JP2939580B2 - Method for producing tea extract powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a tea extract powder, comprising concentrating and drying an extract of tea leaves such as black tea and green tea with little deterioration in quality and little loss of components. It is.

[0002]

2. Description of the Related Art Conventionally, as a method for concentrating a liquid food, a reduced pressure heating and concentration method is mainly used from the viewpoint of concentration efficiency. The loss of ingredients is insignificant and unsuitable as a method for concentrating teas with delicate flavors. There are freeze concentration and reverse osmotic pressure concentration (hereinafter referred to as RO concentration) as a concentration method without applying heat. Freeze concentration is an irreversible turbidity (especially black tea, Oolong tea).

On the other hand, RO concentration using a semipermeable membrane is an excellent method for concentrating tea extracts, for example, as described in JP-A-62-241, since there is almost no loss of extract components and volatile components and no turbidity due to freezing occurs. No.), (JP-A-3-201
No. 945). In another patent, tea extracts are subjected to ultrafiltration, and the permeated liquid is RO-concentrated and mixed with a portion reserved for ultrafiltration (JP-A-56-29954).
JP-A-5-236877) is also disclosed.

However, when drying these RO concentrates, drum drying, spray drying, vacuum heating drying, etc. have good drying efficiencies, but many of the low boiling point volatile components evaporate and escape. On the other hand, when dried by vacuum freeze-drying or low-temperature vacuum drying, irreversible turbidity is obtained because the low-boiling volatile component is retained, but the dehydration rate is slow and the concentrated solution is kept in a frozen state or at a low temperature. (Especially black tea, oolong tea). It is said that this turbidity is caused by polymerization of the pigment, tannin and caffeine in the tea extract.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a tea extract powder which is efficiently concentrated, dried and transparently dissolved while maintaining low-boiling volatile components contained in the tea extract. is there.

[0006]

Means for Solving the Problems As a result of diligent research, the present inventors RO-concentrate an extract of tea leaves on a loose RO membrane having a salt removal rate of 10 to 60% (referred to as concentrate I). The permeated water obtained at this time is RO-concentrated using an RO membrane having a salt removal rate of 93% or more (concentrated solution II), and the concentrated solution II is freeze-dried without mixing both concentrated solutions. The above-mentioned object is achieved by a method of drying by a drying method having a good retention of low-boiling volatile components such as low-temperature vacuum drying and low-temperature spray drying to obtain a dried product and mixing it with a dried product of the concentrate I which has been appropriately dried. Successfully achieved.

[0007]

Next, the present invention will be described in detail.
Since the present invention relates to a method for concentrating and drying tea extracts, the method for extracting tea extracts is not particularly limited, and can be applied to known and publicly used extraction methods,
For example, this is performed as follows. First, an aqueous medium is added to a tea raw material to obtain an extract. The aqueous medium may be simple water or deionized water, and may include saccharides, dextrins, cyclic dextrins, emulsifiers, alcohols,
Antioxidants such as ascorbic acid may be appropriately added, or may be added after extraction. Extraction temperature,
Extraction conditions such as extraction time, amount of solvent, pH, etc.
Alternatively, it may be set appropriately according to the concept of the product.

Next, the extract thus obtained is concentrated. As an enrichment method, RO enrichment with little heat-induced denaturation and flavor loss is used. At that time, as a first step, RO concentration is performed using a loose RO membrane having a salt removal rate of 10% to 60%. As a pressure condition at the time of the concentration operation, when the pressure is high, the concentration speed is high but the clogging (fouling) of the membrane is fast, and when the pressure is low, the clogging is slow, but the concentration speed is low, so that 10 kg / cm ^2. ~ 50
About kg / cm ² is appropriate. If the temperature condition is high, the concentration rate is high, but the coloration, the deterioration of flavor and the like may occur. Therefore, the range of about 20 ° C. to 50 ° C. is suitable. In the case of black tea which is easily turbid at a low temperature, 30 ° C. or more is desirable. . Although it depends on the solid content at the time of extraction, it is about 5 times
20-fold concentration (solids concentration about 10% to 40%)
And so on.

By this operation, most of the high-molecular substances (eg, pigments, tannins, and polysaccharides) in the extract are
It is retained on the concentrate side of the first stage RO concentration, but most of the low molecular weight substances and flavor substances exit to the permeated water side.

Next, as a second stage concentration, the permeated water is RO concentrated using an RO membrane having a salt removal rate of 93% or more. The pressure condition during the concentration operation is 20 kg / cm ²
To 50 kg / cm ^2, the temperature is carried out concentrated to a solids concentration of about 4% to 40% (depending on the concentration of the permeate approximately 5 to 100 times as concentration ratio) becomes at 20 ° C. to 50 ° C. .

