JPH0763317B2 - Method for producing coffee extract - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing coffee extract.

[Conventional technology]

The aroma of roasted coffee is composed of more than 600 types of scent components, and a unique scent is produced by the combination and balance of these scent components. It is no exaggeration to say that it is impossible to create the scent of natural coffee by the combination of known aroma components, and this is where the value and need of coffee as a natural flavor arise. In addition, roasted coffee beans have a tendency to deteriorate or deteriorate in quality during storage because the ground product contains a large amount of highly volatile scent components. Is remarkable.

As a method for separating the scent component of roasted coffee, conventionally known are a steam distillation method, a pressing method, an organic solvent extraction method, and an extraction method using a high-pressure gas such as carbon dioxide. Among them, the steam distillation method is a method in which raw coffee is treated with steam to extract and separate components, and there is a possibility that the scent component may be deteriorated due to contact with steam and water or heat load. The squeezing method is a method of squeezing out coffee extract by squeezing it using a mechanical squeezing means such as an expeller, but it is mechanically operated at a high pressure, so a heat load due to friction is applied, and one It is inevitable that the department will volatilize or deteriorate. Further, the organic solvent extraction method is a method of extracting components soluble in the solvent from coffee using an organic solvent,
In the process of removing the solvent from the extract or in the process of concentrating, the volatile scent component lower than or close to the boiling point of the solvent is disadvantageously lost.

The extraction method of coffee extract using high-pressure gas, especially carbon dioxide (hereinafter referred to as CO ₂ ), allows extraction and separation at room temperature or at a lower temperature than the above extraction methods, and the boiling point (sublimation point) of CO ₂ is a scent component. It is far lower than that of the above, and since CO ₂ is inactive, it does not affect the scent component. However, the extraction method using CO ₂ has the characteristic that the extraction characteristics differ depending on the temperature, pressure and phase conditions (gas, liquid, supercritical state) at the time of extraction, and there is a problem that must be improved. There is.

The extraction of the coffee extract using CO _2, the gas depending on the state of the extraction of the CO ₂ is the extractant, CO ₂ liquid and supercritical gas state (hereinafter, referred to as supercritical CO _2.) Extraction method used by the Are known. For example, Japanese Patent Publication 45-8624, JP-extraction method by gas and liquid CO _2, also JP-B-51-3
In Japanese Patent No. 3185, each extraction method using supercritical CO ₂ is described.

According to the method described in JP-B-45-8624, there is described a method of extracting a volatile scent component and a part of a lipid component by using a gas at 80 to 110 ° C. and CO _{2 at} 0 ° C. or slightly lower liquid. ing. With this method, the extraction pressure of liquid CO ₂ is around 35 kg / cm ² (saturation pressure of CO ₂ at 0 ° C.), so the extraction amount of coffee extract, especially the coffee extract content, is reduced, and the extract is wax-like. The solids of are mixed to form a paste. This causes a problem in handling such as recovery of the extract. In addition, in the extraction method using gaseous CO ₂ , the amount of extraction is small even when the temperature is raised and the time is long, and the extraction efficiency (here, the yield of the extract in a unit extraction operation, which is the same in the following description) is low. There is a problem.

Next, the method described in JP-B-51-33185 discloses CO in a supercritical gas state (pressure of 80 atm or higher and temperature of 31.3 ° C. or higher).
_{In this method} , the extraction operation is carried out in ₂ , and the scent component of coffee is adsorbed on oil containing an antioxidant to extract it. Supercritical
CO ₂ extraction has a larger dissolving ability than that of liquid CO ₂ , so that high extraction efficiency can be obtained, but selective solubility is lowered. That is, the proportion of the scent component in the total extract is small, and the quality is relatively inferior to the extract using liquid CO ₂ .

In addition to the above, JP-A-61-88853 describes an extraction method using a mixed solvent of CO ₂ and ethanol, which is close to a supercritical gas state. This method also suffers from the same drawbacks as in the organic solvent extraction method.

