F206S/C
FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2006
PROVISIONAL SPECIFICATION
(See Section 10 and Rule 13)
A PROCESS FOR RECOVERING VOLATILE AROMA COMPOUNDS FROM A TEA
MATERIAL
HINDUSTAN UNILEVER LIMITED, a company incorporated under
the Indian Companies Act, 1913 and having its registered office
at 165/166, Backbay Reclamation, Mumbai -400 020, Maharashtra, India
The following specification describes the invention

Technical Field
This invention relates to the processing of tea. It particularly relates to recovery of volatile aroma compounds from tea.
Background and Prior Art
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.
Aroma is a major organoleptic quality parameter of tea. Aroma of tea has a significant impact on the consumer's choice of tea and commercial valuation of tea. Therefore, improvement of tea aroma is an ongoing subject of research.
A large amount of volatile aroma compounds are known to be lost during processing. Various methods such as steam stripping, solvent extraction, supercritical carbon dioxide extraction have been used to recover volatile aroma compounds during tea processing, which is then added back to tea products. Steam stripping is carried out at low temperature under vacuum (US4130669, 1978, Procter & Gamble) as it is believed that exposure to high temperature imparts off-flavours and causes deterioration in aroma quality. Operation under vacuum involves additional cost and complexity.
One of the problems associated with the conventional steam-stripping aroma recovery process is that of degradation of volatile aroma compounds and/or reduction in shelf life or stability.
Aroma condensate is typically subjected to a further step of concentration, by distillation, adsorption-desoprption or membrane-based separation. It is relatively difficult to carry


out further concentration of aroma condensate in conventional steam-stripping processes without loss of quality and/or problems of fouling. Therefore, the aroma condensate needs to be added back to the tea immediately at the same processing site, reducing the flexibility of operation.
Further, the present methods do not afford flexibility of adding back aroma condensate to various types of tea without altering the taste characteristics.
It is known to carry out simultaneous extraction of soluble tea solids and aroma recovery from the tea leaves where the vapours during the extraction are condensed to recover volatile aroma compounds. Typically the duration of extraction is relatively small and the ratio of mass of aroma vapours condensed to dry mass of tea material is relatively small. Such processes generally give relatively low yield of aroma.
US3997685 (Procter & Gamble, 1976) discloses a process wherein the mass ratio of total vapours condensed to the dry mass of substrate is relatively large. However, a significant fraction of the total vapours condensed comprise non-volatile tea solids in the substrate material (termed as flavour concentrate in the patent). The ratio of mass of aroma vapours condensed to dry mass of tea material is relatively small.
In view of the limitations in the prior art, one of the objects of the present invention is to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
It is an object of the present invention to provide a process for recovery of volatile aroma compounds that gives relatively high yield.


Another object of the present invention is to provide a process of recovery of volatile aroma compounds which are relatively more stable.
Another object of the present invention is to provide a process of recovery of volatile aroma compounds that is relatively cost-effective.
Another object of the present invention is to provide a process for recovery of volatile aroma compounds so that the tea product, to which recovered aroma is added, has consumer acceptable organoleptic properties.
Yet another object of the present invention is to provide a process for recovery of volatile aroma compounds at relatively high concentration such that the volatile aroma compounds can be transported across geographical locations offering flexibility in tea processing.
Present inventors have surprisingly found that by increasing the mass of condensed aroma-laden vapours per unit mass of tea material whilst reducing entrainment of non-volatile tea solids in the condensate, it is possible to obtain relatively high yield of volatile aroma compounds without compromising quality.
Summary of the invention
According to the present invention there is provided a process for recovering volatile aroma compounds from a tea material comprising the steps of:
a) generating aroma-laden vapours at a pressure of from 0.5 to 1.4 bar absolute from the tea material contacted with water or water vapours, and;
b) condensing the aroma-laden vapours to recover aroma condensate;


