KR20070078527A - Process for preparing caffeine free tea by employing supercritical carbondioxide - Google Patents

Abstract

A method of manufacturing caffeine-free tea by supercritical carbon dioxide extraction of green tea leaves, coffee beans, Oolong tea leaves or black tea leaves containing caffeine is provided. The method selectively removes only caffeine. A raw material for tea production containing caffeine is added with supercritical carbon dioxide containing 0.2 to 0.8%(w/w) of moisture at 40 to 80deg.C and 200 to 400 bars in an extraction device with an extraction tank, heat exchanger, pump, carbon dioxide storage tank, condenser, vacuum separator and pressure reducing valve. The raw material for tea production is green tea leaves, coffee beans, Oolong tea leaves or black tea leaves which contain caffeine.

Description

Process for Preparing Caffeine Free Tea by Employing Supercritical Carbondioxide}

The present invention relates to a method for producing tea from which caffeine has been removed using supercritical carbon dioxide. More specifically, the present invention relates to a method of preparing caffeine-free tea and a method of producing caffeine, which includes a step of selectively removing only caffeine included in food using supercritical carbon dioxide containing water. It is about the car removed.

Green tea is a favorite food of Koreans because of its unique flavor and many beneficial ingredients. Polyphenols and tannins, which are usually represented by catechins, are present at 10% or more and are rich in vitamins A, C, and E. In addition, it contains a lot of flavonoids, caffeine, carotene, and the like, as a mineral, the content of calcium, iron, manganese, zinc is particularly high. The efficacy of green tea is known from anti-oxidant effect, anti-cancer effect, hypoglycemic inhibitor, antibacterial, anti-allergic, cholesterol lowering, increased immunity. However, green tea contains a large amount of caffeine, so you should be careful of side effects such as central nervous excitement, insomnia, dehydration caused by arousal action, so you should refrain from taking excessive green tea.

In order to solve these drawbacks, attempts have been made to remove caffeine from green tea to make green tea without side effects, and actual mass production has been made. A common method used to remove caffeine from green tea is a method of extracting caffeine using an organic solvent. For example, Korean Patent Publication No. 1986-808 discloses a technology for fermenting shredded green tea in the air for at least 30 minutes and treating methylene chloride or ethylene trichloride to remove caffeine contained in tea. In No. 76840, the fraction obtained by partitioning and extracting green tea extract with ethyl acetate was passed through a Sephadex column using a mixed solution of chloroform and methanol as a developing solvent or elution solvent. The technique for extracting the is disclosed, the Republic of Korea Patent Registration No. 107522 discloses a technique for removing the caffeine contained in the green tea by extracting the green tea with chloroform. However, when such a method is used, the food is exposed to toxic organic solvents, and thus the situation is avoided when preparing the food.

Meanwhile, a method of using supercritical carbon dioxide has been proposed as a method for solving the disadvantages of the organic solvent extraction method. The electric method using only carbon dioxide in a pure supercritical state was able to overcome the disadvantages of the organic solvent extraction method in that the safety can be secured, but only caffeine is extracted and many other useful substances are removed together during the extraction process. Green tea treated with supercritical carbon dioxide loses its apparent green color and discolors to brown, has a disadvantage that many useful substances are lost in addition to flavor changes, and are not used.

If only caffeine can be selectively removed using supercritical carbon dioxide, it is possible to manufacture safe and high quality green tea, and efforts are being made to develop it.

Therefore, the inventors of the present invention sought to develop a method for selectively removing caffeine while minimizing the loss of useful components from green tea using supercritical carbon dioxide. As a result, when using supercritical carbon dioxide containing a certain amount of water, Only caffeine could be selectively removed from green tea, and this method was confirmed that the present invention can be applied to various teas including caffeine such as coffee, oolong tea, and black tea in addition to green tea, thereby completing the present invention.

After all, the main object of the present invention is to provide a method for producing a caffeine-free tea using supercritical carbon dioxide.

Another object of the present invention is to provide a caffeine-free tea produced by the electric method.

In order to extract the caffeine component using supercritical carbon dioxide, an extraction apparatus known in the art consisting of an extraction tank, a heat exchanger, a pump, a carbon dioxide storage tank, a chiller (cooling condenser), a pressure reducing separator, and a pressure reducing valve is used. See European Patent No. 925,724). In the electric extraction apparatus, the extraction tank serves to store green tea, the pump serves to pressurize the supercritical carbon dioxide, the heat exchanger serves to heat the supercritical carbon dioxide, and the pressure reducing valve extractor Depressurizes the supercritical carbon dioxide emitted from the decompression chamber, and the decompressor serves to decompress the supercritical carbon dioxide completely to separate gaseous carbon dioxide, and the chiller converts the decompressed carbon dioxide into supercritical carbon dioxide. In addition, the carbon dioxide storage tank serves to store supercritical carbon dioxide.

