WO2020078686A1 - Procédé de production d'un produit à base de thé - Google Patents

Procédé de production d'un produit à base de thé Download PDF

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Publication number
WO2020078686A1
WO2020078686A1 PCT/EP2019/076016 EP2019076016W WO2020078686A1 WO 2020078686 A1 WO2020078686 A1 WO 2020078686A1 EP 2019076016 W EP2019076016 W EP 2019076016W WO 2020078686 A1 WO2020078686 A1 WO 2020078686A1
Authority
WO
WIPO (PCT)
Prior art keywords
tea
leaf
range
dhool
shear
Prior art date
Application number
PCT/EP2019/076016
Other languages
English (en)
Inventor
Lokesh Basavaraju
Swathy Palagiri
Sreeramulu Guttapadu
Original Assignee
Unilever N.V.
Unilever Plc
Conopco, Inc., D/B/A Unilever
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Unilever N.V., Unilever Plc, Conopco, Inc., D/B/A Unilever filed Critical Unilever N.V.
Publication of WO2020078686A1 publication Critical patent/WO2020078686A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23F—COFFEE; TEA; THEIR SUBSTITUTES; MANUFACTURE, PREPARATION, OR INFUSION THEREOF
    • A23F3/00—Tea; Tea substitutes; Preparations thereof
    • A23F3/06—Treating tea before extraction; Preparations produced thereby