characterized in that the mass of aroma condensate per unit dry mass of tea material is greater than 2 and the aroma-laden vapours comprise no more than 1% by weight entrained liquid.
According to another aspect, there are provided volatile aroma compounds obtainable by the process of the present invention.
According to another aspect, there is provided a tea composition comprising volatile aroma compounds prepared by the process of the present invention.
Detailed description of the invention
Tea material
Tea material that can be used in the process of the present invention includes any material obtained from the plant Camellia sinensis or Camellia assamica or derived therefrom after processing such a plant material.
Tea material can be selected from tea leaf, green tea, black tea, tea fibre. Spent tea leaf, i.e. tea leaf that has been subjected to a prior step of extraction of soluble solids can also be used.
Step (a)
The step (a) comprises generating aroma-laden vapours at a pressure of 0.5 to 1.4, more preferably from 0.7 to 1.4 and most preferably from 0.7 to 1.0 bar absolute from the tea material contacted with water or water vapours.
Step (a) is preferably carried out by one of the following:
i. by adding water to the tea material and subjecting the resulting mixture to evaporation, or;
ii. by contacting the tea material with water vapour under distillation condition.


Details of case (i)
Water is added to the tea material in the amount preferably from 10 to 50, more preferably from 10 to 30 and most preferably from 15 to 25 per unit dry mass of the tea material.
The resulting mixture is subjected to evaporation at a temperature preferably from 70 to 110 °C, more preferably from 80 to 105 °C and most preferably from 90 to 100 °C.
The tea material is subjected to evaporation preferably in a batch or semi-batch mode. The evaporation may be carried out in any suitable evaporation equipment. The heat transfer may be direct or indirect. Indirect heating is provided by heat transfer medium without contacting the mixture. Indirect heating can be provided in various types of equipment such as jacketed vessels, or vessels provided with internal or external heating coils. The heating medium is water, steam or thermic fluid. Direct heating can be provided by injection of steam into the mixture. Heating may also be provided by electrical means such as Ohmic heating or electroresistive heating elements.
During evaporation, the ratio of mass of the water to dry mass of the tea material is maintained at preferably from 10 to 50, more preferably from 10 to 30 and most preferably from 15 to 25. The ratio is maintained by replenishing the water that is evaporated. The water can be replenished periodically or continuously.
Details of case (ii)
The tea material may be optionally wetted with water. Amount of water per unit dry mass of the tea material used for wetting is preferably from 0 to 5, more preferably from 1 to 4 and most preferably from 2 to 4.


The tea material, wetted or dry, is then contacted with water vapours under distillation condition. The amount of water vapour contacting with the mixture per unit dry mass of the tea material is preferably from 3 to 15, more preferably from 3 to 10 and most preferably from 3 to 8.
The water vapour is at a temperature preferably from 70 to 110 °C , more preferably from 80 to 105 °C and most preferably from 90 to 100 °C.
Any suitable equipment such as a packed bed can be used. The tea material is supported on a porous plate or a mesh and acts as packing whilst the water vapours are passed through the bed in upward or downward direction. Although the water vapours may be in upflow or downflow configuration, it is particularly preferred that the water vapours flow vertically upwards through the packed bed of the tea material, it is believed that the liquid entrainment can be substantially reduced in the upflow configuration.
Liquid entrainment
The evaporation is preferably carried out in such a way as to
reduce the entrainment of liquid in the aroma-laden vapours.
The present inventors have found that the entrainment of liquid in the aroma-laden vapours leads to an aroma condensate that comprises tea solids that are associated with deterioration of quality. Therefore, the process of the present invention is carried out so as to reduce entrainment of liquid in the aroma-laden vapours.
Accordingly, the aroma-laden vapours comprise no more than preferably 1%, more preferably 0.5%, and most preferably 0.1% by weight entrained liquid. It is particularly preferred that the aroma-laden vapours are substantially free of the


entrained liquid. It is believed that reducing or avoiding liquid entrainment in the aroma-laden vapours leads to reduction in contents of solids in the aroma condensate, which are related to deterioration of quality of aroma condensate.
Preferably, an antifoam agent is added to the tea material prior to or during the step (a) . The resulting reduction in foaming is believed to help in reducing liquid entrainment in the aroma-laden vapours.
Preferably a mechanical defoamer is used during the step (a) . In case (i) , the mechanical defoamer is used whilst subjecting the mixture of tea material with water to evaporation. Mechanical defoamer may be in form of a rotating stirrer above the liquid level that breaks the foam. Alternatively, mechanical defoamer may in form of an ultrasonic vibrator plate placed above the liquid level.
The resulting reduction in foaming due to the mechanical defoamer is believed to help in reducing liquid entrainment in the aroma-laden vapours.
Liquid entrainment separator
Preferably, the aroma-laden vapours are passed through a liquid entrainment separator to separate the entrained liquid from aroma-laden vapours.
The liquid entrainment separator may be a part of the evaporator. Liquid entrainment can be reduced by using an evaporator with a large head space or vapour space. In practice, this can be achieved by reducing the ratio of working volume to the total volume of the evaporator. The ratio of working volume to the total volume of the evaporator is preferably below 0.7, more preferably below 0.6 and most preferably below 0.5.


