Title of Invention


Abstract SUPER CRITICAL FLUID CARBON DIOXIDE (CO2)is utilized to dissolve water souuble caffeine along with aroma of the teas simultaneously in super critical C02 stream at various pressures and temperatures and separate simultaneously caffeine siddolved water fraction and aroma dissolved water fraction along with C02 dissolved moieties in various concentration in both the fractions. TO OPTIMIZE PROCESS PARAMETERS TO ACHIVE 1. decaffeination to less than 0.3% caffeine from maximum of 4.5% in the teas 2. moisture content to retain at 5%,while meething para 1. 3. avoiding need for extranal mechaniocal dryding to meetr para 1 & 2. 4. to maintain structure of the tea partical,avoid generation of fines. 5. dissolve and separate tea aroma obtain water fraction and impregnate the aroma on to decaffeinated tea. 6. a minimum recovery of 94.5% 7. decaffeinated teas suitable for human consumption. KEYWORDS; Tea-camellia sinensis,caffeine,aroma,mousture,wetting,SCFE process,SCF CO2.
Full Text

Title of Invention
Fresh tea leaf and bud plucked from Tea Plant contains besides high moisture of 60 -70% or more, fiber, proteins, fats, chlorophyll pigments which are not soluble in water. Further, they contain other valuable components of importance for well being of consumers such as fermentable polyphenols, caffeine sugar, amino acids and small % of minerals.
During manufacture of teas for beverages of hot and cold, the fresh leaves and buds are subjected to a process of withering, rolling, fermentation and finally drying at high temperatures between 50 - 100° C depending upon the grade of tea to be manufactured.
During this process of manufacture of teas for beverages, the polyphenols are converted to compounds, which are mainly responsible for liquoring qualities of cup of teas such as Theaflavins (TF) and Theorubigenins (TR). These are red and brown with tannin properties. Some of the TRs are precipitated by leaf proteins to form in-soluble bodies which are lost through the tea infusion.
At low temperature of drying more TF is formed and at higher temperature more TR is formed.
In general, TFs are related to the liquor ( infusion ) and TRs are to its depth ( i.e. body and strength).

Ideal tea manufacture produces well balanced of TFs and TRs.
Further, during the process of drying sugars are caramelized and amino acids and chlorophyll are converted to black pigment.
Coffee and tea both contains caffeine are the most widely use stimulants in our society. They are valuable all over the world either as day-to-day drinks or as semi-luxury beverages.
Caffeine, being an alkaloids, has various effects on human metaboHsm. While some of these (such as smooth stimulating effect) are beneficial others are not so desirable and excessive consumption of caffeine can affect health and even cause serious illness in the worst cases. Some individuals suffer ill-effects even from a small amount of cafifeine. In order to cater for such individuals and also for the increasing number of persons solicitous of a healthy lifestyle in general, decaffeination processes have been developed and they have been in use since the beginning of this century. These processes reduces the caffeine content or, in some cases, virtually eliminate caffeine. Some of the decaffeination processes involve conventional solvent extraction, while others involve extraction with compressed C02.
More details on Tea are attached.
Super critical C02 is selective in dissolving only caffeine, aroma and moieties, and does not dissolve any of the polyphenols and polyphenol converted compounds such as TFs and TRs, which are the principle components in obtaining the good quality tea bru, during the decaffeination process.

Description of invention
The teas to be processed for decaffeination are of very wide varieties, consisting basically of black teas and green teas. They are further classified as leaf, orthodox, CTC teas based on the process of tea manufacture. Further, they are sub-divided into varieties of commercial grades based on the composition of particle size and shape.
The leaf tea grades are classified depending upon the size of the tea,

Flowery Pekoe (pp)
Pekoe (PEK)
Broken Orange Pekoe (BOP)
Broken Pekoe (BP)
Pekoe Fannings (PF)
The dust tea grades are classified as below.
Pekoe Fanning 1 (PF 1)
Pekoe Dust 1 (PDl)
Pekoe Dust (PD)
Red Dust (RD)
Super Red Dust (SRD)
Super Fine Dust (SFD)
Due to such a diversified varieties of teas, the decaffeination process has to be carried out carefully taking into consideration of
• Shape of the tea and its hardness
• Range of the particle sizes and % of each range, bulk density based on the sieve analysis.
• Total content of fines
• Caffeine content and
• Moisture content

Due to such large variable factors of teas to be processed, decaffeination process becomes complex and standardization of process is rather complex. However, the following basic process steps are developed in the invention.
1) Wetting of the tea:
Percentage of moisture to be added is determined based on the type of tea, its physical condition such as shape and hardness, capacity to absorb moisture. Initial moisture content of the tea to be processed has its own effect on the decaffeination processing beyond certain percentage say 10%.
Further, the caffeine content in the tea has a significant requirement for additional moisture to be added.
The wetting is carried out in a rotary drum to ensure uniform wetting.
Normally the wetting requirement varies from 15 to 80 % weight to weight basis of the tea to be processed.
The wetted teas are kept for soaking for about 2-4 hours depending upon the kind of tea and othw* associated factors.
Afler soaking, the wetted tea is transferred into the basket which in turn is loaded into the extractor and subjected to SCFE processing. Refer flowchart.
Initially, the air in the extractor is vented off using low pressure C02 and then high pressure super critical C02 is introduced for processing the teas. In the process of standardiration of SCFE C02 extraction process, the pressures varies from 250 to 500 bar at temperatures 40 to 65oC, and mass flow of SCFE C02 at a range of upto 125 kgs/kg of tea (wetted).

