RU2470519C2 - Black tea production - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: inventions group relates to food industry. Tea leaves are air-dried till moisture content is equal to 64-70%. The leaves are macerated by way of their passing through a rotary lobed machine wherein some of lobes are replaced with lobes invertedly reversed. Tea leaves leaving the rotary lobed machine are additionally cut by way of passing through a CTC-machine. The machine blade has 2-6 teeth per inch. Tea leaves are fermented and fire-dried for fermentation termination. Leaves are dried and sorted to produce black leafy tea. Black leafy tea has the appearance of orthodox leafy tea sized Broken Orange Pekoe or bigger.

EFFECT: inventions group allows to manufacture a product with brewing rate and degree typical of CTC tea keeping the appearance of orthodox tea.

7 cl, 16 dwg, 17 tbl, 13 ex

Description

The present invention relates to the processing of tea or, more specifically, to a method for the production of larger, high quality black leaf tea.

Leaf tea can be prepared in the form of green leaf tea or black leaf tea. As a rule, to prepare black leaf tea, the fresh green leaves of the Camellia sinensis plant are dried (soft-dried), ground, fermented (in this process, the enzymes in the tea leaf use atmospheric oxygen to oxidize various substrates to produce brown products), and then subjected fire drying (to dry tea leaves). Green leaf tea is not subjected to fermentation. Partial fermentation can be used to make intermediate-type teas, known as oolong tea (Chinese, yellow tea).

Common sense suggests that in the production of black tea, tea must be macerated in some way to release fermenting enzymes and their substrates in the leaves. Tea can be macerated in various ways, but in a broad sense, there are two main mechanized methods for doing this.

The first method, called "orthodox production", involves passing pre-weighed batches of heavily withered tea leaves through rolls before the stages of fermentation, fire drying and drying. The so-called "orthodox tea" has particles that are aesthetically pleasing to many (reminiscent of dried leaves rather than "granules" of CTC tea - see below), but give less concentrated infusions due to less fermentation and worse brewing of larger particles size.

The second method, the most popular of a number of unorthodox, continuous methods, involves the use of a device resembling a calender that cuts, tears and twists tea leaves. The original device was invented by W. McKercher in 1930, and is universally referred to as a CTC machine (from the words “cut-tear-cure” - “cutting-tear-twist”). Finely chopped product is generally known as "CTC tea" and is characterized by high brewing speed and strong staining. This method provides tea that is more consistent and uniform in quality than the tea of the orthodox production method, but since the CTC method tends to agglomerate the tea material, it looks more like "granules" than fragments of leaves.

Both Orthodox rolls and STS rolls are often used in combination with a rotor blade machine, which is an extruder type machine and is used for pre-conditioning (squeezing / grinding) of leaves before maceration. The rotor blade machine was invented as a form of continuously working orthodox rolls, but, as such, is rarely used at present. Infusions from teas obtained using a rotary vane machine (RLM) are similar to infusions of orthodox teas in terms of infusion properties and infusion rates. These methods, their history and role in tea production are described in "Tea: Cultivation to Consumption" edited by K. C. Willson and M.N. Clifford, Chapman & Hall, 1992.

Generally speaking, consumer preference for orthodox tea or CTC tea is determined by national or regional culture. In many countries, the appearance and texture of leaf tea are important indicators of quality, with larger leaf particles being associated with higher quality. In the West, more and more tea is consumed in filter paper bags, and the color of the infusion therefore becomes more important.

Some consumers, however, want the best of both worlds; that is, loose leaf tea that looks and feels like orthodox tea, but has the characteristics of an infusion of more fully fermented STS tea. The authors of this application have developed methods for producing black leaf teas that resemble orthodox tea, but are brewed like STS tea. Publication WO 99/40799 (Applicant) describes a method that involves exposing whole tea leaves to heat shock, at such a temperature and for such a time that are sufficient to initiate fermentation, after which the tea is allowed to be fermented for such a time and at such a temperature, which is sufficient to achieve the desired properties of the infusion.

Publication WO 00/10401 describes a method for producing quick-brewed teas from whole leaves or large fragments thereof by soaking tea leaves with liquid carbon dioxide in a pressurized vessel, reducing the pressure in the vessel at a speed sufficient to freeze liquid carbon dioxide, applying heat sufficient to to cause sublimation of frozen carbon dioxide, and then initiate fermentation in the leaves, after which the tea is allowed to ferment for a time that is sufficient m to achieve the desired properties of the infusion, and the fermented product is dried to obtain tea from whole leaves.

Publication WO 01/11979 describes and claims black leaf tea, which has the appearance of orthodox black tea, but is characterized in that it has the characteristics of insisting black CTC tea.

A later pending application (publication WO 01/82713) with priority of UK application 0010315.0 describes a method for wilting the first load of freshly picked tea leaves, macerating the dried leaves, then allowing the macerated dried leaves to ferment to produce a batch of fermented leaves (dhool), withering of the second load of freshly picked tea leaves, mixing a batch of fermented leaves obtained from the first load of leaves with withered leaves obtained from the second a swarm of leaf loading, passing the mixture through the rollers, then allowing the mixture passed through the rollers to ferment, and drying the fermented mixture to produce black leaf tea.

The description of Russian patent 1678276 describes a method for processing tea leaves to obtain tea granules and concentrates. Tea leaves wilted to a residual moisture content of about 64 to 65%, then passed through rolls and sorted. The finer sorted fraction is fermented and dried. The larger fraction is cut and passed through the rolls, and then sorted again. Small varieties of tea are further processed to produce tea granules, and larger varieties are used to produce tea concentrates. This method is a modification of orthodox processing, aimed at increasing the output of orthodox tea of high quality. The leaf products according to this description are orthodox teas, that is, teas with slow infusion, strong aroma and weak coloring.

Russian patent 1034686 describes a method for producing good quality black leaf tea in a shorter time than usual. Tea leaves are wilted to a residual 70% moisture, then passed through rolls and sorted. The size of large leaves is reduced. Tea is mixed and simultaneously aerated with atmospheric air at a speed of 45 m ³ / h for 15 minutes, and then dried. This produces orthodox leaf teas, i.e. teas with slow infusion, strong aroma, and faint coloration.

The authors of the present invention, through a deeper understanding of the processes of fermentation and infusion of tea, have developed an alternative method for producing instant brewed large leaf black tea. This method can use adapted tea production equipment (such as RLM and CTC) or new processing equipment, but requires a deep understanding and control of the properties of the starting material (green leaf), and interaction with processing equipment.

In a broad sense, the present invention relates to a method for producing black tea, comprising the steps of withering and maceration of tea leaves, then allowing them to be fermented, fire dried the leaves to stop fermentation, and then dried and sorted the leaves to produce black leaf tea, the method being characterized in that that tea leaves wither to a moisture content between 64% and 70% (preferably between 64% and 68%), before maceration using a controlled application, both shear and compression forces are sufficient to extract juice on the surface of tea leaves, causing the destruction of most cells in the tea leaf, morphological changes in the tissue (cell separation leading to the appearance of air gaps, most often observed in mature leaves) and redistribution of the contents of the cells, which together leads to fermentation and infusion typical of CTC tea while maintaining the appearance of orthodox tea leaves. Preferably, the leaf teas produced by the method of the invention have orthodox Broken Orange Pekoe (BOP) leaf sizes or even larger.

The black leaf tea thus obtained resembles the orthodox processed leaf tea, but is infused in freshly boiled water at a speed exceeding the rate of infusion of an equivalent mass of tea of the same size obtained by the orthodox processing. The quality of the infusion is exceptionally high.

