DE2304073A1 - PROCESS FOR THE MANUFACTURING OF BLACK TEA - Google Patents

Description

^{1 5} JAN. ₁₉₇₃

UHIlEYiB. Ii.Υ »Museuupark 1, Rotterdam / Holland

Process for making τοη black tea

[Priority: January 31, 1972, USA. No. 222 231

The invention relates to the production of black tea from green or unfermented tea. Black tea is usually made by wilting, rolling fermentation and roasting fresh tea leaves. In this process, the natural tea enzymes in the leaf catalyze the fermentation (oxidation) of the polyphenols in the fresh leaf to the polyphenols which are characteristic of black tea. Black tea extracts can also be made from porridges or extracts of unfermented tea by oxidation in the presence of natural tea enzymes. In this process, the unfermented tea can consist of fresh tea leaves, the enzymes of which catalyze the conversion to black tea, or it can be green tea whose enzymes have been inactivated by heating, in which all natural tea enzymes are added to catalyze the conversion to black tea. The term rjc.Mv/arzer Toe is used here both as tea leaves by the above oinexa V eyi & hseji ttheraea t approaches en extracts mi

.,. 230-073

describe. The expression unffermented tea becomes he used to make both fresh tea (whichever is also frozen or can be dried) with living natural tea enzymes as well as green tea, whose enzymes are inactivated were to denote ".

The desirable properties of a black tea product are attractive taste and color when used as a drink or prepared without milk, and high in soluble solids. If the black tea in one immediately soluble (instant) tea powder is to be transferred) it should contain a minimum of "tea cream", which are solids extracted by hot water, but which are in are insoluble in cold water. The present invention relates to a pretreatment of the unffermented tea, which after converting a black tea with these provides desired properties.

The invention provides a method in which unfermented Tea combined with tannase and then converted into black tea in the presence of natural tea enzymes (converted) will

The invention is particularly applicable to processes in which the tannase is mixed with a pulp or extract of unfermented Tea is brought together, which is then converted to black tea. In a preferred embodiment the invention is a flowable homogenate or pulp of fresh tea leaves, preferably with a Water to leaf ratio of 3: 1 to 10: 1, prepared.

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Appropriate working methods for the preparation of the porridge close cryogenic milling, that is a milling of the Tea leaves while maintaining the frozen state with subsequent frying in water or homogenizing of the sea leaves with a desired amount of water in an apparatus "such as a Waring mixer, which both the leaves are crushed and dispersed. The tea leaf pulp is preferably under anaerobic conditions before and held during the tannase treatment to avoid any premature permentation. Maintaining anaerobic Conditions can be achieved by introducing the homogenate into a closed vessel and using nozzles Nitrogen gas to remove entrained oxygen.

The enzyme tannase is obtained as an elaboration product of certain molds belonging to the genus Aspergillus or Penicillium belong to. For example Aspergillus flavus grown on a medium containing Contains tannic acid as the only source of carbon Significant amounts of tannase. Two specific strains of these microorganisms, known as sizeable producers

Tannas are Aspergillus oryzae ATGG No.9362 and Aspergillus niger, ATCC Ko. 16888. A suitable tannase preparation, obtained with a strain of Aspergillus oryzae and commercially available as a powder, Tannase S is the Enzyme Development Corporation. The amount of tannase enzyme preparation, which is added to the slurry is generally 1 to 16, preferably about 8, enzyme units per gram Dry weight of the tea, measured by the Iibuchi et al method,

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which will be described in the following ". Tannase S has about 20,000 enzyme units per gram of powder when measured according to this method

The temperature at which the tannase treatment is carried out is preferably from 25 to 65 ° C and the best Results are obtained at a temperature of about 45.degree The treatment is preferably carried out for at least 15 minutes «,

Following the completion of the tannase treatment before the Conversion is the tea conversion process effected by adjusting the temperature of the tea leaves, the pulp or the homogenate to about 25 C and jetting with air. If the level of aeration is adjusted to approximately maintain oxygen saturation in the slurry,

for example, a satisfactory conversion is achieved in / 80 minutes Regulated amounts are added to the conversion time to abbreviateβ The hydrogen peroxide usually becomes uniform over a. Time of about 20 minutes, beginning about 15 minutes after the start of the ventilation, is added. The end of the The tea conversion process is indicated when the level of acidity in the tea pulp suddenly increases. Ventilation is on for about up to 30 minutes after this increase in oxygen saturation, preferably another 10 minutes if hydrogen peroxide is used »The conversion process is then carried out Heating the porridge to about 85 ° C for about 5 minutes by killing the natural tea enzymes ended *

