ingested by a user and the user's body, and electric stimulation generation means for supplying a current for generating an electric stimulation between the first electrode and the second electrode. The electric stimulation generation means is provided so as to start supplying the current in a state of cathode stimulation in which the second electrode becomes a cathode, and then change the direction of the current so as to switch to a state of anode stimulation in which the second electrode becomes an anode. In the cathode stimulation, the holding time for holding the current at the set value of the current in the cathode stimulation is set to be 0.30 seconds or more.

[0007] A taste presentation method according to one aspect of the present invention includes a procedure of providing a first electrode and a second electrode so that an electric circuit can be formed between food or drink ingested by a user and the user's body, and a procedure of supplying a current for generating an electrical stimulus between the first electrode and the second electrode. In the procedure of supplying the current, the supply of the current is started in a state of cathode stimulation in which the second electrode serves as a cathode, and then the direction of the current is changed so as to switch to a state of anode stimulation in which the second electrode serves as an anode. In the cathode stimulation, the holding time for holding the current at a set value of the current in the cathode stimulation is set to be 0.30 seconds or more.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] FIG. 1 shows an example of a taste presentation device according to one embodiment of the present invention. The taste presentation device 10 in FIG. 1 includes a first electrode 11 provided so as to contact a user 1, a second electrode 12 provided so as to contact food or drink 2 ingested by the user 1, and an electrical stimulation generation unit 13 as an example of electrical stimulation means for supplying a current for generating an electrical stimulus between these electrodes 11 and 12.

[0010] The first electrode 11 is worn, as an example, on the hand or arm of the user 1. A gel-like electrode may be used as the first electrode 11 and attached to the user, or the first electrode 11 may be provided so that the user can hold it by hand. The second electrode 12 is worn, as an example, on a conductive tableware 3 used by the user for eating and drinking. The tableware 3 itself may be used as the second electrode 12. For example, as shown in FIG. 1, the second electrode 12 may be attached to a ladle 3a immersed in a beverage as an example of the food or drink 2, or the ladle 3a itself may be used as the second electrode 12. Alternatively, as shown in FIG. 2, the second electrode 12 may be attached to utensils such as a fork, spoon, chopsticks, etc. (including so-called cutlery) 3b used for ingesting food as an example of the food or drink 2, or those utensils 3b may be used as the second electrode 12. In any case, the first electrode 11 and the second electrode 12 may be configured in an appropriate form as long as an electric circuit is formed between the food or drink 2 ingested by the user 1 and the body of the user 1, and thereby a current for applying an electrical stimulus flows to an organ such as the tongue by which the user 1 perceives taste. The tableware 3 to which the second electrode 12 is to be attached is not limited to the examples of FIGS. 1 and 2, and may be a plate, bowl, teacup, donburi, pot, cup, glass, mug, cup, sake cup, ball, kettle, soup cup, tumbler, water bottle, chopsticks, fork, spoon, knife, ladle, etc., skewer, toothpick, straw, etc. may be the object to which the second electrode 12 is attached.

[0011] As shown in FIG. 3, the electrical stimulus generation unit 13 includes a booster circuit 14, a current output unit 15, a current control unit 16, and noise reduction units 17A, 17B (which may be represented by the reference numeral 17). The booster circuit 14 boosts a direct current supplied from an external power source (not shown) via a PC (abbreviation for personal computer) 20 to a predetermined voltage and supplies it to the current output unit 15. The external power source is, as an example, an alternating commercial power source. The current from the power source is not limited to the example of being supplied via the PC 20, and may be supplied via an appropriate converter such as a converter or adapter having an AC-DC conversion function. A DC power source such as a power battery may be used as the external power source.

[0012] The current output unit 15 shapes the current waveform according to the command value given from the current control unit 16 and supplies it to the electrodes 11 and 12. The current control unit 16 is configured as a computer unit using, for example, a microprocessor. It generates a command value for the current waveform according to the setting information of the current waveform given from the PC 20, and outputs this to the current output unit 15 to control the current supplied to the electrodes 11 and 12. For example, the current control unit 16 controls the direction of the current so that anodic stimulation where the second electrode 12 becomes the anode and cathodic stimulation where the second electrode 12 becomes the cathode can be selected, and can control the magnitude (current value) and the rate of change of the current to the target values given from the PC 20. An example of current control will be described later.

[0013] The noise reduction unit 17 reduces the noise components included in the current supplied between the electrodes 11 and 12. The noise reduction unit 17 is an example of noise reduction means. According to the inventor's study, it has been found that the noise components included in the current are factors that deteriorate the sense of discomfort and the metallic taste, and the greater the noise components, the stronger the sense of discomfort and the metallic taste tend to become. By providing the noise reduction unit 17, the influence of minute noise components on the sense of discomfort and the metallic taste is suppressed to enhance the taste modification effect. Note that the term "reduction" means relatively reducing the noise components in the current compared to the case where the noise reduction unit 17 is not provided, and includes processes such as "removal", "elimination", and "dissolution" where the noise components are reduced to an undetectable level, not limited to the case where the noise components still remain to some extent. "Modification" is a concept that means changing the taste perceived by the user 1 from the original taste perceived when no electrical stimulation is added, and "presentation" is a concept that means making the user 1 perceive the modified taste.

[0014] The noise reduction unit 17 may be configured by using various elements such as capacitors, inductors, or ferrite cores, which are used to reduce noise components in various electric circuits, alone or in appropriate combinations. In the example of FIG. 3, a noise reduction unit 17A is provided on the input side of the boost circuit 14 for the purpose of reducing noise components derived from an external power supply, and a noise reduction unit 17B is provided on the output side of the boost circuit 14 for the purpose of removing noise components corresponding to the internal transmission frequency generated during the boosting of the boost circuit 14. However, the position and number of the noise reduction unit 17 may be appropriately changed according to the internal configuration such as the position of the noise source in the electrical stimulation generation unit 13.