Better solubility of water dissolved caffeine and aroma in the SCF CO2 stream is achieved at about higher pressure upto 500 bar and temperature at about 65°C with optimum CO2 mass flow upto 125 kgs/kg of tea.
The high pressure SCFE CO2 fluidizes the tea particles in the extractor.
The water dissolved caffeine and aroma from the tea particles are dissolved in SCFE CO2 and reaches a saturation point by the time the SCFE CO2 leaves the extractor and enters the Separator 1.
The Separator-1 is set up with different pressures and temperature parameters between 60 to 150 bars and temperatures at 40 - 60 Deg.C. Due to these variations in pressures and temperatures, the water dissolved caffeine separates out from the CO2 stream and is collected in the Separator itself
The maximum concentration of water dissolved caffeine is collected in Separator - 1.
The tea aroma and volatiles dissolved m the SCFE CO2 stream coming out of Separator-1 is vapourized to pressures of re-cycled stream system and enter Separator-2 at pressures of 40 - 45 bar at temperatures around 25°C.
The water dissolved aroma with some dissolved volatiles separates out and collects in Separator 2 and the CO2 gas free of aroma is recovered and re-cycled.
The extraction process is continued to pre-determined period of time to ensure that the total quantity of CO2 passed through the tea to ensure that caffeine is dissolved and the tea is left with desired level of caffeine around 0.10 to 0.30 % or more and moisture at about 4% in the tea.

At the end of the pre-determined time, the extractor is de-pressurized, initially recovering the high pressure CO2 and subsequently venting the CO2 which could not be re-cycled.
The basket containing the decaffeinated tea is removed from the extractor and the decaffeinated tea is collected in stainless steel containers. The decaffeinated teas Avith low moisture content and low caffeine contents is submitted to further processing of aroma impregnation in a rotary drum.
The decaffeination process described above is carried out utilizing a single extractor and two separators resulting in a batch mode operation. The decaffeination processing is also processed utilizing two or more extractors in line and with only two number of separators, as described above. By utilizing two or more extractors, the decaffeination processing will be in continuous mode, unlike with one extractor resulting in a batch mode operations.
The process for decaffeination of tea from various types of teas, were carried out in two sets of processing units (i.e.) a Product Development Unit (PDU) and a Commercial Unit.
The PDU has the following equipment and the processing parameters:
An Extractor with 5 L capacity
Two Separators
High pressure carbon dioxide pump with 1000 bar pressure capacity and a carbon dioxide
re-cycling system with heating and chilling units.
The Commercial Plant has the following equipment: Two extractors with 800 L volume and basket of 600 L capacity. Two separators
High pressure carbon dioxide pump with 550 bar pressure and a carbon dioxide recycling system with heating and chilling units.
Refer to flow diagram

1) Pre-processing wetting:
The teas to be decaffeinated are to be wetted with portable water in rotary drums and by spraying water on to the teas uniformly to enlarge pores and dissolve caffeine and aroma.
Quantity of water to be used varies from 10 to 80 % w/w dry basis of the tea to be decaffeinated depending upon the above mentioned variable qualities of teas to be processed.
2) Dissolving and separating caffeine dissolved water fraction and aroma dissolved
water fraction along with moieties from wetted teas simultaneously;
Step 1 - To obtain caffeine dissolved water fraction containing around 1.0 to 3.5 % of caffeine with lipophillic moieties from wetted teas suspended in a fluid bed in a removable basket at variable condition of SCFE CO2 pressure, temperature and massflow of CO2 in the extractor.
2.1. To obtain aroma dissolved water fraction with lipophillic moieties from teas
suspended in a fluid bed in a removable basket at varied conditions of SCFE - CO2
pressure, temperature and mass flow of CO2 in the extractor.
2.2. The process of saturating SCFE CO2 with the caffeine dissolved water and the
aroma dissolved water alongwith lipophillic moieties is carried out in an Extractor at
varied pressure range of SCF CO2 from 150 to 500 bar and temperatures between 40 to
80oC with mass flow of 20 - 120 kgs of SCF CO2 per kg of tea to be decaffeinated
depending upon the type, quality and quantity of tea being processed.