[Problems to be solved by the invention]

The present invention belongs to the above-mentioned prior art, which is a method for extracting a coffee extract using CO ₂ , and in particular, an improved method for using liquid CO ₂ . That is, while maintaining the quality characteristic that the content ratio of the scent component in the total extract, which is the extraction characteristic of coffee extract with liquid CO _2, is high, the coffee oil amount which is the problem is small and the extraction efficiency is low. It is also an object of the present invention to provide a production method of obtaining a high-quality coffee extract with high extraction efficiency, which is free from the drawbacks such as low extractability and difficulty in extraction operation when the extract becomes pasty. .

[Means for solving problems]

The present inventor, as a result of various tests and studies on a method for extracting a coffee extract from roasted coffee using CO ₂ ,
The present invention has been completed by finding a selective condition capable of extracting a coffee extract with high quality and high extraction efficiency by containing a large amount of coffee oil together with an aroma component. That is, the present invention is a method for producing a coffee extract by extracting coffee scent components and coffee oil from roasted coffee beans or ground products thereof using CO ₂ under high pressure, wherein the extraction temperature is 5 to 30 with liquid CO _2. A method for producing a coffee extract, which comprises extracting at a temperature of ℃ and an extraction pressure of 100 to 300 kg / cm ² .

In the method for producing coffee extract of the present invention, extraction can be performed using an extraction device that has been conventionally used as an extraction method using high pressure CO ₂ . That is, as an example thereof, an outline of the flow sheet of the extraction device is shown in FIG. Less than,
The present invention will be described in detail according to the flow of FIG.

Liquid CO ₂ as the extractant is stored in a storage tank 1 and pressurized to a predetermined extraction pressure by a pump 3 from a lower pipe of the tank through a flow meter 2 and a heat exchanger 4 to a predetermined extraction temperature. After being adjusted, it is pressed into the inside of the extractor from the lower part of the extractor 5. The inside of the extractor 5 is pre-filled with roasted coffee, which is the raw material for extraction, and liquid CO ₂
Rises while sequentially contacting the raw material, and flows out from the upper pipe of the extractor 5. The liquid CO ₂ in which the extract has been dissolved and retained via the extractor 5 is depressurized by the pressure control valve 6 and introduced to the separator 7 while separating the extract. The inside of the separator 7 is set to a temperature / pressure condition in which CO ₂ as the extractant is in a gas state, where the extract is separated from the extractant and taken out from the lower part of the separator 7. On the other hand, the separated CO ₂ gas passes through the pressure control valve 8 and is further cooled by the heat exchanger 9 whose pressure is reduced.
It is liquefied and returned to the storage tank 1 for reuse. In this way, a predetermined amount of CO ₂ is circulated to extract and extract coffee extract from roasted coffee raw materials.

The raw material for extraction can be extracted as coffee beans,
It is desirable to use it after pulverizing it into powder. For milling, a roll mill or the like commonly used for milling coffee beans can be used. It is desirable that the crushed raw material be subjected to extraction treatment as soon as possible after crushing, because volatilization and deterioration of the scent component are likely to occur.

Extraction agent CO ₂ is extracted in contact with the raw material in a liquid state at an extraction temperature of 5 to 30 ° C. and an extraction pressure of 100 to 300 kg / cm ²
Set it under the conditions of. Except for these temperature and pressure conditions,
The scent is inferior in the high temperature region, and the extraction efficiency is low in the low temperature region. Further, when the pressure condition is 100 kg / cm ² or less, the efficiency of the unit operation is lowered in terms of both the time required for extraction and the yield.

Extractant ratio (weight of extractant used per unit weight of extraction raw material) is
Do 10 to 100 times the weight. It is preferably 30 to 50 times by weight. Therefore, for the operation of the above device, the flow rate of liquid CO ₂ is 2 to 5 (kg / hr), and the time required for one extraction is the liquid C 2.
Depending on the flow rate of O ₂ , it is 2 to 8 hours.

