GUPTA ANSHUL (IN)
NARAYANAN VENKATRAJ VENKATRAO (IN)
RASTOGI ANUDEEP (IN)
SINGH GURMEET (IN)
UNILEVER PLC (GB)
UNILEVER HINDUSTAN (IN)
CONOPCO INC DBA UNILEVER (US)
| WO1997046112A1 | 1997-12-11 |
| US20030104632A1 | 2003-06-05 | |||
| EP1527693A1 | 2005-05-04 | |||
| US20070160737A1 | 2007-07-12 | |||
| CN1154798A | 1997-07-23 | |||
| CN101744259A | 2010-06-23 | |||
| CN1113690A | 1995-12-27 |
| Claims: A process for preparing a liquid tea product comprising the steps of: a. providing fresh tea leaf; b. soaking the fresh tea leaf for 12 to 25 hours at a temperature of 15 to 40°C in water with a leaf to water ratio of 1 :5 to 1 :20; c. separating the soaked tea leaf from the water; and, d. heating the resulting water to 60 to 100°C for 30 to 150 minutes to obtain the liquid tea product. A process as claimed in claim 1 comprising the additional steps of: (i) adding 0.25 -5 g of crushed fresh tea leaf, per litre of separated water of step (c) prior to step (d); and, (ii) passing a gas comprising oxygen through the water for 1 hour to 4 hours. 3. A process as claimed in claim 1 or 2 wherein the fresh tea leaf is mildly bruised or cut before the step (b). A process as claimed in claim 1 or 2 further comprising the steps of: a. collecting the water vapour produced on heating in step (d); b. passing the water vapour through a condenser; and, c. collecting the condensate. A process as claimed in claim 4 further comprising the step of concentrating the condensate. 6. A process as claimed in claim 5 wherein the tea aroma concentrate is added back to the liquid tea product. 7. A process as claimed in any one of the preceding claims wherein the soaked tea leaf which is separated from the water is further processed to produce leaf tea product. 8. A liquid tea product as obtainable and/or obtained by a process as claimed in any one of the preceding claims. 9. An aroma condensate as obtainable and/or obtained by the process as claimed in claim 4. |
Technical Field of the invention:
The present invention relates to a tea product. More particularly it relates to a liquid tea product and a process for preparing the same.
Background of the invention:
Tea is a popular beverage consumed throughout the globe. Tea products are available in the markets in different formats. The most common formats are leaf tea, dust tea, liquid packaged tea beverage etc. Most people drink tea as a part of their refreshment. It is believed that consumption of tea drinks provides some kind of freshness to the consumers. Therefore for researchers it has always been an interesting field for developing different tea products with different formats to satisfy consumer needs.
Consumers always tend to use different formats of tea products that provide new sensory experiences which include taste, aroma colour characteristics of the liquor etc. Various methods to provide tea products with improved or different taste are known in the art. Black tea, White tea, Green tea and Oolong tea are processed differently to provide tea with distinct sensorials. Ready to drink tea e.g. liquid tea products are gaining popularity in today's world as consumers do not have to invest in time for brewing tea.
Various processing methods using tea leaves for making tea drinks are known in the art.
CN1 154798A (ANHUI PROV MEDICAL SCIENCE INS, 1997) discloses a process for preparing instant tea. The disclosed process provides for a fast dissolving instant tea powder. The process includes the steps of soaking tea leaf in cold distilled water; coarse filtering; fine filtering; separating supernatant; concentrating by using RO membrane technology; and vacuum freeze drying to obtain an instant tea. The application discloses an instant tea having the original colour, smell and taste of the tea leaf and health-care pharmacologic activity of its main components.
CN101744259 (SUN ZHANGHONG, 2010) relates to a health-care tea drink, which is characterized in that the health-care tea drink is prepared by using aloe leaves and tea as raw materials and by the steps of (1 ) selecting, washing and slicing the aloe leaves, and drying the sliced aloe leaves at the temperature of 70 degrees centigrade for 5 hours; (2) mixing the aloe leaves and the tea leaves, soaking the mixture in water for 10 hours, and drying the mixture to prepare the health-care tea drink. The health-care tea drink has rich nutrients and a sweet taste, and has the functions of killing bacteria, inhibiting bacteria, breaking down toxins, eliminating inflammation and the like and the effects of building body, strengthening immunity performance, resisting cancers and the like.