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An alternative method of working uses an aqueous extract of green tea leaves as the starting material. In this procedure, the extract is given a tannase treatment prior to conversion and the tea conversion process is then effected by combining the tannase treated extract with a tea enzyme preparation. The applied tannase preparation can be immobilized on a solid support such as glass or polymeric material to enable its removal from the system and the reuse of the enzyme. Procedures for accomplishing the establishment of the enzymes on insoluble substrates are in U.S. Patents 3,519,538, 3,536,587 and 3,556,945 and also by Silmen et al in Annual Review of Biochemistry, 1966, Volume 35, pages 873-908, in the article Oolloquim on Insolubilized Enzymes, Biochemical Journal, 1968, Volume 107, pages 1P to 6Ϊ and by H, Weetal in "Enzymes Immobilized on Inorganic Carriers by Covalent Attachement", Research / Development, 1971, Volume 22, pages 18-22 . In general, the processes for insolubilizing enzymes require the enzyme to be attached to an insoluble substrate by covalent bonding, by absorption or by occlusion. The insolubilized enzymes are expediently provided in finely divided i-orm, for example _o glass beads, which can be packed in columns for use in continuous processes. The 'i'ee enzyme preparation can also be immobilized. An example of a tea enzyme preparation is described by Ji.Co and GV / Sanderson in Journal of Pood Science, 1970, volume yj, pages 160 to 164 _O

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Whether the used unf ermented tea is a pulp unf ermented Teas or a green tea extract, the inventive method is preferably "at a pH within a Unit of the natural pH of tea infusions, which is approximately pH 5.6. The sannase treatment before conversion is preferably carried out at a pH of about 5. The tea conversion stage is preferably within the pH range 4.8 to 6.0, most preferably about 5.6. The pH obtained as a result of the tannase treatment falls is preferably before the conversion stage set, for example with potassium hydroxide.

The product of the conversion process, in which a green tea extract is used as the starting material, is a black tea extract. "If a pulp or homogenate of green tea is used as the starting material, the product of the conversion process into an extract and tea leaf residue can be filtered through , Centrifugation or any other working method. The leaf residue can be re-extracted with water if desired to increase the amount of tea solids recovered in the extract, and the material so extracted can be added to the first extract obtained. The black tea extract obtained by any of the above methods can be concentrated and dried by conventional procedures including freeze drying and spray drying to give a cold water soluble instant tea powder. The extract is preferably unveiled by adding calcium chloride and centrifugal Gjert Before * Kon ^ pn ht-i QTMirifl · Τΐτ \ Λ Φτη r "lrrmrn: at> · THo Monr.ro

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added calcium chloride is preferably about 3 wt. i ° of the tea solids and appropriate centrifugation conditions are 6900 g at 10 ⁰ O.

It has been found that tannase treatment of black tea extracts is made by fermentation of green Tea as a solution or porridge, which does not make the tea cream soluble, which is contained in the extracts »The one according to the invention The process, however, prevents the formation of these solids in black tea extract, which causes the tea cream formation cause. While the exact mechanism, according to which the invention proceeds, certainly not so far recognized, it is believed that tannase catalyzes a reaction that leads to the formation of cold-water soluble Tea pigments during the tea conversion process leads to «It is believed that when treated prior to conversion the tannase the hydrolysis of the ester bonds between G-alloyl groups and various compounds which, as is known, are present in unconverted tea leaves, catalyzed. The reaction under consideration will presumably be a deesterification, which according to the following Scheme can run:

OH OH

OH

(Tannase

ROH +

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"8th"

wherein RQH is any of several different compounds means which are present in green tea leaves, including epicatechin and epigallocatechin. It was found that the action of this was catalyzed by tannase Deesterification consists in taking the natural amount of G-allis acid and epicatechin in unconverted greens Increase Tea Leaves “This appears to be the formation of large amounts of epitheaflamic acid during the tea conversion process to favor. Epitheaflamic acid has been shown to be produced in unusually large amounts during the Tea conversion process according to the invention in tea leaves which have undergone a tannase treatment before conversion. Epitheaflamic acid, such as was shown, a desired light, reddish-black tea tart. Color and has very good solubility in cold water.

