JP4313417B1 - Apparatus and method for controlling color shade of tea extract - Google Patents

Abstract

The present invention provides an apparatus and a method capable of controlling the color of a solution after extraction because the evaluation of tea quality depends on the color tone in addition to its flavor.
It is known that catechins, which are the main components of tea, are colorless, but are changed to colored tannins by oxidation. Therefore, the oxidation action of catechin is controlled by using a pair of electrodes 1 and 2 sandwiching the proton conducting membrane 3 and a pair of noble metal electrodes sandwiching a membrane of a solid electrolyte having a functional group capable of transferring hydrogen ions. To control the color of the tea extract.
[Selection] Figure 1

Description

  The present invention relates to an apparatus and a method for controlling the color of a solution by electrolyzing with an electrode and oxidizing and reducing a coloring substance contained in the solution.

In general, the taste of food may be influenced not only by taste but also by other sensations. This is also common to tea, and the quality of tea may be influenced by the appearance evaluation, for example, “It is better if the color is bright and deep”. Therefore, the influence of the change in tea color on the quality is great. Therefore, if the color tone of tea can be freely changed, the quality of tea can be improved. Therefore, there are techniques for controlling the color tone of the extracted liquid by various means such as adjusting the temperature, pressure and the state of the tea leaf during extraction.
JP 2001-17368 A Japanese Unexamined Patent Publication No. 2006-191851

  The prior art works at the time of tea extraction and cannot be applied to tea after extraction. In addition, as means for controlling the tea after extraction, heating, addition of a reagent, and the like can be mentioned, but it is difficult to control the color at that time in terms of adjustment. In addition, the color tone of tea changes depending on the extraction time, the temperature of the penetrant, and the like, and the tea taste changes with the change of color. Therefore, it is difficult to change the color of tea without changing the taste. If I could adjust the color of the tea extract without adding anything, I thought it would be possible to enjoy dark tea without changing the taste.

  Therefore, we investigated the use of electricity as a color control means that can be used in the solution after extraction and is easy to control. It is known that catechins, which are the main components of tea, are colorless, but are converted to colored tannins by oxidation. Therefore, the above problem is solved by proposing an apparatus and a method for controlling the color of a solution containing catechin, which uses this oxidation action and is easily controlled by electricity. The present invention controls the color of a solution by electrolyzing a solution containing a coloring substance using an electrode sandwiched between conductive films capable of transferring charges and oxidizing and reducing the coloring substance contained in the solution. Apparatus and method thereof. Specifically, using a pair of electrodes sandwiched between proton conducting membranes and a pair of noble metal electrodes sandwiching a membrane of a solid electrolyte having a functional group capable of passing hydrogen ions, the color of a solution such as tea leaves containing catechins To control.

  By immersing a pair of electrodes in a solution containing catechin and performing electrolysis, the catechin undergoes an oxidation-reduction reaction to change to colored tannin, and the color concentration of the solution changes. The color concentration of the solution can be controlled by appropriately adjusting the electrolysis time and current. By interposing a proton conducting membrane between the electrodes, electrolysis can be performed even with a poorly conductive solution such as tea extract. As a result, it is difficult to control the tea after extraction, it is difficult to control it, it is not heating or the addition of reagents, it is possible to control the color by electricity, you can drink dark tea without changing the taste, etc. It can be said that the way of enjoying is spread.

[Overall configuration]
The present invention is an apparatus comprising a pair of electrodes 1 and 2 and a proton conductive membrane 3 sandwiched between these plates (see FIG. 1).

[electrode]
The electrodes 1 and 2 used in the present invention are excellent in corrosion resistance, and desirably do not elute ions and impurities that affect the human body during electrolysis. For example, electrodes such as platinum, titanium, and platinum-coated titanium can be used. In the examples, a platinum-coated titanium plate corresponding to the above matters was adopted.
It is desirable that the lead wire connecting portion is curved so that the cathode and the anode do not contact (short-circuit) (see FIG. 1).

