RU2345547C2 - Method for making tea product and obtained product - Google Patents

Abstract

FIELD: food products.

SUBSTANCE: method involves black tea contacting with ascorbic acid, its salts and their mixtures, acidifier and water during at least 5 minutes with further drying of tea product that is infused in water at 5 to 100°C.

EFFECT: quick infusing of tea product with improved red colour.

18 cl, 4 tbl, 8 ex

Description

The present invention relates to a method for producing tea infused or extracted in cold water, starting with black tea as a raw material, and to products obtained in this way, which have an improved red color infusion and quickly infuse.

From leaf tea, green leaf tea or black leaf tea can be obtained. In general, to prepare black leaf tea, the fresh green leaves of the Camellia sinensis plant are dried so that the plucked tea leaves lose moisture and to cause chemical / biochemical changes, especially in aroma, are macerated, fermented, and in this process, the enzymes in the tea leaf use atmospheric oxygen for the oxidation of various substrates to obtain colored products, and then dried at high temperature (to inactivate enzymes). Green tea production does not include a fermentation process, although partial fermentation can be used to produce intermediate types of teas, known as г oolong ’(yellow tea).

Tea is consumed in the form of a hot or cold drink (for example, iced tea). Numerous compounds in the leaves, which give the drink its unique organoleptic properties, are poorly soluble in cold water, so tea is usually infused in water at temperatures close to 100 ^o C.

Tea soluble in cold water is usually prepared by spray drying the liquid obtained by extraction of black tea or fibers obtained from the production of black tea. However, this method requires high temperatures or treatment with harsh chemicals, such as alkalis, which adversely affect the properties of tea, such as taste, color and aroma.

WO 01/70038 (Unilever, 2001) relates to a method for producing black leaf tea infused in cold water, comprising macerating freshly picked tea leaves, fermenting them, heating the leaves to stop fermentation, and then drying them to produce black leaf tea. The method is characterized in that the tea leaves are treated with a solubilizing compound selected from the group consisting of ascorbic acid, dihydroascorbic acid, L-scorbamic acid or 5-phenyl-3,4-diketo-gamma-butyrolactone, preferably at the stage of maceration. The black leaf tea so obtained, infused in water at 5 to 100 ^C. The teas have a good red color. The publication also discloses that tea leaves are preferably treated with a solvent compound in the presence of oxidizing enzymes and / or hydrogen peroxide to enhance the aroma and color of the tea.

Despite the fact that the technology disclosed in WO 01/70038 represents a significant improvement in the production of leaf tea, which is infused quickly and has a good red color, there is a need to produce tea with improved properties using black tea as the starting material. Black tea is a relatively stable product, and the method in which black tea is used as a raw material can be performed in a place quite remote from tea gardens, significantly increasing the flexibility of the method.

The inventors of the present invention unexpectedly found that treating black tea with ascorbic acid and an oxidizing agent, followed by drying, can provide a tea product that infuses in cold water to produce a rich, bright red-colored infusion in a short time.

According to a first aspect, the invention provides a method for producing a tea product comprising contacting black tea with ascorbic acid, a salt or mixture thereof, an oxidizing agent and water for a period of at least 5 minutes, and then drying to obtain a tea product that is infused in water with from 5 to 100 ^about C.

According to a preferred embodiment of the invention, a method for producing a tea product comprises contacting black tea with the following amounts, by weight of black tea: 1-8% ascorbic acid, its salt or mixture thereof, and 0.3-7% oxidizing agent for a period of at least least 5 minutes, followed by drying to less than 5% moisture, to give a black tea that infuses in water at 5 to 100 ^C. in this case ascorbic acid, its salt or a mixture thereof, and the oxidant are contacted with the black tea in in the form of aqueous solutions.

Preferably, black tea is further contacted with 0.1-8% (by weight of black tea) of one or more amino acids before drying. Preferably, one or more amino acids is added as an aqueous solution.

According to a further preferred embodiment, the method for producing black tea comprises contacting black tea with amounts, by weight of black tea, from 2 to 4% ascorbic acid, its salt or mixture thereof, and from 0.3 to 5% hydrogen peroxide for 5 minutes to 24 hours, followed by drying to less than 5% humidity, to obtain a tea product infused in water from 5 to 100 ^° C. In this case, ascorbic acid, its salts or their mixtures and oxidizing agent are brought into contact with black tea in the form of aqueous solutions.