Thus, the first-stage concentrated solution (concentrated solution I) containing a large amount of high-molecular substances such as pigments, tannins and polysaccharides, and the second-stage concentrated solution containing low-molecular substances and flavor substances (Concentrate II) is obtained. Since the concentrate 11 contains no pigment and contains little tannins, it does not cause turbidity even when frozen or kept at a low temperature. Between 80% and 95% of the solids in the tea extract are present in concentrate I and between 20% and 5% are present in concentrate II. Therefore,
The weight ratio of both concentrated solutions is 80:20 if the concentration is the same.
95: 5, and the concentrated solution II is 1/4 to 1/1 of the concentrated solution I.
19 amount.

[0012] Here, R having a salt removal rate of 10% to 60% is used.
The O membrane refers to an RO membrane having an average salt removal rate of 10% to 60% described by a membrane maker in a catalog or the like. For example, NTR-7410 manufactured by Nitto Denko Corporation,
NTR-7450, NTR-7250, S manufactured by Toray Industries, Inc.
U-610, SU-620 and the like. The same applies to an RO film having a salt removal rate of 93% or more, for example, NTR-759HG, NTR-769SR, manufactured by Nitto Denko Corporation.
NTR-729HF, SU-810, SU manufactured by Toray Industries, Inc.
-710 and the like. 93% or more means 93% to 1
Means 00%.

Next, the drying step will be described. When drying a liquid obtained by mixing the concentrated liquid I and the concentrated liquid II or a concentrated liquid concentrated in one step as in general RO concentration, drying efficiency is good in drum drying, spray drying, vacuum heating drying, etc. Many of the low-boiling volatile components evaporate and escape, and when dried by vacuum freeze drying, low-temperature vacuum drying, low-temperature spray drying, etc., the low-boiling volatile components are retained well, but the dehydration rate is slow and drying is slow. Since the required cost is high and the concentrated solution is kept in a frozen state or at a low temperature, irreversible turbidity occurs, and it is not possible to obtain a tea extract powder that dissolves transparently.

Therefore, the present inventors have adopted the following drying method. That is, the concentrated solution I and the concentrated solution II are separately dried, and the concentrated solution II, which has a small amount of liquid and contains a large amount of flavor components but does not become turbid even when kept at a low temperature, is subjected to vacuum freeze drying, low temperature vacuum drying, The concentrated liquid I which is dried by a drying method having a good retention of low-boiling volatile components such as low-temperature spray drying and has a large liquid volume and contains a pigment and tannin has a good drying efficiency other than these drying methods and does not cause turbidity. Dry by a drying method (for example, spray drying). The obtained dried products are mixed appropriately.

According to the above-mentioned method, it is possible to obtain a tea extract powder which dissolves in a transparent manner, without loss of flavor components and extract components, at a low drying cost. The dried product of the concentrated solution I and the dried product of the concentrated solution II do not necessarily need to be mixed, and may be used alone depending on the application.

The teas to which the present invention is directed include black tea,
Teas containing tannins in their components, such as green tea, oolong tea, du Zhong tea, dokudami tea, mate tea, rooibos tea and the like.

[0017]

【Example】

(Example 1) 15 kg of black tea (7.5 kg of Ceylon black tea)
And 7.5 kg of Assam black tea)
-1.5 kg of cyclodextrin and 4 kg of dextrin DE15 (trade name: SANDEC # 150, manufactured by Sanwa Starch Kogyo Co., Ltd.) dissolved in 180 kg of hot water at 82 ° C were stirred at 80 ° C for 10 minutes, extracted and then extracted with tea leaves. The liquid was separated. This solution is centrifuged to remove insoluble substances, and 160 kg of black tea extract having a solid concentration of about 5.2%.
I got

This extract was subjected to NTR-7 manufactured by Nitto Denko Corporation.
Using a 410HG-S2 membrane (salt removal rate: 10%), RO concentration was performed under the conditions of an operating pressure of 30 kg / cm ² and a temperature of 40 ° C. to obtain 26.3 kg of a concentrated solution having a solid concentration of about 28% (concentrated solution A). ) And 130 kg of permeated water were obtained. Next, the permeated water was subjected to an operating pressure of 40 kg / cm using an NTR-759HG-S2 membrane (99.5% salt removal rate) manufactured by Nitto Denko Corporation.
^2. RO concentration under the condition of temperature of 25 ° C., solid concentration of about 20
4.3 kg (hereinafter referred to as concentrated liquid B) of the concentrated liquid was obtained.