The method used to determine the tannase activity of enzyme preparations is a modification of the method as described by Sakaaki Iibuchi, Yasuji Minoda and Koichi Yamade in Agricultural and Biological Ghimistry, Sand 31, page 513 (1967). This method determines the amount of tannic acid which is hydrolyzed in the presence of a measured amount of the tannase enzyme under a variety of conditions by measuring the decrease in absorbance of the substrate at a wavelength of 310 mm using a recording ultraviolet spectrophotometer. The solution used for this test is a 0.004 weight percent tannic acid solution in 0.21M acetate buffer (pH 5.0) _{or equivalent}

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-s-

The tannic acid used is analytically pure tannic acid. 3.0 ml of this solution are placed in a 1 cm cuvette; uf is 3O ⁰ G in the temperature controlled chamber of a pattern registered Cary Model 14 held ultraviolet spectrophotometer. Finally, 0.1 ml of syryme solution is added and the change in absorbance at a wavelength of 310 mm is continuously monitored. The concentration of the enzyme solution is adjusted until a change in absorbance of about 0.10 absorbance units / minute is observed. One unit of Tarina en se did zyinaktivi measured by this method is defined as the activity which a .Modification mm Absorbanseinheit of 1 per minute at 310 (30 ⁰ C, will be 1 cm cell using a 0,004'Mgen tannic acid in 0 , 02M acetate buffer (pH 5.0) with an initial absorbance of about 0.7β

Three Tanninsäurelieferungen were geteste in this test is (a) tannic acid Ii ¹ ./^ catalog no. 1764 by Mallinckrodt Chemical Works, St ₀ Louis, Missouri, and (c) NI tannic ^1. - Catalog Ir, 1198, Allied Chemical Corporation, Morristown, Hew Jersey "All three samples of tannic acid gave the same results when used in the test of Tannase S by the method described, namely 20,000 units per gram.

/ - catalog No. 1750, and (b) tannic acid analysis reagent -

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The following examples illustrate the novel Yerfahren _o The percentages are by weight excessive, unless otherwise specified "

Here are values of what color and veil "of instant tea." Describe products, stated as results, received by performing standard tests using a Hunter D-25 colorimeter. The veil values were through Reflectance is determined and the numbers given indicate the amount of reflected light: the lower the veils number is, the clearer the tea solution is. The tristimulus color determination is based on the measurement of transmitted Light. The L value is the brightness factor: a value of 100 shows no color, while a value of 0 does not show any color! Denotes darkness. The a value is a measure of the red-blue area of colors and the b value is a hatred of the green-yellow line. When tea solutions with beverage strength analyzed, that is 0.35 ^ tea solids, in one 5 cm cell, the preferred L value is in the range from 20 to 35 tons, the preferred a value is at least 8 units ten greater than the L value and the preferred b value is between about 15 and 25.

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example 1

Fresh green tea leaves obtained from a tea plantation in Charleston, South Carolina, were frozen at -40 ⁰ C and

cryogenically ground to a uniform particle size

Clay about 0.5 to 1.0 mm in a hammer mill. These cryogenically "ground tea leaves were used for all of the processing described below. Product A ; A 171 g sample of the ground fresh tea leaves, having a total solids content of about 25 pounds, was made into a 600 ml slurry

one
Water transferred to the reaction vessel and nitrogen gas was passed through the S \ rstem while maintaining the temperature at 25 ° with respect to its G by circulating temperature controlled water through the jacket was kept _β

The tannase treatment before conversion was carried out by adding 16 mg of Tannase S enzyme containing 320 units of activity to the tea leaf homogenate and maintaining the homogenate under anaerobic conditions continuous spraying with nitrogen for 2 hours at 25 ° C. At the end of each tannase treatment time the pH of the homogenate was fallen from green tea leaves to 4.7, and therefore was it is necessary to readjust the pH of the homogenate to the initial pH of 5.6 with 2ΪΤ KOH.

The enzymatic conversion of the green tea was then carried out carried out in the following way. The fermentation was started by changing the spray gas from nitrogen on air. The amount of aeration was adjusted to match the amount of dissolved oxygen in the homogenate To keep saturation. The temperature was raised to 25 ° G during

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all the following conversion kept you constant Gas flow rate kept the amount of solute Oxygen in the homogenate steadily increased to $ 25. After 15 minutes of aeration, a 2M hydrogen peroxide solution was added dropwise added over a period of 20 minutes so that the total volume of added hydrogen peroxide solution is 16.0 ml was. The conversion was continued for about another 10 minutes until the dissolved amount of oxygen rapidly rose from 25? » began to rise to about $ 40 saturation in the homogenate. Aeration was continued for a further 10 minutes, followed by conversion by changing the spray gas was interrupted by air to nitrogen and the pH was again adjusted back to pH 5.6 with 21Ί KOH, which is the natural pH of most converted tea infusions.