2.3. The process of separation of caffeine dissolved water with lipophillic moieties from the saturated SCFE - CO2 stream, from the extractor is carried out in centrifugal Separator-1 at a reduced range of pressures of 60 - 150 bar and temperatures of 40 -80°C. The caffeine dissolved water with lipophillic moieties separated and collected in Separator-1 with dissolved caffeine content around 1.0 to 3.5% and lipophillic moieties upto l%w/w basis.
2.4. The SCFE CO2 stream from Separator-1 saturated vrith low level of aroma and to some extent caffeine dissolved water with minor lipophillic material is vapourized in the Evaporator and separated & collected in the centrifugal Scparator-2 at a further reduced pressures of upto 40 bar, and at temperatures between 15 to 30°C. The material so collected is rich in aroma with traces of caffeine dissolved water with negligible quantities of lipophillic fractions.
The entire process of saturating the SCFE CO2 with caffeine and aroma dissolved water fraction from the tea are separated and collected in two steps with lipophillic moieties in two separators, while the CO2 vaporized gas is re-cycled in the process.
2.5 Optimization:
Decaffeination of tea are carried out on various varieties of teas such as green teas and black teas varieties consisting of leaf, CTC, orthodox, fannings. Even in each variety of tea of different grades based on the quality of the tea, particulate size etc. In some cases, different varieties of teas are blended to meet the customers requirement.
As such, the decaffeination process becomes complicated, since there is no standard for the raw material to be processed from time to time.

The variations of principle characteristics of the teas to be processed are:
Initial caffeine content from Initial moisture content from 3 to 10%
Shape of the particle Flat to granular grades
hard and not very hard
Particulate size 100 to 1000 microns for all teas other than leaf teas
Fines 5-10%
Each of the above factors had varying effects on decaffeination process and processing parameters thus making it complex.
Thus, in the present invention for each variety of tea extensive processing procedures were established before decaffeination process is standardized for each variety of tea to carry on commercial decaffemation.
The above motioned variations in the teas to be processed have a bearing on the following processing steps such as:
• % of water to be added to swell the cells and dissolve caffeine and aroma , and at the same time, to minimize the moisture content in the decaffeinated teas.
• Quantity of tea that can be processed per batch in the extractor of given volume capacity.
• Varying SCFE CO2 pressure and temperature to be used in the extractor
• Varying Pressure and temperatures in separating caffeine dissolved water and moieties in Separator 1.
• Varying Pressure and temperature to vaporize the SCFE CO2 stream commg out from Separator 1.
• Varying pressure and temperature in separating aroma dissolved water from the vaporized CO2 stream in Separator 2.

Keeping the above number of variable factors for each varieties of teas, for optimization of decaffeination process to obtain decaffeinated tea with moisture less than 5%, to maximize the productivity.
The desirable conditions established are;
The particle size to be in the range of 710 to 300 microns other than leaf teas Moisture in the tea to be processed in the range of : 3 to 6 % Caffeine in the tea to be processed in the range of : 1 to over 4 % Particle shape : leafy, granular, flat and fannings.
After determining the above characteristics, the suitable processing parameters as elaborated earlier are selected for each variety of tea to be processed from time to time.
Variant To The Above Process Of Decaffeination:
Since Super Critical CO2 is highly lipophillic, CO2 at high pressure dissolves lipophillic components along with the surface color pigments. Due to this reason, the decaffeinated teas appears dull in physical form compared to the teas used for decaffeination.
However, since polyphenols, polyphenol converted tannins thearobins, theaflavons are not soluble in SCF CO2, hence all these compounds remain in the decaffeinated tea. Presence of TR and TF contributes to the tea bra color and strength.
However, if it is required to retain the physical color of decaffeinated teas, the process is adopted, such that the decaffeination process is stopped at a particular stage by which time, the decaffeination to the required level is achieved (i,e.)
The decaffeinated teas with moisture between 15 - 20% from the extractor basket is collected and dried gently in the suitable drying system to the moisture level of Existing known decaffeination processes:
Coffee and tea both contains caffeine are the most widely use stimulants in our society. They are valuable all over the world either as day-to-day drinks or as semi-luxury beverages.
Caffeine, being an alkaloids, has various effects on human metabolism. While some of these (such as smooth stimulating effect) are beneficial others are not so desirable and excessive consumption of caffeine can affect health and even cause serious illness in the worst cases. Some individuals suffer ill-effects even from a small amount of caffeine. In order to cater for such individuals and also for the increasing number of persons solicitous of a healthy lifestyle in general, decaffeination processes have been developed and they have been in use since the beginning of this century. These processes reduces the caffeine content or, in some cases, virtually eliminate caffeine. Some of the decaffeination processes involve conventional solvent extraction, while others involve extraction with compressed CO2.
In case of fermented teas ( black teas ), special attention has to be paid to preserve the aroma. Decaffeinated teas usually contain less than 0.1% caffeine on dry weight basis.
In order to minimize flavor and aroma losses, the commercial decaffeination of coffee is at present carried out on the green coffee beans before roasting.
In case of decaffeination of tea, it is not an easy task to avoid aroma and flavor losses.