[0015] Next, an example of current control by the current control unit 16 will be described. FIG. 4 shows an example of a current waveform controlled by the current control unit 16, where the horizontal axis represents time and the vertical axis represents the current value. The current value is shown as a positive value when the second electrode 12 is the anode and as a negative value when it is the cathode. In the following description, a change in the current value, regardless of whether it is in the positive or negative direction, in the direction of increasing absolute value is expressed as "increase".

[0016] In the example of FIG. 4, at time t1, it is assumed that user 1 ingests food or drink 2, the electrodes 11 and 12 are electrically connected, and an electric circuit including user 1 is formed. When the formation of the electric circuit is detected at time t1, the current control unit 16 sets the direction of the current so that the cathode stimulation, that is, the first electrode 11 becomes the anode and the second electrode 12 becomes the cathode, and starts supplying the current, and gradually increases the current value to the set value Is1 over a predetermined increase time Tx1. The set value Is1 is a value set as the target value of the current to be maintained by the cathode stimulation. After reaching the set value Is1, the current control unit 16 holds the set value Is1 for a predetermined holding time Ty1. When the holding time Ty1 elapses, the current control unit 16 changes the direction of the current so that the first electrode 11 becomes the cathode and the second electrode 12 becomes the anode, and increases the current value of the second electrode 12 to the set value Is2 over a predetermined inversion time Tx2. The set value Is2 is a value set as the target value of the current to be maintained by the anode stimulation. After the current value reaches the set value Is2 at time t2, the current control unit 16 holds the set value Is2 for a predetermined holding time Ty2, and stops supplying the current when the holding time Ty2 elapses.

[0017] As in the example of FIG. 4, when the polarity is reversed after the start of the current supply, while suppressing the set values Is1 and Is2 of the current to relatively small values, the change effect of taste can be sufficiently elicited by utilizing the polarity reversal, thereby enhancing the taste modification effect. The cathode stimulation can suppress the discomfort of user 1 to a relatively small level while having a weak taste modification effect, and the anode stimulation has a relatively large taste modification effect while tending to cause relatively strong discomfort and electric taste. Therefore, by first performing the cathode stimulation to suppress the discomfort and then reversing the polarity to perform the anode stimulation, a large change amount of the current value during the reversal can be ensured to enhance the taste modification effect. In addition, by relatively suppressing the set value Is2 of the current during the anode stimulation, it is possible to reduce the discomfort and the electric taste.

[0018] In the example of FIG. 4, various parameters that define the current waveform, namely, the set values Is1 and Is2 of the current, the increase time Tx1 until the set value Is1 is reached, the holding time Ty1 of the set value Is1 in cathode stimulation, the inversion time Tx2 for inverting the polarity from cathode stimulation to anode stimulation until the set value Is2 of anode stimulation is reached, and the holding time Ty2 of the set value Is2 in anode stimulation, are set according to environmental conditions such as individual differences of User 1, the degree of the intended taste modification effect, or the type of food or drink 2 to be ingested. Their preferred ranges are as follows.

[0019] First, the holding time Ty1 of the set value Is1 of the current in cathode stimulation will be described. If the holding time Ty1 is excessively short, there is a risk that the effect of preceding cathode stimulation may not easily occur, and it is an important parameter for expressing the effect of cathode stimulation. From the viewpoint of expressing the effect of cathode stimulation, the holding time Ty1 may be set to 0.30 seconds or more, preferably 0.50 seconds or more.

[0020] On the other hand, if the holding time Ty1 is excessively long, the expression of the taste modification effect using anode stimulation may be delayed with respect to the user's eating and drinking actions, possibly giving an unnatural physical sensation. However, there are individual differences in the user's eating and drinking actions, and the upper limit of the holding time Ty1 can also vary in relation to this. When targeting users with relatively fast eating and drinking actions, in comparison with users with slow eating and drinking actions, it is preferable to set the upper limit of the holding time Ty1 relatively short because it is necessary to express the modification effect earlier. On the other hand, when targeting users with relatively slow eating and drinking actions, there is a margin of time to exert the modification effect, so it is possible to set the upper limit of the holding time Ty1 relatively long.

[0021] However, even if only the upper limit of the holding time Ty1 is restricted, if the increase time Tx1 or the inversion time Tx2 is set too long, the time required for the effect of the anodic stimulation to appear will be prolonged. When that time is prolonged, the time difference from when food or drink is put in the mouth until the modified taste is perceived, that is, the time difference between the timing when the user expects taste perception and the timing when the taste is actually perceived, will increase, and there may arise a problem that this gives the user a sense of discomfort. Hereinafter, such a problem may be referred to as unnaturalness of timing. Therefore, in order to appropriately set the time until the anodic stimulation appears, rather than restricting only the upper limit of the holding time Ty1 alone, the total time of the increase time Tx1, the holding time Ty1, and the inversion time Tx2, in other words, from the time t1 when the supply of the current of the cathodic stimulation starts until the time t2 when the current of the anodic stimulation reaches the set value Is2 through the cathodic stimulation, it is preferable to set an upper limit for the elapsed time Te (= Tx1 + Ty1 + Tx2). The holding time Ty1 may be set within the range of such an elapsed time Te. The elapsed time Te may be set to 1.30 seconds or less, preferably 1.20 seconds or less, and more preferably 1.00 seconds or less. Regarding the lower limit of the elapsed time Te, on the premise that the holding time Ty1 is set to be equal to or higher than the above lower limit, it can be set with a standard of 0.70 seconds or more, preferably 0.85 seconds or more. However, since the effect of the cathodic stimulation is greatly affected by the holding time Ty1, it is sufficient to prioritize keeping the elapsed time Te within the above upper limit while setting the holding time Ty1 to be equal to or higher than the above lower limit, and it is not always necessary to strictly limit the lower limit of the elapsed time Te itself.

