Taste sense presentation device and taste sense 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 and the like that uses electrical stimulation to change the taste perceived by a user. [Background technology]

[0002] For users who are forced to eat bland meals with limited salt and sugar content due to health management or other reasons, methods have been proposed for enhancing the saltiness and other flavors to increase satisfaction by presenting food and drink with modified tastes that match the user's preferences using electrical stimulation. For example, a taste presentation device has been proposed that supplies a square-wave current of a constant frequency between an anode that contacts a body part such as the user's neck and a cathode that contacts the food and drink, thereby enhancing the user's sense of taste (see Patent Document 1). Another device has been proposed that supplies a biphasic current to electrodes placed in contact with the user's tongue or the like to electrically stimulate nerve branches that carry taste sensations to the brain (see Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-42991 [Patent Document 2] Special Publication No. 2010-517675 Summary of the Invention [Problem to be solved by the invention]

[0004] When attempting to enhance or otherwise modify the saltiness using electrical stimulation, the user may experience an unnatural sensation or an electric taste. The term "unnatural sensation" refers to an unnatural sensation experienced by the user due to the time lag between putting food or drink in the mouth and sensing the modified taste, or an unnatural sensation felt in a body part close to an electrode when an electric current is passed through the body. The electric taste refers to a metallic or sour taste felt when an electric current is passed through the body. If the current value is reduced to avoid such inconvenience, the saltiness enhancement effect may be weakened, making it difficult for the user to perceive it.

[0005] Therefore, an object of the present invention is to provide a taste presentation device and a taste presentation method that can produce a taste modification effect that can be perceived by the user while keeping the current value relatively small. [Means for solving the problem]

[0006] A taste presentation device according to one embodiment of the present invention comprises a first electrode and a second electrode arranged to form an electrical circuit between the food or drink ingested by a user and the user's body, and an electrical stimulation generating means for supplying a current between the first electrode and the second electrode to generate an electrical stimulation, wherein the electrical stimulation generating means is arranged to start supplying the current in a state of cathodic stimulation in which the second electrode is the cathode, and then change the direction of the current so that the state switches to a state of anodic stimulation in which the second electrode is the anode, and wherein, in the cathodic stimulation, the retention time for maintaining the current at the set value for the cathodic stimulation is set to be 0.30 seconds or more.

[0007] A taste presentation method according to one embodiment of the present invention includes the steps of providing a first electrode and a second electrode so as to form an electrical circuit between the food or drink ingested by a user and the user's body, and supplying a current between the first electrode and the second electrode to generate an electrical stimulation, wherein the current supply step starts the supply of the current in a state of cathodic stimulation in which the second electrode is the cathode, and then changes the direction of the current so that the state switches to anodic stimulation in which the second electrode is the anode, and during the cathodic stimulation, the retention time for maintaining the current at the set value for the cathodic stimulation is set to be 0.30 seconds or more. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of a taste presentation device according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram showing another example of a taste presentation device. [Figure 3] FIG. 2 is a diagram showing a configuration example of an electrical stimulation generating unit. [Figure 4] FIG. 4 is a diagram showing an example of a current waveform supplied from an electrical stimulation generating unit. DETAILED DESCRIPTION OF THE INVENTION

[0009] Fig. 1 shows an example of a taste presentation device according to an embodiment of the present invention. The taste presentation device 10 in Fig. 1 includes a first electrode 11 provided to be in contact with a user 1, a second electrode 12 provided to be in contact with food or drink 2 ingested by the user 1, and an electrical stimulation generator 13 as an example of electrical stimulation means that supplies a current between the electrodes 11 and 12 to generate an electrical stimulation.

[0010] The first electrode 11 is attached to the hand or arm of the user 1, for example. 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 holds it in their hand. The second electrode 12 is attached to 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 stirrer 3 a immersed in a beverage, which is an example of food or drink 2, or the stirrer 3 a itself may be used as the second electrode 12. Alternatively, as shown in FIG. 2 , the second electrode 12 may be attached to a utensil 3 b, such as a fork, spoon, or chopsticks (including so-called cutlery) used to ingest food, which is an example of food or drink 2, or the utensil 3 b may be used as the second electrode 12. In any case, first electrode 11 and second electrode 12 may be configured in any suitable form as long as an electrical circuit is formed between food or drink 2 ingested by user 1 and the body of user 1, thereby allowing a current to flow to electrically stimulate an organ that senses taste, such as the tongue, of user 1. The tableware 3 to which second electrode 12 should be attached is not limited to the examples shown in Figures 1 and 2, and the second electrode 12 may be attached to plates, bowls, rice bowls, rice bowls, bowls, cups, glasses, mugs, sake cups, sake cups, bowls, mugs, teacups, tumblers, water bottles, chopsticks, forks, spoons, knives, spoons, skewers, toothpicks, straws, etc.

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

[0012] Current output unit 15 shapes a current waveform according to a command value given by current control unit 16 and supplies the current to electrodes 11, 12. Current control unit 16 is configured as a computer unit using, for example, a microprocessor, and generates a current waveform command value according to current waveform setting information given by PC 20, and controls the current supplied to electrodes 11, 12 by outputting this to current output unit 15. For example, current control unit 16 can control the direction of the current so that anodal stimulation, in which second electrode 12 is the anode, and cathodal stimulation, in which second electrode 12 is the cathode, can be selected, and the magnitude (current value) and rate of change of the current can be controlled to target values ​​given by PC 20. An example of current control will be described later.