The liquid entrainment can also be a separate equipment. Liquid entrainment separator is preferably selected from a spacer column, impingement separator, baffle plates, cyclone separator, packed bed collector or wire mesh collector. The spacer column is a long vertical tube or pipe with the vapour-liquid mixture flowing vertically upwards.
Step (b)
The aroma-laden vapours obtained in the step (a) are condensed
to recover the aroma condensate.
The mass of the aroma condensate per unit dry mass of the tea material is preferably greater than 2, more preferably greater than 3, and most preferably greater than 5.
The mass of aroma condensate per unit dry mass of the tea material is preferably up to 10.
The aroma condensate comprises no more than preferably 0.1%, more preferably 0.05%, and most preferably 0.01% by weight of solids. The term "solids" as used herein means unevaporated solid residue after drying the condensate to evaporate liquid. The drying is typically carried out at a temperature of 100 °C for a period of 24 hours.
The condensate recovery rate or the mass of condensate
recovered per unit dry mass of the tea material per hour is
preferably from 0.1 to 10, more preferably from 0.2 to 4 and
most preferably from 0.5 to 2.
The step of condensing aroma-laden vapours can be carried out in any suitable equipment. Examples of suitable equipment include, but are not limited to, shell and tube or double pipe heat exchangers. Heat exchanger is preferably vertically mounted. The aroma-laden vapours are preferably on the tube


side whilst the cooling fluid is on the shell side or on the annulus side.
Pretreatment of the tea material
According to a preferred aspect, the process preferably comprises a step of enzymatic pre-treatment of the tea material prior to the step (a). The process preferably comprises a step of incubating the tea material in an aqueous medium comprising an enzyme selected from cellulase, pectinase, amylase, p-glucosidase, primverosidase or mixture thereof, prior to the step(a).
The aqueous medium comprises an enzyme selected from cellulase, pectinase, p-glucosidase, primverosidase or mixture thereof. It is particularly preferred that the enzyme is selected from pectinase, p-glucosidase, primverosidase or mixture thereof.
The term cellulase refers to a class of enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze the cellulolysis (or hydrolysis of cellulose) . However, there are also cellulases produced by other types of organisms such as plants and animals. Several different kinds of cellulases are known, which differ structurally and mechanistically. The EC number for this group of enzymes is EC 3.2.1.4. Some commercially available enzymes of this class include CELLULASE AP® (Amano Enzymes, Inc.) and VISCOFERM® (Novozyme).
The active cellulase content of an enzyme is measured as enzyme activity on carboxymethyl cellulose (CMC) and expressed as carboxymethyl cellulose unit, abbreviated as CMCU according to the standard practice in the field. The term CMCU refers to picomoles of glucose formed per minute using carboxymethyl cellulose as substrate and cellulase enzyme under standardized conditions. The protocol for estimation of


CMCU is described by Lever (1972 Analytical Biochemistry 47, 273-279, 1972).
The activity of the cellulase is preferably from 105 to 107 more preferably from 5 x 105 to to 5 x 106, and most preferably from 5 x 105 to 2 x 106 CMCU per kg dry mass of the tea material.
The term pectinase refers to enzymes that break down pectin, a polysaccharide substrate that is found in the cell walls of plants. Pectinase can be extracted from fungi such as Aspergillus niger. Some commercially available enzymes of this class include VISCOZYME® (Novozyme) and EXTRACTASE® (Advanced Enzyme Technologies) .
Activity of pectinase enzyme is measured in terms of Apple Juice Depectinase Unit, commonly abbreviated as AJDU. It is based on the time required to depectinase an unclarified apple juice substrate at pH 3.5 and 45 °C. The end point is determined by isopropyl alcohol precipitation. Activity is then determined by correlating depectinization time to the unknown sample with that of a pectinase standard of known activity using a defined single strength apple juice substrate according to procedure - number 400.16 (dated May 22, 1992) of Solvay Enzymes, USA. Details are given in US6132727 (Rohde et al, 2000) which is incorporated herein by reference.
The activity of the pectinase is preferably from 104 to 10 x 107, more preferably from 0.5 x 105 to 5 x 106, and most preferably from 0.5 x 105 to 2 x 106 AJDU per kg dry mass of the tea material.
The tea material may be optionally wetted with water prior to addition of the aqueous medium to the tea material.