The temperature and the pressure in the separator 7 are set and maintained under the operating conditions of the extraction temperature or lower and the saturation pressure of CO ₂ at the separation temperature or lower (CO ₂ is in a gaseous state).

According to the method of the present invention, the extract has high extraction efficiency,
In addition, as the coffee extract as the extract, a coffee extract exhibiting the characteristics of the flavor of the raw material very well can be obtained. According to the method of the present invention, the extract is obtained as an oil, and can be easily taken out from the separator without using any solvent or the like.

[Example 1] In order to examine the relationship of the extraction pressure on the yield of coffee extract under constant extraction conditions, the extraction pressure conditions were changed to 5 stages, and the other extraction conditions were the same, and an extraction test was conducted.

Roasted coffee (commercial blended product) crushed with a coffee mill as an extraction raw material using the extraction device shown in FIG.
Put 0g into an extractor with an internal volume of 4 and extract liquid CO at an extraction temperature of 15 ℃
₂ was passed for 4 hours at a flow rate of 4 kg / hr for extraction. With such settings, the extraction pressures are 55, 100, 150 and 2 respectively.
Extraction operation was performed with 5 levels of 50 and 300 kg / cm ² . The results are shown as a ratio with the yield at an extraction pressure of 300 kg / cm ² as 100, and the results shown in Table 1 are obtained.

From Table-1, the extraction rate of coffee extract increases with the increase of extraction pressure, reaching the maximum at 250 to 300 kg / cm ² ,
It was estimated to be constant above that.

[Example 2] In the case of using liquid CO ₂ as an extractant, in order to compare the effect and difference of the extraction temperature on the extract yield and quality, the operating conditions such as extraction pressure, flow rate, and extraction time were made the same, The extraction test was conducted by changing the extraction temperature. We also compared liquid CO ₂ and supercritical CO ₂ .

The same ground coffee as that used in Example 1 was used as a raw material, and 400 g of each was used as an extraction raw material in each test. The extraction test was performed using the same extraction device as in Example 1, and the liquid CO ₂ was extracted at the extraction temperatures of 5, 15 and 30 ° C., and in the case of supercritical CO ₂ .
Extraction was carried out at 40 and 70 ° C. with a total of 5 levels, a pressure of 250 kg / cm ² , and a flow rate of 4 kg / hr for 4 hours. The results are shown in Table-2.

From the test results shown in Table-2, the extraction amount of coffee extract is
A slight increase tends to occur as the extraction temperature increases, but there is no significant difference.

Next, for the quality evaluation of the extracted coffee extract, a sensory evaluation of the aroma of the extract attached to the scented paper by 20 specialized panels and a ranking method (Nikka Giren "Sensory Inspection Handbook" 297-305 (1973) } It went according to.

Liquid CO ₂ extract has a more straightforward scent characteristic of raw coffee than that of supercritical CO ₂ extract, and it has a light and bright aroma, which cannot be obtained by conventional extracts. It was evaluated as a very excellent coffee extract. Moreover, when the coefficient of the agreement of Kendall's rank was determined and tested for the results of these sensory evaluations, the agreement of the rank was recognized at a significance level of 1%. Furthermore, when the significance between the coffee extracts of the liquid CO ₂ extraction group and the supercritical CO ₂ extraction group was determined by Kramer's test,
A significant difference was observed at a significance level of 1%. From this, too
It was revealed that the coffee extract produced by the method of the present invention has an excellent evaluation in terms of quality as compared with that of the conventional method.

[Example 3] As a result of the test in Example 2, liquid CO ₂ extraction group and supercritical C
Since there was a significant difference in the sensory evaluation between the coffee extracts in the O ₂ extraction group, the following test was performed to confirm whether or not there was a difference in the content component composition between the two extracts.

The same ground coffee as that used in Example 1 was used as a raw material, and 400 g of each was used as an extraction raw material in each test. The extraction test was carried out using the same extraction device as in Example 1, using a liquid
CO ₂ has an extraction temperature of 15 ℃, and in the case of supercritical CO ₂ , the extraction temperature is 40 ℃.
And other extraction conditions are set the same (extraction pressure is 250 kg /
cm ^2, and the extraction test flow rate 4 kg / hr, 4 hr liquid passing) to.