[0013] The noise reduction unit 17 reduces noise components contained in the current supplied between the electrodes 11 and 12. The noise reduction unit 17 is an example of a noise reduction means. The inventors' research revealed that noise components contained in the current contribute to worsening the discomfort and electric taste, and that the greater the noise component, the stronger the discomfort and electric taste tend to be. By providing the noise reduction unit 17, the impact of minute noise components on the discomfort and electric taste is suppressed, enhancing the taste modification effect. The term "reduction" refers to a relative reduction in noise components in the current compared to when the noise reduction unit 17 is not provided. It is not limited to cases where some noise components remain, but also encompasses processes such as "removal," "elimination," and "elimination" that reduce noise components to an undetectable level. "Modification" refers to changing the taste perceived by the user 1 from the original taste perceived without the application of electrical stimulation, and "presentation" refers to allowing the user 1 to experience a modified taste.

[0014] The noise reduction unit 17 may be configured by using various elements, such as capacitors, inductors, or ferrite cores, used to reduce noise components in various electrical circuits, either singly or in combination. In the example of Fig. 3, a noise reduction unit 17A is provided on the input side of the boost circuit 14 to reduce noise components originating from an external power supply, and a noise reduction unit 17B is provided on the output side of the boost circuit 14 to remove noise components corresponding to an internal oscillation frequency generated during boosting of the boost circuit 14. However, the positions and number of the noise reduction units 17 may be changed as appropriate depending on the internal configuration of the electrical stimulation generation unit 13, such as the position of a noise source.

[0015] Next, an example of current control by current control unit 16 will be described. Fig. 4 shows an example of a current waveform controlled by current control unit 16, with the horizontal axis representing time and the vertical axis representing current value. The current value is represented by a positive value when second electrode 12 serves as an anode, and a negative value when it serves as a cathode. In the following description, a change in current value, whether positive or negative, will be referred to as an "increase" if the absolute value increases.

[0016] In the example of FIG. 4 , assume that at time t1, user 1 ingests food or drink 2, establishing electrical continuity between electrodes 11 and 12 and forming an electrical circuit including user 1. When the formation of an electrical circuit is detected at time t1, current control unit 16 sets the current direction to cathodal stimulation, i.e., the first electrode 11 as the anode and the second electrode 12 as the cathode, and begins supplying current. The current value is gradually increased to a set value Is1 over a predetermined increase time Tx1. The set value Is1 is a value set as a target value of the current to be maintained during cathodal stimulation. After reaching the set value Is1, current control unit 16 maintains the set value Is1 for a predetermined retention time Ty1. After the retention time Ty1 has elapsed, the current control unit 16 changes the current direction 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 a set value Is2 over a predetermined reversal time Tx2. The set value Is2 is a value set as a target value of the current to be maintained during anodic stimulation. After the current value reaches the set value Is2 at time t2, the current control unit 16 maintains the set value Is2 for a predetermined maintenance time Ty2, and stops the supply of current when the maintenance time Ty2 has elapsed.

[0017] As shown in the example of Figure 4, when the polarity is reversed after the current supply begins, the set current values ​​Is1 and Is2 can be kept relatively small while the polarity reversal can be used to fully elicit the taste-altering effect, thereby enhancing the taste-modifying effect. Cathodic stimulation tends to minimize the discomfort felt by the user 1 but have a weak taste-modifying effect, while anodic stimulation tends to maximize the taste-modifying effect but induce a relatively strong discomfort and electric taste. Therefore, by first performing cathodic stimulation to minimize the discomfort, and then reversing the polarity to perform anodic stimulation, the amount of change in the current value during the reversal can be increased, enhancing the taste-modifying effect. In addition, by keeping the set current value Is2 during anodic stimulation relatively small, the discomfort and electric taste can be reduced.

[0018] In the example of Figure 4, the various parameters that define the current waveform, namely, the current setting values ​​Is1 and Is2, the increase time Tx1 until the setting value Is1 is reached, the holding time Ty1 of the setting value Is1 for cathodic stimulation, the reversal time Tx2 until the polarity is reversed from cathodic stimulation to anodic stimulation and the setting value Is2 for anodic stimulation is reached, and the holding time Ty2 of the setting value Is2 for anodic stimulation, are set according to environmental conditions such as individual differences between users 1, the degree of the desired taste modification effect, or the type of food or drink 2 to be ingested, and their preferred ranges are as follows:

[0019] First, we will explain the retention time Ty1 of the current setting value Is1 for cathodic stimulation. If the retention time Ty1 is too short, it may be difficult to achieve the effect of prioritizing cathodic stimulation, and it is an important parameter for achieving the effect of cathodic stimulation. From the perspective of achieving the effect of cathodic stimulation, the retention time Ty1 should be set to 0.30 seconds or more, preferably 0.50 seconds or more.

[0020] On the other hand, if the retention time Ty1 is excessively long, the onset of the taste-modifying effect using anodic stimulation in response to the user's eating and drinking behavior may be delayed, resulting in an unnatural sensation. However, there are individual differences in users' eating and drinking behavior, and the upper limit of the retention time Ty1 may also change in relation to this. When targeting users who eat and drink relatively quickly, it is necessary to have the taste-modifying effect appear earlier than users who eat and drink slowly, so it is preferable to set the upper limit of the retention time Ty1 relatively short. On the other hand, when targeting users who eat and drink relatively slowly, there is more time for the taste-modifying effect to be exerted, so it is possible to set the upper limit of the retention time Ty1 relatively long.