The converted homogenate was heated to 85 ° C. and held at this temperature for 5 minutes. The tea extract was then separated from the brewed tea leaves by filtering the heated homogenate through Miracloth. Calcium chloride (1 Jo on a tea solid basis) was extract of tea was added to the filtered and the solution was maintained at 25 ⁰ C for 45 minutes "Finally, the extract at 4 ⁰ C was cooled, and by centrifugation at 6900 g χ polished for 10 minutes . The polished extract was then freeze-dried in a Stokes freeze-dryer P-9, operated at a shelf temperature of 95 ⁰ C, a plate temperature of -50 ⁰ C and a vacuum of 25 Torr for 24 hours, a cold-water soluble urn

- ~ ■ ■ ■ - 3 0 9 8 3 3 / Q ~ 3 ~ 8 2

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Win instant tea powder. This in high yield instant tea product obtained, referred to as product A in of Table 1 below when in a cold water drink at the normal solids concentration of about 0.35 / »transferred, was remarkably equal to tea, of excellent Color and a Hilchreaiction as typical for beverage starch infusions, as is usually the case black tea leaves prepared.

Products B ^, B ^ and B ^: The procedure used to make Product A was repeated using the same amounts of material except that no hydrogen peroxide was added during fermentation. The dissolved oxygen levels remained constant at 25? O for about 45 minutes when the expected rapid increase in the level of dissolved oxygen in the extract was observed. All subsequent steps in the production of product A were followed. The freeze-dried instant tea powder obtained in this way is designated as product B _{1 in} Table 1 below. The same high yield of tea solids was obtained in making product B _{1 as was} obtained in making product A, but product B was considerably less in color.

The process for the production of product B ^ described above was repeated, except that in the Aonvertierun / _r; sverfahren the length of the ventilation time after the level of dissolved oxygen increased to over $ 40 saturation, from 10 to '50 i- “The freeze-dried

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_ ~ \ _ " 230A073

Instant tea powder, obtained according to this modified process, is designated as Bp in Table 1 below and was characterized as more tea-like than product B ^ of darker color and good red coloring »

The procedure was repeated for a further preparation, with the extra ventilation time being increased from 20 to 60 minutes became. The yield of this instant tea powder, as a product B ~ in the following Table 1, was similar to that as it had been obtained for product B ^ and Bp, but Product B ^ had a much darker reddish tea color than Product B. and Bp.

Product G ; The procedures used in making Product A were repeated using the same amounts of material with the following modifications: (a) the tannase treatment prior to conversion was omitted, (b) a quarter of the amount of hydrogen peroxide was added in the conversion procedure, and (^ ) Tannase enzyme treatment was carried out in the homogenate after conversion. The post-conversion tannase treatment was initiated at the end of the conversion time by jetting the homogenate with nitrogen gas (to create anaerobic conditions) and adding 15 mg of tannase S (a total of 300 enzyme units as defined in Example 1) to the homogenate. The treatment was carried out at 45 ° C. under nitrogen for 2 hours, after which the pH of the treated extract was readjusted to the natural value of pH 5.6 with 2N KOH.

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The results associated with this product, which is designated as product G, are compiled in Table 1 and show that a tannase treatment after the conversion leads to considerably lower process yields than a tannase treatment before the conversion; compare process yields of Product C to those for Products A, B ₁ , B ₂ or B ^ in Table 1. Further, Product G lacks the good tea-like color of Product A, as shown by the higher tristimulus L value, which is a very light coloring indicates, and. the lower tristimulus a value, which indicates a lack of reddish color "

Products D and E: The procedure as described for product A was repeated with the following changes: (a) the tannase treatment before conversion was omitted for the entire experiment, (b) the hydrogen peroxide was removed from the conversion procedure as for Product "B .. omitted, and (c) after fermentation and separation of the converted tea extract from the tea leaf residue by filtration. The extract was divided into two equal parts of 240 ml, each of which contained 2.8% solids. One part was further treated as described for product A, with the modification that the defogging treatment with calcium chloride was omitted The freeze-dried instant tea product obtained by this procedure was designated as product D. The second portion of the extract obtained as above was treated with tannase in the following V / else treated: The extract was placed in a temperature controlled water bath, maintained at 50 ⁰ C and 15 mg Tann ase S

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Enzyme was added, which is equivalent to a total of 300 enzyme units is as defined in Example 1, or 40 enzyme units per gram of tea solids extracted. The treatment was continued for 90 minutes, after which the pH of the treated extract came back up the natural pH of 5.6 was adjusted with 2N KOH. Of the portion treated with Tannase "and adjusted to pH the extract was polished and freeze-dried according to the Procedure as described above for product A, with the modification that the defogging treatment with calcium chloride was left out. The instant freeze-dried tea product thus obtained was named product E.