In one example, using adapted commercial tea production equipment, freshly picked tea leaves are dried to a target moisture content of between 64 and 70%, preferably from 64 to 68%, passed through a RLM modified to provide increased shear and compression forces. The RLM can be modified by replacing at least some of the blades of the machine with blades facing in the opposite direction. Such equipment, capable of providing the required shear and compression forces, can be used instead of the modified radar. The processing stage on the modified RLM can be followed by the stage of cutting, cutting or grinding, to further impart a given size and shape to the particles. The additional cutting step can be carried out by passing once through a CTC machine, modified so that its rolls have fewer teeth per inch (tooth / inch) than a conventional CTC machine. For example, the rolls of a modified CTC machine preferably have 2 to 6 teeth per inch, instead of the usual 8-10 teeth per inch. This allows the modified CTC machine to reduce the size of very long leaves and cuttings without producing agglomerated finely chopped leaf particles typical of traditional CTC tea. As an alternative to using the modified CTC machine, other slicing or grinding devices can be used to provide the required characteristics of black tea.

“Tea” for the purposes of the present invention means Camellia sinensis var. sinensis or Camellia sinensis var. assamica. It also includes rooibos tea obtained from Aspalathus linearis , although it is a poor source of enzymes for endogenous fermentation. "Tea" also encompasses the blending products of any two or more of these teas.

“Leaf tea” means plant material obtained from a tea plant that has not been brewed.

Black leaf tea means essentially fermented leaf tea.

“Orthodox leaf size” means the leaf size of orthodox leaf tea corresponding to the sizes for orthodox leaf tea indicated in Tables 1 and 2.

For clarity, the words “comprises” and “provides” encompass, but are not necessarily, the meanings “consists of” or “formed of”. In other words, the listed stages or signs are not exhaustive.

Brief Description of the Drawings

Figure 1 - block diagram of the method according to the invention.

Figure 2 - DCPR frequency histogram of large leaf black tea obtained by the method described in pending international application (publication WO 01/82713 with priority application UK 0010315.0). See example 4.

Figure 3 - DCPR frequency histogram of large leaf black tea obtained by the method according to the invention, using a modified rotor-blade machine (RLM), without subsequent cutting using a CTC machine with 6 teeth per inch. See example 4.

Figure 4 - DCPR frequency histogram of large leaf black tea obtained by the method according to the invention, using a modified RLM, followed by cutting using a CTC machine with 6 teeth per inch. See example 4.

Figure 5 is a graph in which the characteristics of the infusion of some orthodox and CTC teas are compared with the characteristics of teas obtained by the method described in pending international application WO 01/82713 with priority of UK application 0010315.0 and the method according to the invention. See example 5.

6 is a graph in which the quality and color of milk-free infusions obtained with some orthodox and CTC teas are compared with infusions obtained with teas according to WO 01/82713 and with teas obtained according to the invention. See example 6.

7 is a graph in which the quality and color of milk-infused infusions obtained with some orthodox and CTC teas are compared with infusions of teas obtained in accordance with the method described in WO 01/82713 and the method of the invention. See example 7.

Fig. 8 is a graph comparing the brewing performance of large leaf black teas obtained by the method described in WO 01/82713 and the method of the invention. See example 8.

Fig.9 is a graph comparing the performance of infusion of large leafy black teas obtained by the method described in WO 01/82713, and the method according to the invention. See example 8.

10 is a graph showing theaflavin levels obtained by fermenting tea leaves in the method of the invention. See example 11.

11 is a graph showing the color of infusions obtained from leaf tea prepared by the method according to the invention, and from tea leaves obtained by other methods. See example 11.

On Fig shows the structure of tea leaves obtained by the method according to the invention, as it is visible through a microscope. See example 11.

Fig. 13 is a graph showing the yields obtained with modifications of the method of the invention. See example 12.

Fig is a graph showing the bulk density of teas obtained with modifications of the method according to the invention. See example 12.

Fig is a graph showing the color of infusions of tea leaves obtained with modifications of the method according to the invention. See example 12.

The method according to the invention combines the stages usually associated with CTC production, with the stages usually associated with orthodox production and / or with the stages usually associated with the processing of non-food products, in such a way that provides quick-brewing large quality loose leaf tea within the desired profile particle sizes.

The preferred scheme of the method according to the invention is presented in figure 1. The stages shown in dotted rectangles are optional.

In this method, the loading of freshly picked tea leaves (the so-called green leaf) is wilted before maceration. Leaves can wither in any convenient way, for example, by storing them for a certain period of time, usually, for example, up to 16-24 hours, during which they undergo various biochemical and physical changes, and, as a rule, lose moisture. The leaves should be dried so that the specific moisture content in the sheet is 64-70%, preferably 64-68%. This moisture content is higher than in conventional orthodox tea production (where the final moisture content, as a rule, is less than 60% and often about 50%). However, it is lower than moisture content in the production of traditional CTC tea, where the final moisture content should be higher than 68%, usually 70-72%, otherwise, too much heat is generated in the mechanical components of the CTC machine, especially in commercial production. This controlled withering is important not only for creating aroma (as is traditionally believed), but also for ensuring optimal STS-type fermentation (where a higher moisture content leads to improved oxidation of polyphenols), and for changing the physical properties of the sheet, in order to optimize their interaction with maceration equipment, and provides the necessary commercial performance.

Then, the wilted leaf is subjected to a controlled application of shear and compression using some appropriate means to obtain leaf tea having the appearance of an orthodox leaf tea. The authors of the present invention found that the action of specific shear and compression forces on the leaf during maceration leads to effective internal destruction (both to the loss of integrity of most individual cells inside the tea leaf, and to morphological changes in its tissue - to cell separation, leading to the formation of air gaps, most often observed in mature leaves), as well as a redistribution of the contents of the cells, which together leads to fermentation and infusion, typical of CTC teas, while maintaining The outside view of orthodox tea leaves. The loss of integrity of individual cells allows polyphenolic substrates to mix with the key oxidative enzyme, polyphenol oxidase, which is a necessary precondition for fermentation. Fermentation also requires oxygen, and the formation of air gaps in leaf tissue helps to overcome the oxygen restriction observed in larger leaf fragments. In addition, the present method allows this destruction of cells and tissues with a moisture content that is more optimal for fermentation than in conventional orthodox production. Introduced air gaps are stored in the fire-dried tea, which leads to faster hydration and infusion when brewing tea.

The operation of processing equipment, in order to provide the necessary shear and compression forces, depends on the nature of the equipment and the power supply. Important criteria are exposure to tea leaves during maceration. This effect is evaluated by visual assessment of the fermented leaf (juice is emitted to the surface, but without unnecessary loss of juice from the pressed leaf), analysis of the fermented leaf (structure), and also the resulting tea (infusion characteristics). For each particular piece of equipment, operating parameters can be set, provided that the above characteristics are provided. For example, a standard 15-inch RLM equipped with vanes facing in the opposite direction, as described in the present method, works with a given capacity (for example, 1500 kg / h) and with an outlet installed to achieve a current of 35 ± 5 amperes. Similarly, the clearance of an 8.5-inch CTC machine with 6 teeth per inch is set to achieve a current of 28 ± 3 amperes.

Shear and compressive effects can be provided using a modified RLM. The radar assembly contains an outer cylindrical casing covering a central conveying rotor connected to the blades located opposite each other, with each subsequent pair of blades mounted at right angles to the adjacent pair. The outer casing has ribs protruding inward to which tea leaves are pressed as they pass through the machine. The output end of the radar is connected to an adjustable cone or diaphragm, limiting the inlet and providing pressure control inside the device. In a preferred modified RLM for use in the present method, at least some of the RLM blades are replaced with reverse facing blades. Although not wanting to be bound by any theory, the authors believe that the modified RLM provides higher pressure on the material in the device. Alternatively, similar equipment capable of providing the required shear and compression forces can be used instead of the modified RLM (for example, various extruder and roll designs are possible). This stage may be followed by an additional stage of cutting, slicing or grinding, to obtain tea of the desired size and shape. Preferably, a modified CTC machine is used in which the rolls have fewer teeth per inch than conventional CTC machines. Modified CTC machine rolls preferably have 2 to 6 teeth per inch instead of the usual 8-10 teeth per inch. This allows the modified CTC machine to reduce the size of very long leaves and cuttings without obtaining small leaf fragments characteristic of traditional CTC tea. In addition, in the traditional CTC production, these small leaf particles are agglomerated as a result of repeated cutting, which leads to the granular appearance of the fire-dried CTC tea. Alternatively, a slicing or grinding apparatus can be used that can provide the desired size and / or shape profile located after the modified RLM. The inventors have found that cutting devices, in particular food cutting devices, such as the J9-A model for two-dimensional cutting with a feed tape and rotary knives, and food processing devices, such as a COMITROL ™ food processor with rotary cutting microheads manufactured by Urschel Laboratories Incorporated, Valparaiso, Indiana, USA, are particularly suitable for this purpose.

