阅读说明：本技术 茶产品的生产方法 (Process for producing tea products ) 是由 L·巴萨瓦拉朱 V·戈文德斯瓦米 S·古塔帕杜 于 2018-05-28 设计创作，主要内容包括：本发明涉及叶茶产品的制备方法,其包括以下步骤：(a)在厌氧条件下,将新鲜茶叶在4℃至60℃的温度下温育14至60小时；和(b)使经温育的叶经历回转运动。(The present invention relates to a process for the preparation of a leaf tea product comprising the steps of: (a) incubating fresh tea leaves at a temperature of 4 ℃ to 60 ℃ for 14 to 60 hours under anaerobic conditions; and (b) subjecting the incubated leaves to a gyratory motion.)

1. A process for the preparation of a leaf tea product comprising the steps of:

a. incubating fresh tea leaves at a temperature of 4 ℃ to 60 ℃ for 14 to 60 hours under anaerobic conditions; and

b. the incubated leaves were subjected to a gyratory motion.

2. The method of claim 1, wherein the gyrating motion is provided by a rotating device.

3. The method of claim 2, wherein the rotating device is a centrifuge.

4. A process according to any one of the preceding claims wherein there is no step of comminuting the tea leaves prior to step (b).

5. A process as claimed in claim 1 or 2 further comprising the step of comminuting the tea leaves after step (b).

6. A process as claimed in claim 5 further comprising the step of fermenting the comminuted tea leaves.

7. A process as claimed in any one of the preceding claims further comprising the step of drying the tea leaves at a temperature of 50-150 ℃.

8. The method of any one of the preceding claims, wherein the anaerobic conditions are achieved by:

i. placing the fresh tea leaves in a container and closing the container; or

Placing the tea leaves in a container, purging a substantially oxygen-free gas through the container and closing the container, or placing the leaves in an airtight chamber or under vacuum.

9. The process of claim 8, wherein the anaerobic conditions are achieved by placing the fresh tea leaves in a container and closing the container.

Technical Field

The present invention relates to a process for the production of tea products. More particularly, the present invention relates to a process for the production of black leaf tea products with a light colored tea soup (liquor).

Background

Tea is one of the most widely consumed beverages in the world. Several varieties of tea products exist, such as black tea, green tea, oolong tea. Different tea varieties are obtained by following different processes starting from raw tea leaves.

Of all the existing tea varieties, black tea is considered the most popular. The black tea is characterized by bright red tea soup. In some regions, black tea is also consumed with the addition of milk. Those consumers believe that adding milk enriches the taste of tea beverages. Therefore, in the case of milk tea, the requirement for bright color tea is a major concern.

Meanwhile, another problem associated with tea plants is that a large amount of aluminum is known to accumulate, which is believed to affect the sensory properties of the tea product. Aluminum is also considered unhealthy if drunk in higher quantities.

There is prior art disclosing tea products with enhanced organoleptic properties.

WO 2013/075912(Unilever) relates to a process for the production of black tea products with enhanced organoleptic properties. It discloses a process for the preparation of a tea product, said process comprising the steps of: (a) taking fresh tea leaves; (b) incubating fresh leaves at a temperature of 4 ℃ to 60 ℃ for 4-36 hours under anaerobic conditions; (c) subjecting the incubated leaves to comminution; and (d) fermenting the pulverized leaves by maintaining the leaves at a temperature of 15-35 ℃ for 15 minutes to 3 hours.

WO 2014/206883(Unilever) discloses a process for the production of a longleaf tea product having black tea characteristics. The method comprises the following steps: (a) incubating fresh tea leaves at a temperature of from 4 ℃ to 60 ℃ for from 4 to 36 hours under anaerobic conditions; and (b) exposing the leaves to a temperature of from 15 ℃ to 35 ℃ for from 70 minutes to 4 hours; wherein there is no step of comminuting the tea leaves prior to the incubation and/or prior to step (b).

US 2007/0071870(Conopco Inc.) discloses a method of making black or green tea with oolong tea aroma. The method utilizes tumbling to physically wind the leaves to produce the oolong tea aroma and does not involve the traditional sun withering step.

GB692778(Alexander Maurice Hugo) discloses a tea manufacturing process in which fresh leaves are subjected to stages of withering, crushing, rolling, fermentation, enzyme deactivation and drying, or a selected sequence of these stages, while in a single closable rotatable container which may be heated and may be placed under vacuum or both.

There is also prior art disclosing tea products with reduced aluminium content.

WO 2012/069290(Unilever) discloses a process for the manufacture of tea products. More particularly, the invention relates to a process for the preparation of tea juice. The method comprises expressing juice from fresh tea leaves, thereby producing leaf residue and tea juice, characterised in that an alkaline agent is added to the tea leaves in a mass ratio of from 0.001:1 to 0.08:1 prior to or during expression of the juice. The disclosed method minimizes the amount of aluminum in the final product.