Preferably, the black tea is further subjected to contacting with one or more amino acids in an amount of 0.1 to 2% (based on the weight of black tea) before drying. Preferably, one or more amino acids is added as an aqueous solution.

The invention also relates to tea obtained or which can be obtained by this method. Tea made in this way is infusible / extractable in cold water and hot water, and the infusion / extract exhibits an improved red color. Tea is also infused quickly in water.

It is particularly preferred that black tea is first brought into contact with ascorbic acid, its salts or mixtures thereof, and one or more amino acids (if used) before it is brought into contact with an oxidizing agent.

"Tea" for the purposes of the present invention means a sheet material from Camellia sinensis var. sinensis or Camellia sinensis var. assamica . It also includes rooibos tea derived from Aspalathus linearis , however it is an insufficient source of internal enzymes. "Tea" also includes the product of mixing two or more of any of these teas.

“Leaf tea” for the purposes of this invention means a tea product that contains one or more sources of tea in a non-instant form.

“Cold water infusion” for the purposes of this invention means to obtain good color, aroma and mouthfeel in a short infusion time, i.e. less than 10 minutes, but preferably less than 5 minutes at a temperature at or between 5 and 30 ° ^C.

To prevent doubt, the word “including” means inclusion, but not necessarily “consisting of” or “composed of”. In other words, the listed stages or options should not be exhaustive.

Tea production, especially black tea production, traditionally includes drying, maceration, fermentation and heating. Black tea for the purposes of the invention is obtained by the aforementioned method or any other known method of preparing black tea.

The present invention relates to the additional processing of black tea obtained as described above for the preparation of a tea product infused in cold water. Processing includes contacting black tea (leaf / dust) or secondary products, or a mixture of green leaf tea with black tea, or sorted black tea, or solid particles of tea coated with black tea with ascorbic acid, its salts or mixtures thereof, and an oxidizing agent, preferably peroxide hydrogen, with or without the addition of peroxidase, in the presence of moisture to enhance the infusion of black tea in cold water. It is also preferred that black tea is contacted with one or more amino acids prior to drying. All of these agents are preferably added in the form of aqueous solutions. Alternatively, they can be dry mixes followed by the addition of water. Tea is thus brought into contact for at least 5 minutes and is preferably dried to less than 5% moisture. The solution is used once or in divided doses. The treatment is preferably carried out by spraying or dipping. Black tea can be processed both after exiting the dryer and after sorting.

Ascorbic acid, its salts or mixtures thereof, including sodium or calcium salts, are preferably added in an amount of from 1 to 8 wt.% Tea, more preferably from 2 to 4 wt.% Tea. Ascorbic acid, its salts or mixtures thereof are preferably added in the form of an aqueous solution.

Amino acids that may optionally be used according to this invention include one or more of alanine, arginine, asparagine, cystine, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophan, tyrosine and valine. Amino acids can be used alone or as a mixture. They are either mixed with ascorbic acid, or added separately. The amount of amino acids is preferably between 0.1 and 8 wt.% Tea, more preferably from 0.1 to 2 wt.% Tea. The resulting solution of ascorbic acid and amino acids can be used once or in divided doses. The treatment is preferably carried out in the form of spraying or dipping.

Preferably, aqueous solutions of ascorbic acid its salts or mixtures thereof and amino acids (if used) should be heated before contacting with tea, preferably to a temperature greater than 50 ° ^C. The amounts of water may be between 10 and 100 wt.% Of tea, more preferably from 30 to 100 wt.% Tea, most preferably from 40 to 100%.

Preferably, the oxidizing agent is added to black tea after adding ascorbic acid and amino acid (if used). The oxidizing agent may be hydrogen peroxide, calcium peroxide, magnesium peroxide, oxygen (other than oxygen scattered in the surrounding atmosphere) or any compound that can release oxygen under the conditions of the method. The oxidizing agent may be an enzyme that can release hydrogen peroxide. Preferably, the oxidizing agent is hydrogen peroxide. The oxidizing agent is preferably added in an amount of 0.3 to 7% by weight of tea. If the oxidizing agent is hydrogen peroxide, then it can be added as a 10 to 75% solution in water. Typically, hydrogen peroxide is available as a 30% solution of hydrogen peroxide in water. The oxidizing agent is more preferably added in an amount of 0.3 to 5% by weight of tea. The solution can be used once or in divided doses. The treatment is preferably carried out in the form of spraying or dipping.