[Proton conducting membrane 3]
The proton conducting membrane of the present invention is used for passing electricity in a black tea extract having poor electrical conductivity. The proton conductive membrane is preferably an ion exchange membrane type, and in the examples, Nafion 324 manufactured by DuPont was used. It is desirable that the size be slightly larger than the electrodes 1 and 2 so that the cathode and the anode do not contact (short-circuit) (see FIG. 1).

[Others]
The electrodes 1 and 2 and the proton conducting membrane 3 need to be in close contact with both sides of the membrane for the passage of electricity. In this example, the electrode contact portion was fixed using an insulating plastic clip (see FIG. 2).
Examples in which the present invention is applied to black tea extract are described below.

The sample black tea was prepared by extracting 1.8 g of Nitto black tea tea bag made by Mitsui Norin Co., Ltd. for 5 minutes with 1 L of tap water heated for 7 minutes in a microwave oven. FIG. 3 shows an experimental apparatus. It was used to sandwich the proton conductive membrane (area 7.2cm ²⁾ as an electrode between a pair of platinum coated titanium (electrode area 4.0 cm ^2). The electrode and the proton conductive membrane were tightly fixed with an insulator. Electrolysis was performed for 90 minutes at 2.0 A at a constant voltage of 36.7 V while cooling and stirring with a cool stirrer. To observe the color change, collect 10 ml each of the reaction solution for each electrolysis time (0, 5, 10, 15, 20, 30, 40, 60, 90 minutes) and dilute 6 times with ion-exchanged water. Then, the absorbance at a wavelength λ = 480 nm, which is a brown absorption wavelength, was measured using a spectrophotometer (Hitachi U0080D).

[Comparative Example 1]
Further, in order to verify the influence of electrolysis, as a comparative example 1, the proton conducting membrane was not sandwiched between the electrodes, and instead, the same operation was performed with a glass plate interposed as a spacer. The experimental results are shown in FIG.

[Consideration on Example 1 and Comparative Example 1]
From FIG. 4, compared to Comparative Example 1 in which the proton conductive membrane was not sandwiched by electrolysis using the product of the present invention with improved conductivity across the proton conductive membrane, even in black tea with originally poor conductivity, It can be seen that the color of black tea becomes darker as the electrolysis time increases. This is because the use of a proton exchange membrane increases the conductivity between the electrodes, so that the progress of electrolysis is accelerated and the color change also increases. If a proton conducting membrane is not used, the electrical conductivity between the electrodes is low and the current does not flow easily. Therefore, it is considered that the progress of electrolysis is extremely slow and the color change is small.

  Examples in which the present invention is applied to a solution containing catechin will be described below. A sample of green tea was prepared by dissolving 0.5 g of “Shincha-boiled green tea (upper rice cake) 0.5 g, heated in a microwave oven for 7 minutes. The results of the experiment are shown in FIG.

  As a solution containing catechin, “Healthia Water” manufactured by Kao Corporation was used, and the other operations were carried out in the same manner as in Example 1, and the change in the color of Helsia Water was observed. In addition, when the absorbance was observed with a spectrometer, the measurement was performed without diluting the reaction solution 6 times as in Example 1. The experimental results are shown in FIG.

[Consideration regarding Examples 1 to 3]
It is said that the color of tea is largely due to tannin (a mixture of catechins). The chemical formula of the oxidation polymer of theaflavin, epicatechin, and epigallocatechin gallate, which are the main components of tannin, is shown in FIG. The colorless catechin is oxidatively polymerized into tannins, and these molecules appear colored because they have long conjugated chains as shown in FIG. Black tea is an extract containing tannin peculiar to black tea, which is produced by fermenting tea leaves and oxidatively polymerizing catechins in the tea leaves with an oxidase. Therefore, the phenomenon that the color of black tea in FIG. 4 becomes dark is presumed that the catechins contained in black tea are oxidatively polymerized by electrolysis and the above-mentioned substances are generated. In addition, it is presumed that the solution containing catechins other than black tea was also oxidatively polymerized to generate chromogenic substances.