This supercritical carbon dioxide extractor is used to remove the caffeine component from the green tea as follows: first, green tea is added to the extraction bath, supercritical carbon dioxide passed through the pump and the heat exchanger is introduced into the bottom of the extraction bath, and then The extracted caffeine component and the supercritical carbon dioxide mixture are discharged to the top of the extraction tank, the discharged mixture is depressurized through a pressure reducing valve, the carbon dioxide is collected in a gaseous phase in a decompression separator, and the extracted caffeine component is collected. Will perform the steps.

The present inventors can effectively extract and remove the caffeine component from the green tea when using the above-described method, but the disadvantage that various useful ingredients such as α, β, γ and δ types of tocopherol present in green tea are lost in large quantities. In order to overcome, various studies have shown that caffeine is water soluble. In other words, when only pure supercritical carbon dioxide is used, various components contained in green tea are removed from the green tea without being distinguished, but when supercritical carbon dioxide mixed with a certain level of water is used, the temperature and pressure conditions are adjusted to control caffeine. It was predicted that only water-soluble components such as can be removed.

Therefore, the inventors have established a mixture ratio of water to be mixed with supercritical carbon dioxide and extraction conditions of caffeine using supercritical carbon dioxide mixed with water, and thus, supercritical carbon dioxide containing 0.2 to 0.8% (w / w) of water is produced. By using, when extracted at a pressure of 200 to 400 bar at a temperature of 40 to 80 ℃, it was found that only caffeine can be effectively selected and removed. In addition, it was confirmed that even when the method is applied to coffee, oolong tea, black tea, etc. other than green tea, only caffeine can be selectively removed without losing useful ingredients.

Accordingly, the method of manufacturing caffeine-free tea using the supercritical carbon dioxide of the present invention provides a water content of 0.2 to 0.8% (w / w) under conditions of 40 to 80 ° C. and 200 to 400 bar in a dimension material including caffeine. Including the supercritical carbon dioxide to include, including the process of extracting and removing caffeine from the electric dimension material, the dimension material including caffeine used at this time is not particularly limited, green tea leaves, coffee beans, oolong tea leaves, black tea leaves, etc. Preference is given to using.

Since the caffeine-free tea of the present invention is selectively removed only caffeine, it will be widely used in the development of tea processed products having high added value and new functional foods using the same.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention in more detail, it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited by these examples in accordance with the gist of the present invention. .

Example 1 Measurement of Caffeine Extraction Efficiency of Supercritical Carbon Dioxide Containing Water

Example 1-1 : Comparison of Caffeine Extraction Efficiency of Supercritical Carbon Dioxide According to the Addition of Water

Comparison of caffeine removal efficiency with the removal of caffeine using pure supercritical carbon dioxide and the removal of caffeine with supercritical carbon dioxide containing 0.35% moisture: extraction tank, heat exchanger, pump, carbon dioxide storage tank , 100 g of green tea leaves were filled in the extraction tank of the supercritical carbon dioxide extracting device consisting of a cooling condenser, a pressure reducing separator, and a pressure reducing valve, and caffeine was removed by supercritical carbon dioxide. At this time, the extraction temperature was 50 ℃, the pressure was 300bar, the supercritical carbon dioxide used for extraction was water-free or supercritical carbon dioxide containing 0.35% moisture, the flow rate of supercritical carbon dioxide is 50g / min 7 By extracting and removing caffeine for a time, green tea leaves from which caffeine was removed were obtained. Then, the obtained green tea leaves were dried, extracted with hot water at 80 ° C. for 30 minutes, and filtered to obtain a liquid component, which was purified by HPLC (fixed phase: AQUA 5μ C18, 250 × 4.6mm, mobile phase: 0.5% (v / v). ) It is applied to a concentration gradient solution of 10 to 60% (v / v) using acetic acid-containing water and methanol, elution rate: 1.0mL / min, and caffeine remaining in green tea leaves using an ultraviolet detector (260nm). The content of was measured, and the caffeine removal rate was calculated therefrom, and each was compared (see Table 1a).

Comparison of Caffeine Removal Efficiency from Green Tea According to Water Content in Supercritical Carbon Dioxide Water content Caffeine Content Before Extraction Caffeine Content After Extraction Caffeine Removal Rate 0% 0.35% 2.12% by weight 2.12% by weight 0.30% by weight 0.20% by weight Z 85.8% 90.6%

As shown in Table 1a, by removing the caffeine using supercritical carbon dioxide containing water it was found that the removal efficiency is improved by about 5.6%.

Example 1-2 : Comparison of useful component removal rate of supercritical carbon dioxide according to the addition of water

By removing the caffeine until the removal efficiency of caffeine is 90% by the same process as in Example 1-1, the content of tocopherol remaining in the green tea leaves was analyzed by HPLC (mobile phase: methanol, column: C18, detector: fluorescent detector). Excitation (298 nm) and emission (330 nm) were used to measure the respective tocopherol contents, from which toropherol removal rates were calculated and compared (see Table 1b).