The macerated leaves are then left to ferment. The term "fermentation" is usually used in the context of alcohol production to describe the action of exogenous enzymes. However, in tea, fermentation is the oxidative process that tea undergoes when certain endogenous enzymes and substrates are combined after the destruction of cells and tissues. During this process, the colorless catechins in the leaves are converted into a complex mixture of yellow substances and substances from orange to dark brown, and a large number of aromatic volatile compounds are formed. Fermentation is described in detail in Tea: Cultivation to Consumption by Willson and Clifford (See pages 490-494 and Chapter 17). Fermentation can be carried out in a fermenter, if desired.

The inventors have found that the macerated sheet should be left to ferment for at least one hour, preferably for a period of more than two hours, but preferably not more than 3 hours. The preferred fermentation period is from about 120 to 140 minutes, more preferably about 125 minutes. Leaving leaves for fermentation for a period of more than three hours may adversely affect the quality of the final product. It can also cause an increase in costs. Although these periods are dependent on ambient temperature, they are comparable to normal periods of fermentation of CTC tea.

Fermentation is preferably carried out at ambient temperature, i.e. about 25 ° C., although a temperature of 18 ° C. or even 15 ° C. may be suitable. If desired, fermentation can be accelerated at slightly higher temperatures, for example 30 ° C. The use of an oxygen-enriched atmosphere in a fermentation tank (vat) also promotes fermentation.

If desired, it is possible to initiate fermentation in the dried leaves by heat shock at such a temperature and with a duration that is sufficient to initiate fermentation, as described in international application WO 99/40799 (applicant).

Alternatively, you can soak the dried tea leaves with liquid carbon dioxide in a container under pressure, then reduce the pressure in the container at a speed sufficient to freeze liquid carbon dioxide, apply heat sufficient to sublimate the frozen carbon dioxide, and then initiate fermentation in the leaves, leaving them to ferment for a time sufficient to achieve the desired properties of the infusion, and dry the fermented product to obtain tea from whole leaves. Such a method is described in international application WO 00/10401 (applicant). Another alternative way of destroying the leaves and initiating the fermentation of the leaves passed through the rolls is to freeze and thaw the leaves.

If desired, the fermented tea leaf can be treated with tannase (flavanol gallate esterase) to produce de-salated catechins and gallic acid (which subsequently results in high levels of theaflavins and non-gallated thearubigins during fermentation), or can be treated with tannase and then with hydrogen peroxide in an amount sufficient for endogenous peroxidases to oxidize gallic acid released by tannase treatment. These treatments give colored types of tea and enhance the aroma. They are described in detail in international application WO 00/47057 (applicant), the description of which is incorporated herein by reference.

If desired, the size profile can be further adjusted by including in the method the screening step of the fermentable sheet (see FIG. 1). Such an operation fractionates fragments of macerated leaves by size by passing a fermentable sheet through a vibrating sieve. The mesh size of the sieves is selected in accordance with the desired change in the final size profile. The material passing through the sieve is sent directly to the fermentation, while the material held on the sieve is subjected to an additional cutting step, which can be carried out using, for example, a RLM, a CTC machine or a cutting / cutting device, such as which are manufactured by Urschel. After cutting, this material is also sent to fermentation. The screening step can be carried out immediately after primary maceration or, preferably, after short fermentation (15-30 minutes), which reduces the "stickiness" of the particles of the fermented material.

As a final step, the fermented mixture is subjected to fire drying, air drying, and sorting to produce black leaf tea that resembles orthodox tea leaf tea but infuses freshly boiled water at a rate exceeding the rate of infusion of the equivalent mass of orthodox tea.

Fire drying heats and dries tea to destroy fermenting enzymes, and thereby stops fermentation. This leads to a decrease in moisture content to less than 5%, preferably 2.5-3%, and also leads to additional chemical / biochemical oxidation and changes in the aroma of tea. Fire drying typically involves exposing the tea to a stream of dry, hot air, for example in a fluidized bed device.

Dried loose leaf tea can be sorted by size using any sorting and classification tools known to those skilled in the art. Appropriate sorting tools are described in Tea: Cultivation to Consumption edited by K.C. Willson and M.N. Clifford, Chapman & Hall, 1992, pages 500 to 502. Before sorting, extra-large material that does not pass, for example, through a 8 mesh Boulton sieve (hole size 2.6 mm), can be removed and then can be removed fibrous material by passing tea through or near electrostatically charged rolls. Then, leaf tea can be passed through a series of vibrating screens, on which various sizes are held and assembled. In the following examples, the sieves described in table 1 are used to separate black leaf tea into five dimensional ranges.

Table 1 Size range Number of meshes Cell hole LL Large Leaf 12-8 1.5-2.6 mm ML Midleaf 20-12 1.0-1.5 mm SL Small Leaf 32-20 0.5-1.0 mm Fl leaf crumbs 40-32 0.4-0.5 mm D Dust Below 40 below 0.4 mm

Large leaf (LL) and medium leaf (MM) black teas are particularly preferred when black tea is intended to be infused directly in water, although these teas can also be used in infusion bags if required. For this reason, the method according to the invention should maximize the yield of tea of larger sizes if black loose tea is to be brewed directly. However, if the black leaf tea obtained by the method according to the invention is intended for use in bags, then it is preferable to carry out the method according to the invention in such a way as to maximize the amount of tea of smaller sizes, for example medium-leaf (ML) and / or small-leaf (SL) black teas in final product. By modifying the method of the present invention, as described below, the distribution of size ranges in the black leaf tea product can be brought to the desired size ranges.

The particle size of leaf tea is universally measured in the tea trade, as it is a critical factor in consumers' assessment of the acceptability and quality of tea. As explained in Tea: Cultivation to Consumption edited by K.C. Willson and M.N. Clifford, Chapman & Hall, 1992, pages 502, there is no universal standard, although the International Organization for Standardization has issued the international standard ISO 6078-1982, which provides some guidance in this regard. Some common sizes of leaf tea are listed in table 14.2 on page 501 of the above Willson and Clifford links and are shown in table 2. However, this table does not provide a complete list of varieties corresponding to orthodox leaf teas.

table 2
Varieties of tea, in decreasing order of particle size Varieties Abbreviation Source Whole leaves Gfop Orthodox production only FOP OP Leaf fragments Fbop Products mainly only from production using rotary vane machines Bop BP Crumbs Bopf Products mainly from production using CTC OF Pf Dust PD RD

The product of the method of the invention is preferably sorted to produce orthodox-looking loose tea peeled broken orange pekoe (BOP) tea or larger if black tea is intended to be directly infused in boiling water to produce a beverage. Smaller varieties may be preferred if black leaf tea is to be used in infusion bags.

Large leaf (LL) black leaf tea from table 1 can be classified as Pekoe, with the sorting system shown in table 2, medium leaf tea (ML) would be classified as Broken Orange Pekoe, small leaf (SL) would be classified as Broken Orange Pekoe Fannings and ground ( FL) would be classified as Pekoe Dust.

A more detailed classification system for orthodox leaf tea varieties used by the inventors of the present invention is shown in Table 3. Many of these varieties are listed in the Appendix to ISO 6078-1982, published by the International Organization for Standardization. Where this occurs, the abbreviation according to ISO is given in the last column of table 3.