CN1 1 13690A (MO BAIHE, 1995) relates to a tea, tea product and its production method. Its method is as follows: the dried fresh green tea leaf or oolong tea leaf is soaked in a basic aqueous solution for 1 -15 min., and then the tea leaf is dredged out from water, and packed and sealed, and cold-stored for 1 -12 h., and then is fermented at low temp., and then is placed in freezer and stored at 18-odd degrees below zero so as to make the theophylline contained in tea leaf permeate through the tea leaf surface to form theophylline frost, thus it is made into a basic frozen tea with original tea fragrance, or the basic frozen tea is steeped in hot boiling water for the first time, then the theophylline is quickly dissolved in the water, and then is passed through the process of filtering centrifuge separation so as to obtain its theophylline solution, and then the tea passed through the above-mentioned process also is steeped for 2-8 times (or more than that), so that a drinkable tea liquor can obtained. We have found that by keeping fresh tea leaf in water (before processing it to produce conventional leaf tea product) for long hours followed by separation of the liquid from it provides a liquid tea drink which is not appealing to the consumers due to its colour characteristics.
Thus, a liquid tea product with enhanced colour characteristics remains to be desired.
Objects of the Invention:
It is therefore an object of the present invention to provide a liquid tea product with improved colour characteristics.
It is another object of the invention to provide a process for producing a liquid tea product with enhanced colour characteristics.
It is a further object of the present invention to provide a liquid tea product with increased red colour.
It is yet another object of the present invention to economically provide a liquid tea product with increased colour characteristics along with regular leaf tea product, by using the same tea leaf.
The present inventors have surprisingly found that by keeping the fresh tea leaf in water for a particular period of time in a particular ratio followed by separating the tea leaf from the resultant water and heating the resultant water for a particular time at a selected temperature provides a liquid tea product with improved colour characteristics and is able to satisfy consumer need.
Furthermore, the present inventors have surprisingly found that the aroma recovered from the vapour produced while heating the separated liquid has novel floral characteristics. Summary of the invention:
According to a first aspect, the present invention provides a process for preparing a liquid tea product comprising the steps of:
a. providing fresh tea leaf;
b. soaking the fresh tea leaf for 12 to 25 hours at a temperature of
15 to 40°C in water with a leaf to water ratio of 1 :5 to 1 :20;
c. separating the soaked tea leaf from the water; and,
d. heating the resulting water to 60 to 100°C for 5 to 150 minutes to obtain the liquid tea product.
According to a preferred aspect of the present invention there is provided a process of the first aspect comprising additional steps of:
(i) adding 0.25 -5 g of crushed fresh tea leaf, per litre of separated water of step (c) prior to step (d); and,
(ii) passing a gas comprising oxygen through the water for 1 to 4 hours.
According to a further preferred aspect of the present invention there is provided a process of the first aspect and the preferred aspect further comprising the steps of:
a. collecting the water vapour produced on heating in step (d);
b. passing the water vapour through a condenser; and,
c. collecting the condensate, which is rich in tea aroma. These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. It is noted that the figures given in the description below are intended to clarify the invention and are not intended to limit the invention to those figures 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 format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated. Detailed description of the invention:
"Tea" for the purposes of the present invention means material from Camellia sinensis, var . sinensis or Camellia sinensis var . assamica. It also includes Rooibos tea obtained from Aspalathus linearis. "Tea" is also intended to include the product of blending two or more of any of these materials.
"Fresh tea leaves" refers to tea leaves and/or stem that have never been dried to a water content of less than 30% by weight, and usually have a water content in the range 60 to 90%. "Green tea" refers to substantially unfermented tea. "Black tea" refers to substantially fermented tea. "Oolong tea" refers to partially fermented tea.
"Water-soluble tea solids" means solids extractable from tea in boiling water. For leaf tea, water-soluble tea solids means water extract as
determined by the method set forth in the International Standard ISO
9768:1994(E) entitled "Tea - Determination of water extract".