Thus, there is a need for a brighter tea product with lower aluminum content.

It is therefore an object of the present invention to provide a process for the production of tea products with a lower amount of aluminium.

It is another object of the present invention to provide a process for providing a brighter tea product with lower amounts of aluminium.

The present inventors have surprisingly found, while working on this problem, that a process comprising the steps of anaerobic incubation followed by subjecting the incubated leaves to a gyratory motion results in a tea product having a bright colored broth with a lower level of aluminium, thereby satisfying one or more of the above objectives.

Disclosure of Invention

In a first aspect the present invention provides a process for the preparation of a leaf tea product comprising the steps of:

a. incubating fresh tea leaves at a temperature of 4 ℃ to 60 ℃ for 14 to 60 hours under anaerobic conditions; and

b. the incubated leaves were subjected to a gyratory motion.

In a second aspect the present invention provides a leaf tea product as obtained and/or obtainable by the process of the first aspect.

These and other aspects, features and advantages will be apparent to those of ordinary skill in the art upon reading the following detailed description. For the avoidance of doubt, any feature of one aspect of the invention may be used in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of. In other words, the listed steps or options need not be exhaustive. It should be noted that the examples given hereinafter in the specification are intended to illustrate the present invention, and are not intended to limit the present invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Numerical ranges expressed in the form of "x to y" (or "x-y") are understood to include x and y. When, for a particular feature, multiple preferred ranges are described in the form of "x to y" (or "x-y"), it is understood to also encompass all ranges combining the different endpoints.

Detailed Description

"tea" for the purposes of the present invention refers to material from Chinese tea (Camellia sinensis var. sinensis) and/or assamica tea (Camellia sinensis var. assamica). Material from assam tea is particularly preferred because it has a higher level of tea active than chinese tea.

"leaf tea" for the purposes of the present invention refers to a tea product (i.e. "made tea") which contains tea leaves and/or stems in an unaged form and which has been dried to a moisture content of less than 30% by weight and typically to a moisture content of from 1 to 10% by weight.

By "fresh tea leaves" is meant tea leaves, shoots and/or stems which have never been dried to a moisture content of less than 30% by weight and typically have a moisture content of from 60 to 90%.

"fermentation" refers to the oxidation and hydrolysis processes that tea undergoes when certain endogenous enzymes and substrates are brought together (e.g., by mechanical disruption of cells by maceration of leaves). During this process, the colourless catechins in the leaves are converted into a complex mixture of yellow and orange to dark brown polyphenolic substances.

"Black tea" refers to fully fermented tea. Black tea has different characteristics from green tea. Black tea is more astringent and less bitter than green tea. The red color of the black tea soup is also significantly higher than that of green tea. Black tea also contains higher levels of theaflavins.

The present invention provides a process for the preparation of a leaf tea product comprising the steps of:

a. incubating fresh tea leaves at a temperature of 4 ℃ to 60 ℃ for 14 to 60 hours under anaerobic conditions; and

b. the incubated leaves were subjected to a gyratory motion.

Step (a):

step (a) comprises incubating fresh tea leaves at a temperature of from 4 ℃ to 60 ℃ for from 14 to 60 hours under anaerobic conditions. The term "anaerobic conditions" as used herein means that the gas phase in contact with the leaves has less than 3% by volume of oxygen, preferably less than 2% by volume, and more preferably less than 1% by volume. It is particularly preferred that the gas phase in contact with the leaves is substantially free of oxygen.

The fresh leaves can be selected from two leaves and one bud, three leaves and one bud, or more than three leaves and one bud. The duration between plucking fresh tea leaves and incubation is preferably less than 24 hours, more preferably less than 12 hours, and most preferably less than 8 hours. However, if the tea leaves are stored at a temperature preferably below 15 ℃, the duration between picking of fresh tea leaves and incubation may be longer than 24 hours.

Anaerobic conditions:

anaerobic conditions are optionally achieved by:

i. placing fresh tea leaves in a container and closing the container; or

Placing the tea leaves in a container, purging a substantially oxygen-free gas through the container and closing the container, or placing the leaves in an airtight chamber or under vacuum.

Preferably, the anaerobic conditions are achieved by:

placing fresh tea leaves in a container and closing the container, or;

the tea leaves are placed in a vessel, a substantially oxygen-free gas is purged through the vessel, and the vessel is closed.

By placing fresh leaves in a container and closing the container, the oxygen concentration in the gas phase decreases over time and anaerobic conditions are achieved after keeping the container closed for a certain time. The duration of the closed container is preferably greater than about 3 hours, more preferably greater than 4 hours, and most preferably greater than about 6 hours or even greater than about 8 hours.