Table 3
Classification of sizes of orthodox sheets Orth
sheet size Grade name ISO reduction O Churamoni dust
Dust three CD P Dust D Q Pekoe dust secondary fannings PD R Broken Orange Pekoe Fannings Pekoe Fannings Bopf
Pf S Fannings
Fannings two   T Broken orange pekoe
Leafy Broken Orange Pekoe Fannings
Broken tea Bop
BT U Leafy Broken Orange Pekoe
Small pekoe
Flowery Broken Orange Pekoe Fbop V Pekoe P W Large pekoe EPS Broken pekoe souchong X Orange pekoe OP Y Broken pekoe
Broken pekoe two BP
BP2 Z Broken tea two
Broken mixed BT2
BM

Black leaf tea produced by the method of the invention is orthodox in shape, preferably with a leaf size of “T” or higher (preferably “V” or even larger), as indicated in table 3, if the black leaf tea is intended to be brewed directly in boiling water to produce a drink. Smaller varieties may be preferred if black leaf tea is to be used in bags. As will be seen later in Example 2, the tea taster evaluates medium leaf black teas (ML) produced in Example 1 as grade T and large leaf black teas (LL) as grade V. Black leaf tea with a small leaf (SL) as described in table 1, would be classified as grade R, and black leaf tea in the form of leaf crumbs (FL), as described in table 1, would be classified as P / Q.

The authors of the present invention and tea tasters are very pleasantly surprised by the quality of tea obtained by the method according to the invention. This tea not only has the appearance of orthodox leaf tea and quickly infuses with the red infusions associated with CTC tea, but it also has a very high overall quality and aroma. Thus, this method effectively provides the most useful characteristics of both CTC teas and orthodox teas in one product.

The method according to the invention uses a less complex process than the method described in international application WO 01/82713 (with priority of application UK 0010315.0), and gives a product with a stronger aroma (and for this reason, higher quality, as estimated by international tea tasters) . There is also great flexibility with respect to changing the shape and / or size of the sheet.

Orthodox appearance

A tea taster can clearly distinguish between teas that have the look of orthodox tea and teas that have the look of tea treated with a CTC machine. From the layman’s point of view, orthodox tea tends to be flat, rolled up and twisted, and STS tea is more like granules in appearance. Although tea tasting (which includes sorting) is more of an art than a science, the professional precision with which experienced tea tasters can evaluate and sort tea into varieties should not be underestimated.

In Example 2, an experienced tea taster rated black leaf tea prepared by the method of the invention as orthodox tea.

Orthodox particle shape appearance

Smoothing and various twisting operations that characterize the production of orthodox black tea tend to produce split clippings from leaf fragments, while the more destructive grinding action of CTC machines produces granule-like fragments of tea that are more uniform in size and shape. For this reason, it is possible to characterize tea particles with an orthodox appearance as having an average length that is preferably at least twice the average width of tea particles (i.e., with an aspect ratio of 2: 1), and more preferably at least three times the average particle width of tea (i.e., with an aspect ratio of 3: 1).

In addition to this, as an attempt to determine the orthodox appearance, the applicant has developed a method for effectively measuring the roundness of tea fragments, or rather, their deviation from perfect roundness (see examples 3 and 4). This method involves obtaining images of tea fragments and measuring the ratio of the actual perimeter to the perimeter of a circle with the same area (DCPR). DCPR is defined by

where P is the observed perimeter of the particle and A is its observed area. As a result, this is the relationship between the actual perimeter of the object and the perimeter of a circle having the same area as the object. This parameter has a minimum value of DCPR = 1 if the object is round. All other forms have DCPR values greater than one. These values are size independent.

The aspect ratio, compared to the DCPR, with respect to the regular rectangles, can be compared as follows: 1: 1 (1,128), 2: 1 (1,197), 3: 1 (1,303), 4: 1 (1,410), 5: 1 (1,514), 6: 1 (1,612), 7: 1 (1,706), 8: 1 (1,795), 9: 1 (1,881) and 10: 1 (1,962). Of course, in practice, the irregular edges of tea particles slightly increase DCPR.

Black leaf tea according to the invention is such a tea, where preferably at least about 5% of the tea particles have a DCPR of 1.6 or higher, more preferably at least about 10% of the tea particles have a DCPR of 1.6 or higher, and even more preferably, at least about 15% of the tea particles of DCPR 1.6 or higher. This corresponds to the aspect ratio for the DCPRs under consideration, reaching 6: 1.

Modification of the appearance by cutting after processing on a rotary vane machine (RLM)

Analysis of samples (quartiles) (see example 4) shows that exposure of leaves for higher pressure during maceration (as in the modified RLM, but without the subsequent cutting step) can lead to a higher percentage of larger sheet particles, in features in larger fractions. Although this may be beneficial in some cases, the production of more uniform particles is necessary for many applications, especially for packaging in tea bags. Processing a leaf using a cutting step (such as on a CTC machine with 6 teeth per inch) after maceration, for example in a modified RLM, can modify the appearance in a positive way if black leaf tea is intended for use in bags. The product still resembles an orthodox sheet, but is now more uniform in shape (that is, “more square”) and can be used to fill bags.

The nature of the infusion of CTC tea, determined by the performance of the infusion

Black leaf tea prepared by the method of the invention resembles orthodox processed black tea at least at the macroscopic level, but it differs in infusion characteristics from orthodox tea. The product of the method according to the invention demonstrates the infusion characteristics observed, as a rule, in STS teas. These characteristics include the speed and degree of infusion, determined by the intensity of staining achieved over a period of time.

The infusion performance is partially determined by the particle size of the sheet. Small leaves or parts of leaves have a larger surface to volume ratio than large leaves or parts of leaves, and thus tend to more quickly infuse than large leaves. The applicant has shown in Example 5 that, when using comparable leaf sizes, orthodox teas infusions tend to be less red and yellow than CTC teas, and that teas obtained by the method of the invention infuse more like leaf CTC teas than like orthodox loose leaf tea.

Ideally, the black leaf tea of the invention is preferably infused at a rate that is at least as fast as the infusion rate of an equivalent mass of the same tea or tea of comparable size obtained by the STS treatment. Black leaf tea can be mixed with orthodox black tea or tea granules, in order to achieve the desired characteristics of the infusion.

The kinetics of tea infusion according to the invention is compared with teas according to international application WO 01/82713 and it can be seen that for the two varieties presented (large and medium leaf), the leaf tea according to the invention infuses faster and provides a darker infusion. The aforementioned WO publication describes a method for producing an orthodox sheet with infusion of a CTC type, which involves the simultaneous passage through rolls of a freshly baked sheet and a fermented CTC sheet. The present invention provides a product with similar or improved infusion characteristics in a less complex way (i.e., not requiring separate processing lines for the sheet and CTC product).

Type of CTC-infusion, determined by the quality of the infusion

The nature or type of CTC infusion can be determined by an experienced tea taster both in the presence and absence of milk, both qualitatively and quantitatively, on an appropriate industrial scale. Experienced tasters can score the quality of the infusion (that is, evaluating the attributes of taste, including volatile substances that determine aroma), color, brightness and density using a scale such as that described in examples 6 and 7.

The black leaf teas of the invention, brewed without milk (which is typical in Continental Europe and the USA) or with the addition of milk (which is typical in the UK), provide an infusion quality that resembles the quality of STS teas rather than orthodox teas. The difference was found to be sharper when milk infusions were evaluated. In fact, infusions with the addition of milk from black leaf teas according to the invention were found to be as well colored as infusions from CTC tea.

You can even define black teas according to the invention as those in which, when they are brewed in plain water (Crawley, United Kingdom) for 2 minutes and 15 seconds, at a concentration of 13.3 g / l, and then 10 ml of milk is added to them 235 ml of infusion, the quality of the infusion is in the range between 4 and 6, but preferably in the range between 5 and 6.