The present invention provides for a process for preparing a liquid tea product comprising the steps of:
a. providing fresh tea leaf; soaking the fresh tea leaf for 12 to 25 hours at a temperature of 15 to 40°C in water with a leaf to water ratio of 1 :5 to 1 :20;
separating the soaked tea leaf from the water; and, heating the resulting water to 60 to 100°C for 5 to 150 minutes to obtain the liquid tea product.
Providing fresh tea leaf
Step (a) of the process of the invention comprises providing fresh tea leaves. The tea leaf is provided in freshly plucked form, i.e. without any further processing. The fresh tea leaf preferably includes leaf and stem material. Most preferably the fresh tea leaf includes actively growing buds, e.g. in the form of the first two or three leaves together with the unopened bud (so-called "two- and-a-bud" and/or "three-and-a-bud" material). It is particularly preferred that the fresh tea leaves include material from
Camellia sinensis var . assamica as this variety naturally has a high level of tea actives. Most preferably the fresh leaves are fresh leaves from Camellia sinensis var . assamica. The fresh tea leaves are preferably not withered prior to soaking in water and preferably have a moisture content of greater than 75% by weight.
Preferably, the fresh tea leaf is mildly bruised or cut before step (b), i.e. to mildly damage the tea leaf. This can be achieved by any suitable process in the tea industry e.g. crushing, tearing, wounding etc.
When the fresh tea leaves are bruised or cut, it is preferred that the soaking in water occurs directly after the bruising. In particular it is preferred that soaking in water occurs within 20 minutes of bruising, more preferably within 10 minutes and most preferably within 5 minutes. Soaking the tea leaf
Step (b) of the process of the invention includes soaking the fresh tea leaves in water. Once the leaves have been harvested, the whole leaves are added into water or preferably slightly wounded or bruised before adding into water as described above.
The fresh tea leaves are soaked in water preferably in a vessel. It is preferred that soaking of the leaves in water takes place with an excess amount of water. The amount of water used to soak the leaves is such that the leaf to water ratio is 1 :5 to 1 :20. Preferably the ratio is 1 :8 to 1 :20, more preferably 1 : 10 to 1 :20 and further more preferably 1 : 12 to 1 :20. The tea leaves are soaked in water for 12 to 25 hours, preferably for 15 to 25 hours and more preferably for 18 to 25 hours. The water for soaking the tea leaves has a temperature in the range of 15°C to 40°C. Preferably the temperature of the water is 25°C to 40°C and more preferably 30°C to 40°C.
Without wishing to be bound by theory, it is believed that during the soaking step the water soluble solids are extracted from the tea leaves into the water by means of diffusion of the water soluble solids from the whole tea leaves or slightly bruised tea leaves to the water. This is surprising because it was not previously thought that diffusion could occur in such a high amount at such low temperature. Furthermore an additional step of heating to produce a highly acceptable tea product is even more surprising.
Separating the soaked tea leaf from the water
Step (c) of the process of the invention comprises separating the soaked tea leaf from the water. In the separation step, the soaked tea leaf is separated by a separation process to provide tea leaf residue and resultant water. Those of ordinary skill in the art will recognize a number of suitable mechanisms for effecting such removal, including centrifugation, super centrifugation, filtration, ultra filtration, etc. Preferably the separation is by filtration. A normal strainer may also be preferably used for separating the leaves from the water. Heating the resulting water
Step (d) of the process of the invention comprises the step of heating the resulting water at a temperature in the range of 60 to 100°C, more preferably from 70 to 100°C and most preferably from 80 to 100°C. The heating step may be carried out in an evaporator. A person skilled in the art is aware of the various types of evaporators that can be used. The step of heating is preferably carried out in a vacuum evaporator. The preferred ranges of vacuum are in the range of 150 -300 mm of Hg (absolute), more preferably 200 to 300 mm and further more preferably 250 to 300 mm. The heating step is most preferably done in a rotator vacuum evaporator. Preferably the
temperature of the water bath of the rotator vacuum evaporator is kept around 75 to 95°C more preferably it is kept around 80 to 90°C. The heating is carried out for a time of 5 to 150 minutes, preferably for 10 to 150 minutes, more preferably for 30 to 150 minutes, further more preferably for 50 to 150 minutes and most preferably from 70 to 150 minutes.