In some processes involving supercritical carbon dioxide, the flavor and aroma components are extracted before decaflfeination, and the tea is subsequently re-impregnated with these components after decaffeination.
When using organic solvents as extractants, careful attention to the conditions is required to minimize these losses. Although decafFeination of teas usually carried out on the black tea after oxidation and drying, better results can be obtained by decaflfeinating the green leaf before drying.
Decaffeination Processes in practice:
Many of the conventional process for decaffeination involve the use of organic solvent such as methylene chloride or ethyl acetate. Such processes consist mainly of four steps, namely:
1. Swelling the raw materials with water, thus rendering the caffeine available for extraction;
2. extracting the caffeine from the raw material with the organic solvent (which should not be water-soluble).
3. stream stripping to remove all residual solvent from the decaffeinated material.
4. drying the decaffeinated material to bring their moisture level to value of 5 - 6%.
Many solvents were in use in decafFeination processes. Initially benzene was used but because of its toxicity and flammability, it is not being used any more. When chlorinated solvents first became available at low prices, tricholoroethylene was sometimes used but this solvent also has now been superseded. Methylene chloride is the only chrlorinated hydrocarbon currently used as a decaffeination solvent. Other commercial solvents used are ethyl acetate.
Water decafFeination and supercritical carbondioxide extraction have now become well-established process. However, it is still necessary in these processes to humidify the

material before extraction (step 1) and to return them to their initial humidity afterwarus (step4 i.e. drying the decaffeinated material to bring their moisture level to value of 5 -6%.), but the remaining 2 steps in the extraction process differ substantially from those in the conventional solvent extraction processes.
Methylene chloride is still in use as a decaffeination solvent, its advantages of being non-combustible and highly volatile.
Ethyl acetate is also used as the decafFeination solvent. However, unlike methylene chloride ethyl acetate is flammable and as a consequence, the extraction installation has to be designed to be explosion proof Investment costs are therefore higher than for the methylene chloride process.
In recent years there has been growing awareness among consumers about the use of synthetic chemical solvents in the food industry. This has led to the development of processes utilizing innocuous solvents of 'natural' origin. Water is a very good solvent for caffeine but has a very low selectivity. It also dissolves the many other water-soluble compounds present in the material. Quite complex processes are required to overcome this difficulty.
With the development of new high pressure extraction techniques, it became possible to use compressed supercritical carbon dioxide as a good solvent. Caffeine is soluble in it to a useful extent and it does not remove the other water-soluble components present in the green or black teas.
The advantages of decafFeination by SCF CO2 are;
□ The process losses of material apart from caffeine and to some extent waxes, the
extraction are very low. □ The extracted cafFeine is of very high purity and if it is isolated requires only
refining to provide a saleable product.

Known decaffeination by Super Critical CO2 processes: Zosel K., 1974 US Patent 3806619 proposed to moisten the tea and contacted with a stream of CO2 in a pressure vessel at 70 to 90 C and a pressure between 160 to 220 bar. The caffeine diffuses from the raw material which passes into washing tower. The caffeine is washed with CO2 rich stream with water (between 70 to 90 Deg.C) and the water-saturated CO2 is recycled to the extractor. After 10 hours of recycling virtually all the caffeine will have been transferred to the wash water, from which it can be separated by distillation.
In the second of Zosel's processes extraction conditions are the same as in the first process but in this case the caffeine is removed from the CO2 extract by passing this through a bed of activated carbon in which the caffeiune is adsorbed. The caffeine could in principle be recovered from the carbon but this is not practical for economic reasons.
The disadvantages of the above process are loss of flavor and aroma
Vilzlhum and Hubert have addressed this problem and described a multistage procedure
for the production of caffeine-free tea.
In the first state, the aroma components are removed from the tea by extraction with dry supercritical carbondioxide at 250 bar and 50 deg.C and these components are collected.
The de-aromatized leaves are moistened and decaffeinated by extraction with moist CO2 and the moist decaffeinated leaves are then vacuum dried at 50 deg.C.
The dried leaves are re-aromatized by expanding a CO2 solution of the aroma components from stage 1 into a vessel containing the leaves.
The main disadvantages of existing SCFE decaffeination processes adopted are;
The decaffeinated teas after decaffeination processing are produced with high moisture content of about 20%.