The organic properties of tea according to the invention were compared with the properties of tea according to WO 01/82713 using organoleptic analysis (QDA). This analysis revealed significant differences in the aromas of the two products, while the higher scores for the aroma went to the tea according to the invention (due to the higher quality, according to the estimates of the tasters).

Black leaf tea, obtained by the method according to the invention, can be mixed with orthodox processed black tea or tea granules to obtain the desired characteristics of the infusion.

The method of the invention is now described with reference to the following illustrative examples.

EXAMPLE 1

Black tea production

The process of the invention was carried out on an industrial scale at Brooke Bond, Kenya. The green leaf of standard quality was wilted for 16 hours to a final moisture content of 68 ± 1%. The blown sheet was passed through a 15-inch Vikram rotor blade machine equipped with 3 vanes facing in the opposite direction with a capacity of 1,500 kg / h. The RLM was tuned to a current of 35 ± 5 amperes (to create the necessary pressure). The fermentable sheet (dhool - “dhul”) from the RLM was fed directly to an 8.5-inch CTC machine equipped with rolls with 6 teeth per inch. The gap between the rollers was set to maintain a current of 28 ± 3 amperes. The fermentable sheet from the CTC machine was loaded into GWA fermentation tanks connected to humidified air supply means. The air flow through the fermentable sheet was set to maintain the fermentation temperature of 22 ± 2 ° C, over a period of time of 125 ± 10 minutes. Tea was subjected to fire drying in a fluidized bed, maintaining the outlet air temperature of 180 ± 5 ° C, to a final moisture content of 2.5-3.0%. After drying, the material was passed through a 8 mesh Boulton sieve (hole size 2.6 mm) to remove material that was too large. The fibrous material was removed using electrostatically charged rolls. Leaf tea was then sorted using Boulton sieves. Cell sizes on Boulton screening equipment were selected according to the desired particle size ranges, and the sizes shown in Table 1 above were separated and collected.

Evaluation of the product obtained in this process is described in examples 2-8.

EXAMPLE 2

Differentiation of the appearance of orthodox and CTC teas using an experienced tea taster

The authors of the present invention ask an experienced tea taster to choose 17 teas from around the world, some of which are Orthodox, some of them CTC. Then they ask the expert to classify these teas, as well as two samples of each of the two varieties of black leaf teas, which are produced using the method of example 1 (one medium leaf (ML), the other leaf (LL)).

The taster assigns a three-letter code to each sample. The first letter of the three-letter code means whether leaf tea has the appearance of leaf tea made using orthodox production (O), CTC production (C), or a mixture thereof (M). The second letter indicates the size of the sheet, in accordance with the grades, as described above in table 3. The third letter indicates the type of sheet, in accordance with the rating system shown below in table 4.

Table 4
Sheet Type Classification Type of Sheet description one Powdery 2 A lot of cuttings / fibers 3 Cuttings / Fibers four Mixture / few fibers 5 Rather mixed 6 Satisfactory 7 Good 8 Very good 9 Special / Excellent Type

Estimates are made taking into account a number of factors, including sheet size, curl, surface area and color. The three-letter code assigned by the taster to each sample is presented in Table 5. In each tea case, the tea taster classified the black teas of the invention as having an orthodox appearance.

Table 5
Comparison of known and new teas by an experienced tea taster The code Type of Source Grade Sheet ODX1 Orthodox Indonesia Bopf OT5 ODX2 Orthodox China Bop OT3 ODX3 Orthodox Assam Fbop OU5 ODX4 Orthodox Ceylon EBOP OU8 ODX5 Orthodox Ceylon Bop OT5 ODX6 Orthodox Indonesia Bop OT6 ODX7 Orthodox Ceylon Bop OT5 CTC1 CTC Shiongo BP1 CH6 CTC2 CTC Ecuador BP1 CH3 CTC3 CTC Kawuzi BP1 CH4 CTC4 CTC Indonesia BP1 CH3 CTC5 CTC Vietnam Bop Ci3 CTC6 CTC Malawi BP1 Ci4 CTC7 CTC Kenya, Rukuriri BP1 CH7 CTC8 CTC Kenya Bonnet BP1 CH4 CTC9 CTC Ceylon BP1 CH4 CTC10 CTC Assam BP Chs ML Sample 1 Example 1 Kenya, Kerijo ML OT5 ML Sample 2 Example 1 Kenya, Kerijo ML OT5 LL Sample 1 Example 1 Kenya, Kerijo LL Ov5 LL Sample 2 Example 1 Kenya, Kerijo LL Ov5

EXAMPLE 3

DCPR Relationship Analysis

As indicated above, smoothing operations, of various types of twisting that characterize the production of orthodox black tea, tend to produce split fragments of tea leaves, while the more destructive grinding effect of CTC machines and the tendency of the CTC method to agglomerate produce granular fragments of tea. The author developed a method for effectively measuring the roundness of tea fragments or, rather, their deviation from absolute roundness.

The method involves obtaining images of tea fragments and measuring the ratio of the actual perimeter to the perimeter of a circle of the same area (DCPR). DCPR is defined using the expression

where P is the observed perimeter of the particle, and A is its observed area. As a result, the ratio of the actual perimeter of the object and the perimeter of the circle, that is, a hypothetical circle that has the same area as the object, is obtained.

This parameter has a minimum value of DCPR = 1 (for a round object). All other forms have DCPR values greater than one. These values are independent of the size of the object.

Samples of some teas from around the world used in Example 2 are sampled and compared with samples of medium leaf (ML) teas and large leaf teas (LL) prepared in accordance with the method of Example 1. In each case, small samples are randomly taken with a spatula.

Only images of the external shape of the particles (i.e. silhouettes), but not surface details, should be obtained. It is also important that shadows are excluded. For this reason, leaf samples are distributed on a glass sheet and placed under a WILD M8 ™ backlight microscope at low magnification. Choose an increase that allows you to see the maximum possible number of particles in the field, but at the same time allows you to see each particle large enough to make significant measurements. The selected increase gives a visible field size of 21 × 15.75 mm.

Images are captured using a JVC KY 55 ™ camera and the NOETECH ™ image grabber (“grabber”). The pixel resolution is 768 × 576. Some background is left visible in each micrograph, in order to make sure that the shape of the particles is not distorted due to excessive illumination. For each sample, twelve or fifteen visible fields are scanned, giving a total number of particles, usually about 300-400. All images are continuously archived.

An image analyzer (KONTRON KS 300 ™) is used to measure binary images (that is, those where all pixels are either black or white). The surface areas to be measured are made white, the background remains black. “Segmentation” is the process by which a binary image is obtained from the original.

The original image is made monochrome. Choose a threshold level below which everything becomes black (pixel value = 0), and above which everything becomes white (that is, pixel value = 255). The threshold level varies slightly from image to image, and is selected in such a way as to avoid either expansion or contraction of the external shape of the particles; typically it is approximately 140. This gives an image in which the particles are black and the background is white.

The image is reversed (that is, converted in such a way as to obtain white particles on a black background), and any particles in contact with the edge of the image (and for this reason, partially shaded) are erased. The end result at this stage is a binary segmentation mask. Masks also archive.

Before measurement, each image passes through the “opening” procedure, which three times alternately expands and narrows the external dimensions of the particles. This gives the effect of a slight smoothing of the surfaces and the removal of small parts of the surface that do not contribute to the overall shape or size of the object, but which can increase the assessment of its perimeter. This part of the procedure is carried out in the above KONTRON KS 300 ™ image analyzer.

Particles are then measured and data is collected from all images in each sample set. The results are shown below in table 6.