This process results in the improvement of the tea colour of the resultant water from a pale yellow colour to brownish coloured liquor that is very similar to the tea extract obtained from black tea.
In a preferred aspect the present invention provides a process comprising additional steps of:
(i) adding 0.25 -5 g of crushed fresh tea leaf, per litre of separated water of step (c) prior to step (d); and,
(ii) passing a gas comprising oxygen through the water for 1 hour to 4 hours. Optionally after separating the water from the leaves after soaking, 0.25 - 5 g, preferably 0.5 - 5 g, more preferably 1 - 5 g of crushed tea leaf per litre is added to the water. The water containing the crushed tea leaf is then optionally subjected to agitation by passing a gas comprising oxygen preferably air. The gas may be passed for 1 to 4 hours preferably for 1 to 3 hours. These additional steps result in a much darker red coloured liquid.
When these additional steps are included in the process, the time of heating of the resultant water may be reduced. The preferable time for heating is from 6 to 60 minutes, more preferably from 8 to 30 minutes and most preferably for 10 to 15 minutes.
In a further preferred aspect, the process of the present invention further comprises the steps of:
a. collecting the water vapour produced on heating in step (d);
b. passing the water vapour through a condenser; and,
c. collecting the condensate, which is rich in tea aroma. When the process includes the step of collecting the water vapour, the exhaust gas of the vacuum evaporator is passed through a condenser to condense water vapour and aroma volatiles. The tea aroma is preferably recovered as a condensate and the residual liquor is collected as a liquid tea product. For example, the exhaust gases from the evaporator are directed to a condenser and the aroma compounds along with the water are condensed. The condenser condenses the vapour by recirculating cold water through a jacket (usual procedure of condenser operation). The temperature of the cold water which is recirculated is in between 0 to 10°C more preferably in between 0 to 5°C and most preferably between 0 to 2°C. In this way it is possible to produce a liquid tea product with enhanced colour and a tea aroma together by processing tea leaves wherein the recovered tea aroma can be added back to the liquid product or any other tea product. The condensate obtained may be concentrated by any known process. For example, the aroma may be concentrated by reverse osmosis, distillation, cryo- concentration, freeze drying, and/or staged/partial condensation to prepare a tea aroma concentrate. It is particularly preferred to use the process of distillation for the concentration. The tea aroma is preferably concentrated to an aroma content of at least 1000 mg/L, more preferably still at least 10000 mg/L, and most preferably to aroma content in the range of 100, 000 mg/L to a concentrate that is purely aroma oil (e. g. 100 - 500 g/L).
After obtaining the liquid tea product by separating the resultant water from the residual tea leaf, the tea leaf is preferably processed further to produce a leaf tea product. This process preferably includes the usual steps in manufacturing black leaf tea which include withering, macerating, fermenting and drying.
By way of the present invention it is now possible to produce a liquid tea product, an aroma composition and a leaf tea product starting from the same leaves. Thus the process of the present invention is extremely efficient and economical because it produces three products together by using the same leaves. Liquid tea product
In a preferred embodiment the present invention also provides a liquid tea product as obtainable and/or obtained by the process of the present invention.
Preferably the liquid tea product comprises 200 to 1500 mg, more preferably of 200 to 1400 mg and most preferably 200 to 1300 mg of total polyphenols per litre. The liquid tea product also preferably comprises 50 to 750 mg, more preferably 75 to 750 mg and most preferably 100 to 700 mg of catechins per litre. The liquid tea product preferably comprises 30 to 300 mg, more preferably 35 to 250 mg and most preferably 40 to 200 mg of caffeine per litre. The aroma condensate
In a further preferred embodiment the present invention also provides an aroma condensate as obtainable and/or obtained by the process of the present invention. The aroma condensate as obtained by the process of the present invention has total organic volatile compounds in the range of 400 to 1000 ppm, more preferably 450 to 1000 ppm and still more preferably 500 to 1000 ppm.