• Requiring mechanical drying at high temperature
• Mechanical drying results in structural change in the tea particles
• More fines are generated
• Offnote in the decaffeinated teas
• Yields at about 85-88% only.
• Aroma loss
However, in the present invention:
• Decaffeination and aroma recovery is carried simultaneously.
• Maintaining the low moisture level avoiding mechanical drying
• No structural change in the tea particle
• Impregnating aroma on to the decaffeinated teas
• Recovery at 94%
Some factors considered in the present invention:
Extractor Vessel and Internals (Function of Extractor Basket):
It is desirable ( or even necessary ) to enclose the teas to be decaffeinated in a set of "baskets" which are placed in the extractor vessel. This procedure is necessary in the case of teas, which tend to form compacts, agglomerates when extracted in deep bed. Such agglomerates can be virtually impossible to extract, fiirthermore, the compressed tea bed containing them does not flow rapidly with the result that is nearly impossible to discharge it from the extraction vessel without mechanical raking.
The tea which has been moistened prior to decaffeination shows this behaviour to a market degree, the effect being reinforced by the liberation of mucilage substances during moisturization and extraction. The above effects do not occur in a very shallow beds but, in case of tea they do occur in beds of height approaching that of the extractor which are

used for commercial purpose. Experience shows that the maximum bed height which can be allowed if the formation of agglomerates is to be avoided in beds of wet tea is between one and two meters (corresponding to maximum bulk density between 380 and 420 kgs/M3, depending upon the type of tea and particle size). The height of commercially useful extractors considerably exceeds this and for this reason it is necessary to insert the tea into the extractor within close permeable baskets.
Agglomerates can be studied and by practical experience it is possible to avoid the difficulty by careful control of the pressure gradient in the extractor and de-pressurizing reasonably slow.
Care should be taken when designing tea extraction to ensure that
□ The gas velocity through the basket does not exceed the fluidization velocity □ The product (pressure drop ) (cross section area) over a given section of bed does not exceed the weight of tea in that section.
If the CO2 velocity is allowed to rise sufficiently for fluidization to occur, the height of the bed extends and the large fast-moving bubbles appear. These effects produce channeling and also lead to the formation of compressed agglomerates for which it is virtually impossible to extract any caffeine. The minimum fluidizing velocity can be calculated for example, by the Thronglimp equation. Figure below shows this quantity for bed of wet tea as a function of particle size (hydraulic diameter) and CO2 density. The CO2 densities shown are in a range appropriate for decaffeination plant.
The overall flow rate of CO2 is largely determined by the required rate of production. Provided this overall flow rate is known, the minimum bed diameter can be calculated for the minimum fluidizing velocity.
Figure shows the corresponding pressure drop for unit height of bed. These are higher than those calculated from standard correlations.

Minimum fluidising velocity as a function of particle size and CO2 density (rho) in a bed of wet tea (rho is expressed in kg m-3).

Minimum bed diameter as a function of particle size and CO2 density for a typical

Advantages and disadvantages of baskets:
As seen above, the use of basket is unavoidable in the case of beds (of wet for example which agglomerate. In other cases, the economic advantages must be balanced against the economic disadvantages. This balance tilts against their use in plant with long extraction times.
The disadvantages are

The port through which the baskets are inserted and removed must have a diameter equal to the entire cross section of the extractor. This is an expensive modification since the closure must be quick-acting. It adds about 30% to the cost of the extractor.
The baskets themselves are not cheap and add about 18% to the extractor cost; The use of baskets increases the height of the extractor for a given payload (or reduces the payload volume for a given extractor shell) increasing extractor cost by about 3%. Increasing the extractor height may also entail increasing the height of the production building.

The advantage in the use of baskets is that it enables the extractor to be 'on-line' for a higher proportion of the time. There are two reasons for this.
• The rate at which solids can be removed from and fed into the extractor is substantially increased.
• The 'downtime' associated with cleaning filter elements is eliminated since, when baskets are used, the filters are attached to these and are cleaned on a regular basis when the baskets are removed. An increase in availability of about 7% is achieved in this way. Also it is comparatively easy to ensure that the bed within each basket is homogeneous, thus increasing the efficiency of extraction.

The benefit derived from the quicker charge/discharge operation is apparent for small extraction times.
An indispensable condition for caffeine extraction is that the crude tea be soaked up to a water content of ca.80%.
Background of Invention:
The fundamentals of Super Critical Fluid Processing and High Pressure CO2 as SCFE media:
Separation processes play a crucial role in biomaterial processing. A gas, when compressed isothermally to pressures more than its critical pressure, exhibits enhanced solvent power in the vicinity of its critical temperature (Diepen and Scheffer, 1948), such fluids are called supercritical fluids (SCF) and their corresponding thermodynamic state is illustrated in Figure .
A supercritical fluid exhibits desirable transport properties that enhance its adaptability as a solvent for liquid extraction processes. The density of the SCF is closer to that of liquids and its viscosity is low comparable to that of gases. Ifigh density SCF contributes to high diffiisivity equivalent to that of liquids; hence the faster dissolution of solute particles in SCF has contributed to the increasing usage of SCF as a solvent for extraction purposes.
Carbon dioxide is by far the most extensively used solvent due to its non-toxic, inert and non-flammable nature and while remaining and inexpensive and environmentally acceptable substance.