The ratio of the mass of water to the dry mass of the tea material during the step of incubating is preferably from 2:1 to 12:1, more preferably from 2:1 to 8:1, and most preferably from 3:1 to 6:1.
The step of incubating is for a period of preferably 5 to 200 minutes, more preferably from 15 to 150 minutes and most preferably from 30 to 90 minutes.
The step of incubating is at temperature between from preferably 5 and 70 °C, more preferably between 15 and 60 °C, and most preferably between 25 and 60 °C.
It is preferred that the tea material is subjected to mixing during the step of incubating. The mixing may be intermittent or throughout the duration of incubation. Mixing may be by means of an impeller attached to a rotating arm or by rotating the container to achieve mixing by tumbling of the contents.
Concentration of aroma condensate
According to a preferred aspect, the aroma condensate obtained at the end of step (b) may be further concentrated. The concentration of aroma condensate can be carried out by distillation, adsorption-desorption, or by membrane separation processes such as pervaporation and reverse osmosis.
Distillation
The aroma condensate is subjected to distillation to separate the concentrated aroma from the condensate. It will be appreciated that aroma condensate that comprises less than 0.1% by weight solids allows distillation at relatively high temperature without causing deterioration in quality of aroma.


Adsorption-desorption
The aroma condensate is contacted with adsorbents such as activated carbon, zeolites, or polystyrene-divinyl benzene resins for selective adsorption of the aroma components whilst the relatively aroma-free water is discarded. Subsequently, steam, hot water, organic solvents or supercritical fluid such as carbon dioxide is contacted with the aroma-laden adsorbent to recover the concentrated aroma. It will be appreciated that the aroma condensate comprising less than 0.1% by weight solids allows for concentration of aroma without causing contamination of adsorbent and/or the medium used for desorption.
Membrane separation
Pervaporation or reverse osmosis can be used for concentration of aroma. It will be appreciated that the aroma condensate comprising less than 0.1% by weight of solids allows concentration of aroma whilst substantially reducing the fouling of membranes.
Aroma add-back
Recovered aroma condensate, or further concentrated aroma condensate can be added back to tea products to enhance aroma. Aroma condensate may be sprayed onto a leaf tea product, instant tea product or a ready to drink product. A drying step may be required for leaf tea and instant tea to bring the moisture content down to stabilize the final product subsequent to aroma add-back.
According to one aspect, there are provided volatile aroma compounds prepared by the process of the present invention.
The steps of drying can be carried out by using equipment such as fluid bed dryer, tray dryer, vacuum dryer


and freeze dryer for leaf tea and spray dryer, thin film dryer or freeze dryer for instant tea.
According to one aspect of the present invention, there is provided a tea composition comprising volatile aroma compounds prepared by the process of the present invention.
Examples
The invention will now be demonstrated with examples. The examples are by way of illustration only and do not limit the scope of the invention in any manner.
Example 1
109.8 g of high grown Sri Lankan tea broken mixed fannings having moisture content of 8%, was taken into a round bottom flask. 2000 mL water was added. The resulting mixture was slurry with the mass of water per unit dry mass of tea material being about 20. The slurry was heated to induce boiling of the liquid at 1 bar absolute pressure. The aroma-laden vapours were passed through a liquid entrainment separator before passing them through the condenser. The liquid entrainment separator was a vertical column of 1 meter length wherein the aroma-laden vapours flowed in vertically upward direction allowing entrained liquid droplets, if any, to condense on the wall and flow back into the evaporator, thus preventing any entrained liquid from reaching the condenser. The rate of vapour generation was maintained at approximately 100 g/hour. The aroma-laden vapours were condensed by passing through a condenser operating on a cooling utility at 25 C. A total of 600 mL condensate was collected after 6 hours.
Evaluation of quantity, quality and stability of aroma
The total organic carbon in the aroma condensate was measured
using a Shimadzu TOC analyzer-5000A. Higher value of total