[0022] Even when the lower limit of the holding time Ty1 and the upper limit of the elapsed time Te are set within the above ranges, the increase time Tx1, the holding time Ty1, and the inversion time Tx2 can be appropriately combined. As a guideline, for the increase time Tx1, if it is too short, the user may feel a stimulus and feel uncomfortable, so it is preferably set to 0.10 seconds or more, more preferably 0.15 seconds or more, and even more preferably 0.20 seconds or more. On the other hand, from the perspective of keeping the elapsed time Te within the above range, the increase time Tx1 is preferably set to 0.50 seconds or less. Regarding the holding time Ty1, if the upper limit is set to approximately 0.80 seconds or less, the possibility of avoiding the above-mentioned inconveniences even for users with fast eating and drinking behaviors increases. Further, regarding the inversion time Tx2, if it is too short, the user may feel a stimulus and feel uncomfortable, so it is preferably set to 0.20 seconds or more. On the other hand, from the perspective of keeping the elapsed time Te within the above range, the inversion time Tx2 is preferably set to 0.50 seconds or less.

[0023] Regarding the holding time Ty2 of the set value Is2 of the current in the anodic stimulation, an appropriate range of the time length for maintaining the taste modification effect may be determined according to the environment such as the length of the user's eating and drinking actions and the type of food and drink, and the holding time Ty2 may be set according to the determined appropriate range.

[0024] Next, the set values Is1 and Is2 of the current will be described. Regarding the set values Is1 and Is2 of the current, their absolute values may be set to be equal to each other or may be set to be different from each other. Regarding the absolute values of the set values Is1 and Is2 themselves, appropriate settings can be made according to the target taste modification effect. As a guideline, it is preferably set in the range of 0.01 mA to 1.00 mA, more preferably in the range of 0.05 mA to 0.70 mA, and even more preferably in the range of 0.05 mA to 0.50 mA. However, when the absolute values of the set value Is1 in the cathode stimulation and the set value Is2 in the anode stimulation are relatively large, there is a possibility that the user may easily feel the electrotaste. Alternatively, when the absolute value of the set value Is2 in the anode stimulation is equal to or greater than the absolute value of the set value Is1 in the cathode stimulation, the effect of the anode stimulation may be relatively large and the user may easily feel the electrotaste. In order to avoid such inconveniences, the absolute values of the set values Is1 and Is2 may be set to be equal to each other, and the upper limit of the absolute value may be set to 0.30 mA or less. Also, when the set values Is1 and Is2 are set to be equal, from the viewpoint of expressing the taste modification effect, it is preferable to set the lower limit of the absolute values of the set values Is1 and Is2 to 0.25 mA or more. Alternatively, setting the magnitude relationship of the absolute values of the set values Is1 and Is2 such that the absolute value of the set value Is1 in the cathode stimulation is greater than the absolute value of the set value Is2 in the anode stimulation is also one of the preferable countermeasures.

[0025] The current waveform shown in FIG. 4 is an example, and the waveform may be set in consideration of various matters such as the purpose of applying an electrical stimulus, that is, from the viewpoint of how to modify the taste and present it to the user 1, the type of the food or drink 2 to be the target of taste modification, or the preferences and other personalities of the user 1. In the example of FIG. 4, the current values at the rise time Tx1 and the reversal time Tx2 are changed at a constant rate of increase, but the changes in these currents may be quadratic curves or other non-linear changes. Also, at the hold times Ty1 and Ty2, the current value may not be fixed at a constant value and may be changed within an acceptable range. For example, the current waveform may be set to an appropriate waveform such as a sine wave or a sawtooth wave. As long as such a change can be recognized as being set as the target value of the current for applying the cathode stimulus and the anode stimulus, it is possible to regard it as the set value of the current in each of the cathode stimulus and the anode stimulus.

[0026] In the above form, a noise reduction means is provided to reduce the sense of discomfort, but the noise reduction means is not necessarily essential. When the influence of the noise component is relatively small, the noise reduction means may be omitted. Even when the noise reduction means is omitted, when the above-described hold time Ty1, elapsed time Te, set values of the current Is1, Is2, etc. are set within their suitable ranges, as compared with the case where they are set outside the suitable ranges, it is possible to improve the taste modification effect while keeping the current value relatively small.

[0027] As long as the food or drink to which the present invention presents taste can pass an electric current for generating an electric stimulus, various foods and drinks may be included. If the food or drink contains moisture, it is possible to pass an electric current. Preferably, the food or drink containing 20% by weight or more of moisture, more preferably 25% by weight or more, and still more preferably 30% by weight or more of moisture can be targeted. The effect of modifying taste can be exerted on various foods and drinks as long as they contain taste components. For example, when enhancing the saltiness of a food or drink containing salt, the present invention can be preferably applied to a food or drink containing 0.05% by weight or more of salt, more preferably 0.1% by weight or more, and still more preferably 0.15% or more of salt. Specific foods and drinks include noodles such as ramen, soups, meat dishes such as sausages and tempura, and meat processed products, fish dishes such as grilled fish and fish roe, and fishery processed products, egg dishes and egg processed products, tofu dishes and tofu processed products, cheese, processed cooking products, vegetable dishes and vegetable processed products, powdered food dishes, fried foods, hot pot dishes, simmered dishes such as curry, alcoholic beverages such as beer and wine, near-water beverages, sports beverages (isotonic beverages), fruit juice beverages, milk beverages, vegetable juice beverages, acidic beverages, carbonated beverages, whey beverages, coffee beverages, black tea beverages, green tea beverages, oolong tea beverages, barley tea beverages, energy drinks, or non-alcoholic beverages such as beer-taste beverages can be mentioned as the targets of taste modification according to the present invention. The taste to be modified is not limited to saltiness, and various tastes such as sweetness, sourness, umami, bitterness, astringency, pungency, lipid taste, carbonation feeling, and alcohol feeling can be modified and presented by the present invention.