Ascorbic acid, its salts or mixtures thereof, an oxidizing agent and water are preferably left in contact with black tea at the stage of the process, known as aging, for at least 5 minutes. Aging can be performed for up to 24 hours. The aging is preferably carried out at a temperature of from 10 to 60 ^about C.

The tea can be dried using any method known in the art, preferably to produce tea with a moisture content of less than 5%.

Water infusions of the tea made in the manner described above, in water at temperatures in the range from 5 ^to 100 ° C will give tea with better color and good flavor. Cold water infusions may be prepared at temperatures ranging from 5 to 30 ° ^C.

It should be understood that the method of the invention can be successfully used to improve quality and add value to any low-loss black teas without loss.

The method according to the invention is further described with reference to non-limiting examples of its implementation.

EXAMPLES

Example 1

Ascorbic acid (3 g) was dissolved in 100 ml of hot water. This solution was then heated in a boiling water bath for 5 minutes. The hot solution was sprayed onto 100 g of black tea. Approximately 5 ml of a 30% hydrogen peroxide solution was added. Maintained at 25-30 ^{° C} for about 15 minutes, followed by drying in a fluid bed drier at 130-140 ^{° C} to reduce the moisture content to less than 5% in black tea basis.

Example 2

The method of Example 1 was carried out and 0.5 g of phenylalanine was added to 100 ml of water.

Comparative Example A

100 g of black tea was wetted with 100 ml of hot water. Maintained at about 25-30 ^{° C} for 15 minutes followed by drying in a fluid bed drier at 130-140 ^{° C} to reduce the moisture content to less than 5% in black tea basis.

Comparative Example B

The method of comparative example A was carried out, except that an additional 5 ml of 30% hydrogen peroxide was sprayed immediately after the addition of water.

Comparative Example C

The method of comparative example A was carried out, except that a solution of 0.5 g of phenylalanine in 100 ml of water, which was heated in a boiling water bath for 5 minutes, was sprayed on tea instead of 100 ml of water used in comparative example A.

Comparative Example D

The method of comparative example C was carried out, except that 3 g of ascorbic acid was used instead of 0.5 g of phenylalanine.

Comparative Example E

The method of Example 1 was performed, except that 0.5 g of phenylalanine was used instead of 3 g of ascorbic acid.

Comparative Example F

Ascorbic acid (3 g) and phenylalanine (0.5 g) were dissolved in 100 ml of hot water. This solution was then heated in a boiling water bath for 5 minutes. The hot solution was sprayed onto 100 g of black tea. Approximately 5 ml of a 30% hydrogen peroxide solution was added. Maintained at 25-30 ^{° C} for about 15 minutes, followed by drying in a fluid bed drier at 130-140 ^{° C} to reduce the moisture content to less than 5% in black tea basis.

The teas prepared in this way in comparative examples A to F and examples 1 and 2 were tested for infusion in water in the following way.

The method of preparation of cold water infusion

1 g of each sample of black tea was infused in 100 ml of water at 25 ^about C for 5 minutes. The solutions were filtered to obtain cold tea infusions, and the color of the obtained infusions was measured using a Hunter Lab Ultrascan XE ™ colorimeter in transmission mode. The data are presented in Table 1.

Color measurements

L * a * b * measurements for color were performed on a Hunterlab UltraScan XE ™ colorimeter under the following conditions:

Cuvette - 2 cm (quartz), mode - transmission, light source - D65, observations - 10, scale - CIELAB. The reflection coefficient was also determined at 520 nm.

50 ml of the prepared infusion was placed in a 2 cm quartz cuvette, transmittance / reflection coefficient was measured under the conditions mentioned above.

Values of a * were taken into account as the redness values of tea. The higher the value, the more red the tea. 520 nm represents the wavelength at which red is absorbed. The higher the absorption value, the more intense the red color.

Table 1 Example but* 520 nm absorption one 41.5 1.10 2 50,4 1.51 BUT 28.6 0.77 AT 30.7 0.85 FROM 21,4 0.59 D 28.3 0.78 E 29.4 0.83 F 25.0 0.66

The data in table 1 show that there is a synergistic effect when adding ascorbic acid and hydrogen peroxide to black tea (Examples 1 and 2) compared with the addition of any one of these ingredients. An additional effect is achieved due to the additional contact of tea with phenylalanine (Example 2).