/ Phase diagram of a pure material and the thermodynamic state of various separation processes (Rizvi, 1987),

Products of biological origin are often thermally labile, lipophilic, non-volatile and required to be kept ahd processed around room temperature. Carbon dioxide (CO2) has a critical temperature of 31 Deg. C ,which makes it a particularly attractive media for the extraction of biological materials.
For logical reasons, supercritical fluid extraction (SFE) using CO2 has emerged as an attractive unit operation for the processing of food and biological materials.
Phase Equilibrium and solubility:
Several techniques have been developed to measure the solubility of a solute in supercritical fluids. The methods of solubility measurement fall into four general categories, namely, dynamic or flow methods, static or equilibrium methods, chromatographic methods and spectroscopic methods.
The dynamic or flow apparatus for solubility measurement is quite popular due to its simplicity. The solvent ( with a co-solvent, if desired) flows into a packed extraction vessel containing the solute at a give flow rate. It is critical that the solute and the solvent reach equilibrium at the experimental pressure and temperature before the solvent exits the flow cell. The compressed fluid mixture is then sampled and allowed to expand. The solute is then measured by gas chromatography, spectrophotometry, spectrofluorimetry or any other suitable analytical technique. The solubility thus measured must be independent of flow rate .
Another alternative is commonly used to obtain supercritical fluid-liquid equilibrium data is the static recirculation method.
At low pressure the density of the gas is rather small and at near-critical conditions the density increases rapidly to that of the liquid. Thus, the solubility parameters varies from zero at normal pressures increasing rapidly as the critical pressure is approached. Such a rapid change in solvent strength provides the basis for this powerful solvent extraction

technique, the biomaterial is solubilized in the supercritical fluid at the pressure and temperature conditions of its highest solubility and then a small change in temperature or pressure or both will bring a substantial decrease in the solvent power of CO2 and precipitate a single solute or fractionate a group of solutes exhibiting similar physico-chemical properties in sequential pressure and/or temperature manipulations.
Solubility as a function of density of pure CO2:
Supercritical extraction is based on the observation that near its critical temperature, the density of a pure supercritical fluid is highly sensitive to pressure. As a first approximation, since the solvent power of a fluid generally increases with density, slight changes in pressure at near-critical conditions can drastically affect solubilities.
Mass transfer operations and economics:
The design of extraction systems requires reliable data on mass transfer and hydrodynamics. Unlike solid feeds, the mass transfer resistances associated with the morphology (e.g. external shell) of the material are absent for liquid feeds, which conceptually indicates that SCF processing of liquids must be relatively more cost effective than that of solids.
Natural products are often present in solid matrices. The internal and external mass transfer resistances from the bound state of the material of interest to release it into the SCF need to be ascertained. Little attention has been paid to the mass transfer aspects to date. These resistances may contribute to major economic demand in terms of energy and processing costs. For most natural substances, a decision must be made between materials whose geometry may not be destroyed during the process e.g. coffee, tea, tobacco materials whose geometry may be destroyed or for which even a pretreatment may be possible e.g. oilseeds, hops, plant alkaloid substrates.

So, there is not much choice in the hands of a process engineer concerning those materials for which the geometry must not be destroyed, as in the case of tea, the SCF has to enter the pores of the solid matrix, reach the chemical species of interest dissolve it and then supercritical solution has to diffuse out of the solid matrix and mix with the bulk stream.
Moreover, considering the complex nature of biological substrate matrices with hard shells, multilayers with varying porosity and the bound state of the extractable material, investigation have to rely on a good deal of empiricism.
For materials whose geometry can be altered for SCF processing, like in the case of spices, the particle size and shape factor need to be selected carefully to give high mass flux rates of the biomaterial from the particle into the fluid.
At temperatures about their critical temperatures, gases do not liquefy on raising pressure. They can still exhibit liquid - solvent properties if the pressure is sufficient high for the density to approach a liquid - value. The dissolving power of the solvent is then strongly density dependent and can be varied by changing the pressure.
Carbon dioxide has been the solvent almost universally considered in recent years for application in the food and related industries because of its good health and safety characteristics.
By controlling the pressure, a range of selectivities and dissolving powers can be obtained with a given solvent at a given temperature.
Because of diffusivity and viscosity behaviour of near critical solvents, it is to be anticipated that they should give better penetration into the pores, matrices and hence, faster and more efficient extraction in extractant film control processes than do normal liquid solvents.

Near critical extraction with a solvent, which is gaseous under normal conditions has the advantage that nearly all the solvent will automatically be expelled when the product comes to ambient pressure.
The comparatively low dissolving power of near critical solvents tends to be associated with good selectivity, resulting in good quality and clean products. Low extraction temperatures associated with the use of liquid CO2 are also helpful to eliminate thermal degradation of the product.
Carbon dioxide has been the solvent used in virtually all recent commercial developments and is most important solvent for near critical extraction in the food industry.
It has the following advantages:
It is a GRAS (generally regarded as safe) substance.
It is neither combustible or explosive.
It is less harmful to the environment than many traditional solvents.
It is readily available in commercial quantities at a reasonable price.
The general rules of extraction with carbon dioxide can be summarized:
Lipophilic compounds such as hydrocarbons, ethers, esters, ketones and aldehydes are
easily extracted.
Polar substances such as sugars, polysaccharides, amino acids, proteins, phosphatides,
glycosides, and inorganic salts are not soluble.
Fractionation is possible when the substances display differences in volatility, molecular
weight or vapour pressure.