Analytical results for products D and E are compiled in Table 1. These results show that there is a striking improvement in the yield of cold water soluble instant tea solids, that is, in process yield, when tannase treatment is applied prior to converting green tea leaf homogenates, as can be seen by comparing the results for products A, B ₁ , B _£ and B ₃ with those for products G, D and E in table 1 “Neither a tannase treatment after the conversion of green tea leaf homogenates (product C) nor a tannase treatment after the extraction of extracts (product E) are effective for the Increase in the yield of cold-water-soluble instant tea solids via the non-tannase treatment process (product D).

Besides being made from fresh green tea leaves in

were, never had

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B ₂ (Table 1) excellent instant tea qualities insofar as they had good cold water solubility, good reddish black tea color in solution, good tea taste and a good milk reaction. «The other products lacked one or more of these qualities.

Table 1 Effect of tannase treatment on instant

Tea products obtained from tea conversion system homogenates

Extraction process Polierungs- tristimulus product yield loss fo% yield ° / o Color

I from

Tannasebshand- 37 »2 treatment before conversion: HpOp added

Tannase treatment before conversion: no H ₉ O ₉ added ^{c ά}

Same as B ₁ : 37.0 20 minutes extra ventilation

Same as B ₁ 38.0 60 minutes of extra ventilation

Tannase treatment after conversion: H ₂ O ₂ added (1/4 amount)

X)

IC a Tannas e - 31.9 be ti.'indluri - '^: no H ₉ O, wetted

34.4

34.0

34.0

10.6

34.0

14.2

27.0

18.7

25.9 27.3

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23.2 33.0 16.2

42.9 44.2 29.9

34.9 46.7 24.1

18.9 26.6 13.3

50.2 35.1 34.5

37.1 39.6 25.7

35, ß 37.9? 4; 7

E (port setting)

Tannase treatment after extraction; no BLO " added.

Example 2

The pre-conversion lannase treatment and peroxide addition conditions as described for the recovery of product A in Example 1 "were repeated using different temperatures for the tannase treatment step. All other conditions and treatment parameters were not changed. The tannase treatment was carried out in each pail 16 mg of tannase S enzyme preparation with a content of 320 units of enzyme activity was added to the tea leaf homogenate with a content of 171 g of tea leaves. The reaction mixtures were then each held at 25, 35, 45, 55 or 65 0 for 2 hours, was sprayed during the homogenate with nitrogen gas. wax completion of the tannase treatment, the temperature of the reaction mixture to 25 ⁰ C was stopped and the further processing of the tea solids was carried out as described for product A in example 1. Doppe.! kontrollversuehe were performed at each temperature, wherein Tannase not to the tea leaves homogenate was added although the homogenate was kept for 2 hours at the specified temperature with constant spraying with nitrogen gas «

The results of these experiments follow in Table 2. These results show that T _a nnasebehandluhg of Teehomogenaten the yield of cold water soluble instant tea solids

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Improved at all tannase treatment temperatures that were used, increases in process yield of more than $ 50 were achieved at the higher tannase treatment temperatures, and the tannase treatment always resulted in products with a darker, tea-like appearance, indicating that the tannase treatment was effective for the creation of conditions which lead to the extraction of colored tea components which are soluble in cold water, in contrast to the slightly soluble colored substances which are formed if the tannase treatment is omitted before the conversion. Only at 65 ⁰ C, the highest temperature used, a poor conversion was observed from tea solids, as indicating the bright color of the final product. This effect was probably a consequence of the considerable inactivation of the tea leaf enzymes, namely polyphenol oxidase and peroxidase, which takes place during the tannase treatment before the conversion at the high temperature. *

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Table 2 Effect of temperature in the tannase treatment before

Conversion to the results, obtained, from Teekomvertierun _b -s- homogenates '

Tannase treatment
before conversion

no

Yes

no

Yes

no

Yes

no

Yes

no

Yes

Temperature extraction O _n yield #

25 25 35 35 45 45 55 55 65 65

NoDo = not specific

32.5 38.4 32.9 37.3 31.7 37.0 31.2 39.9 28.6

37.9 polishing loss f> 18.9 8.3

16.0 5.4

16.0 3.8

16.8

6.1 16.1

• 4.5

Procedural Tristimulus Earbe yield '

26.4 35.2 27.6

35.3 26.6 35.6 26.0 37.5 24.0 36.2

Yy a.