Infusion rate

The rate at which tea infused in cold water was also investigated. The effect was investigated for comparative example A and examples 1 and 2. Determined the color of the infusion after 30 seconds, 3 and 5 minutes. The data are presented in Table 2.

table 2 Example Time (minutes) but* 520 nm absorption BUT 0.5 4.31 0.28 3.0 18.91 0.55 5,0 23.98 0.66 one 0.5 26.71 0.64 3.0 30.27 0.73 5,0 39.06 1,02 2 0.5 31.98 0.72 3.0 45.24 1.17 5,0 49.93 1.49

The data presented in table 2 show that the teas prepared by the method according to the invention (examples 1 and 2) infuse faster and give a better red color within a short period compared to control teas. Additional effects were also found when using phenylalanine in combination with ascorbic acid and hydrogen peroxide (example 2).

Aroma / Taste Improvement - Gas phase chromatography over liquid

The additional effects of contacting black tea with phenylalanine are shown by measuring levels of key molecules that provide a pleasant odor, such as phenylacetaldehyde and benzaldehyde. Data for comparative examples and examples are shown in table 3.

Table 3 Example Phenylacetaldehyde
(peak area) Benzaldehyde
(peak area) one 6679 50156 2 1770134 96077 BUT 15349 33937 AT 11063 28654 FROM 9683 42449 D 8522 37137 E 153824 77466 F 75130 92055

Comparative Example G

The experiment of Example 2 was performed without black tea, and the color a * was measured at zero, 30 and 60 minutes, as compared with Example 2 and Comparative Example A.

The data are summarized in Table 4

Table 4 Example a * at time zero a * after 30 minutes a * after 60 minutes BUT 21.79 17.17 15.84 2 50.63 54.27 53.65 G -0.38 -0.62 -0.79

Table 4 shows that black tea is necessary to produce red.

Thus, it is possible by the present invention to produce black leaf tea, which infuses quickly in hot or cold water and provides a good red color.

Claims (18)

1. A method of obtaining a tea product, comprising:
(i) contacting black tea with aqueous solutions of ascorbic acid, its salts or mixtures thereof, and an oxidizing agent for a period of at least 5 minutes; and subsequent
(ii) drying to obtain a tea product that is infused in water at from 5 to 100 ° C. 2. The method according to claim 1, in which the amount of ascorbic acid, its salts or mixtures thereof is from 1 to 8 wt.% Black tea. 3. The method according to claim 2, in which the amount of ascorbic acid, its salts or mixtures thereof is from 2 to 4 wt.% Black tea. 4. The method according to claim 1, in which the amount of oxidizing agent is from 0.3 to 7 wt.% Black tea. 5. The method according to claim 4, in which the amount of oxidizing agent is from 0.3 to 5 wt.% Black tea. 6. The method according to claim 1, in which the oxidizing agent is selected from one or more of hydrogen peroxide, calcium peroxide, magnesium peroxide, oxygen, an enzyme that can release hydrogen peroxide. 7. The method according to claim 6, in which the oxidizing agent is hydrogen peroxide. 8. The method according to any one of claims 1 to 7, in which the oxidizing agent is added after adding ascorbic acid, its salt or a mixture thereof to black tea. 9. The method according to any one of claims 1 to 7, in which black tea is brought into contact with ascorbic acid, its salts or their mixtures and an oxidizing agent for a holding time of from 5 minutes to 24 hours 10. The method according to any one of claims 1 to 7, in which the water is heated to a temperature of 10-60 ° C before contacting with black tea. 11. The method according to any one of claims 1 to 7, in which black tea is dried to a moisture content of less than 5%. 12. The method according to any one of claims 1 to 7, in which black tea is additionally brought into contact with one or more amino acids before drying. 13. The method according to item 12, in which the amount of one or more amino acids is from 0.1 to 8 wt.% Black tea. 14. The method according to item 13, in which the amount of one or more amino acids is 0.1 to 2 wt.% Black tea. 15. The method according to item 12, in which one or more amino acids is selected from one or more of alanine, arginine, asparagine, cystine, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophan, tyrosine and valine. 16. The method according to item 12, in which the oxidizing agent is added after adding one or more amino acids to black tea. 17. Tea product obtained by the method according to any one of claims 1 to 16. 18. Tea product, which can be obtained by the method according to any one of claims 1 to 16.