[0028] The taste enhancement effect (e.g., saltiness), the sense of discomfort, and the degree of metallic taste in the present invention can be easily and clearly determined by trained panelists. General methods can be used for the evaluation criteria and the way of summarizing the evaluations among panelists. The number of panelists for evaluating the taste enhancement effect (e.g., saltiness), the sense of discomfort, and the degree of metallic taste in the present invention may be one, but from the perspective of obtaining a more objective evaluation, the lower limit of the number of panelists can be, for example, two or more, preferably three or more. Also, from the perspective of implementing the evaluation test more simply, the upper limit of the number of panelists can be, for example, twenty or less, ten or less. When there are two or more panelists, for the evaluation of the taste enhancement effect (e.g., saltiness), the sense of discomfort, and the degree of metallic taste, the average of the evaluations of all panelists regarding the taste enhancement effect (e.g., saltiness), the sense of discomfort, and the degree of metallic taste of the food or beverage sample may be adopted. When integer evaluation points are assigned to each evaluation criterion, the average value of the evaluation points of all panelists may be adopted as the evaluation of the taste enhancement effect (e.g., saltiness), the sense of discomfort, and the degree of metallic taste. As described above, when adopting the average value of the evaluation points, a value obtained by rounding the first or second decimal place (preferably the second decimal place) of the average value may be adopted. In addition, when there are two or more panelists, in order to reduce the variation in the evaluations of each panelist, it is preferable to perform an operation of standardizing the evaluation criteria so that the evaluation criteria of each panelist are as consistent as possible before conducting the actual sensory evaluation test. Such a standardization operation includes evaluating the taste intensity of a plurality of types of food or beverage samples with known taste enhancement effects (e.g., saltiness), as well as the degree of discomfort and the degree of metallic taste by each panelist, and then comparing the evaluation points to confirm that there are no significant deviations in the evaluation criteria of each panelist. Also, by such a prior standardization operation regarding the evaluation criteria, when the evaluation points are given at any of a plurality of levels (e.g., any of the five levels of 1, 2, 3, 4, 5), it is preferable to make the standard deviation of the evaluations of the taste enhancement effect (e.g., saltiness), the sense of discomfort, and the degree of metallic taste by each panelist within 0.5.

Example

[0029] Next, the tests conducted to confirm the effects of the present invention will be described. The test conditions are as follows.

[0030] (1) Regarding test conditions [Test apparatus] For the test, as shown in FIG. 1, an apparatus configured with electrodes and an electrical stimulation generation unit configured as shown in FIG. 3 was used as the test apparatus. However, a commercial power supply of 100 V AC was used as the external power supply, which was converted to DC of 20 V and 2.25 A by an AC adapter and supplied to the boost circuit. In the test apparatus, stainless metal was used for both the first electrode and the second electrode. The first electrode was configured to be held by the subject's hand, and the second electrode was connected to a conductive ladle. The conductive ladle was placed in a cup containing a sample of food or drink. Regarding the noise reduction unit, an inductor, model number LQM21PN4R7MGRD, manufactured by Murata Manufacturing Co., Ltd., was used for the noise reduction unit 17A for the purpose of reducing noise components derived from the external power supply, and an inductor, type MLZ2012, model number MLZ2012N101LT000, manufactured by TDK Corporation, was used for the noise reduction unit 17B corresponding to the internal transmission frequency of the boost circuit.

[0031] [Food and drink samples] The following were prepared as samples of food and drink to be ingested. · Test food sample: A commercially available low-salt instant miso soup was prepared with 1.5 times the amount of hot water than the specified amount. The amount of salt equivalent per meal was 1.2 g, and the salt equivalent of the test food sample was 0.5 wt%. · Test food conditions: The test food sample was consumed at room temperature (20 - 25 °C).

[0032] [Evaluation method] · Subjects Three subjects were selected who were confirmed by pre-examination to be able to distinguish differences in saltiness intensity at a salt concentration of 0.03% by weight. Before the actual sensory evaluation test, the appropriateness of the selected subjects was confirmed as follows. That is, in order to reduce the variation in the evaluations of each subject, a plurality of known food and drink samples were used to evaluate the saltiness enhancement effect, discomfort, and the degree of electrotaste as taste intensities. Taste presentation was performed by applying an electrode for electrical stimulation to the tongue. The evaluation scores of each subject were compared, and it was confirmed that there was no significant deviation in the evaluation criteria among the subjects. Furthermore, it was also confirmed that the standard deviation of the evaluations of the saltiness enhancement effect, discomfort, and the degree of electrotaste by each subject was within 0.5. · Method of ingesting food and drink and method of evaluation Each subject was made to ingest the test food sample using the test device. Ingestion was performed by the method in which each subject directly put their mouth on the cup containing the test food sample placed in a cup with a conductive spoon. During ingestion, a current for taste stimulation was supplied between the electrodes from the electrical stimulation generation unit, and each subject was given points according to the criteria in Tables 1 to 3 below for each of the saltiness enhancement effect, sense of energization, and electrotaste, thereby obtaining a sensory evaluation. The saltiness enhancement effect is an index evaluated as an index indicating the degree of taste modification effect. The sense of energization is an unnatural feeling that may be felt in the body part close to the electrode when a current is passed, and is an index evaluated as an index indicating the degree of discomfort. After obtaining the sensory evaluation, the value obtained by rounding off the third decimal place of the average value of the evaluation scores of all the subjects was determined as the average value of the evaluation results. Also, based on the free offer from the subject, the problem due to the time difference from when the food and drink was put in the mouth until the modified taste was perceived, that is, the unnaturalness of the timing described above, was also evaluated as another index indicating the degree of discomfort.