[0021] However, even if only the upper limit of the retention time Ty1 is limited, if the increase time Tx1 or the reversal time Tx2 is set too long, the time required for the effect of anodic stimulation to manifest will be prolonged. If this time is prolonged, the time lag between putting food or drink in the mouth and sensing the modified taste, i.e., the time difference between the timing when the user expects to sense the taste and the timing when the taste is actually sensed, will increase, which can cause a problem of discomfort to the user. Hereinafter, this problem may be referred to as "unnatural timing." Therefore, to appropriately set the time until the onset of anodic stimulation, rather than limiting the upper limit of the retention time Ty1 alone, it is preferable to set an upper limit on the total time of the increase time Tx1, the retention time Ty1, and the reversal time Tx2—in other words, the elapsed time Te (=Tx1+Ty1+Tx2) from time t1 when the supply of current for cathodic stimulation begins to time t2 when the current for anodic stimulation reaches the set value Is2 after cathodic stimulation. The retention time Ty1 can be set within this range of the elapsed time Te. The elapsed time Te should be set to 1.30 seconds or less, preferably 1.20 seconds or less, and more preferably 1.00 seconds or less. The lower limit of the elapsed time Te can be set to 0.70 seconds or more, preferably 0.85 seconds or more, assuming that the retention time Ty1 is set to the above lower limit or more. However, since the effect of cathodal stimulation is significantly affected by the retention time Ty1, it is sufficient to set the retention time Ty1 to the above lower limit or more while prioritizing keeping the elapsed time Te to the above upper limit or less; it is not necessarily necessary to strictly limit the lower limit of the elapsed time Te itself.

[0022] Even when the lower limit of the retention time Ty1 and the upper limit of the elapsed time Te are set within the above ranges, the increase time Tx1, retention time Ty1, and reversal time Tx2 can be appropriately combined. As a guideline, since an excessively short increase time Tx1 may cause the user to feel irritation and discomfort, it is recommended to set it to 0.10 seconds or more, preferably 0.15 seconds or more, and more preferably 0.20 seconds or more. On the other hand, from the viewpoint of keeping the elapsed time Te within the above range, it is recommended to set the increase time Tx1 to 0.50 seconds or less. Setting the upper limit of the retention time Ty1 to approximately 0.80 seconds or less increases the likelihood of avoiding the above-mentioned inconveniences even for users who eat and drink quickly. Furthermore, since an excessively short reversal time Tx2 may cause the user to feel irritation and discomfort, it is recommended to set it to 0.20 seconds or more. On the other hand, from the viewpoint of keeping the elapsed time Te within the above range, it is recommended to set the reversal time Tx2 to 0.50 seconds or less.

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

[0024] Next, the current setting values ​​Is1 and Is2 will be described. The current setting values ​​Is1 and Is2 may be set so that their absolute values ​​are equal to each other, or so that they are different from each other. The absolute values ​​of the setting values ​​Is1 and Is2 themselves can be set appropriately depending on the desired taste-modifying effect, but as a guide, they should be set in the range of 0.01 mA to 1.00 mA, preferably 0.05 mA to 0.70 mA, and more preferably 0.05 mA to 0.50 mA. However, if the absolute values ​​of the setting value Is1 for cathodic stimulation and the setting value Is2 for anodic stimulation are relatively large, the user may be more likely to perceive an electric taste. Alternatively, if the absolute value of the setting value Is2 for anodic stimulation is equal to or greater than the absolute value of the setting value Is1 for cathodic stimulation, the effect of anodic stimulation may be relatively large, making the user more likely to perceive an electric taste. To avoid such inconveniences, it is advisable to set the absolute values ​​of the set values ​​Is1 and Is2 equal to each other and set the upper limit of the absolute values ​​to 0.30 mA or less. Furthermore, when the set values ​​Is1 and Is2 are set equal, 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, from the viewpoint of achieving a taste-modifying effect. Alternatively, one preferable solution is to set the magnitude relationship between the absolute values ​​of the set values ​​Is1 and Is2 so that the absolute value of the set value Is1 for cathodic stimulation is greater than the absolute value of the set value Is2 for anodic stimulation.

[0025] The current waveform shown in FIG. 4 is merely an example, and the waveform may be set taking into consideration various factors, such as the purpose of providing the electrical stimulation, i.e., how the taste should be modified and presented to the user 1, the type of food or beverage 2 to be modified, or the preferences and other characteristics of the user 1. In the example of FIG. 4, the current values ​​during the increase time Tx1 and the reversal time Tx2 are changed at a constant rate of increase, but these current changes may also be nonlinear, such as a quadratic curve. The current values ​​during the retention times Ty1 and Ty2 may also be varied within an acceptable range rather than being fixed at a constant value. For example, the current waveform may be set to an appropriate waveform, such as a sinusoidal waveform or a sawtooth waveform. Even if such changes are made, they can be considered as the current setting values ​​for the cathodic and anodic stimulations, as long as they are recognized as target values ​​for the currents for providing the cathodic and anodic stimulations.

[0026] In the above embodiment, the noise reduction means is provided to reduce the sense of discomfort, but the noise reduction means is not necessarily required. If the influence of noise components is relatively small, the noise reduction means may be omitted. Even if the noise reduction means is omitted, if the retention time Ty1, elapsed time Te, current setting values ​​Is1 and Is2, etc., are set within their preferred ranges, it is possible to improve the taste modification effect while keeping the current value relatively low compared to when they are set outside the preferred ranges.