34.9 36.7

22.6 33.2 30.8 36.8 19.4 29.8

N.Do * N, D.

20.7 31.9

NJD. NJD.

20.3 30.9

39.1 30.0

30.3 34.2

24.3 15.8 21.3 13.8 N.D. H, 9, N.Do 14.3 26.9 21.0

Example 5

A 200 g of kuster decayed green tea leaf was in Dissolve 700 ml of water and turn into instant tea solids that are soluble in cold water converted following the procedure of Example 1 * for product A. The talmas treatment before the conversion was carried out using 20 mg of tannase S containing 400 units of tannase activity during After conversion was effected for 2 hours at 45 g under nitrogen and extraction, the extract was divided into three 250 ml portions, each containing 2.4% solids and the portions were de-veiled with calcium chloride as follows: the three portions were de-veiled by adding 1.2 and $ 3 (on a tea solids basis) calcium chloride treated. the

Portions were then held at 25 ° G for 45 minutes. ; Finally, the portions were clarified by centrifugation at 6900 χ g for 10 minutes at 4 ° G and the polished Extracts were freeze dried.

Analytical results (Table 3) show that the clarity ί

of the cold-water-soluble instant tea samples obtained fluctuates

when the amount of calcium chloride used is changed. i

jhlm excellent clarity of the product was obtained with 3 $ Galciumchloridbehandlung with only a small loss of tea solids, istβ as shown by the very small reduction in the information obtained in this treatment yield

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Table 3 Effect of Caleium Chloride Entries

treatment of instant tea products obtained from a tea converter

tion homogenate system

Calcium chloride polishing process Trist imulus-i; 'arbe amount f * loss fo yield% L from veil

based on extraction yield of 56,

1 8.5 33.1 27.8 39.6 19.5 45

3 9.7 32.7 30.4 41.8 21.2 25

5 10.1 52.5 31.6 42.0 21.9 8

Example 4

Five 171 g samples of ground green tea leaves with a content of 257 ° dry weight were treated as described for product A in Example 1 with the modification that the amount of the tannase enzyme used in the tannase treatment before the conversion was changed, 4 ml Hydrogen peroxide was added during the conversion and $ 3 calcium chloride was used in all defogging treatments. The amount of tannase used in the tannase treatment before conversion was 32, 16, 8, 2 and 0 mg of tannase S per sample, which is 18, 8, 4, 1 and 0 janzym units (as defined in Example 1) each g dry weight of the green tea leaves. The results obtained in these three experiments are summarized in the table and show that the use of 8 units of tannase per g dry weight of fresh green tea leaves gives the highest extraction yields and the lowest polishing losses.

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substances is reduced, the overall process yield is low and the result is comparable to the product how it is obtained without tannase treatment, the use of 16 units per gram of tea solids, on the other hand no additional benefit.

Table 4 Effect of tannin tightness applied to the Treatment before conversion to instant tea products, obtained from the tea conversion farm.

units
of tannase jistract i ons -
yield f> Polieruni
loss ° j , 6 ψ- procedure-
o rousing Tri st imulus-Far-
be a b per gram of greener
Tea leaves , 5 loot $> L. 32.9 32.8 0 28.9 21 , 5 22.7 47.6 34.1 31.1 1 34.8 19th , 6 28.0 45.2 40.3 23.6 4th ■ 35.0 11 , 3 31.0 34.1 43.9 21.7 8th 37.0 10 33.1 31.2 44.9 25.4 16 35.8 7th 33.2 36.7 Example 5

A 171 g sample of ground green tea leaves with a total solids content of about $ 25 was converted to an instant tea product using the procedure for Product A in Example 1 with the following modifications: The tannase treatment. Before the conversion it was followed exactly with the modification that a temperature of 45 ⁰ G was maintained throughout. The conversion procedure was modified by using a quarter of the hydrogen peroxide additive, ie 4 ml of a 2Vi solution. The defogging treatment was modified to use 3y £ (total tea solids basis) calcium chloride. The instant tea product obtained in accordance with this procedure is produced by experienced tea

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taste as remarkably similar in all respects found to be a swan tea leaf infusion »