Table 6
Comparison of known and new teas by measuring the frequency of appearance of particles having certain DCPR relationships SAMPLE % DCPR
<1.2 % DCPR
1.2-1.39 % DCPR
1.4-1.59 % DCPR
≥1.6 Ctc1 12.5 68.0 16.7 2.9 ctc3 25.0 61.9 9.5 3,7 ctc6 20.3 65.6 9.7 4.4 ctc8 12,4 66.0 19.5 2.1 ctcl0 19.7 66.3 12,2 1.8 odxl 8.1 53,4 24.3 14.3 odx2 21.5 56.2 13.6 8.7 odx3 4.3 34.2 36,2 25.3 odx4 3.2 33.7 33.0 30,2 odx5 12.6 48.8 28.0 10.6 odx7 11,4 40.5 29.6 18.5 odx7 11,4 40.5 29.6 18.5 Example 1 ML 4.3 41.3 32,5 21.9 Example 1 LL 4.2 34.8 37.0 24.0

CTC teas showed a much higher proportion of particles in the class DCPR <1.2 (10-25%) than in the class ≥1.6 (3-4%); that is, they consisted mainly of material with a low aspect ratio. Orthodox teas had a greater scatter. ODX2 was very similar to CTC in character, while ODX3 and ODX4 contained only 3-4% of particles in the class DCPR <1.20, but 25% and 30% in the class ≥1.6. But, as a rule, the well-known orthodoxly produced teas contained significantly more particles having a DCPR equal to or greater than 1.6 than the known STS teas.

Black leaf teas obtained by the method according to the invention, as shown, have a higher percentage of particles, especially in larger fractions having a DCPR equal to or greater than 1.6, thus confirming their orthodox appearance.

EXAMPLE 4

Modification of appearance by cutting after a rotary vane machine

DCPR analysis was also carried out on large leaf teas produced (a) using the method described in international application WO 01/82713 (having priority of application UK 0010315.0) (see table 7 and figure 2), (b) using a modified RLM, as described in example 1, but without subsequent cutting by a CTC machine with 6 teeth per inch (see table 8 and FIG. 3), and (c) using a modified RLM as described above, followed by cutting with a CTC machine with 6 teeth per inch, as described in example 1 (see table 9 and figure 4). The results are presented in the frequency histograms, in figure 2, 3 and 4.

Table 7
Quartile analysis of large leaf tea made by the method described in GB 0010315.0 DCPR Frequency% 0.00-0.99 1.00-1.19 1.20-1.39 1.40-1.59 1,60-1,79 1.80-1.99 2.00-2.19 2.20-2.39 2.40-2.59 Quartile 1 0 14.09 50.34 18.79 10.74 2.68 2.01 0.67 0 Quartile 2 0 11.84 53.95 22.37 9.21 0.66 1.32 0.66 0 Quartile 3 0 3.31 49.67 30.46 11.26 3.31 1.32 0.66 0 Quartile 4 0 3.27 33.33 37.25 13.07 9.15 3.27 0.65 0

Table 8
Quartile analysis of large leaf tea made by the method of the invention without subsequent cutting with a 6-tooth CTC machine DCPR Frequency% 0.00-0.99 1.00-1.19 1.20-1.39 1.40-1.59 1,60-1,79 1.80-1.99 2.00-2.19 2.20-2.39 2.40-2.59 Quartile 1 Quartile 2 Quartile 3 Quartile 4 0
0
0
0 4.42
0
0
1.79 44.25
40.71
23.89
15.18 28.32
26.55
32,74
35.71 16.81
14.16
25.66
18.75 5.31
9.73
12.39
11.61 0.88
3,54
2.65
10.71 0
5.31
2.65
2.68 0
0
0
3.57

Table 9
Quartile analysis of large leaf tea made by the method of the invention followed by cutting with a 6-tooth per inch CTC machine DCPR Frequency% 0.00-0.99 1.00-1.19 1.20-1.39 1.40-1.59 1,60-1,79 1.80-1.99 2.00-2.19 2.20-2.39 2.40-2.59 Quartile 1 Quartile 2 Quartile 3 Quartile 4 0
0
0
0 6.72
5.88
5.19
2.19 41.79
45.59
48.15
28.47 27.61
35.29
21.48
41.61 15.67
8.09
14.81
17.52 4.48
5.15
8.15
8.03 2.99
0
2.22
1.46 0.75
0
0
0 0
0
0
0

From these results, it was concluded that exposure of leaves for higher pressure during maceration (as in the modified RLM) can provide a higher percentage of large-sheeted particles, especially in larger fractions.

Processing the sheet using a cutting step (such as on a CTC machine with 6 teeth per inch) after the RLM can modify the appearance so that although the product still resembles an orthodox sheet, it is more uniform in shape (i.e. "more square "), making the resulting black loose leaf tea suitable for use in tea bags.

EXAMPLE 5

Differentiation of orthodox and CTC-teas according to the characteristics of infusion

Orthodox teas, as a rule, infuse more slowly than STS teas. This reflects the degree of maceration. For this reason, it can be expected that black leaf tea, which resembles orthodox tea, is infused like orthodox tea.

The authors selected 13 teas from around the world used in Example 2 and compared the brewing characteristics of these teas with two samples of medium leaf teas made by the method described in international application WO 01/82713 (applicant) (designated 143 ML and 147 ML in table 10) , and two samples of medium-leaf teas (ML varieties) produced by the method of example 1 (indicated in table 10 269 ML and 270 ML). Teas were selected solely on the basis of comparable leaf sizes. This is necessary because small leaves have a larger surface to volume ratio than large leaves and thus, in any case, tend to infuse faster than large leaves.

In each case, 200 ml of boiling deionized water was added to a pre-heated thermos flask containing 2 g (± 0.05 g) of loose tea. The flask was fixed and quickly turned over, then the leaves were allowed to brew for 3 minutes. The flask was then flipped back and the infusion was filtered through WHATMAN 541 ™ filter paper using a Buchner funnel and flask under vacuum.

The color of the infusions was measured on a HUNTERLAB ULTRASCAN Xe ™ colorimeter using a standard analytical method (as provided by the manufacturer). The results shown in table 10 below correspond to an optical path length of 1 cm, with a D65 lamp and a viewing angle of 10 °.

Staining was measured and presented using three color measurements, L *, a * and b *. L * represents turbidity / darkness, with L = 0 representing black and L = 100 representing white or colorless. A * represents red / green, with high positive a * values corresponding to red, and high negative a * values corresponding to green. B * represents blueness / yellowness, while high positive values of b * correspond to yellow and high negative values of b * correspond to blue.

Table 10
Characteristics of infusion of leaf teas of comparable size SAMPLE L * a * b * ODX01 83.1 8.5 69.7 ODX02 81.9 8.3 61.2 ODX05 82,2 11,2 79.9 ODX06 82.5 9.3 74,2 ODX07 79.1 11.9 72.5 CTC01 80.8 12.8 82.8 CTC02 79.7 13.5 80.7 CTC03 77, 9 19.1 91.9 CTC04 80,4 12.5 80,4 CTC07 77.3 12.0 75.3 CTC08 75,4 14.7 80,4 CTC09 74.3 17.5 85.3 CTC10 74.3 18.7 91.2 143 ml 80.45 14.12 82.92 147 ml 78.55 16.9 86.95 269 ML 79.47 16.28 91.50 270 ml 80.72 14.56 89.09

The values of a * and b * are presented in the form of a graph in figure 5. Each point on the graph corresponds to the position of the color of the infusion in the color space. The points near the upper right corner of the graph represent infusions with stronger yellow or red components, respectively.

As can be seen in FIG. 5, the leaf teas of the invention (269 ML and 270 ML) fall into the result area for CTC teas rather than the result area of orthodox teas. This clearly shows that the black leaf teas of the invention are infused rather as STS tea than as orthodox tea.

EXAMPLE 6

Differentiation of orthodox and CTC teas according to the characteristics of infusion without milk

The authors insisted each of the 17 teas from around the world used in Example 2 and compared the characteristics of the infusion of these teas with several samples of large-leaf (LL) and medium-leaf (ML) teas made by the method according to the international application WO 01/82713 (applicant) (samples) are indicated in table 12 143, 146, 147, 149, 152 LL and 143, 146, 147, 149, 152 ML), and samples of large-leaf (LL) and medium-leaf (ML) teas made by the method of example 1 (samples are indicated in table 12 280, 281 LL and 280, 281 ML).