[0027] The food and beverages that can be subjected to the taste sensation by the present invention may include various foods and beverages as long as they can pass an electric current to generate an electrical stimulus. Any food and beverage containing water can be subjected to the electric current, but the target foods and beverages are preferably foods and beverages containing 20% ​​or more by weight of water, more preferably 25% or more by weight, and even more preferably 30% or more by weight. The taste-modifying effect can be exerted on various foods and beverages as long as they contain taste components. For example, when enhancing the saltiness of salty foods and beverages, the present invention can be suitably applied to foods and beverages containing 0.05% or more by weight of salt, more preferably 0.1% or more by weight, and even more preferably 0.15% or more by weight of salt. Specific examples of foods and beverages that can be subject to taste modification by the present invention include noodles such as ramen, soups, meat dishes and processed meat products such as sausages and fried chicken, fish dishes and processed seafood products such as grilled fish and fish eggs, egg dishes and processed egg products, tofu dishes and processed tofu products, cheese, cooked and processed foods, vegetable dishes and processed vegetable products, flour dishes, fried foods, hot pots, stews such as curry, alcoholic beverages such as beer and wine, near-water beverages, sports drinks (isotonic drinks), fruit juice drinks, milk beverages, vegetable juice drinks, acidic beverages, carbonated beverages, whey beverages, coffee drinks, black tea drinks, green tea drinks, oolong tea drinks, barley tea drinks, energy drinks, and non-alcoholic beverages such as beer-flavored beverages. The taste that can be modified is not limited to saltiness; various tastes such as sweetness, sourness, umami, bitterness, astringency, stimulating taste, fatty taste, carbonated taste, and alcoholic taste can be modified and presented by the present invention.

[0028] The taste (e.g., salty) enhancement effect, the degree of strangeness, and the intensity of the electric taste in the present invention can be easily and clearly determined by a trained panelist. The evaluation criteria and the method for summarizing the panelists' evaluations can be general methods. The number of panelists evaluating the taste (e.g., salty) enhancement effect, the degree of strangeness, and the intensity of the electric taste in the present invention may be one. However, from the viewpoint 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. Furthermore, from the viewpoint of conducting the evaluation test more easily, the upper limit of the number of panelists can be, for example, 20 or less, or 10 or less. When there are two or more panelists, the evaluation of the taste (e.g., salty) enhancement effect, the degree of strangeness, and the intensity of the electric taste of the food or beverage sample may be performed by using the average of the evaluations of all panelists regarding the taste (e.g., salty) enhancement effect, the degree of strangeness, and the intensity of the electric taste of the food or beverage sample. When an integer evaluation score is assigned to each evaluation criterion, the average of the evaluation scores of all panelists may be used as the evaluation of the taste (e.g., saltiness) enhancement effect, the degree of strangeness, and the intensity of the electric taste. As described above, when the average evaluation score is used, the average may be rounded to one or two decimal places (preferably two decimal places). Note that when there are two or more panelists, in order to reduce the variability in the evaluations of each panelist, it is preferable to standardize the evaluation criteria so that the evaluation criteria of each panelist are as consistent as possible before conducting the actual sensory evaluation test. Such standardization may involve having each panelist evaluate the taste intensity of multiple food and beverage samples known to have a taste (e.g., saltiness) enhancement effect, as well as the degree of strangeness and the intensity of the electric taste, and then comparing the evaluation scores to ensure that there is no significant discrepancy between the evaluation criteria of each panelist. Furthermore, by standardizing the evaluation criteria in advance, when evaluation points are given on one of multiple levels (for example, one of five levels: 1, 2, 3, 4, and 5), it is preferable to ensure that the standard deviation of each panelist's evaluation of the taste (for example, saltiness) enhancement effect, discomfort, and intensity of the electric taste is within 0.5. [Example]

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

[0030] (1) Test conditions [Test equipment] For the test, the test equipment used had electrodes configured as shown in Figure 1 and an electrical stimulation generator configured as shown in Figure 3. However, a commercial 100V AC power supply was used as the external power source, which was converted to 20V, 2.25A DC by an AC adapter and supplied to the boost circuit. In the test equipment, both the first and second electrodes were stainless steel. The first electrode was configured to be held in the subject's hand, and the second electrode was connected to a conductive stirrer. The conductive stirrer was placed in a cup containing a food or beverage sample. Regarding the noise reduction section, noise reduction section 17A, which is intended to reduce noise components originating from the external power supply, used an inductor manufactured by Murata Manufacturing Co., Ltd., part number LQM21PN4R7MGRD. For noise reduction section 17B, which corresponds to the internal oscillation frequency of the boost circuit, an inductor of the MLZ2012 type manufactured by TDK Corporation, part number MLZ2012N101LT000, was used.

[0031] [Food and drink samples] The following food and drink samples were prepared: Tasting sample: Commercially available reduced-salt instant miso soup was prepared using 1.5 times the amount of hot water than the recommended amount. The salt equivalent per serving was 1.2g, and the salt equivalent of the tasting sample was 0.5% by weight. Tasting conditions: The samples were tasted at room temperature (20-25°C).