The concentrated solution A is spray-dried at a hot air inlet temperature of 160 ° C. and a chamber temperature of 100 ° C. to obtain a powder of about 7 kg.
(Referred to as powder 1). The concentrate B was pre-frozen at −30 ° C., freeze-dried in vacuum at a vacuum of 0.1 to 0.2 torr, and pulverized to obtain about 0.8 kg of powder (hereinafter referred to as powder 2). Mix the total amount of powder 1 and powder 2 and mix tea powder 3
I got

Comparative Example 1 Concentrated liquid A and concentrated liquid B obtained in the same manner as in Example 1 were mixed to obtain concentrated liquid C. The concentrated liquid C was heated at a hot air inlet temperature of 160 ° C and a chamber temperature of 100 ° C.
Was spray-dried under the conditions described above to obtain black tea extract powder 4.

Comparative Example 2 Concentrated liquid A and concentrated liquid B obtained in the same manner as in Example 1 were mixed to obtain concentrated liquid C. Concentrate C is pre-frozen at −30 ° C. and a vacuum of 0.1 torr to 0.2 torr.
The mixture was freeze-dried in a vacuum and crushed to obtain black tea extract powder 5.

1 g each of the three points of the black tea extract powder 3 obtained in Example 1, the black tea extract powder 4 obtained in Comparative Example 1, and the black tea extract powder 5 obtained in Comparative Example 2,
After dissolving in 20 cc of water (60 ° C.), the sensory test of the flavor and the measurement of the transparency (transmittance at 750 nm) were performed. Table 1 shows the results.

[0023]

[Table 1]

As can be seen from Table 1, the black tea extract powder 3 produced according to the method of the present invention is rich in a flower-like light aroma unique to black tea and has a transmittance of 92.1% and is transparently dissolved. On the other hand, black tea extract powder 4
Has a good transparency but a weak top note and a heavy incense throughout. Also, the whole amount of freeze-dried black tea extract powder 5
Is turbid with a transmittance of 71.6%.

Example 2 18 kg of high-grade green tea was put into 360 kg of 75 ° C. deionized water in which 0.3 kg of sodium ascorbate had previously been dissolved.
Extract with stirring for 5 minutes to separate tea leaves and liquid. The obtained extract was filtered with a filter having a pore size of 1 micron (TCW-1NP).
PS, manufactured by Toyo Roshi Kaisha, Ltd.) to obtain 300 kg of an extract having a solid content of about 1.7%.

This extract was subjected to NTR-7 manufactured by Nitto Denko Corporation.
Using a 250-S2 membrane (60% salt removal rate), RO concentration was performed under the conditions of an operating pressure of 40 kg / cm ² and a temperature of 25 ° C.
27.0 kg of concentrated liquid with a solid content of about 17% (concentrated liquid D)
And 267 kg of permeated water were obtained. The permeated water is supplied to Nitto Denko Corporation NTR-769SR-S2 membrane (salt removal rate 96
%), Operating pressure 35 kg / cm ² , temperature 25 ° C.
RO was concentrated under the condition of 3.9 to obtain a concentrated solution having a solid content concentration of about 10%.
kg (Concentrate E) was obtained.

3.3 kg of DE16 dextrin (trade name: BLD, manufactured by Sanmatsu Kogyo KK) is dissolved in 27 kg of the concentrated solution D, and the hot air inlet temperature is 170 ° C. and the chamber temperature is 11
It was spray-dried at 0 ° C. to obtain about 7.6 kg of powder. After mixing and dissolving 1.0 kg of the above-mentioned BLD in 3.9 kg of the concentrated solution E, the mixture was preliminarily frozen at −30 ° C., freeze-dried at a vacuum of 0.1 to 0.2 torr, and pulverized to 1.3 kg of powder.
I got Mix both powders, instant sencha 8.9kg
I got

When one gram of this powder was dissolved in 160 cc of hot water and the flavor was observed, it had a fragrance characteristic of sencha.
The taste was indistinguishable from regular sencha.

(Example 3) 20 kg of oolong tea (iron Kannon 3 grade) was put into 240 kg of hot water at 80 ° C, and
After stirring and extracting at a temperature of 8 ° C. for 10 minutes, the tea leaves and the liquid were separated. This liquid was clarified by centrifugation to obtain 202 kg of oolong tea extract having a solid content of about 2.2%.