[0033]

Table 1

[0034]

Table 2

[0035]

Table 3

[0036] Regarding the saltiness enhancement effect in Table 1, an evaluation of 3 points or more was considered "effective", and regarding the energized feeling in Table 2 and the electro-taste in Table 3, evaluations of 3 points or less were each considered "no problem".

[0037] (2) Confirmation of the influence of the holding time of the cathode stimulation and the elapsed time until the start of the anode stimulation Tests were conducted to confirm the influence of the holding time of the cathode stimulation and the elapsed time until the start of the anode stimulation on the saltiness enhancement effect and the like. In that test, as shown in Fig. 4, current control was applied such that the cathode stimulation was made prior and then the polarity was reversed to the anode stimulation, and the increase time Tx1, the holding time Ty1, and the reversal time Tx2 were set as in Test Examples 1 to 5 in Table 4. The saltiness enhancement effect and the energized feeling in each test example were evaluated according to the above evaluation method. In any of Test Examples 1 to 5, the absolute values of the set current values Is1 and Is2 were each 0.50 mA, and the holding time Ty2 in the anode stimulation was set to 0.80 seconds.

[0038]

Table 4

[0039] The evaluation results of the saltiness enhancement effect and the energized feeling in Test Examples 1 to 5 are as shown in Table 4. The evaluation results show the average value of the evaluation scores of each subject to two decimal places in addition to the individual evaluation scores for each subject. The three subjects were designated as P1 to P3. For the saltiness enhancement effect, the higher the score, the higher the evaluation, and for the energized feeling, the lower the score, the higher the evaluation. Therefore, the difference between the average values of the two was calculated and shown in the rightmost column of Table 4. The difference in the average value can be used as an index indicating that the expression of the saltiness enhancement effect and the suppression of the energized feeling are achieved to a greater extent as the value is larger.

[0040] According to the comparison of Test Examples 1 to 5, in Test Examples 1, 3 to 5 where the holding time Ty1 in the cathode stimulation is 0.50 seconds, the average value of the saltiness enhancement effect is 4. Despite the set value Is2 of the current during the anode stimulation being a relatively small value of 0.50 mA, it can be confirmed that a sufficient saltiness enhancement effect is obtained by performing the cathode stimulation first. On the other hand, in Test Example 2 where the holding time Ty1 is set to 0.25 seconds, the average value of the saltiness enhancement effect is less than 3, and the effect of performing the cathode stimulation first is not necessarily fully obtained. Regarding the sense of electric shock, in any of Test Examples 1 to 5, the average value of the evaluation scores is within 3 points or less, which is set as the standard of "no problem". However, when comparing the degree of manifestation of the saltiness enhancement effect and the suppression effect of the sense of electric shock using the difference in the average values as an index, Test Example 2 has the lowest difference in the average values. The reason is considered to be that the holding time Ty1 is short. Summarizing the above, if the holding time Ty1 in the cathode stimulation is 0.30 seconds or more, which is greater than that of Test Example 2, it can be judged that while suppressing the set value Is2 of the current in the anode stimulation to a relatively small value, the saltiness enhancement effect can be manifested, and furthermore, the sense of electric shock can also be moderately suppressed. If the holding time Ty1 is set to 0.50 seconds or more as in Test Examples 1, 3 to 5, the effect of performing the cathode stimulation first can be more reliably exerted. From the above, it is judged that the holding time Ty1 may be 0.30 seconds or more with some margin from the 0.25 seconds of Test Example 2. Preferably, if the holding time Ty1 is set to 0.35 seconds or more, more preferably 0.40 seconds or more, and most preferably 0.50 seconds or more, it is speculated that the sense of electric shock, that is, the unnatural feeling that may be felt near the electrode, can be suppressed to a non-problematic level, and the saltiness enhancement effect and the sense of electric shock can be more reliably made compatible.

[0041] Regarding the influence of the elapsed time Te, it was evaluated as the unnaturalness of the timing due to the free offers from the subjects. As a result, for any of Test Examples 1 to 5 including Test Example 1 with the maximum elapsed time Te, there were no offers from the subjects, and it was confirmed that it was within the allowable range without any particular problems. The elapsed time Te is judged to be 1.30 seconds or less with some margin for 1.20 seconds of Test Example 1 as long as the holding time Ty1 secures 0.30 seconds or more as described above. Therefore, preferably, if the elapsed time Te is set to 1.20 seconds or less, more preferably 1.00 seconds or less, it is inferred that more surely, there will be no time difference (unnaturalness of timing) between the timing of taking food or drink into the mouth and the taste perception, and both the saltiness enhancing effect and the sense of electric current can be achieved simultaneously.

[0042] Also, when setting the elapsed time Te to be equal to or less than the above upper limit, the upper limit of the holding time Ty1 is within a range not exceeding the elapsed time Te. Considering that the increase time Tx1 was 0.15 seconds and the reversal time Tx2 was 0.20 seconds in Test Example 4, it is a value obtained by subtracting the increase time Tx1 and the reversal time Tx2 from the upper limit of the holding time Te of 1.30 seconds, i.e., 0.95 seconds or less, preferably 0.85 seconds or less, more preferably 0.75 seconds or less, and most preferably 0.65 seconds or less. It is inferred that there will be no time difference (unnaturalness of timing) between the timing of taking food or drink into the mouth and the taste perception, and both the saltiness enhancing effect and the sense of electric current can be achieved simultaneously. Regarding the lower limit of the elapsed time Te, it is sufficient if it is 0.70 seconds or more with some margin for 0.60 seconds of Test Example 2, and it is inferred that it is more certain if it is set with the 0.85 seconds or more of Test Example 3 as a reference.