  Therefore, in order to verify this, the same experiment was performed with a beverage not containing catechin, and the color change was observed. In this comparative experiment, the same brown color as black tea can be compared with the absorbance at an absorption wavelength λ = 480 nm, and barley tea, which is a solution extracted from barley seeds instead of tea leaves, is contained in tea but barley tea. In order to verify the effect of caffeine not contained, coffee was roasted and ground, and coffee was extracted from the components of the powder, and electrolysis was used to compare the color changes.

[Comparative Example 2]
Hereinafter, Comparative Example 2 in which the present invention is applied to a solution containing no catechin and the difference is compared will be described. The same operation as in Example 1 was performed using barley tea obtained by extracting 10 g of Rojo tea tea bag made by Copro Co., Ltd. for 5 minutes with 1 L of tap water heated for 7 minutes in a microwave oven as a sample of a solution not containing catechin. The change in the color of barley tea was observed. The experimental results are shown in FIG.

[Comparative Example 3]
The same operation as in Example 1 was carried out using a coffee solution prepared by dissolving 0.5 g of Nescafe “Roasted Nescafe Flavored Instant Coffee” in 1 L of tap water heated for 7 minutes in a microwave oven as a sample of a solution containing no catechin. Observed coffee color change. The experimental results are shown in FIG.

  From the experimental results, the rate of change in absorbance of each solution due to electrolysis is defined as “(change rate) = (absorbance at wavelength λ = 480 nm) / (absorbance at 0 minutes of electrolysis time)” and is shown in FIG.

  4-10, it can be read that the absorbance increases with electrolysis in each solution containing catechins as described above. The color change occurred in the solution containing catechin, but almost no change was observed in barley tea. This is presumed to be caused by a component unique to tea leaves not contained in barley tea. As described above, black tea contains catechins that are not contained in barley tea. Therefore, this color change, as originally expected, changed the molecules such as catechins, which are not contained in barley tea, to tannin, theaflavin, thearvidin and their oxidation polymers by electrolysis, and the color became darker. It is thought that.

  Since it is possible to control the color concentration of a solution containing catechin, by applying the present invention to a bath agent containing catechin or a dye containing catechin, a decrease in the freshness of the color tone over time can be controlled. Can be used for a long time.

It is an apparatus diagram of the present invention. It is the best embodiment figure of this invention. It is an apparatus figure in the Example of this invention. It is the figure which showed the light absorbency change of the black tea by the electrolysis of Example 1 and Comparative Example 1. It is the figure which showed the light absorbency change of the green tea by the electrolysis of Example 2. FIG. FIG. 6 is a graph showing changes in the absorbance of Helsia water due to electrolysis in Example 3. It is the figure which showed the chemical formula of the substance of the main component of a tannin. It is the figure which showed the light absorbency change of barley tea by the electrolysis of the comparative example 2. It is the figure which showed the light absorbency change of the coffee by the electrolysis of the comparative example 3. It is the figure which showed the change rate of the light absorbency accompanying electrolysis in each solution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode 2 Electrode 3 Proton conductive film 4 Clip 5 Sample 6 Stirrer 7 Cool stirrer 8 Ammeter 9 Voltmeter

Claims (2)

Catechin using a device that controls the color of the solution by electrolyzing the solution containing catechin using a pair of electrodes sandwiched between proton conductive membranes and oxidizing and reducing the catechin contained in the solution. Method for controlling the color of the solution containing. Using a pair of noble metal electrodes with a solid electrolyte membrane having a functional group capable of passing hydrogen ions, the solution containing catechin is electrolyzed and the catechin contained in the solution is oxidized and reduced. A method for controlling the color of a solution containing tea catechins using an apparatus for controlling the color of the solution.