The yield of the extract is 28g for liquid CO ₂ (7g / 100g raw material),
In the case of supercritical CO ₂ , it was 30.4 g (7.6 g / 100 g raw material). All were tan oil extracts containing strong coffee aroma.

Gas chromatographic analysis was performed on the two extracts thus obtained in order to see the difference in scent component composition. Shimadzu GC-9AM with hydrogen ionization detector
-Type gas chromatograph, column is carbowax
Using a 20M (Carbowax 20M) fused silica capillary column (manufactured by Hewlett-Packard), the temperature was raised from 60 ° C to 200 ° C at a heating rate of 2 ° C / min. Regarding the obtained gas chromatograph, the liquid CO ₂ extract is shown in FIG. 2 and the supercritical CO ₂ extract is shown in FIG.

Volatile components in each extract were converted to acetic acid [peak (2) in the figure]
Using the column as a guide, divide into fractions with a long retention time (RT) on the column and fractions with a small retention time (RT).
To the peak (3)], and the two were compared. The content of all volatile components, acetic acid and components of each fraction in each extract was calculated using benzyl alcohol [peak (4) in the figure] as an internal standard. The results are shown in Table-3.

Needless to say, the fraction with a low RT is a collection of components having a low boiling point and low polarity as compared with the fraction with a high RT, and forms a top note as a scent component.

From Table-3, the liquid CO ₂ extract has a higher relative concentration of the extract components having a smaller RT than that of the supercritical CO ₂ extract. This means that there is a difference in selective extraction characteristics, and it is considered that the extraction method according to the present invention exhibits excellent extraction ability with respect to the components forming the top notes with low polarity in coffee. This is in good agreement with the result of the sensory evaluation of Example 2.

〔The invention's effect〕

As is clear from the examples, the extraction method according to the present invention is
In the method of extracting coffee extract from roasted coffee, it is possible to obtain high-quality coffee extract with high extraction efficiency as compared with the conventional method using CO ₂ as an extractant.
Further, a coffee extract having no physical defect that makes it difficult to extract the coffee extract is obtained.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an outline of the extraction device used in the coffee extract manufacturing method of the present invention and the flow thereof. 2 and 3 are gas chromatographs of the extract according to the method of the present invention and the control extract in Example 3, respectively. In the figure, 1 is a storage tank, 2 is a flow meter, 3 is a pump, 4 and 9 are heat exchangers, 5 is an extractor, 6 and 8 are pressure control valves,
7 is a separator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hajime Ohinata 6-2 Umegaoka, Midori-ku, Yokohama, Kanagawa Prefecture Central Research Institute, Japan Tobacco Inc. (72) Naoko Inoue 6-2, Umegaoka, Midori-ku, Yokohama, Japan Tobacco Industry Co., Ltd. Central Research Institute (72) Inventor Yukio Omata 6-2 Umegaoka, Midori-ku, Yokohama-shi, Kanagawa Japan Tobacco Industry Co., Ltd. Central Research Institute (72) Inventor Yukio Shimizu 3-5 of Midorigaoka, Hamura-cho, Nishitama-gun, Tokyo 8 Inside Fuji Flavor Co., Ltd.

Claims (2)

[Claims] 1. A method for producing a coffee extract by extracting a scent component of coffee and coffee oil from roasted coffee beans or a ground product thereof using carbon dioxide under high pressure,
A method for producing a coffee extract, which comprises extracting with carbon dioxide in a liquid state at an extraction temperature of 5 to 30 ° C., an extraction pressure of 100 to 300 kg / cm ² , and an extractant ratio of 10 to 100 times by weight. 2. The method for producing a coffee extract according to claim 1, wherein the extraction is carried out under the condition that the extractant ratio is 30 to 50 times by weight.