This extract was subjected to NTR-7 manufactured by Nitto Denko Corporation.
Using 410HG-S2 membrane (10% salt removal rate)
R0 was concentrated under the conditions of an operating pressure of 40 kg / cm ² and a temperature of 35 ° C. to obtain 21.5 kg of a concentrated solution having a solid concentration of about 18% (concentrated solution G) and 177 kg of permeated water. In this permeated water, 1.5 kg of cyclodextrin-containing liquid dextrin (trade name: Celldex SA-30: 30% of solid content is cyclodextrin, syrup having a solid content of 75%, manufactured by Nippon Shokuhin Kako Co., Ltd.) was dissolved. Thereafter, using an NTR-729HF-S2 membrane (manufactured by Nitto Denko Corporation) (93% salt removal rate), RO concentration was performed under the conditions of an operating pressure of 40 kg / cm ² and a temperature of 27 ° C., and the concentration of the solid content was about 28%. 5.5 kg of liquid
(Concentrate H) was obtained.

To 21.5 kg of the concentrated solution G, 5 kg of liquid maltodextrin (trade name: TK-75, solid content concentration: 75%, manufactured by Matsutani Chemical Industry Co., Ltd.) was mixed, and the hot air inlet temperature was 160 ° C. and the chamber temperature was 105 ° C. Spray drying,
About 7.2 kg of powder was obtained. The concentrated liquid H was prepared at a temperature of 0 ° C to 12 ° C.
C. and a vacuum degree of 5 to 15 torr, followed by vacuum drying and pulverization to obtain about 1.4 kg of powder. The two powders were mixed to obtain 8.6 kg of instant oolong tea.

When 1 g of the obtained instant oolong tea was dissolved in 150 cc of hot water and the flavor was observed, the oolong tea had a good jasmine aroma characteristic of high-grade oolong tea, had good transparency, and was sufficiently compatible with regular products. there were.

Example 4 25 kg of gyokuro were put into 400 kg of deionized water at 60 ° C. in which 0.2 kg of ascorbic acid and 5 kg of the same dextrin BLD used in Example 2 were dissolved, and stirred for 10 minutes. And separate. The obtained extract is centrifuged to remove insoluble substances, and Gyokuro extract 318 having a solid content of about 2.6%.
kg.

This extract was subjected to NTR- manufactured by Nitto Denko Corporation.
Using a 7410HG-S2 membrane (10% salt removal rate)
RO concentration was performed under the conditions of an operating pressure of 40 kg / cm ² and a temperature of 25 ° C., to obtain 29.3 kg of a concentrated solution having a solid concentration of about 25% (concentrated solution J) and 285 kg of permeated water. The permeated water is supplied to Nitto Denko Corporation NTR-759HG-S2 membrane (salt removal rate 9).
Using 9.5%), RO was concentrated under the conditions of an operating pressure of 40 kg / cm ² and a temperature of 25 ° C. to obtain 4.2 kg of a concentrated solution having a solid content of about 18% (concentrated solution K).

The concentrated liquid J was spray-dried under the conditions of a hot air inlet temperature of 160 ° C. and a chamber temperature of 105 ° C. to obtain a powder of about 7.2.
kg. Maltosyl cyclodextrin (trade name: Isoelite P, manufactured by Saltwater Port Sugar Co., Ltd.)
0.8 kg is dissolved and 15000 r. p. After 15 minutes of homogenization at 100 ° C., the mixture was spray-dried at a low temperature such that the product temperature became 15 ° C. to 30 ° C. at a hot air inlet temperature of 100 ° C. and a chamber temperature of 70 ° C. to obtain about 1.5 kg of powder. Both powders were mixed to obtain 8.7 kg of powdered gyokuro extract.

2 g of the obtained powdered gyokuro extract was added at 40 ° C.
It was dissolved in 100 cc of warm water, and the flavor was observed. It had a unique flavor of gyokuro and the so-called “'Oi Kaori”, which was comparable to that extracted by the general method of adding gyokuro. Was.

[0037]

According to the above-mentioned method, it is possible to obtain a tea extract powder which dissolves in a transparent manner, without loss of flavor components and extract components, at a low drying cost.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-88948 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) A23F 3/30 A23F 3/22 A23F 3 / 26

Claims (1)

(57) [Claims] 1. In the reverse osmotic pressure concentration of an extract of tea leaves, the extract is first concentrated in a loose RO membrane having a salt removal rate of 10% to 60%, and the obtained permeated water is converted in a second step. Concentration is performed using an RO membrane having a salt removal rate of 93% or more, the two concentrated solutions are dried separately, and both dried products are mixed to obtain a tea extract powder. Vacuum freeze-drying, or low-temperature spray drying, or low-temperature vacuum drying, a method for producing a tea extract powder,