A second experiment was carried out following the above process conditions with the modification that the pH of the homogenate was not adjusted back to pH 5.6 with 2N KOH after the tannase treatment _o The conversion process was therefore initiated at the unusually low pH 4.7, What Resulted From Tannase Treatment Before Conversion “Very little color change was noted during the conversion process in this pail, with the result that the final product was light in color and had none of the red color characteristic of black sea. This is also indicated in the analytical values (Table 5) for these two products, where a normal tristimulus a color value is found for the pH adjusted product, but an unusually low value is obtained when the conversion process is in a homogenate with a pH is carried out as low as 4.7. The difference was attributed to the low annual activity of the natural tea enzymes caused by the low pH 4.7 resulting from the tannase treatment which resulted in poor conversion of green tea solids to black tea. Thus, the second attempt gave a slightly better result yield than the first attempt, presumably because a lower conversion had taken place ο However, the product obtained in experiment 2 as unacceptable befundene because of its poor color in fact, this product is like a jbjocbx unkonvertierteix, tannasebehandelten green tea extract.

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co O CD CO CO co

σ to oo BO

Table 5 Effect of pH on Green Tea Conversion Process

Vercäuch Kr. Mr the Conver- Extraction- Polishing- Procedure- -ristlmulus-Parbe

tation process yield ° / Ό loss fö yield fo Z Γ pH used

1 5.6 37.0 10.6 55.1

² 4.7 38.7 7.0 - 36.0

_L- , 2 a , 9 b_ , 7 51 , 3 43 , 9 21 S. 54 19th 22nd

ho

Ul ■ '

i ■■

O CD

Example 6

Five 171 g samples of cryogenically nipped green tea leaves ($ 26 dry weight) were treated as described in Example 1 for Product A except that the duration of the tannase treatment was changed prior to conversion, 4.0 ml of 2M hydrogen peroxide during the tea conversion process were added and 3f ° Galcium was applied for the defogging treatment. The anaerobic tannase treatment was carried out at 25 G for 0, 15, 30.60 and 120 minutes using 8 enzyme units per g dry weight of green tea leaves, the pH being maintained at 5.6 by adding small amounts of ΖΈ potassium hydroxide " At the end of this tannase treatment prior to conversion, aeration was started and conversion was carried out with aeration and maintenance of oxygen saturation in the reaction

mixture carried out at 25 ° C and a pH of 5.6. The pH was maintained at 5.6 during the conversion process by adding small amounts of 2N potassium hydroxide. Extraction, polishing and freeze-drying of the instant tea products were carried out as described for product A in example 1. The tannase treatment of 120 minutes before conversion was repeated, but without the addition of tannase as a control.

The results obtained for the six products prepared - as described above, are compiled in Table 6. All of these pre-conversion tannase treatments resulted in Obtaining good black tea-like products, except that the 0 Hinute tannase treatment resulted in a product which is of

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lighter in color than the others was "omission of the tannase treatment resulted in an overall eststoffen which were too light in color to be regarded as satisfactory for a black tea product in poor yield of cold water soluble i'eef.

Table 6. Effect of the duration of the tannase treatment

the conversion based on the results obtained from the tea conversion homogenate.

Tannase extract! ons- polishing- process- trirstimulus-color treatment- yield y> r- rens- -j time (min .; loss yield -

% 1

control

(no

Sßannase) 28.9

O 55.3

15 54.9

50 55.1

60 57.6

j 120 56.7

Example 7

21.6
9.1
11.1
12.4
14.4
15.5

22.7 47.6 52.9 52.8

50.5 57.5 42.0 25.8

51.0 52.9 41.5 22.8

50.7 52.5 41.6 22.5 52.2 55.2 42.2 25.0

51.8 52.2 41.5 22.4

A lee-Iinzymzubereitung is "made W.Sanderson in Journal of Pood Science, 1971, Volume 55, pages 160 to 164" of fresh tea leaves according to the procedure described by H "co _e and G The tea enzyme preparation is described in the following Tea conversion process used

1000 g of fresh gr ^; One tea leaves are ground on a Fitzmühle, "the veined leaves are then sufficiently ground

hot water to get a 10 to 1 ratio of water to the to surrender

Leaf mass / uria using the 3-cell sweeping current extraction system, described by Seltzer et al in U.S. Patent 2,927,860. The extract is made from the insoluble tea leaf

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residue separated by centrifugation to obtain an extract zi obtained which weighs about 10 kg and about 3.7 / 'ό solids contains.