Definitions

  • the present invention relates to a process for producing a tea product. More particularly the present invention relates to a process for producing a leaf tea product with rich red colour and brighter infusion properties.
  • Tea is one of the most popular beverages in the world. It is believed that consumption of tea refreshes our mind. Polyphenols that present in the tea also considered to be good for human health.
  • Black tea is generally prepared by a process which includes the steps of withering, macerating, fermenting and firing/drying. The characteristic colour, flavour and aroma of black tea are produced during deferent stages of black tea manufacturing. In tea processing, the term ‘fermentation’ is traditionally used to refer to enzymatic oxidation. After fermentation, the tea is dried at high temperature to arrest enzyme action and to reduce the moisture content to a low level.
  • Black tea is predominantly characterized by its rich red and bright coloured infusion. Therefore, there has always been interest in improving the redness and brightness of the liquor produced by a black leaf tea product to enhance the black tea characteristics.
  • US 2008/01 18602 discloses a process for the manufacture of a tea product which is readily infusible and has improved red colour.
  • the process comprises contacting black tea with ascorbic acid and/or its salts, an oxidizing agent and water for a period of at least 5 minutes followed by drying to prepare a tea product that is infusible in water at 5 to 100°C.
  • WO 2013/075912 discloses a process for producing a black tea product with enhanced sensorials.
  • the process involves a step of anaerobic incubation at specific temperatures and for specific durations and provides tea products having a relatively high amount of polyphenols which have the sensorials of black tea, but without the addition of any exogenous theaflavins and/or catechins.
  • WO14206883A1 discloses a process of producing a long leaf tea product with black tea characteristics. The process comprises the steps of: (a) incubating fresh tea leaf at a temperature in the range 4 degrees centigrade to 60 degrees centigrade under anaerobic conditions for a period of 4 to 36 hours; and (b) exposing the leaf at a temperature of 15 to 35 degrees centigrade for 70 minutes to 4 hours; wherein there is no step of comminution of the tea leaf before incubation and/or before step (b).
  • the present inventors have surprisingly found that a process which includes a step of incubation of tea leaves at low temperature followed by exposing the tea leaf to an ambient temperature (about 25°C) produces a tea product that provides an infusion with enhanced red colour and brightness value and thereby satisfying one or more of the above-mentioned objects.
  • a process for preparing a leaf tea product comprising the steps of:
  • Tea for the purposes of the present invention means material from Camellia sinensis var. sinensis and/or Camellia sinensis var. assamica. Especially preferred is material from var. assamica as this has a higher level of tea actives than var. sinensis.
  • Leaf tea for the purposes of this invention means a tea product that contains tea leaves and/or stem in an uninfused form, and that has been dried to a moisture content of less than 30% by weight, and usually has a water content in the range 1 to 10% by weight (i.e.“made tea”).
  • “Fresh tea leaf” refers to tea leaf, buds and/or stem that have never been dried to a water content of less than 30% by weight, and usually have moisture content in the range 60 to 90%.
  • “Fermentation” refers to the oxidative and hydrolytic process that tea undergoes when certain endogenous enzymes and substrates are brought together, e.g. by mechanical disruption of the cells by maceration of the leaves. During this process, colourless catechins in the leaves are converted to a complex mixture of yellow and orange to dark-brown polyphenolic substances.
  • Black tea refers to substantially fermented tea. Black tea has different characteristics to green tea. Black tea is more astringent in taste and less bitter than green tea. The redness of black tea liquor is also significantly higher than that of green tea. Black tea also contains higher level of theaflavins.
  • the present invention provides a process for preparing a leaf tea product comprising the steps of:
  • c. comminuting the incubated leaf to produce dhool; and d. subjecting the comminuted dhool to a step of shear wherein shear is provided at a shear rate in the range of 5000/s to 25000/s.
  • Step (a) includes incubating fresh tea leaf at a temperature in the range 0°C to -200°C for a period of 3 minutes to 8 hours.
  • the preferred temperature of the incubation is -2°C to -200°C, more preferably -4°C to -200°C.
  • the period of incubation is preferably 5 minutes to 8 hours, more preferably 20 minutes to 7 hours, furthermore preferably 30 minutes to 6 hours and most preferably 1 to 5 hours.
  • Any suitable device for low temperature incubation can preferably be used. These kinds of device can maintain the temperature within the above range for the purpose of the incubation.
  • a regular refrigerator can also be preferably used for this purpose.
  • freezing with liquid nitrogen or other suitable material such as dry ice can also be preferably used.
  • This type of material is known to provide freezing at a very low temperature e.g. -196°C for liquid nitrogen and -78.5°C for dry ice. Dry ice generally more preferable for this purpose as it is simple to handle when compared to liquid nitrogen.
  • Step (b) may preferably be carried out by keeping the incubated leaves at an ambient temperature of 25°C to 35°C.
  • the incubated leaves may be just spread on a tray in an open atmosphere as described above.
  • step (b) the tea leaves are subjected to a step of comminution (size reduction) to produce dhool.
  • This step of size reduction is preferably carried out by crushing, tearing and curling (known in the art of tea processing as CTC).
  • CTC crushing, tearing and curling
  • One or more CTC steps may be carried out.
  • the incubated leaf breaks up and releases enzymes that exist in the leaf.
  • the incubated tea leaf is rolled in an orthodox roller or comminuted in a rotorvane, or a combination thereof. During these steps, precursors present in the tea leaf become amenable to the enzymes.
  • step (c) there is an additional step of subjecting the comminuted dhool to a step of shear.
  • the dhool is subjected to shear for 30 seconds to 15 minutes by passing the dhool through an instrument with shear rate in the range of 5000/s to 25000/s.