[0032] [Evaluation method] ·subject Three subjects were selected based on a preliminary test that confirmed their ability to distinguish between salty taste intensities at a salt concentration of 0.03% by weight. Prior to the actual sensory evaluation test, the suitability of the selected subjects was confirmed as follows: Specifically, to reduce variability in each subject's evaluation, they were asked to evaluate the saltiness enhancement effect, discomfort, and the intensity of the electric taste using several known food and beverage samples. Tastes were presented using an electrode for electrical stimulation placed on the tongue. The evaluation scores of each subject were compared to confirm that there was no significant discrepancy in the evaluation criteria between subjects. Furthermore, it was confirmed that the standard deviation of each subject's evaluation of the saltiness enhancement effect, discomfort, and the intensity of the electric taste was within 0.5. ·Method of intake and evaluation of food and drink Each subject consumed a food sample using the test device. The sample was placed in a cup equipped with a conductive stirrer, and each subject placed the cup directly to their mouth. During consumption, a taste stimulation current was applied between the electrodes from the electrical stimulation generator. A sensory evaluation was obtained by having each subject score the saltiness enhancement effect, the sense of electricity, and the electric taste according to the criteria in Tables 1 to 3 below. The saltiness enhancement effect was evaluated as an index of the degree of taste modification. The sense of electricity is an unnatural sensation that can be felt in parts of the body close to the electrodes when an electric current is applied, and was evaluated as an index of the degree of discomfort. After obtaining the sensory evaluation, the average score of all subjects was rounded to two decimal places to obtain the average evaluation result. In addition, based on the subject's free request, the time lag between putting the food or drink in the mouth and the perception of the modified taste, i.e., the unnatural timing described above, was also evaluated as another index of the degree of discomfort.

[0033] [Table 1]

[0034] [Table 2]

[0035] [Table 3]

[0036] For the saltiness enhancement effect in Table 1, a score of 3 or more was evaluated as "effective," and for the electric sensation in Table 2 and the electric taste in Table 3, a score of 3 or less was evaluated as "not problematic."

[0037] (2) Confirmation of the effects of the duration of cathodic stimulation and the time elapsed until the start of anodic stimulation Tests were conducted to confirm the influence of the duration of cathodic stimulation and the time elapsed until the start of anodic stimulation on the salty taste enhancement effect. In these tests, current control was applied in which cathodic stimulation preceded anodic stimulation and then reversed polarity to anodic stimulation, as shown in Figure 4. The increase time Tx1, the duration Ty1, and the reversal time Tx2 were set as shown in Test Examples 1 to 5 in Table 4, and the salty taste enhancement effect and the electrical sensation in each test example were evaluated according to the evaluation method described above. In all of Test Examples 1 to 5, the absolute values ​​of the current settings Is1 and Is2 were set to 0.50 mA, and the duration Ty2 of anodic stimulation was set to 0.80 seconds.

[0038] [Table 4]

[0039] The evaluation results of the salty taste enhancement effect and electric sensation in Test Examples 1 to 5 are shown in Table 4. The evaluation results show the individual evaluation scores for each subject as well as the average evaluation scores for each subject, rounded to two decimal places. The three subjects are represented as P1 to P3. The higher the score for the salty taste enhancement effect, the higher the evaluation, and the lower the score for the electric sensation, the higher the evaluation. Therefore, the difference between the two average values ​​was calculated and listed in the right-hand column of Table 4. The larger the difference in the average values, the more it can be used as an indicator of the achievement of both the salty taste enhancement effect and the suppression of the electric sensation.

[0040] Comparing Test Examples 1 to 5, the average saltiness enhancement effect was 4 in Test Examples 1 and 3 to 5, in which the cathodal stimulation retention time Ty1 was 0.50 seconds. This confirms that a sufficient saltiness enhancement effect can be achieved by performing cathodal stimulation first, despite the relatively small current setting value Is2 of 0.50 mA during anodal stimulation. On the other hand, in Test Example 2, in which the retention time Ty1 was set to 0.25 seconds, the average saltiness enhancement effect was less than 3, indicating that the effect of performing cathodal stimulation first is not necessarily sufficient. Regarding the sensation of electrical current, the average evaluation score for all Test Examples 1 to 5 was below 3 points, the standard for "no problem." However, when comparing the degree of saltiness enhancement and the suppression of electrical current sensation using the difference in the average values ​​as an indicator, Test Example 2 had the lowest difference in the average values. This is believed to be due to the short retention time Ty1. Considering the above, it can be concluded that if the retention time Ty1 for cathodic stimulation is 0.30 seconds or more, which is longer than that of Test Example 2, the salty taste enhancement effect can be achieved while keeping the current setting value Is2 for anodic stimulation relatively small, and furthermore, the electric sensation can be moderately suppressed. Setting the retention time Ty1 to 0.50 seconds or more, as in Test Examples 1, 3 to 5, can more reliably achieve the effect of prioritizing cathodic stimulation. From the above, it can be concluded that the retention time Ty1 should be 0.30 seconds or more, allowing for some leeway on the 0.25 seconds of Test Example 2. It is presumed that setting the retention time Ty1 to preferably 0.35 seconds or more, more preferably 0.40 seconds or more, and most preferably 0.50 seconds or more will suppress the electric sensation, i.e., the unnatural sensation sometimes felt near the electrodes, to an acceptable level, and more reliably achieve both the salty taste enhancement effect and the electric sensation.

[0041] The influence of the elapsed time Te was evaluated as the unnaturalness of the timing based on the subject's free request. As a result, no subjects reported any issues with any of Test Examples 1 to 5, including Test Example 1, which had the longest elapsed time Te, and it was confirmed that the elapsed time Te was within the acceptable range without any particular problems. As long as the retention time Ty1 was at least 0.30 seconds, it was determined that the elapsed time Te should be 1.30 seconds or less, allowing for some leeway over the 1.20 seconds of Test Example 1. Therefore, it is presumed that setting the elapsed time Te to 1.20 seconds or less, more preferably 1.00 seconds or less, would more reliably eliminate the time lag between the timing of putting food or drink in the mouth and the time of taste perception (unnatural timing), and would enable both the salty taste enhancement effect and the sensation of electricity to be achieved.