Before conversion, the extract is subjected to a tannase treatment by adding 0.5 g of tannase enzyme with a specific activity of 15,000 units / g. The extract is then maintained at 25 ⁰ C for 60 minutes with gentle stirring "After completion of the tannase treatment before. After conversion, the pH of the extract is adjusted to about 5.6. A soluble tea enzyme preparation which is obtained from about 100 g of tea leaves according to the Co and Sanderson method as described above and which is contained in about 10 ml of solution then added to the extract to bring about the tea conversion process. The extract is held at around 25 C during the conversion process. The extract is then aerated by jetting with air in a ratio sufficient to maintain the dissolved oxygen level at saturation until the primary fermentation is complete, as indicated by a rapid increase in the dissolved oxygen level. The conversion is completed by continuing the aeration of the extract in the same proportion for about 30 minutes after the end of the first Feriuentierungsperiode "The converted tea extract entschlei ^ is ert and polished by adding 3, 0 ^c ß> (based on the total TEEx 'eststoffe) of calcium chloride to the extract, cooling the extract to 1O ⁰ C, holding the extract at 10 ⁰ C for 30 minutes and then clarifying the extract by centrifugation. golier ^^^ extract is. "then kernent- ri ^{to 20 1} ^ solids

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-29- 2304Ü73

and freeze-dried.

The cold water-soluble instant tea product obtained in this way represents a high yield of solids and its color, taste and kilch reaction are similar to those of black sea brewed in iris.

Example 8

Example 7 is repeated with only one major change in the procedure. Ede enzyme preparations, both natural tea enzymes like tannase, are immobilized and used in this form. The immobilization of both Tannase S and the natural tea enzyme from fresh green tea leaves is effected by the diazo coupling process described in

the corresponding enzyme US Pat. No. 3,519,538 o The process consists in / on glass beads by means of a chemical coupling agent of the type described in the PS as an enzyme-azo-silane glass bead.

j ben is »

ι ·

Before using the immobilized enzyme preparation

qn> preconditioned by mixing with portions of tea extract.

Two consecutive preconditioning treatments including stirring the extract and enzyme during

5 i-iinuten at 5O ⁰ C are preferred. \

The extract from fresh tea leaves is prepared according to The procedure of Example 7 x 10 kg of the extract with a content of 3.7 / »solids are immobilized with the Tarinase S by adding glass beads with the enzyme aera extract treated at 50 C. The suspension is during 12U 1-u.nuten stirred under constant nitrogen spray to to ensure anaerobic conditions «,

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The suspension treated with Tarmase is decanted and the pH adjusted to about 5.6 by the addition of potassium hydroxide, on which the preparation was fixed by enzymes from fresh tea leaves, are added. The temperature of the suspension is kept at 25.degree. Oxygen is passed through the suspension to a 25 ^c / ° ige. Maintain saturation until the primary "fermentation is complete, as indicated by a rapid increase in the dissolved oxygen level." The conversion is completed by continuing aeration of the extract in the same proportion for about 30 minutes, after the end the primary permentation period.

The converted tea extract is decanted and de-creamed, following the conditions as given in example 1 « The de-creamed extract is then freeze-dried following the conditions also described in Example 1 are specified. The freeze-dried powder, -if in cold Dissolved spring water, shows good cold water solubility, a light reddish tea-like color with a pleasant taste of good, freshly brewed black tea and a light one pink color when milk is added.

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Claims (7)

Claims : 1 \ Method of making black tea, being unfermented Tea is converted to black tea in the presence of natural tea enzymes, characterized in that the unfermented tea with tannase before its conversion is brought together to black tea. 2. The method according to claim 1, characterized in that the unfermented tea with 1-16 enzyme units of tannase per g Tea exudates are brought together. Jo Method according to one of the preceding claims, thereby marked that the unfermented tea with tannase in the Form a pulp of fresh tea leaves in a ratio of water to tea leaves of 3: 1 to 10: 1 together 4. The method according to «_nspruch 3, characterized in that the Porridge combined with tannase under anaerobic conditions and then converted to black tea under aerobic conditions, using the natural tea enzymes be supplied by the fresh tea leaves. 5. The method according to claim 1, characterized in that the unfermented tea is brought together with tannase in the i'orm of a green tea extract and then converted to black tea in the presence of an added natural tea enzyme preparation _o 6ο method according to claim S, characterized in that the Tannase is immobilized on a solid support. 7. The method according to claim 5 or 6, characterized in that that the natural tea enzyme preparation is immobilized on a solid support. - ■ 3098 3 3/0382