In each case, to simulate the preparation of tea in Continental Europe, 2.0 g (± 0.05 g) of tea were infused in 250 ml of freshly boiled tap water (Crawley, United Kingdom) for 1.5 minutes, and an experienced tea taster evaluated the quality of the infusion with respect to its taste (T), color (C), brightness (B) and aftertaste (M). The TCBM nomenclature used to express the evaluation results in this example and example 7 replaces the previously used QCBT nomenclature, in which the property now expressed as T (taste) was expressed as Q (quality) and the property now expressed as M (aftertaste) , expressed as T (density). This represents the only nomenclature change since the valuation methodology is the same as before.

The quality of the infusion was evaluated on a scale of 0.6 to 9.4, as shown below in table 11.

Table 11
Assessment of the quality of infusion T - Taste 0.6 (fresh) 9.4 (aromatic) C - Coloring 0.6 (yellow) 9.4 (red) B - Brightness 0.6 (weak) 9.4 (bright) M - Aftertaste 0.6 (liquid) 9.4 (thick)

The results are presented below in table 12.

Table 12
Evaluation of the quality of infusion without milk SAMPLE T C B M ODX1 4.0 3.0 4.2 3.0 ODX2 2.6 2.6 2,8 2.6 ODX3 4.4 2.2 4.0 4.0 ODX4 4.0 4.4 4.4 4.6 ODX5 5.2 2.2 5,4 3.0 ODX6 4.6 2.0 5,6 2.6 ODX7 4.4 3.0 5.2 4.0 CTC1 5,0 4.0 6.0 3.6 CTC2 3.0 4.2 5,0 3.4 CTC3 4.0 4.2 5,0 2.2 CTC4 3.4 4.6 5,0 3.0 CTC5 2,8 4.4 4.6 3.6 CTC6 2.6 3.2 4.0 3.0 CTC7 5,6 2.0 6.0 2,8 CTC8 4.6 4.6 5.8 4.6 CTC9 3.6 4.4 5,6 4.0 CTC10 4.8 4.0 5.8 5,0 143 LL 5,0 3.8 5.2 4.0 146 LL 4.6 4.2 5.2 4.2 147 LL 5.2 4.0 5,4 4.0 149 LL 5,0 4.2 5.2 4.2 152 LL 5,4 3.6 5,4 4.0 143 ml 4.8 4.4 5.2 4.4 146 ml 4.4 4.8 5,4 4.6 147 ml 4.6 4.4 5,4 4.4 149 ml 4.8 4.4 5,4 4.4 152 ML 5,0 4.0 5,4 4.0 280 LL 5,0 4.0 5,0 4.2 281 LL 5.2 4.0 5,0 4.0 280 ML 5,0 4.4 5,0 4.4 281 ML 5.2 4.4 5,0 4.6

The values of T (taste) and C (color) are given in the form of a graph in Fig.6. In Fig. 6, it can be seen that known STS teas tend to provide infusions of a more saturated color than known orthodox teas. From figure 6 it is also clear that the black teas of the invention infuse rather as better colored STS teas than as orthodox teas.

EXAMPLE 7

Differentiation of the characteristics of the infusion of Orthodox and CTC-teas with milk

The authors brewed each of the 17 teas from around the world used in Example 2 and compared the brewing characteristics of these teas with several samples of large-leaf (LL) and medium-leaf (ML) teas made by the method according to international application WO 01/82713 (applicant) (samples are indicated in table 13 143, 146, 147, 149, 152 LL and 143, 146, 147, 149, 152 ML), and samples of large-leaf (LL) and medium-leaf (ML) teas made by the method of example 1 (samples are indicated in table 13 280, 281 LL and 280, 281 ML).

In each case, to simulate the preparation of tea in the UK, 3.125 g (± 0.05 g) of tea was infused in 235 ml of freshly boiled tap water (Crawley, United Kingdom) for 2 minutes 15 seconds (static infusion). Then the liquid was poured into 10 ml of partially skim milk, and an experienced tea taster evaluated the quality of the infusion with respect to its taste (T), color (C), brightness (B) and aftertaste (M). The quality of the infusion was evaluated on a scale of 0.6 to 9.4, as shown above in table 11. The results are shown below in table 13.

Table 13
Evaluation of the quality of infusion for brewing with milk SAMPLE T C B M ODX1 4.2 3.2 4.4 3.6 ODX2 2,4 2.0 2.0 2.6 ODX3 4.2 2.6 4.6 3.8 ODX4 3.8 2,8 4.0 4.6 ODX5 5,6 3.6 5.8 3.2 ODX6 4.4 3.2 5,4 3.0 ODX7 4.0 2,8 4.6 4.0 CTC1 4.6 4.0 6.0 3.6 CTC2 2,8 4.2 4.4 3.0 CTC3 3.8 6.6 4.2 2.2 CTC4 3.2 5,0 4.0 2,8 CTC5 2,8 4.2 4.4 3.8 CTC6 3.0 5.8 4.0 3.0 CTC7 5,6 4.0 6.4 3.0 CTC8 3.6 7.2 3.6 4.2 CTC9 4.0 4.0 5,0 4.0 CTC10 4.6 4.0 6.0 4.6 143 LL 4.6 5,6 4.0 4.0 146 LL 4.2 5,6 4.2 4.0 147 LL 5,0 5.2 4.8 4.2 149 LL 4.6 5,4 4.4 4.0 152 LL 5.2 5,0 5,0 4.2 143 ml 4.4 5.8 4.0 4.4 146 ml 4.2 6.0 4.0 4.4 147 ml 4.6 5,6 4.4 4.4 149 ml 4.4 5.8 4.2 4.6 152 ML 5,0 5,0 5,0 4.2 280 LL 4.8 4.4 5,0 4.4 281 LL 5.2 4.6 5,0 4.4 280 ML 5 4.8 5.2 4.6 281 ML 5.2 4.8 5.2 4.8

The values of T (taste) and C (coloring) are given in the form of a graph in Fig.7. In Fig. 7, it can be seen that all known STS teas provide infusions with milk in more saturated colors than all known orthodox teas. From Fig. 7 it is also clear that the black teas of the invention provide infusions with milk comparable to the best known STS teas.

EXAMPLE 8

Comparison of the infusion characteristics of black leaf teas made by the method of WO 01/82713 and the method of the invention

2 g of large-leaf and medium-leaf black teas made by the method according to international application WO 01/82713 (applicant), and 2 g of samples from two downloads of black leaf teas made by the method of example 1, from the same tea leaves, were infused in 200 ml boiling water, and the rate of infusion was monitored by measuring the absorption coefficient at 445 nm. Measurements for large leaf teas are shown in graph form in Fig. 8, and measurements for medium leaf teas are shown in graph form in Fig. 9.

From both figures it is clear that black teas made by the method according to the invention infuse much faster and more fully than tea made by the method described in international application WO 01/82713.

EXAMPLE 9

The following black teas are prepared at the Brooke Bond tea factory in Kenya from the same tea leaves collected, (a) standard CTC tea, (b) tea produced on standard RLM, (c) tea produced by the method of the invention using modified RLM, and (d) tea produced by the method of the invention using a modified RLM and then a 6-tooth CTC machine. The produced teas were evaluated by experienced tasters as described above in Example 6, and the ratings are shown in Table 14.

Table 14 SAMPLE T C B M CTC 4.8 3.4 5,6 3.8 Standard RLM 5,6 3.0 5.8 3.8 Modified RLM 5,0 3,5 5,4 3,7 Modified RLM and 6-tooth CTC machine 5.1 3,7 5,4 4.0

You can see that the use of a modified RLM to apply the necessary shear and compression forces in the method according to the invention provides higher color estimates. In addition to changing the distribution of varieties, the use of a CTC machine with 6 teeth per inch after the treatment step on the modified RLM leads to even higher color estimates.