[0043] Regarding the increase time Tx1, considering that even though all of Test Examples 2 to 4 are 0.15 seconds, there is a difference in the average value difference, and even in Test Example 1 with the maximum value, the average value difference is good. Although it should not be strictly limited, it is inferred that setting its lower limit to generally 0.10 seconds or more, preferably 0.15 seconds or more, more preferably 0.20 seconds or more, and the upper limit to 0.50 seconds or less is sufficient. Regarding the inversion time Tx2 as well, considering that even though all of Test Examples 2, 3, and 5 are 0.20 seconds, there is a difference in the average value difference, and even in Test Example 1 with the maximum value, the average value difference is good. Although it should not be strictly limited, it is inferred that setting it within the range of 0.20 seconds or more and 0.50 seconds or less is sufficient.

[0044] In addition, in Test Examples 1 to 5, an attempt was made to evaluate the electrotaste as well. However, in any of the test examples, the average value of the evaluation scores exceeded 3, and no difference was observed among the test examples. Therefore, there is room for further consideration regarding the reduction of electrotaste for the various parameters set in Test Examples 1 to 5. On the other hand, the purpose of suppressing the set value of the current in the anodic stimulation to a level where the user's sense of electric shock is reduced or eliminated while expressing the saltiness enhancement effect to a degree that the user can perceive can be achieved, as judged from the comparison of Test Examples 1 to 5, by setting at least the holding time Ty1 to 0.30 seconds or more as described above. Furthermore, if the elapsed time Te is set to 1.30 seconds or less, an effect of suppressing the unnaturalness of the timing can be expected.

[0045] (3) Confirmation of the influence of the set value of the current A test was conducted to confirm the effects of the set values Is1 and Is2 of the current in cathode stimulation and anode stimulation. In that test, as shown in Figure 4, current control was applied such that cathode stimulation was performed first and then the polarity was reversed to anode stimulation, and the set values Is1 and Is2 of the current were set as shown in Test Examples 6 to 13 in Table 5. Note that the set values Is1 and Is2 in Table 5 are absolute values. The three subjects were designated as P1 to P3. In Test Examples 6 to 13, the current increase time Tx1 for cathode stimulation was set to 0.30 seconds, the current holding time Ty1 was set to 0.50 seconds, the reversal time Tx2 was set to 0.40 seconds, and the current holding time Ty2 for anode stimulation was set to 0.80 seconds. These set values are the same as those in Test Example 1 in Table 4. In Test Example 6, since the absolute values of the set values Is1 and Is2 of the current are both 0.50 mA, the conditions are the same as those in Test Example 1.

[0046]

Table 5

[0047] The evaluation results of the saltiness enhancement effect, the sensation of electric current passing through, and the electric taste in Test Examples 6 to 13 are as shown in Table 5. The evaluation results show, in addition to the individual evaluation scores for each subject, the average value of the evaluation scores for each subject with two decimal places. For the saltiness enhancement effect, the higher the score, the higher the evaluation; for the sensation of electric current passing through and the electric taste, the lower the score, the higher the evaluation. Therefore, as the difference in the average values of these evaluation results, the value obtained by subtracting the average value of the sensation of electric current passing through and the average value of the electric taste from the average value of the saltiness enhancement effect was calculated and shown in the rightmost column of Table 5. In Table 5, the larger the difference in the average value, the more it can be used as an indicator showing that both the manifestation of the saltiness enhancement effect and the suppression of the sensation of electric current passing through and the electric taste are achieved.

[0048] As is clear from Table 5, in Test Example 6 where the absolute values of the set values Is1 and Is2 of the currents for cathode stimulation and anode stimulation are set equal to each other and the absolute value is 0.5 mA, although an evaluation of "there is an effect" for the saltiness enhancement effect and "no problem" for the sense of energization is obtained, there is no sufficient reduction effect regarding the metallic taste. On the other hand, in Test Examples 10 and 11 where the absolute values of the set values Is1 and Is2 are set equal to each other, since the absolute values are set small at 0.30 mA and 0.10 mA, not only the sense of energization but also the metallic taste has been improved to 3 or less, which is the criterion of "no problem". Further, in Test Examples 7, 8, 9, 11, and 13 where the absolute value of the set value Is1 in cathode stimulation is set larger than the absolute value of the set value Is2 in anode stimulation, although the saltiness enhancement effect somewhat decreases as the set value Is2 decreases, regarding the sense of energization and the metallic taste, the evaluation score is sufficiently suppressed to be smaller than 3, which is the criterion of "no problem". In light of those results, it can be judged that if the absolute values of the set values Is1 and Is2 of the current are set equal to each other and to 0.30 mA or less, or if the absolute value of the set value Is1 in cathode stimulation is set larger than the absolute value of the set value Is2 in anode stimulation, it is possible to suppress the sense of energization and the metallic taste to an acceptable level while expressing the saltiness enhancement effect to an appropriate degree.