[0042] Furthermore, when setting the elapsed time Te below the above upper limit, the upper limit of the retention time Ty1 must be within a range that does not exceed the elapsed time Te, and 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 estimated that if the retention time Ty1 is set to 0.95 seconds or less, which is the value obtained by subtracting the increase time Tx1 and the reversal time Tx2 from the upper limit of 1.30 seconds for the retention time Te, preferably 0.85 seconds or less, more preferably 0.75 seconds or less, and most preferably 0.65 seconds or less, there will be no time lag between the timing of putting the food or drink in the mouth and the time of taste perception (unnatural timing), and both the salty taste enhancement effect and the sense of electricity will be achieved. Regarding the lower limit of the elapsed time Te, it is sufficient to set it to 0.70 seconds or more, with some leeway added to the 0.60 seconds of Test Example 2, and it is estimated that setting it to 0.85 seconds or more of Test Example 3 as a guideline will be more reliable.

[0043] Considering that the increase time Tx1 produced differences in the average values ​​even when it was 0.15 seconds in all of Test Examples 2 to 4, and that the difference in average values ​​was good even in Test Example 1, which had the maximum value, it is presumed that it is sufficient to set the lower limit to about 0.10 seconds or more, preferably 0.15 seconds or more, and more preferably 0.20 seconds or more, and the upper limit to 0.50 seconds or less. Considering that the reversal time Tx2 produced differences in the average values ​​even when it was 0.20 seconds in all of Test Examples 2, 3, and 5, and that the difference in average values ​​was good even in Test Example 1, which had the maximum value, it is presumed that it is sufficient to set the reversal time Tx2 in the range of 0.20 seconds or more and 0.50 seconds or less.

[0044] In addition, in Test Examples 1 to 5, an attempt was made to evaluate the electric taste. However, the average score exceeded 3 in all Test Examples, and no difference was observed between the Test Examples. Therefore, the various parameters set in Test Examples 1 to 5 need further consideration in terms of reducing the electric taste. On the other hand, comparing Test Examples 1 to 5, it can be determined that the goal of suppressing the current setting value for anodic stimulation to a level that reduces or eliminates the user's sense of electric current while exhibiting a salty taste enhancement effect that the user can perceive can be achieved by setting the retention time Ty1 to at least 0.30 seconds, as described above. Furthermore, setting the elapsed time Te to 1.30 seconds or less is expected to have the effect of suppressing the unnaturalness of the timing.

[0045] (3) Check the effect of the current setting value A test was conducted to confirm the effects of the current setting values ​​Is1 and Is2 on cathodic and anodic stimulation. In the test, current control was applied, in which cathodic stimulation preceded anodic stimulation and then reversed polarity to anodic stimulation, as shown in Figure 4. The current setting values ​​Is1 and Is2 were set as shown in Test Examples 6 to 13 in Table 5. The setting values ​​Is1 and Is2 in Table 5 are absolute values. The three subjects are designated P1 to P3. In Test Examples 6 to 13, the cathodic stimulation current increase time Tx1 was set to 0.30 seconds, the current hold time Ty1 was set to 0.50 seconds, the reversal time Tx2 was set to 0.40 seconds, and the anodic stimulation current hold time Ty2 was set to 0.80 seconds. These setting values ​​were the same as those in Test Example 1 in Table 4. Test Example 6 had the same conditions as Test Example 1, since the absolute values ​​of the current setting values ​​Is1 and Is2 were both 0.50 mA.

[0046] [Table 5]

[0047] The evaluation results of the salty taste enhancement effect, electric sensation, and electric taste in Test Examples 6 to 13 are shown in Table 5. The evaluation results show the individual evaluation scores for each subject as well as the average evaluation scores for each subject, rounded to two decimal places. The higher the score for the salty taste enhancement effect, the higher the evaluation, and the lower the score for the electric sensation and electric taste, the higher the evaluation. Therefore, the difference between the average values ​​of these evaluation results was calculated by subtracting the average values ​​for the electric sensation and electric taste from the average value for the salty taste enhancement effect, and these values ​​are listed in the right-hand column of Table 5. The larger the difference in the average values ​​in Table 5, the more it can be used as an indicator that the salty taste enhancement effect is achieved while the electric sensation and electric taste are suppressed.

[0048] As can be seen from Table 5, when the absolute values ​​of the set currents Is1 and Is2 for cathodic and anodic stimulation were set equal, Test Example 6, in which the absolute value was 0.5 mA, achieved a rating of "effective" for the salty taste enhancement effect and "not problematic" for the electric sensation, but did not achieve a sufficient reduction in the electric taste. In contrast, Test Examples 10 and 11, in which the absolute values ​​of the set currents Is1 and Is2 were set equal, were set small, at 0.30 mA and 0.10 mA, respectively, thereby improving both the electric sensation and the electric taste to below the "not problematic" standard of 3. Furthermore, in Test Examples 7, 8, 9, 11, and 13, in which the absolute value of the set current Is1 for cathodic stimulation was set larger than the absolute value of the set current Is2 for anodic stimulation, the salty taste enhancement effect decreased somewhat as the set current Is2 decreased, but the evaluation scores for the electric sensation and the electric taste were kept well below the "not problematic" standard of 3. In light of these results, it can be concluded that if the absolute values ​​of the current setting values ​​Is1 and Is2 are set equal to each other and not more than 0.30 mA, or if the absolute value of the setting value Is1 for cathodic stimulation is set greater than the absolute value of the setting value Is2 for anodic stimulation, it is possible to achieve an appropriate salty taste enhancement effect while suppressing the electrical sensation and taste to an acceptable level.