EXAMPLE 10

Factory-scale experiments were conducted to evaluate the effect of processing on a modified RLM and on a CTC machine with 6 teeth per inch on the yield of different varieties of leaf tea produced by the method of the invention. Four experiments were carried out: (a) using a standard RLM (RV), (b) using a modified RLM with several vanes turned in the opposite direction (MRV), (c) using a standard RLM (RV) and then a CTC machine with 6 teeth per inch, (d) using a modified RLM with multiple vanes (MRV) and then a CTC machine with 6 teeth per inch as a maceration step. All other parameters of the method were kept constant, as in example 1. The resulting dried leaf teas were sorted using Boulton sieves 8, 12, 20, 32 and 40. The hole sizes in the sorting sieves are shown in table 1.

Oversized particles that were held on an 8 mesh sieve and small particles that passed through a 40 mesh sieve were considered waste. Of course, it is important that the amount of waste is kept as low as possible. Table 15 demonstrates that the amount of particle waste can be reduced by using a modified RLM in accordance with the method of the invention. The use of modified RLM also increases the amount of large leaf (LL) variety produced, compared to the use of unmodified RLM.

Table 15 LL% ML% SL% Fl% D% % Waste RV only 21 32 fourteen one one 31 Mrv only 27 35 fifteen one 0 21

Table 16 shows that CTC cutting further reduces the amount of waste in the product, and that using a modified RLM before CTC cutting, 6 teeth / inch, results in less waste than when an unmodified RLM is used. This table also demonstrates that STS cutting after the RLM processing stage increases the number of medium- (ML) and small-leaf (SL) sizes, making the resulting black tea suitable for use in tea bags.

Table 16 LL% ML% SL% Fl% D% % Waste RV / CTC eleven 39 33 3 2 12 MRV / CTC 13 38 36 3 2 8

EXAMPLE 11

Samples of three batches of small leaf (SL) and ground (FL) black teas prepared by the method of Example 1 were evaluated by the method similar to that described in Example 6. The samples were identified in Table 17 as SL-1, SL-2, SL-3, FL-1, FL-2, and FL-3. The taste assessment (T) was carried out on STS-processed black leaf tea obtained by traditional STS treatment from the same green leaf as the samples processed by the method according to the invention. CTC teas were sorted using Boulton, 15, 25, and 40 mesh sieves. Black loose tea collected between 15 and 25 mesh sieves is indicated in Table 17 PF1, and black loose tea collected between 25 and 40 mesh sieves is designated PD. Samples from three different downloads were evaluated. These downloads are indicated in table 17 as PF1-1, PF1-2, PFl-3, PD-1, PD-2 and PD-3.

Table 17 Example 1 T CTC Processing T SL-1 5.2 Pf1-1 3.8 SL-2 5.2 Pf1-2 3.8 SL-3 5.2 Pfl-3 4.0 FL-1 4.8 PD-1 3.8 FL-2 5.2 PD-2 3.8 FL-3 5.2 PD-3 3.8

From table 17 it can be seen that black leaf teas obtained by the method according to the invention achieve higher taste ratings than those observed in tea of traditional CTC processing of a similar size.

EXAMPLE 12

In order to optimize the present method, and to better understand it, a pilot scale work program was carried out in the UK (Colworth Research Laboratory). In this case, the method according to the invention was compared in which tea leaves were macerated by twisting at high pressure, followed by cutting at low pressure, with the traditional CTC method and with a method in which tea leaves were macerated only by cutting at low pressure (which is not included) in the present invention). The effects of treating the tea leaf under high pressure during maceration were determined during these pilot scale processing experiments.

The green leaf (Kenyan Clone 35) obtained as a chilled batch from Brooke Bond plantations (Kenya) was dried to a moisture content of 68 ± 1%, and either macerated using low pressure cutting using an Alexanderwerk AWBS 150 Vegetable Slicer, or passed through the rolls at high pressure using a Twin Roll Mill (RSG Colworth), operating with a speed ratio of 4: 1, with a gap width of 150 μm, followed by cutting at low pressure. After maceration, the fermentable sheet was left to ferment for 120 minutes at 25 ° C, and then dried in a laboratory fluidized bed dryer. An analysis of theaflavin levels (FIG. 10) during fermentation clearly demonstrates increased fermentation in the material subjected to passage through rolls. This is also reflected in the color measurements made on the infusions from the prepared tea samples (Fig. 11). Small, medium and large varieties were analyzed, and in all cases the samples passed through the rolls gave more colored infusions. In this case, the effect became more pronounced when the particle size increased. Microscopic examination of the macerated sheet shows that the stage of passing through the rolls introduces a significant amount of air gaps into the tissue (Fig. 12), which are also stored in the tea made. These air gaps allow for faster hydration and infusion of tea particles during the infusion process.

EXAMPLE 13

We compared the use of a CTC machine with 6 teeth per inch to modify the sheet after processing on the RLM, as described in the method of example 1, and the use of Urshel Comitrol (model 3600). This was carried out on a pilot scale at the Brooke Bond Tea Factory in Kenya. The green leaf was wilted in trays to a moisture content of 68-70% and introduced into an 8-inch RLM operating at a speed of 200 kg / h. The fermented sheet of RLM was passed either through a CTC machine or through Comitrol, with one of three different heads (with different hole sizes, 3.0 mm, 4.0 mm or 5.00 mm). After maceration, this sheet was fermented in two continuous fermentation units (CFU 1, 60 minutes, temperature 20-22 ° C; CFU 2, 80 minutes, temperature 24-26 ° C), and then dried in a fluidized bed dryer and sorted, with obtaining large-leaf (LL), medium-leaf (ML) and small-leaf (SL) varieties. Varieties obtained using a Comitrol device were compared with varieties obtained using a CTC machine with 6 teeth per inch, as described in Example 1. FIG. 13 shows the yields obtained using the above procedures. Fig. 14 shows bulk (bulk) densities of dry black teas produced using the above procedures. Fig shows the color of the infusions, represented by the value of "a *" (that is, the "redness" of the infusion, measured as described in example 5), for infusions made from teas produced using the above methods. Comitrol can be used instead of the 6-tooth per inch STS machine, with a higher bulk density (which is an advantage for packaging, in particular tea bags) and the ability to manipulate particle size distribution by selecting different heads.

Claims (7)

1. A method of producing leaf black tea of the size of Broken Orange Pekoe or larger, comprising the steps of withering tea leaves, macerating these leaves, fermenting and fire-drying the leaves to stop the fermentation, and then drying and sorting them to produce black leaf tea, characterized in that tea leaves are wilted to a moisture content between 64% and 70%, and the leaves are macerated by passing them through a rotor-blade machine, in which at least some of the blades are replaced by blades reversed with torah and tea leaves leaving the rotor-blade machine are additionally cut by passing through the STS machine, the blade of which has from 2 to 6 teeth per inch. 2. The method according to claim 1, in which the tea leaves are wilted to a moisture content between 64 and 68%. 3. The method according to claim 1, wherein the dried black leaf tea is sorted to select Broken Orange Pekoe or larger black leaf tea. 4. The method according to claim 1, wherein the dried black leaf tea is sorted to select Broken Orange Pekoe and / or Broken Orange Pekoe Fannings black leaf tea. 5. The method according to claim 1, in which the dried leaves are macerated by passing them through an extruder device. 6. Black leaf tea obtained by the method according to any one of claims 1 to 5, having the appearance of an orthodox leaf tea of the size of Broken Orange Pekoe or larger. 7. Black leaf tea according to claim 6, which, when infused in boiling water for 3 minutes at a concentration of 10 g / l, provides an infusion that has a * value of at least 14, and a b * value of at least 88, as measured on a Hunterlab Ultrascan Xe colorimeter using a standard analytical method.

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