[0049] When setting the magnitude relationship of the above set values to Is1 = Is2, by setting the absolute value of the set value Is1 of the current within the range of 0.30 mA or less, which is the set value Is1 in Test Example 10, the energization feeling and the electrical taste become "acceptable". When it is set to 0.50 mA, the electrical taste exceeds the "acceptable" range. Therefore, it is inferred that if it is 0.30 mA or less, the degree of the electrical taste will be "acceptable". Therefore, in the case of set values Is1 = Is2, by preferably setting the absolute values of the set values Is1 and Is2 to 0.30 mA or less, it is possible to achieve any of the saltiness enhancement effect, the energization feeling, and the electrical taste. Regarding the lower limit of the absolute values of the set values Is1 and Is2, in Test Example 12 where it is 0.10 mA, the "saltiness enhancement effect" is below 3 which is the level of "effective". Considering environmental conditions such as individual differences among users, the degree of the target taste modification effect, and differences in the food and drink items targeted, by setting it to 0.25 mA or more, corresponding effects can be expected.

[0050] Also, when setting the magnitude relationship of the set values Is1 and Is2 to Is1 > Is2, from the perspective of the manifestation of the effect, the absolute value of the set value Is1 of the current in the cathode stimulation is understood to be reliable within the range of 0.50 mA or less, which is the set value Is1 in Test Examples 6 to 9. However, considering environmental conditions such as individual differences among users, the degree of the target taste modification effect, and differences in the food and drink items targeted, there is a possibility of obtaining corresponding effects even if it is 0.70 mA or less, and further 1.00 mA or less. Regarding the lower limit of the absolute values of the set values Is1 and Is2, as an example, corresponding effects can also be expected even if it is 0.05 mA or more, and further 0.01 mA or more.

[0051] The various aspects of the present invention derived from each of the above-described embodiments, modification examples, and examples are described below. In the following description, corresponding components illustrated in the accompanying drawings are appended in parentheses in order to facilitate the understanding of each aspect of the present invention, but the present invention is not limited to the illustrated forms by this.

[0052] A taste presentation device (10) according to an aspect of the present invention includes a first electrode (11) and a second electrode (12) provided so as to be able to form an electric circuit between food and drink (2) ingested by a user and the user's body, and an electric stimulation generation means (13) for supplying a current for generating an electric stimulation between the first electrode and the second electrode. The electric stimulation generation means is provided to start supplying the current in a state of cathode stimulation in which the second electrode becomes a cathode, and then change the direction of the current so as to switch to a state of anode stimulation in which the second electrode becomes an anode. In the cathode stimulation, the holding time (Ty1) for holding the current at the set value (Is1) of the current in the cathode stimulation is set to be 0.30 seconds or more.

[0053] A taste presentation method according to an aspect of the present invention includes a procedure of providing a first electrode (11) and a second electrode (12) so as to be able to form an electric circuit between food and drink (2) ingested by a user and the user's body, and a procedure of supplying a current for generating an electric stimulation between the first electrode and the second electrode. In the procedure of supplying the current, the supply of the current is started in a state of cathode stimulation in which the second electrode becomes a cathode, and then the direction of the current is changed so as to switch to a state of anode stimulation in which the second electrode becomes an anode. In the cathode stimulation, the holding time (Ty1) for holding the current at the set value (Is1) of the current in the cathode stimulation is set to be 0.30 seconds or more.

[0054] Cathode stimulation can suppress the discomfort and metallic taste felt by the user to a relatively low level, while the taste modification effect is weak. On the other hand, anode stimulation has a relatively large taste modification effect, but there is a tendency to cause discomfort and metallic taste. The discomfort and metallic taste in anode stimulation increase as the current value during anode stimulation increases. Also, the taste modification effect tends to be more effectively manifested as the amount of change in current when starting anode stimulation is larger. Therefore, if cathode stimulation is performed first and then the polarity is reversed to perform anode stimulation, it is possible to increase the amount of change in current value during the reversal to enhance the taste modification effect, and at the same time, relatively suppress the set value of the current during anode stimulation to suppress the increase in discomfort and metallic taste. Furthermore, the effect of performing cathode stimulation first is affected by the holding time during which the current value should be maintained at a predetermined set value in cathode stimulation. The shorter the holding time, the lower the effect of performing cathode stimulation first. Therefore, by setting the holding time to 0.30 seconds or more, it is possible to achieve the manifestation of the effect of performing cathode stimulation first, suppress the current value in anode stimulation to be low, and cause the user to feel the taste modification effect.

[0055] In the taste presentation device according to the above aspect, the holding time in the cathode stimulation may be set to 0.50 seconds or more. According to this, the effect of performing cathode stimulation first can be more surely manifested.

[0056] The elapsed time (Te) from the start of current supply in the cathode stimulation until the current reaches the set value (Is2) of the current in the anode stimulation in the anode stimulation may be set to 1.30 seconds or less. The taste modification effect is manifested after the anode stimulation starts. If the elapsed time until the current reaches the set value in the anode stimulation is prolonged, the manifestation of the taste modification effect is delayed with respect to the user's eating and drinking actions, which becomes a factor for the user to feel discomfort. Therefore, by setting the elapsed time to 1.30 seconds or less, it is possible to manifest the taste modification effect at a time in accordance with the user's eating and drinking actions, and reduce or eliminate discomfort.

[0057] In the taste presentation device of the above aspect, the absolute value of the set value (Is1) of the current in the cathode stimulation may be set to be larger than the absolute value of the set value (Is2) of the current in the anode stimulation. When such a magnitude relationship is set, while suppressing the set value of the current during anode stimulation to be relatively small, the change amount of the current value during polarity inversion can be increased to more surely exhibit the taste modification effect.

[0058] When the absolute value of the set value of the current in the cathode stimulation is larger than the absolute value of the set value of the current in the anode stimulation, the absolute value of the set value (Is1) of the current in the cathode stimulation may be set to 0.50 mA or less. According to this, by further limiting the absolute value of the current during anode stimulation to be smaller than 0.50 mA, it is possible to enhance the discomfort and the suppressing effect of the metallic taste during anode stimulation.