Comparison of Tocopherol Removal Rate According to Water Content in Supercritical Carbon Dioxide Water content Content of Tocopherol Before Extraction Tocopherol content after extraction Tocopherol Removal Rate 0% 0.35% 36.4mg / 100g Green Tea 36.4mg / 100g Green Tea 6.1mg / 100g Green Tea 29.6mg / 100g Green Tea 83% 19%

As shown in Table 1b, the removal of caffeine using supercritical carbon dioxide containing water was able to reduce the splatter ratio of green tea tocopherol by about 4.5 times.

This result was analyzed to be due to the characteristics of tocopherol: Tocopherol is a representative oil-soluble vitamin, in which if the supercritical carbon dioxide lacks water, the green tea leaves filled with the extractor lose their initial moisture and are dried, and then tocopherol is a nonpolar solvent. While dissolved and lost in supercritical carbon dioxide, the supply of water containing supercritical carbon dioxide prevents the drying of the filled green tea and blocks the possibility of tocopherol dissolving in supercritical carbon dioxide, thereby preventing its loss. It was analyzed. In addition, the water-containing supercritical carbon dioxide is partly polarized to have a property that the tocopherol is not easily dissolved, it is expected that another reason to prevent the loss of tocopherol.

Example 1-3 : Sensory Evaluation of Green Tea Removed Caffeine by Supercritical Carbon Dioxide

The sensory evaluation of each caffeine-free green tea prepared in Example 1-1 was a 5-point measurement method (1 point: very bad, 2 points: bad, 3 points: normal, 4 points: good, 5 points: very Good) (see Table 1c).

Comparison of Sensory Evaluation of Caffeinated Green Tea by Supercritical Carbon Dioxide According to Water Content Water content flavor incense color 0% 0.35% 3.4 4.3 3.0 4.2 2.1 3.8

As shown in Table 1c, the green tea from which caffeine was removed using supercritical carbon dioxide containing water exhibited an excellent level of taste and aroma compared to the green tea from which caffeine was removed using pure supercritical carbon dioxide, resulting in a decrease in the flavor of green tea. It was confirmed that there is an effect to prevent. In particular, the color of green tea is very close to the green color, which is clearly distinguished from the brown color of the control group. Therefore, it was found that the method of preparing caffeine-free tea using the supercritical carbon dioxide of the present invention does not impair the taste, aroma and color of green tea.

Example 2 Establishment of Caffeine Extraction Conditions Using Supercritical Carbon Dioxide Added with Water

Example 2-1 : Establishment of Pressure Conditions in Extracting Caffeine Using Supercritical Carbon Dioxide Added with Water

An attempt was made to establish the pressure conditions for extracting caffeine using supercritical carbon dioxide with added water, ie, changing the temperature to 50 ° C. and changing the pressure to 100, 200, 300, 400 and 500 bar, respectively. Caffeine was removed from green tea under the same conditions as using the supercritical carbon dioxide containing 0.35% moisture of Example 1-1, and then the removal rate of caffeine was compared (see Table 2a).

Removal of Caffeine from Green Tea by Using Supercritical Carbon Dioxide Containing Water Pressure (bar) Caffeine Content Before Extraction Caffeine Removal Efficiency 100 200 300 400 500 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 24.7% 61.7% 90.6% 93.7% 93.7%

As shown in Table 2a, caffeine was effectively removed when a pressure of 200 bar or more was applied, and the removal efficiency of caffeine was no longer increased when a pressure of 500 bar or more was applied, so that caffeine was removed from green tea under a pressure of 200 to 500 bar. It can be seen that it is preferable to remove.

Example 2-2 Establishment of Temperature Conditions in Extracting Caffeine Using Supercritical Carbon Dioxide Added with Water

We tried to establish the temperature conditions for extracting caffeine using supercritical carbon dioxide with moisture: that is, the pressure was 300 bar, except that the temperatures were changed to 30, 40, 50, 60, 70, 80 and 90 ° C, respectively. The caffeine was removed from the green tea under the same conditions as those using the supercritical carbon dioxide containing 0.35% moisture of Example 1-1, and then the caffeine removal rate was compared (see Table 2b).

Removal of Caffeine from Green Tea by Using Supercritical Carbon Dioxide Containing Water Temperature (℃) Caffeine Content Before Extraction Caffeine Removal Efficiency 30 40 50 60 70 80 90 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 68.7% 81.1% 90.6% 93.3% 94.7% 95.6% 95.6%

As shown in Table 2b, caffeine was effectively removed under a temperature of 40 ° C. or higher, and the removal efficiency of caffeine was no longer increased under a temperature of 90 ° C. or higher. Thus, caffeine was removed from green tea leaves under a temperature of 40 to 90 ° C. It was found to be desirable to remove. However, when the extraction at 60 ℃ or more appeared a phenomenon that the quality such as color and taste of the extracted green tea appeared, it was confirmed that the extraction at 50 ℃ more preferred.