Therefore by way of present invention it is now possible to provide aroma condensate with relatively higher amount of organic volatile compounds.
Organic volatile compounds with respect to the present process preferably means the organic compounds (aroma) which tends to come out from the solution at a temperature preferably greater than 50°C, more preferably greater than 55°C and most preferably greater than 60°C at atmospheric pressure. The higher the temperature the higher the rate of evaporation is. The organic volatile compounds in the aroma condensate preferably include linalool, linalool oxide, damascenone and methyl salicylate (floral aroma). The aroma condensate also preferably comprises t-2hexanal, C3-Hexenol, 1 -pentanol and tt24nonadienal (green aroma).
The preferred ratio of floral to green aroma compounds (measured as described in the examples below) for the aroma condensate obtained by the process of the invention is greater than 0.3, more preferably greater than 0.4, most preferably from 0.5 to 5. Now the invention will be demonstrated with the help of examples. The examples are for illustration only and do not limit the scope of the invention.
EXAMPLES
Measurement Methods
(a) Colour measurement:
Colour (CIE L * a * b * values) was measured using a Hunter lab Ultrascan XE (Model-USXE/UNI version 3.4, Hunterlab Associates Laboratories Inc. Virginia). A halogen cycle lamp was used as the light source. The illuminant used was D65 and the measurements were made at 10°-Observer angle. Measurements were made using a quartz cuvette of 10 mm path length. Liquid tea product was filled up to the brim in the cuvette and placed in the instrument for colour measurement. The instrument was calibrated using a standard white tile
(Hunterlab Duffuse/8°, mode-RSEX, Port-1 " and area- large) in accordance with the instructions provided in the instruction manual. The L * a * b * values were measured at room temperature (~25°C). (b) Total Polyphenols (TPP):
Total polyphenol contents were determined using the ISO method for the determination of content of total polyphenols in tea - Colorimetric method using Folin-Cicalteu reagent (ISO 14502-1 :2005). (c) Catechin content:
Total catechin contents were determined using the ISO method for the determination of catechins in green and black tea, using high performance liquid chromatography (ISO 14502-2:2005). (d) Total soluble solids (TSS): Total soluble solids were measured as follows (ISO9768:1994 (E)). A dry pan was kept in a hot air oven for 2 hrs at a 1 10°C. The pan was then placed in a dessicator for weighing; the reading was noted down and the pan was put back in the dessicator immediately and then placed in the hot air oven. 2 gm of black tea was taken in a paper cup. After that 100 ml_ of boiling water at 100°C was added to the black tea. The solution was stirred for 2 minutes. After 2 minutes the liquor was filtered using a Whatman 541 filter paper. The filtrate was collected in a beaker and the volume was made up 100 ml_ with deionised water. After that the 100ml of the hot tea liquor was put in the weighed pans and placed on a water bath maintained at a 90-100°C for evaporation. After complete evaporation the pan was taken and wiped with a clean cloth to remove any remaining water from the bottom and kept in a hot air oven for drying for 12 hrs at 1 10°C. The final weight of the pan was taken and subtracted from the initial weight to obtain the amount of soluble solids in the tea.
(e) Total organic carbon (TOC)
The Total organic carbon content of the condensate accumulated during the heating step was determined by a Shimadzu total organic carbon analyzer (model no. 5000 A). The TOC value was used as an estimate to quantify the amount of organic volatiles in the condensate.
Amount of aroma on TOC basis = TOC (ppm) x volume of aroma collected
Dry weight of material used Process for the preparation of liquid tea products
Example 1 :
A liquid tea product of the invention was made by submerging 1 kg of freshly plucked tea leaf (from a tea plantation in Southern India and having moisture content of -80% by weight) into 10 kg of water at a temperature of ~25°C in a vessel. The fresh tea leaves were allowed to stand in the water for a period of 20 hours. After this period the resultant water in the vessel was separated by means of a strainer with a pore size less than 0.1 mm. Then the water was heated in a rotary vacuum evaporator (Labrota 5000, Heidolph) for a period of 90 minutes with constant heating in a water bath which was maintained at a temperature of ~90°C and a pressure of -250 mm Hg absolute. The heated liquor was collected as liquid tea product.