[0059] Alternatively, the absolute values of the set values (Is1, Is2) of the current in each of the cathode stimulation and the anode stimulation may be equal to each other and set to be 0.25 mA or more. Also, the absolute values of the set values (Is1, Is2) of the current in each of the cathode stimulation and the anode stimulation may be equal to each other and set to be 0.30 mA or less. According to these forms, while suppressing discomfort and the metallic taste, the taste modification effect can be surely exhibited.

[0060] When setting the elapsed time to 1.30 seconds or less, the absolute values of the set values of the current in each of the cathode stimulation and the anode stimulation are set to 0.50 mA or less, the increase time (Tx1) from the start of the supply of the current in the cathode stimulation until the current reaches the set value is set to 0.10 seconds or more, and the inversion time (Tx2) while changing the current from the set value in the cathode stimulation to the set value in the anode stimulation may be set to 0.20 seconds or more. According to this, it is possible to suppress a sudden change in the current during cathode stimulation and during the inversion from cathode stimulation to anode stimulation, and suppress or avoid the occurrence of discomfort caused by the change in the current.

[0061] In the taste presentation device of the above aspect, the first electrode may be provided so as to contact the user's body, and the second electrode may be provided so as to contact the food or drink. By arranging the electrodes in this way, an electric circuit can be formed between the food or drink and the user's body when the food or drink is ingested.

[0062] The electric stimulation generation means may include noise reduction means (17A, 17B) for reducing noise components in the current. By reducing the noise components in the current supplied between the electrodes with the noise reduction means, it is possible to suppress the influence of the noise components on discomfort and the taste of electricity, and enhance the intended taste modification effect.

[0063] The noise reduction means (17A) may be provided so as to reduce noise components derived from the power supply. When the electric stimulation generation means includes a booster circuit (14), the noise reduction means (17B) may be provided so as to reduce noise components corresponding to the internal transmission frequency in the booster circuit. According to these forms, it is possible to effectively reduce the noise components that cause deterioration of discomfort and the taste of electricity.

Explanation of Reference Numerals

[0064] 10 Taste presentation device 11 First electrode 12 Second electrode 13 Electric stimulation generation unit (electric stimulation generation means) 14 Booster circuit 17A, 17B Noise reduction unit (noise reduction means) Tx1 Increase time in cathode stimulation Ty1 Holding time in cathode stimulation Tx2 Inversion time Te Elapsed time

Claims

1. A first electrode and a second electrode provided so as to be able to form an electric circuit between the food and drink ingested by the user and the body of the user; An electric stimulation generating means for supplying a current for generating an electric stimulation between the first electrode and the second electrode; The electric stimulation generating means is provided to start supplying the current in a state of cathode stimulation in which the second electrode becomes a cathode, and then change the direction of the current so as to switch to a state of anode stimulation in which the second electrode becomes an anode; In the cathode stimulation, the holding time for which the current should be held at the set value of the current in the cathode stimulation is set to 0.30 seconds or more, a taste presentation device.

2. The taste presentation device according to claim 1, wherein the holding time in the cathode stimulation is set to 0.50 seconds or more.

3. The taste presentation device according to claim 1, wherein the elapsed time from the start of supplying the current in the cathode stimulation until the current reaches the set value of the current in the anode stimulation in the anode stimulation is set to 1.30 seconds or less.

4. The taste presentation device according to claim 1, wherein the absolute value of the set value of the current in the cathode stimulation is set to be larger than the absolute value of the set value of the current in the anode stimulation.

5. The taste presentation device according to claim 4, wherein the absolute value of the set value of the current in the cathode stimulation is set to 0.50 mA or less.

6. The taste presentation device according to claim 1, wherein the absolute values of the set values of the current in each of the cathode stimulation and the anode stimulation are equal to each other and set to 0.25 mA or more.

7. The taste presentation device according to claim 1, wherein the absolute values of the set values of the current in each of the cathode stimulation and the anode stimulation are equal to each other and set to 0.30 mA or less.

8. The absolute values of the set values of the current in each of the cathode stimulation and the anode stimulation are set to 0.50 mA or less, The increase time from the start of supplying the current in the cathode stimulation until the current reaches the set value is set to 0.10 seconds or more, and the inversion time while changing the current from the set value in the cathode stimulation to the set value in the anode stimulation is set to 0.20 seconds or more, the taste presentation device according to claim 3.

9. The taste presentation device according to any one of claims 1 to 8, wherein the first electrode is provided so as to contact the user's body, and the second electrode is provided so as to contact the food or drink.

10. The taste presentation device according to any one of claims 1 to 8, wherein the electrical stimulation generation means includes noise reduction means for reducing noise components in the current.

11. The taste presentation device according to claim 10, wherein the noise reduction means is provided so as to reduce noise components derived from the power supply.

12. The taste presentation device according to claim 10, wherein the electrical stimulation generation means includes a booster circuit, and the noise reduction means is provided so as to reduce noise components corresponding to the internal transmission frequency in the booster circuit.

13. A procedure for providing a first electrode and a second electrode so as to form an electrical circuit between the food or drink ingested by the user and the user's body, and a procedure for supplying a current for generating an electrical stimulus between the first electrode and the second electrode, wherein in the procedure for supplying the current, the supply of the current is started in a state of cathode stimulation in which the second electrode becomes a cathode, and then the direction of the current is changed so as to switch to a state of anode stimulation in which the second electrode becomes an anode, In the cathode stimulation, the holding time for holding the current at the set value of the current in the cathode stimulation is set to be 0.30 seconds or more. A taste presentation method.

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