  • shear preferably means the act of producing strain in the structure of a substance/material.
  • Shear as mentioned herein preferably means damaging the comminuted dhool in a controlled way wherein the residence time of the dhool in the shear producing instrument is relatively high compared to maceration in a CTC machine.
  • the direction of application of force and the stress transfer preferably to be perpendicular to each other.
  • the shear is produced by passing the dhool through an instrument. This is preferably done by using a mechanical device.
  • the preferred mechanical devices are screw press, plough shear mixer etc.
  • the dhool is exposed to shear preferably for 30 seconds to 5 minutes and most preferably 30 seconds to 3 minutes.
  • the shear rate for the above step is preferably in the range of 10000 /s to 15000 /s.
  • the shear is the rate at which a material deforms at a given speed in a channel having a defined depth and diameter.
  • the shear rate is: p D N
  • Shear Rate H
  • the equipment there is a rotating shaft inside a channel through which the material is to be passed.
  • the rotation of this shaft conveys the material from one end (inlet) of the instrument to the other end (outlet). During this conveyance the material experiences shear as against the wall of the channel and the shaft.
  • the shaft is preferably having screw like extensions, it is known as screw press.
  • Channel depth means the longitudinal distance from the shaft to the wall of the channel.
  • the shear rate as calculated using the above equation is approximately 10000 / s.
  • pressure applied for the process is in the range of 10 4 to 10 6 Pa, more preferably 10 4 to 5 X 10 5 Pa, furthermore preferably 10 4 to 2 X 10 5 Pa and most preferably 10 4 to 5 X 10 4 Pa.
  • the filling percentage of the dhool in said instrument is also considered as a controlling parameter.
  • the words“filling percentage” preferably means the percentage of the instrument’s available volume (i.e. capacity) that is filled by the dhool.
  • the filling percentage of the dhool in said instrument is in the range of 35% to 80%, more preferably 40% to 80%, furthermore preferably 50% to 80% and most preferably from 60% to 80%.
  • the dhool preferably undergoes fermentation. This step may be carried out by keeping the comminuted leaf at a temperature of 10°C to 60°C for 15 minutes to 5 hours.
  • the preferred temperature of fermentation is in the range of 20°C to 50°C and more preferably 25°C to 45°C.
  • the preferred period of fermentation is in the range of 30 minutes to 4 hours and more preferably 1 hours to 3 hours.
  • the fermented dhool may preferably be dried.
  • the dhool is dried to a moisture content preferably less than 10% by weight of the tea leaf, more preferably less than 5% by weight of the tea leaf, to obtain the black leaf tea product.
  • the drying step is preferably carried out by thermal drying, freeze drying or vacuum drying.
  • Thermal drying is preferably carried out by contacting the leaf with air; with the temperature of air being preferably 80 to 160°C, more preferably 90 to 150°C, most preferably 100 to 130°C. Thermal drying may be carried out in any conventional dryer. However, a fluidized bed dryer or a tray dryer is particularly preferred for thermal drying.
  • the leaf can also be dried by vacuum drying. During vacuum drying the tea leaf is subjected to an absolute pressure of preferably from 66.7 to 6.67 X 10 4 Pa, more preferably from 6.67 X 10 3 to 3.9 X 10 4 Pa and most preferably from 1 .3 X 10 4 to 2.67 X 10 4 Pa.
  • Vacuum drying is carried out at a temperature in the range of preferably 20 to 70°C, more preferably 25 to 60°C and most preferably 30 to 55°C. Vacuum drying may be carried out in any suitable vacuum drier, preferably in a rotary vacuum drier.
  • Fresh tea leaves were harvested from a Kenyan tea garden, and withered for 18 hours at about 25°C.
  • the withered leaves were subjected to CTC (cut tear curl) for 4 times to obtain macerated dhool.
  • the macerated dhool was fermented (exposed to air at 25°C) for 90 minutes, and then dried to a moisture content of less than 5% by weight (at 140°C in a fluidized bed dryer) to obtain a black leaf tea product.
  • Fresh tea leaves were harvested from a Kenyan tea garden, and withered for 18 hours at about 25°C.
  • the withered leaves were incubated at a low temperature by placing them into a freezer for 4 hours.
  • the temperature of the freezer was - 20°C.
  • the frozen leaves were taken out from the freezer and kept at a temperature of 25°C for 1 hour.
  • the tea leaves were subjected to CTC (cut tear curl) for 4 times to obtain macerated dhool.
  • the macerated dhool was then fermented (exposed to air at 25°C) for 90 minutes, and then dried to a moisture content of less than 5% by weight (at 140°C in a fluidized bed dryer) to obtain a black leaf tea product.
  • Fresh tea leaves were harvested from a Kenyan tea garden, and withered for 18 hours at about 25°C.
  • the withered leaves were incubated at a low temperature by placing them into a freezer for 4 hours.
  • the temperature of the freezer was- 20°C.
  • the frozen leaves were taken out from the freezer and kept in at a temperature of 25°C for 1 hour.
  • CTC cut tear curl
  • the macerated dhool was subjected to shear by passing the dhool through a screw press (Model No: Vincent ® CP4) at a pressure of 2 bar.
  • the diameter of the screw press used was 12.7 cm, the channel depth of 0.1 cm and it was operating at 25 rpm (rotational speed).
  • the shear was calculated to be 9969.5 /s.
  • the residence time for the shear step was 2 minutes.
  • the filling percentage for this experiment was 75% of the instrument’s capacity.
  • the macerated dhool was then fermented (exposed to air at 25°C) for 90 minutes, and then dried to a moisture content of less than 5% by weight (at 140°C in a fluidized bed dryer) to obtain a black leaf tea product.
  • Tea infusions were prepared for all the above tea products by infusing 2 g of leaf tea in 200 ml_ of freshly boiled deionized water for 2 minutes without stirring. Infusions colour measurements were done using the following procedure:
  • L* 100, which represents a perfect reflecting diffuser.
  • L * 0, which represents black.
  • the a * and b * axes have no specific numerical limits. Positive a * is red and negative a * is green. Similarly, positive b * is yellow and negative b * is blue.
  • Example 1 provides much redder and brighter infusions when compared with the control example (Example A). It is also clear that an additional step of shear produces tea product that provides an infusion with much higher a* and b* value (Example 2).