Example 2:
In a preferred embodiment of the invention, 1 Kg freshly plucked tea leaf (from the tea plantation in Southern India and having moisture content of -80% by weight) was bruised by a manual process before submerging in order to slightly damage the leaf followed by the same procedure as Example 1 .
Example 3:
In a further preferred embodiment the liquid tea product of the invention was made by submerging 1 kg of freshly plucked tea leaf (from the tea plantation in Southern India and having moisture content of -80% by weight) into 10 kg of water at a temperature of ~25°C in a vessel. The fresh tea leaves were allowed to stand in the water for a period of 20 hours. After this period the resultant water in the vessel was separated by means of a strainer with a pore size less than 0.1 mm. Fresh tea leaves with moisture content of 76-80% were finely ground with a mortar and pestle. One gram of the ground fresh leaf was added per litre of the separated water. Pressurized ambient air (approx 10 atm) was passed through the liquor for 3 hours. The whole system was automatically stirred due to passage of high pressure ambient air and there was no manual mixing / stirring. Finally the liquor was filtered through a strainer. The liquid thus obtained was heated at 75°C for 8 minutes to obtain the liquid tea product.
Example 4: In another preferred embodiment the process of example 3 was repeated with tea leaves which were bruised by a manual process before submerging in order to slightly damage the leaf Example A:
A comparative liquid tea product was made by submerging 1 kg of freshly plucked tea leaf (from the tea plantation in Southern India and having moisture content of -80% by weight) into 10 kg of water at a temperature of 25 °C in a closed vessel such that it was not exposed to air. The fresh tea leaves were allowed to stand in the water for a period of 20 hours. After this period, the mixture of submerged leaf and water was filtered through a filter to separate it into the leaf tea residue and the resultant water. The resultant water was collected as the comparative liquid tea product. Example B:
A second comparative liquid tea product was prepared by providing 1 kg freshly plucked tea leaf (from the tea plantation in Southern India and having moisture content of -80% by weight) that was bruised by a manual process before submerging it in order to slightly damage the leaf followed by the same procedure of example A.
Comparison of CIE L * a * b * values
The a * and b * values of the liquid tea products were measured using the procedure as stated above. A higher a * value represents increased redness while a higher b * value represents increased yellowness (brightness). The results are summarized in Table 1 .
Table 1 :
Example a * value b * value
A -0.35 10.47 B -0.37 10.41
1 4.05 22.84
2 4.24 25.22
3 5.06 23.37
4 8.88 35.65
From Table 1 it is evident that the liquid tea products of examples 1 , 2, 3 and 4 (according to the invention) have much higher a * and b * values than the comparative examples A and B. Therefore the liquid tea products of the invention are redder and brighter than the examples outside the invention.
Compositional analysis of the tea products:
The compositions of the liquid tea products of Examples 1 , 2, 3 and 4 were measured using the analysis methods described above. The results are summarized in Table 2 (amounts are given in mg / L).
Table 2:
Component (mg/L) 1 2 3 4
Total soluble solids 1087 2601 1 100 1986
TPP 240 1275 305 560
Gallic Acid 41 .3 33.3 13.5 15.8
EGC 89.6 273 102 243
EC 1 .7 7 1 .5 7
EGCG 28.4 281 .3 38 99.6
ECG 6.3 66 13 57
Total Catechins 126 642 155 407
Theaflavins Not detectable Not detectable 30.3 66.1
Caffeine 70.1 186.1 42.6 70.65 Comparison of aroma profiles obtained after condensing the vapour
In the preparation of the liquid tea product of Examples 1 and 2 (described above) the vapour exhausts produced from the rotary vacuum evaporator were passed through the condenser which was cooled using circulant at 2°C. The aroma condensates from the condenser were collected (Example 5).
For comparison, aroma was captured from dhool, by a known process as follows: 1 kg of fresh tea leaf (from the tea plantation in Southern India and having moisture content of -80% by weight) was withered to a moisture content of - 75 % by keeping it at room temperature (~ 25°C). Then the tea leaf was macerated by a CTC machine 4 times followed by fermentiation of the leaf at atmospheric conditions (~25°C) for ~ 90 minutes. The leaf was then dried in a low convection (vacuum, Model- Labrota 5000 by Heidolph) to a moisture content of ~ 55% where the ratio of amount of inlet air to amount of moisture evaporated was about 0. 05 kg /kg. The aroma condensate was collected using a condenser operated at 5°C.