[0049] When the magnitude relationship of the set values ​​is set to Is1 = Is2, setting the absolute value of the current set value Is1 to a range of 0.30 mA or less, which is the set value Is1 in Test Example 10, results in "no problem" with the electric sensation and electric taste. Setting it to 0.50 mA puts the electric taste outside the "no problem" range. Therefore, it is inferred that the level of the electric taste will be "no problem" if the absolute value is 0.30 mA or less. Therefore, when the set value Is1 = Is2, the absolute values ​​of each of the set values ​​Is1 and Is2 are preferably set to 0.30 mA or less to achieve both the salty taste enhancement effect, the electric sensation, and the electric taste. Regarding the lower limit of the absolute values ​​of the set values ​​Is1 and Is2, considering that the "salty taste enhancement effect" in Test Example 12, which is 0.10 mA, falls below the "effective" level of 3, and considering environmental conditions such as individual user differences, the degree of the target taste modification effect, and differences in the target foods and beverages, setting them to 0.25 mA or more can be expected to provide a reasonable effect.

[0050] Furthermore, when the magnitude relationship between the set values ​​Is1 and Is2 is set such that Is1 > Is2, the absolute value of the set value Is1 of the current for cathodic stimulation is considered to be reliable from the viewpoint of effective expression when it is in the range of 0.50 mA or less, which is the set value Is1 of Test Examples 6 to 9. However, taking into consideration environmental conditions such as individual differences between users, the degree of the desired taste modification effect, and differences in the target foods and beverages, it is possible that a reasonable effect can be obtained even with a value of 0.70 mA or less, or even 1.00 mA or less. As for the lower limit of the absolute values ​​of the set values ​​Is1 and Is2, for example, a value of 0.05 mA or more, or even 0.01 mA or more can be expected to have a reasonable effect.

[0051] Various aspects of the present invention derived from the above-described embodiments, modifications, and examples will be described below. In the following description, to facilitate understanding of each aspect of the present invention, corresponding components shown in the accompanying drawings will be written in parentheses, but this does not mean that the present invention is limited to the illustrated forms.

[0052] A taste presentation device (10) according to one embodiment of the present invention comprises a first electrode (11) and a second electrode (12) arranged to form an electrical circuit between the food or drink (2) ingested by a user and the user's body, and an electrical stimulation generating means (13) for supplying a current to generate an electrical stimulation between the first electrode and the second electrode, wherein the electrical stimulation generating means starts supplying the current in a state of cathodic stimulation in which the second electrode is the cathode, and then changes the direction of the current so as to switch to a state of anodic stimulation in which the second electrode is the anode, and during the cathodic stimulation, a retention time (Ty1) for maintaining the current at a set value (Is1) for the cathodic stimulation is set to be 0.30 seconds or more.

[0053] A taste presentation method according to one embodiment of the present invention includes the steps of providing a first electrode (11) and a second electrode (12) so as to form an electrical circuit between the food or drink (2) ingested by a user and the user's body, and supplying a current between the first electrode and the second electrode to generate an electrical stimulus, wherein the current supply step starts the supply of the current in a state of cathodic stimulation in which the second electrode is the cathode, and then changes the direction of the current so as to switch to a state of anodic stimulation in which the second electrode is the anode, and during the cathodic stimulation, a retention time (Ty1) for maintaining the current at a set value (Is1) for the cathodic stimulation is set to be 0.30 seconds or more.

[0054] Cathodic stimulation reduces the discomfort and electric taste felt by the user, but has a weak taste-modifying effect. On the other hand, anodic stimulation increases the taste-modifying effect, but tends to induce discomfort and an electric taste. The discomfort and electric taste experienced by anodic stimulation increase with increasing current value during anodic stimulation. Furthermore, the taste-modifying effect tends to be more effective with increasing current change when anodic stimulation is initiated. Therefore, by performing cathodic stimulation first and then reversing the polarity to perform anodic stimulation, it is possible to ensure a large change in current value during reversal, thereby enhancing the taste-modifying effect, while keeping the current setting for anodic stimulation relatively low to suppress the increase in discomfort and an electric taste. Furthermore, the effect of performing cathodic stimulation first is affected by the retention time during which the current value must be maintained at a predetermined value during cathodic stimulation. The shorter the retention time, the less effective the cathodic stimulation becomes. Therefore, by setting the retention time to 0.30 seconds or more, it is possible to achieve the effect of prioritizing the cathodic stimulation, and while keeping the current value for the anodic stimulation low, it is possible to achieve a taste-modifying effect that the user can feel.

[0055] In the taste presentation device of the above aspect, the retention time of the cathodic stimulation may be set to 0.50 seconds or more, thereby more reliably achieving the effect of prioritizing the cathodic stimulation.

[0056] The elapsed time (Te) from the start of supply of the current during the cathodic stimulation until the current during the anodic stimulation reaches the set value (Is2) of the current during the anodic stimulation may be set to 1.30 seconds or less. The taste modifying effect is exerted after the anodic stimulation begins, and if the elapsed time until the current reaches the set value during the anodic stimulation is prolonged, the taste modifying effect is delayed in relation to the user's eating and drinking actions, causing the user to feel uncomfortable. Therefore, by setting the elapsed time to 1.30 seconds or less, the taste modifying effect can be exerted at a time that is in sync with the user's eating and drinking actions, thereby reducing or eliminating the feeling of discomfort.