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  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Polymers & Plastics (AREA)
  • Tea And Coffee (AREA)

Abstract

La présente invention concerne un procédé de préparation d'un produit à base de thé en feuilles comprenant les étapes consistant à : a. incuber une feuille de thé fraîche à une température comprise entre 0 °C et -200 °C pendant une durée de 3 minutes à 8 heures ; b. placer la feuille incubée dans un environnement qui a une température comprise entre 15 °C et 45 °C pendant 1 à 8 heures ; c. broyer la feuille incubée pour produire du dhool ; et d. soumettre le dhool broyé à une étape de découpe dans laquelle un cisaillement est réalisé à un taux de cisaillement de 5000/s à 25000/s.
PCT/EP2019/076016 2018-10-17 2019-09-26 Procédé de production d'un produit à base de thé WO2020078686A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP18200938 2018-10-17
EP18200938.1 2018-10-17

Publications (1)

Publication Number Publication Date
WO2020078686A1 true WO2020078686A1 (fr) 2020-04-23

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111990482A (zh) * 2020-08-21 2020-11-27 中国农业科学院茶叶研究所 一种采用“二重一轻”组合工艺的玫瑰花香红茶加工方法

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB511895A (en) * 1938-07-25 1939-08-25 Lyons & Co Ltd J Improvements in the manufacture of tea
CN1729807A (zh) * 2004-08-06 2006-02-08 福建农林大学 一种高茶黄素、茶红素工夫红茶的制备方法
US20080118602A1 (en) 2004-01-16 2008-05-22 Venkatraj Venkatrao Narayanan Process for the Manufacture of a Tea Product and Products Obtained Thereby
WO2012069323A1 (fr) * 2010-11-24 2012-05-31 Unilever Nv Produit à base de thé
WO2013075912A1 (fr) 2011-11-22 2013-05-30 Unilever N.V. Procédé pour produire un produit à base de thé
CN103431088A (zh) * 2013-09-06 2013-12-11 江苏丘陵地区镇江农业科学研究所 一种脱咖啡因红茶的加工工艺
CN103918817A (zh) * 2014-03-18 2014-07-16 安徽天方茶业（集团）有限公司 一种祁眉红茶的加工工艺
WO2014206883A1 (fr) 2013-06-28 2014-12-31 Unilever N.V. Procédé pour produire un produit de thé
CN105532952A (zh) * 2016-02-04 2016-05-04 信阳师范学院 一种茶叶加工方法及茶叶
WO2017076612A1 (fr) * 2015-11-02 2017-05-11 Unilever N.V. Procédé de production d'un produit à base de thé
CN106962522A (zh) * 2017-05-17 2017-07-21 张松波 提高红茶品质的方法

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB511895A (en) * 1938-07-25 1939-08-25 Lyons & Co Ltd J Improvements in the manufacture of tea
US20080118602A1 (en) 2004-01-16 2008-05-22 Venkatraj Venkatrao Narayanan Process for the Manufacture of a Tea Product and Products Obtained Thereby
CN1729807A (zh) * 2004-08-06 2006-02-08 福建农林大学 一种高茶黄素、茶红素工夫红茶的制备方法
WO2012069323A1 (fr) * 2010-11-24 2012-05-31 Unilever Nv Produit à base de thé
WO2013075912A1 (fr) 2011-11-22 2013-05-30 Unilever N.V. Procédé pour produire un produit à base de thé
WO2014206883A1 (fr) 2013-06-28 2014-12-31 Unilever N.V. Procédé pour produire un produit de thé
CN103431088A (zh) * 2013-09-06 2013-12-11 江苏丘陵地区镇江农业科学研究所 一种脱咖啡因红茶的加工工艺
CN103918817A (zh) * 2014-03-18 2014-07-16 安徽天方茶业（集团）有限公司 一种祁眉红茶的加工工艺
WO2017076612A1 (fr) * 2015-11-02 2017-05-11 Unilever N.V. Procédé de production d'un produit à base de thé
CN105532952A (zh) * 2016-02-04 2016-05-04 信阳师范学院 一种茶叶加工方法及茶叶
CN106962522A (zh) * 2017-05-17 2017-07-21 张松波 提高红茶品质的方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111990482A (zh) * 2020-08-21 2020-11-27 中国农业科学院茶叶研究所 一种采用“二重一轻”组合工艺的玫瑰花香红茶加工方法
CN111990482B (zh) * 2020-08-21 2022-03-11 中国农业科学院茶叶研究所 一种采用“二重一轻”组合工艺的玫瑰花香红茶加工方法

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