The aroma condensates were analysed by head space gas chromatography (HSGC) using a gas chromatography unit (PERKIN ELMER XL) and a
Headspace autosampler (Turbo Matrix 40) with the following parameters.
Gas Chromatography Conditions
Column type Mega bore column (CP WAX 52CB)
Column initial temperature 35°C
Column initial time 2 minutes
Ramp 10°C
Column final temperature 230°C
Injector temperature 230°C
Detector temperature 250°C
Split Flow 50 mL/min
Helium flow rate 20 mL/min Helium pressure 13.6 psi
Hydrogen flow rate 45 mL/min
Air flow rate 450 mL/min
Head Space Conditions
Oven Temperature 75 °C
Needle Temperature 100°C
Transfer temperature 1 10 °C
GC cycle time 33 min
Thermostating time 20 min
Pressurization time 3.0 min
Injection time 0.3 min
Withdrawal time 0.5 min
Vial venting ON
The results of the aroma profile analysis are given in Table 3.
Table 3
Comp-C Ex-2 Ex-1
Volume 200 (mL/kg of 100 (mL/kg 100 (mL/kg fresh weight of separated separated dhool) ) water) water)
TOC (mg/L) 450 210 130
Total volatile organic
compounds (mg/kg dry
weight of leaf) 360 780 500
Green aroma volatile compounds
t-2hexanal (ppm) 315.40 0.44 0.44
C3-Hexenol (ppm) 80.99 16.48 1 .77
1 -pentanol (ppm) 37.99 1 .20 0.26 tt24nonadienal (ppm) 0.00 1 .06 1 .12
Total green aroma volatile
compounds (ppm) 434.38 19.19 3.59 Floral aroma volatile compounds
Linalool (ppm) 52.47 7.31 5.02
Methyl Salicylate (ppm) 15.22 3.70 3.02 β-Damascenone (ppm) 1 .40 0.31 0.21
Total floral aroma volatile
compounds (ppm) 69.09 1 1 .32 8.25
Ratio of floral aroma volatiles:
green aroma volatiles 0.16 0.59 2.29
Table 3 shows that the aroma condensates contained compounds which are strong indicators of the desired aroma of tea. The condensates from Examples 2 and 1 had significantly higher ratios of the desired floral aroma volatile compounds (linalool, methyl salicylate and β-Damascenone) to the green aroma volatiles (t-2hexanal, C3-Hexenol, 1 -pentanol, tt24nonadienal) than the comparative aroma condensate (Comp-C). Thus, it is evident that the process of the invention provides a tea aroma which has higher floral characteristics. Thus it is evident that the invention provides a process to produce a liquid tea product with significant amount of floral aroma components, and where the tea product has colour properties similar to that of black tea.
Sensory analysis of the liquid tea product:
The liquid tea products of Examples 1 -4, A and B were tasted by a group of professional tea tasters. They evaluated the samples in terms of colour appearance and taste. The results are summarized in Table 4, from which it is evident that the liquid tea products obtained by the process of the invention have better sensorials than the comparative Examples A and B.
Table 4
Sensory Parameters
Example Colour Appearance Taste
1 Light brown Light teaness, little bitter 2 Bright reddish brown Good teaness, good in tea flavour
3 Very bright reddish brown Good teaness, good in tea flavour
4 Very bright reddish brown Good teaness, good in tea flavour
A Very light green, No teaness
totally clear liquid
B Light green, clear Lacking teaness
Black leaf tea products were made from the leaf which had been separated from the water after soaking in Examples 1 and 2. These black leaf teas were found to be comparable and acceptable in terms of flavour, taste and
appearance, to a regular black leaf tea product.
It is evident from the above that by way of present invention now it is possible to provide a darker liquid tea product, a novel floral aroma condensate and a regular leaf tea product starting from the same tea leaves.
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