Example 2-3 Establishment of Moisture Content Conditions for Caffeine Removal Using Supercritical Carbon Dioxide with Water Added

We tried to establish the temperature conditions for extracting caffeine using supercritical carbon dioxide with water: that is, the pressure was 300 bar, the temperature was 50 ° C., and the content of water contained in supercritical carbon dioxide was 0.0-1.0% (w). caffeine was removed from green tea under the same conditions as in Example 1-1, except for changing to (w / w), and the removal rate of caffeine was compared (see Table 2c).

Removal of Caffeine from Green Tea Using Supercritical Carbon Dioxide Containing Water, Changes in Removal Efficiency According to Changes in Water Content Water content (%, w / w) Caffeine Content Before Extraction Caffeine Removal Efficiency 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 2.12 wt% 85.8% 86.0% 87.6% 88.7% 90.9% 93.1% 95.9% 97.8% 98.4% 98.4% 98.4%

As shown in Table 2c, when the water content in the supercritical carbon dioxide is 0.2% (w / w) or more, the removal efficiency of caffeine is rapidly improved, and in the case of 0.8% (w / w) or more, the caffeine is no longer Since the removal efficiency of was not increased, it was confirmed that it is preferable to use supercritical carbon dioxide containing water in the content of 0.2 to 0.8% (w / w).

Summarizing the results of the above Examples 2-1 to 2-3, supercritical water containing water in a content of 0.2 to 0.8% (w / w) under a temperature condition of 40 to 90 ℃ and a pressure condition of 200 to 500 bar When using carbon dioxide, it was confirmed that the caffeine can be effectively removed from the green tea leaves.

Example 3 Comparison of Tocopherol Removal Rate Using Supercritical Carbon Dioxide Added Water for Teas Other Than Green Tea

The extractor of the known supercritical carbon dioxide extractor was filled with coffee beans, oolong tea leaves and black tea leaves 100g, respectively, and the caffeine was removed with supercritical carbon dioxide until the removal efficiency of caffeine was 90%. At this time, the extraction temperature was 50 ℃, the pressure was 300bar, the supercritical carbon dioxide used for extraction was water-free or supercritical carbon dioxide containing 0.35% moisture, the flow rate of supercritical carbon dioxide is 50g / min 7 After caffeine was extracted for the time, the removal rate of tocopherol was compared by the method of Example 1-2 (see Table 3).

Removal Rate of Tocopherols from Coffee, Oolong Tea and Black Tea According to the Water Content in Supercritical Carbon Dioxide sample Content of Tocopherol Before Extraction Tocopherol content after extraction per 100g of sample Tocopherol Removal Rate Moisture 0% Water 0.35% Water 0.35% Water 0.35% Coffee beans Oolong tea leaves Black tea leaves 23.4mg / coffee beans 100g 31.2mg / oolong tea leaves 100g 33.7mg / black tea leaves 100g 4.7mg 5.8mg 6.5mg 18.1mg 25.2mg 27.7mg 80.0% 81.5% 80.8% 32.7% 19.3% 17.9%

As shown in Table 3, the caffeine removal method using the water-containing supercritical carbon dioxide of the present invention was found to be a method of minimizing the loss of useful substances in not only green tea, but also caffeine-containing coffee, oolong tea and black tea.

As described and demonstrated in detail above, the present invention uses a supercritical carbon dioxide containing water, the method of producing caffeine-free tea, including the step of selectively removing only caffeine contained in the food prepared by the electric method Provide tea with depleted caffeine. Since the caffeine-free tea of the present invention is selectively removed only caffeine, it will be widely used in the development of tea processed products having high added value and new functional foods using the same.

Claims (4)

Supercritical, comprising the step of extracting and removing caffeine by adding supercritical carbon dioxide containing 0.2 to 0.8% (w / w) of water under conditions of 40 to 80 ℃ and 200 to 400 bar to the dressing material containing caffeine Caffeine-free tea manufacturing method using carbon dioxide. The method of claim 1, Dimensional material containing caffeine is characterized in that the green tea leaves, coffee beans, oolong tea leaves or black tea leaves Method for producing caffeine-free tea using supercritical carbon dioxide. The method of claim 1, Characterized in that the extraction unit consisting of an extraction tank, a heat exchanger, a pump, a carbon dioxide storage tank, a cooling condenser, a pressure reduction separator and a pressure reducing valve Method for producing caffeine-free tea using supercritical carbon dioxide. Tea prepared by the method of claim 1, wherein the caffeine is removed.