TEA- Introduction:
The Tea Plant is a kind of evergreen laurel tree and is taxonomically classified as camellia senensis. The tea plant spontaneously grows widely from tropical to temperate regions in Asia and have been closely associated with people's life since the dawn of history. The infusing leaves camellia senensis in water produces a fragrant beverage (i.e.) mildly astringent and bitter in the mouth called Tea, People began enjoying tea over 2000 years ago and in the year 2037 B.C. , the Chinese Emperor and Sheng Nung discovered the drink when leaves fell into the pot of boiling water.
Today, tea is a truly global drink enjoyed hot and iced for its ability to revive, refresh and relax the body and mind. Tea, was originally valued for its medicinal qualities that was first reported by Chinese Scholars in a medical text, the Pen T's, about 20 centuries ago, and it is a potential helpfiil properties of tea that are gaining scientific merit today. The constituents which have a considerable influence on taste and color characteristics of tea are polyphenolic bodies, caffeine, non-caffeine nitrogenous compounds, hectic substances, sugars, minerals and other compounds jointly or separately, but exact role played by each has not well understood.
A tea shoot consisting of two leaves and terminal bud, which constitute the normal the best material for tea manufacture, contains 74 - 77% moisture (surface dry) and 23-26% solid matter. About half of the solid matter insoluble in water and is made up of fruit fibre, cellulose, proteins, fats, etc.
The soluble part includes about the tea polyphenolic bodies, over 20 amino acids, caffeine sugars, and organic acids. Traces of number of substances which may be connected with essential oil, responsible for the aroma of tea, have been recorded. The following table quoted from Harler gives an idea of the constituents of fresh shoots of Assam tea.

Total polyphenol group makes up about 30% in the solid matter of the tea shoots. The polyphenols are popularly called tannins, although they have no tannin properties. This group consisting mainly the bodies called flavanols or catechins 6 of which are present in tea leaf as major component. Oxidisable matter, another term used to indicate the catechins, make up about 1/5 th of the solid matter. Polyphenolic bodies in tea shoots decreases in quantity from bud to stalk. The catechins also show the same trend. This explains the effects of the standard plucking and the tea quality.
The corser leaves lower down the stem, shows the market decrease in caffeine as well.

Principle of Tea Processing:
Tea can be manufactured in number of ways, but usually it is made into black or green tea. One of the most important processes in tea manufacturing for drink is fermentation. The process of unfermented tea results in green tea. The black teas are fermented teas and they are of two distinctive types orthodox and CTC.
Black tea manufacturing consisting of drying processes and the number of mechanical operations combined with or alternated with chemical and enzymatic reaction. Tea leaf is processed quantitatively into the finished product, since during processing no substances apart from oxygen are added, no substances other than water is extracted. The characteristics of the beverage made from the finished product are determined from the major components of leaf (i.e.) the polyphenols, the pectic substances, the flavoring constituents and caffeine, and later component particularly for its stimulative effect.
From a practical point of view, the chain of operations in black tea, processing can be distinguished in:
Sorting and grading
The freshly plucked young shoots of tea bush constitutes the basic material for tea processing, or withered by moisture evaporation during 16 to 20 hours to prepare the leaf for fiirther processing. Withering continues to a stage, in which the material physically can be rolled without breaking up excessively and chemically has undergone certain changes in which, the concentrated juice can be wrung out by a twisting action.

During the rolling of withered leaf, the cell content of the bruished material is mixed and erated. Started by an enzyme taking up atmospheric oxygen, the polyphenolic bodies in the leaf belonging to the catehin group and more or less oxidized: subsequently, yellow theaflavins and red and brown thearobigens are produced.
After rollmg, the material is subjected to further fermentation by spreading it under adequate conditions of temperature and humidity and such a period that the best possible quality of mate-tea is obtained from the given basic material.
Next tofermentation, other changes are taking place includes the development of characteristic odour (aroma) of tea. At the correct moment fermentation is stopped almost completely by removing the moisture from fermentation material by drying process.
Apart from moisture removal and any activation of oxidizing inside, some of the unchanged catechins are changed chemically then, while gums are dried through the enzymatic action to a warmish the tea. Furthermore, sugars are caramelized, resulting the smell of burnt toast or caramel type of dried tea.
By the drying processing, not only fermentation process is stopped, but a dry finished product is obtained, that can be easily handled, is capable of more or less prolonged storage without deterioration and can be conveniently supplied to the customer.
Some details of above process:
Changes during withering
During withering, the first stage of processing, the freshly plucked tea shoots with 70 to 83 % of water are partially dehydrated to moisture content ranging from 45 to 75 % of water. Besides, chemical changes also takes place.