[0057] In the taste presentation device of the above aspect, the absolute value of the set value (Is1) of the current for the cathodic stimulation may be set to be larger than the absolute value of the set value (Is2) of the current for the anodic stimulation. When such a magnitude relationship is set, the set value of the current for the anodic stimulation is kept relatively small, while the amount of change in the current value at the time of polarity reversal is increased, thereby more reliably achieving the taste modification effect.

[0058] When the absolute value of the set current value for cathodic stimulation is greater than the absolute value of the set current value for anodic stimulation, the absolute value of the set current value (Is1) for cathodic stimulation may be set to 0.50 mA or less. By limiting the absolute value of the current during anodic stimulation to be even smaller than 0.50 mA, it is possible to enhance the effect of suppressing discomfort and electric taste during anodic stimulation.

[0059] Alternatively, the absolute values ​​of the current setting values ​​(Is1, Is2) for the cathodic stimulation and the anodic stimulation may be equal to each other and set to 0.25 mA or more. Furthermore, the absolute values ​​of the current setting values ​​(Is1, Is2) for the cathodic stimulation and the anodic stimulation may be equal to each other and set to 0.30 mA or less. These configurations can reliably achieve a taste-modifying effect while suppressing discomfort and an electric taste.

[0060] When the elapsed time is set to 1.30 seconds or less, the absolute values ​​of the set current values ​​for each of the cathodic stimulation and the anodic stimulation may be set to 0.50 mA or less, the increase time (Tx1) from the start of current supply for the cathodic stimulation until the current reaches the set value may be set to 0.10 seconds or more, and the reversal time (Tx2) during which the current is changed from the set value for the cathodic stimulation to the set value for the anodic stimulation may be set to 0.20 seconds or more. This suppresses abrupt changes in current during cathodic stimulation and when reversing from cathodic stimulation to anodic stimulation, thereby suppressing or avoiding discomfort caused by changes in current.

[0061] In the taste presentation device of the above aspect, the first electrode may be provided so as to be in contact with the user's body, and the second electrode may be provided so as to be in contact with the food or drink. By arranging the electrodes in this manner, 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 electrical stimulation generating means may include noise reducing 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 reducing means, it is possible to suppress the effects of the noise components on discomfort and electric taste, and to enhance the intended taste modifying effect.

[0063] The noise reduction means (17A) may be provided to reduce noise components originating from a power source. When the electrical stimulation generating means includes a boost circuit (14), the noise reduction means (17B) may be provided to reduce noise components corresponding to an internal oscillation frequency of the boost circuit. These configurations make it possible to effectively reduce noise components that cause discomfort or a worsening of the electric taste. [Explanation of symbols]

[0064] 10 Taste presentation device 11 1st electrode 12 2nd electrode 13 Electrical stimulation generating unit (electrical stimulation generating means) 14 Boost circuit 17A, 17B Noise reduction unit (noise reduction means) Tx1 Increase time in cathodal stimulation Ty1 Retention time in cathodal stimulation Tx2 inversion time Te Elapsed Time

Claims

1. a first electrode and a second electrode provided so as to form an electrical circuit between the food or drink ingested by the user and the user's body; an electrical stimulation generating means for supplying a current between the first electrode and the second electrode to generate an electrical stimulation; The electrical stimulation generating means is configured to start supplying the current in a state of cathodic stimulation in which the second electrode is a cathode, and then change the direction of the current so as to switch to a state of anodic stimulation in which the second electrode is an anode, In the cathodic stimulation, the current is maintained at the set value for the cathodic stimulation for a retention time of 0.30 seconds or more.

2. The taste presentation device according to claim 1 , wherein the retention time of the cathodic 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 supply of the current in the cathodic stimulation until the current in the anodic stimulation reaches the set value of the current in the anodic 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 cathodic stimulation is set to be larger than the absolute value of the set value of the current in the anodic stimulation.

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

6. 2. The taste presentation device according to claim 1, wherein the absolute values ​​of the set currents for the cathodic stimulation and the anodic stimulation are equal to each other and are set to 0.25 mA or more.

7. 2. The taste presentation device according to claim 1, wherein the absolute values ​​of the set currents for the cathodic stimulation and the anodic stimulation are equal to each other and are set to 0.30 mA or less.

8. The absolute value of the set value of the current for each of the cathodal stimulation and the anodal stimulation is set to 0.50 mA or less, The taste presentation device of claim 3, wherein the increase time from the start of supplying the current in the cathodic stimulation until the current reaches the set value is set to 0.10 seconds or more, and the reversal time during which the current is changed from the set value in the cathodic stimulation to the set value in the anodic stimulation is set to 0.20 seconds or more.

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

10. 9. The taste presentation device according to claim 1, wherein the electrical stimulation generating means includes a noise reducing means for reducing noise components in the current.

11. The taste presentation device according to claim 10 , wherein the noise reduction means is provided to reduce noise components originating from a power source.

12. 11. The taste presentation device according to claim 10, wherein the electrical stimulation generating means includes a booster circuit, and the noise reducing means is provided to reduce noise components corresponding to an internal oscillation frequency in the booster circuit.

13. providing a first electrode and a second electrode in such a manner that an electrical circuit can be formed between the food or drink ingested by a user and the user's body; and applying an electrical current between the first electrode and the second electrode to generate an electrical stimulus; In the step of supplying the current, the supply of the current is started in a state of cathodic stimulation in which the second electrode is a cathode, and then a direction of the current is changed so as to switch to a state of anodic stimulation in which the second electrode is an anode; A taste presentation method in which, during the cathodic stimulation, the retention time for maintaining the current at the set value for the cathodic stimulation is set to be 0.30 seconds or more.

Images