Alternatively and more preferably, anaerobic conditions are achieved by: the leaves are placed in a vessel, a substantially oxygen-free gas is purged through the vessel, and the vessel is closed. The substantially oxygen-free gas is preferably nitrogen or carbon dioxide, more preferably nitrogen.

In the above step (i) or (ii), once the container is closed, there is no particular limitation on the pressure in the container. The pressure within the closed vessel is preferably from 1 to 1000mmHg absolute, more preferably from 10 to 800mmHg absolute, and most preferably 20 mmHg.

It is preferred that the leaf has as low a water loss as possible during this step. This is advantageously and conveniently achieved by carrying out this step under closed conditions. The incubated tea leaves after this step contain preferably 70-75 wt% water.

Incubation temperature:

the temperature of step (a) is in the range of from 4 ℃ to 60 ℃, preferably from 4 ℃ to 55 ℃, more preferably from 10 ℃ to 40 ℃.

Duration of anaerobic incubation:

the plucked leaves are incubated under anaerobic conditions for 14 to 60 hours, preferably 16 to 55 hours, and most preferably 18 to 48 hours.

Step (b):

after the incubation step as discussed above, the incubated leaves are subjected to a gyratory motion.

A gyrating motion is a motion in which an object moves in a circular path relative to a fixed center point. The circular path may be vertical or horizontal. This may be achieved by a slewing device/arrangement.

Rotary devices are known for mechanical screening, separation, sieving, clarification, and the like.

For the purposes of the present invention, the rotating device preferably provides a gyrating motion. The most preferred spinning device is a centrifuge.

"revolutions per minute" (rmp) indicates the rotational speed of the rotating device. The rotational speed depends on the radius of rotation, which depends on the device. Therefore, the protocol typically specifies the Relative Centrifugal Force (RCF), rather than the rotational speed. This is usually expressed in multiples of 'g' (the standard acceleration due to gravity at the surface of the earth). The RCF can be calculated from the rotational speed using the following formula:

RCF＝1.12×R×(S/1000) ²

where R is the centrifuge radius (in mm), S is the rotational speed of the centrifuge (in rpm), and RCF is expressed in units of gravity (gravity or Xg).

In the case of the present invention, the RCF preferably ranges from 6000 to 14000 × g, more preferably from 8000 to 14000 × g, and most preferably from 9000 to 12000 × g.

Preferably, there is no step of comminuting the tea leaves prior to step (b).

After the above step, the leaves are preferably subjected to a crushing step. This may preferably be done by crushing, tearing and curling, known as CTC. One or more CTC steps may be performed. In this step, the incubated leaves are broken and the enzymes present in the leaves are released.

Alternatively, the comminuting step may preferably be performed by rolling the leaves in an orthographic roller (orthogodox roller) or comminuting in a rotor blade or a combination thereof. During these steps, the precursors present in the tea leaves become suitable for the enzyme.

After comminution, the tea leaves are preferably subjected to fermentation. The fermentation is carried out by keeping the leaves at a temperature of 15-35 ℃ for 15 minutes to 3 hours. Preferably, the fermentation temperature is from 25 to 35 deg.C, and more preferably from about 30 to 35 deg.C. The fermentation time is preferably 30 minutes to 6 hours, more preferably 1 to 5 hours, and most preferably 1 to 4 hours. In this stage, the leaves undergo enzymatic reactions that produce the typical black tea characteristics.

The tea leaves may then preferably be dried. During the drying step, the tea leaves are preferably dried to a moisture content of less than 10% by weight of the total mass of the tea leaves, more preferably less than 5% by weight of the total mass of the tea leaves, to obtain the leaf tea.

The drying step is preferably carried out by thermal drying, freeze drying or vacuum drying.

The thermal drying is preferably carried out by contacting the leaves with air; wherein the temperature of the air is preferably 50-150 deg.C, more preferably 60-130 deg.C, and most preferably 80-120 deg.C. The thermal drying can be carried out in any conventional dryer. However, fluidized bed dryers or tray dryers are particularly preferred for thermal drying.

The leaves may also be dried by vacuum drying. During vacuum drying, the tea leaves are preferably subjected to an absolute pressure of from 5 to 500mmHg, more preferably from 50 to 300mmHg, and most preferably 100 and 200 mmHg. Vacuum drying is carried out at a temperature of preferably 20-70 ℃, more preferably 25-60 ℃ and most preferably 30-55 ℃. The vacuum drying may be carried out in any suitable vacuum dryer, preferably a rotary vacuum dryer.

The invention will now be illustrated by way of examples. The following examples are for illustrative purposes only and in no way limit the scope of the present invention.