organic carbon is indicative of higher concentration of aroma compounds in the aroma condensate and therefore, of higher quantity of aroma.
The solids content in the aroma condensate were measured gravimetrically as follows. 50 mL of aroma condensate was weighed and dried in oven at 100 °C for 24 hours. The amount of solid residue was weighed to calculate % solids by weight in the aroma condensate.
Colour is indicative of quality of aroma condensate. Colourless aroma condensate can be blended or added back in various types of tea. Further the colourless aroma condensate indicates absence of solids so that the aroma condensate can be further concentrated in a relatively easy manner. Pale brown or any other colour of aroma condensate indicates presence of solids that can have deleterious effect on the quality of aroma condensate.
Stability of aroma condensate was measured as follows: Phenyl acetaldehyde, a key component of tea aroma, was used as a marker compound. Amount of phenyl acetaldehyde in the aroma condensate was measured by gas chromatography at t = 0 (initial) immediately after the condensation. The aroma condensate was kept at 25 °C for 48 hours and the final amount of phenyl acetaldehyde was measured (t = 48 hours) . The ratio of final to initial amount of phenyl acetaldehyde is a measure of aroma stability, with lower ratio indicating unstable aroma whilst high ratio indicating stable aroma
Example 1-A
The process of example 1-A was same as the process of example 1, except that the condensate was collected over 15 minutes.


Example 1-B
The process of comparative example 1-B was similar to the process of example 1 in all respects, except that the aroma-laden vapours were directly passed from the evaporator to the condenser, without using the liquid entrainment separator. From material balance, it was established that the aroma-laden vapours comprised greater than 1% by weight entrained liquid. Water soluble solids were 0.15% by weight in the aroma condensate.
Example 1-C
The process of comparative example 1-C was similar to the process of example 1 in all respects, except that the evaporation was carried out a pressure of 0.18 bar absolute.
Example 2- The effect of enzymatic pre-treatment of the tea material
The tea material of the Example 1 was pretreated with pectinase enzyme prior to the step (a) . The tea material was wetted with an aqueous medium comprising pectinase (obtained from Advanced Enzyme Technologies, India). The activity of the pectinase was 106 AJDU Apple Juice Depectinase Units per kilogram dry mass of the tea material. The wetted tea material was incubated at 55 °C for 60 minutes. The incubated tea material was then subjected to all the steps as described in Example 1.


The results are tabulated below.
Table 1: Summary of examples 1, 2 and comparative examples 1-A to 1-C

Ex No Liquid
entrainment
separator Water-soluble
tea solids in
condensate (%
by mass) Pressure (bar abs) Aroma
condensate
(kg/kg dry
mass of
tea)
1 Yes 0 1 5.94
1-A Yes 0 1 0.16
1-B No 0.15 1 5.94
1-C Yes 0 0.18 6.78
2 Yes 0 1 6.0
Table 2: Quantity, quality and stability of aroma.

Ex No Total organic
carbon (mg/
kg dry mass
of tea The ratio of final (t = 48
hours) to
initial (t =0)
amount of
phenyl
acetaldehyde Colour
1 472 1 Colourless
1-A 70.75 1 Colourless
1-B 472* 0.4 Pale Brown
1-C 64.15 1 Colourless
2 1323 1 Colourless
* Total organic carbon of volatile components of aroma


It is clear that the process of the present invention (Example 1) provides an aroma condensate in high yield (472 mg/kg dry mass of tea material), which is of good quality and stability.
In the process of comparative example 1-A, the resulting quantity of aroma was found to be significantly less as compared to that obtained by the process of Example 1.
In the process of comparative example 1-B, although the amount of aroma condensate obtained was relatively high, the quality was not acceptable as the colour of aroma condensate obtained was pale brown. Further, the aroma condensate was relatively unstable as indicated by degradation of phenyl acetaldehyde.
In the process of comparative example 1-C, the amount of total organic carbon in the aroma condensate was found to be significantly less than that in the aroma condensate obtained by the process of the Example 1.
From the results of Example 2, it is clear that the process with the enzymatic pre-treatment provides an aroma condensate with a further significant enhancement in yield, without compromising quality and stability characteristics.
It will be appreciated that the process of the present invention provides relatively high yield of volatile aroma compounds at relatively high concentration in the aroma condensate without compromising on stability in a relatively cost-effective manner.