Protein breaks down and a significant increase in caffeine content is also noted. Withered leaf has the smell of apples.
Changes during fermentation:
The polyphenols in the cell sap undergo series of chemical changes during fermentation process which is initiated after withered leaf has been macerateu during rolling. Some of the polyphenols are converted into compounds, which are mainly responsible for the liquoring qualities of a cup of tea. The polyphenolic compounds which have been found to change during fermentation, are epigallo catechin (EGC) and its gallate (epigallo) -catechingallate, EGCG, to which most probably epicatechingallate (ECG) should be added. Rate of conversion of these polyphenols is a function of temperature and oxygen concentration and of their amount and nature. The oxidation of polyphenols upon exposure to air is very slow, unless bought about by the activity of the appropriate enzyme (i.e.) polyphenol oxidase or catecol oxidase.
The basis of fermentation is to bring in presence of oxygen, enzyme substrate together by rupturing the membrane, so that the polyphenols can be fused into cytoplasma. This is brought about during rolling by withering action, on the withered leaf tissues and by mechanical disruption of its cells.
Action of enzyme oxidase is the oxidation of polyphenol bodies through ortho-quinones. Subsequently, the ortho-quinones by a process known as demerization condense to bisflavanols and these in turn rapidly condense to theaflavins (TF) which are yellow bodies. On additional oxidation, controlling by enzyme action, transforms these TFs to thearubingenins (TR). These are red and brown with tannin properties. Finally, some of the TRs are precipitated by leaf proteins to form insoluble bodies which are lost through the tea infusion. Over fermented teas, therefore, contains less TR than well fermentated ones.

The complete chain of reaction may be set out as follows: Epigalocatechin,n its gullate and probably epicatechin:
En2yme Oxidation
Theaflavins (TFS)
Thearubigins (TR)
Precipitation with proteins
Insoluble substances
Towards the close of fermentation, the accumulated TFS are continuously converted to TRS. Temperature has a profound effect:
At lower temperature, more TF is formed and At higher temperatures, more TR is formed
TFs are related to the liquor (infusion) and TRs are to its depth (body and strength)
Ideal fermentation produces with proper balance of TFs and TRs. The finished black tea contains, both TFs and TRs and the reaction does not complete during normal manufacture.

Changes during drying:
Drying the mass of disintegrated tea shoots reduces the moisture content from about 60 to some 3 - 4 % and thus largely, or may be even, completely inactivates the polyphenol oxidase. The enzymatic and chemical changes are brought more or less to a standstill only when the leaf has reached extremely high degree of dryness. Besides, the above indicated changes, sugars are caramelized, and some of the unchanged catechins are altered in structure. Then the enzyme pectase produces the varnish from pectin when the leaf dries at 49oC. As the leaf temperature rises during the drying process, the pectase is destroyed. It is believed that chlorophyll amino acids formed during withering conditions, contributes to the black color of made-tea. It is also found the release of gallic acid during drying is one of the important factors in the context blackness of the teas. The teas fired at higher temperatures (100°C) has increased gallic acid content and more blackish in color.
We Claim:
SCFE CO2 process of decaffeination for reduction of caffeine from various varieties of the teas (Camellia sinensis) with the following characteristics:
? Decaffeination to very low levels of caffeine to 0.4% and less.
? Maintain the moisture content of decaffeinated teas with less than 5% during the decaffeination processing itself
? Eliminating a need for mechanical drying
? Retain the structure of the tea particle,
? Impregnate the aroma separated in the process on to the decaffeinated tea
? Optimalize the recovery of decaffeinated tea around 94.5% depending upon the condition of the tea to be processed.

What is claimed, is
SCFE C02 process of decaffeination for reduction of caffeine from various varieties of the teas (Camellia sinensis) with the following characteristics:
? Decaffeination to very low levels of caffeine to 0.4% and less.
? Maintain the moisture content of decaffeinated teas with less than 5% during the decaffeination processing itself
? Eliminating a need for mechanical drying
? Retain the structure of the tea particle,
? Impregnate the aroma separated in the process on to the decaffeinated tea
? Optimalize the recovery of decaffeinated tea around 94.5% depending upon the condition of the tea to be processed.
Teas to be decaffeinated have the following variable characteristics:
o Caffeine content between 1 - 5 % w/w dry basis,
o Moisture content between 2 - 10 % w/w dry basis.
o Particle size between 100 to 1000 microns with varying percentage of particles
for all teas other than leaf teas. o Geometry of the tea particle varies from flat cut sizes to granular grades. o Varieties of teas - black, green teas of different grades like leaf, orthodox, CTC,
dustv fannings and also of different blends.

Other important characteristics of teas and SCFE C02 processing considered are:
o Caffeine exists in the teas in free and combined form, easily dissolves in water.
o Caffeine dissolved water, saturates the SCF CO2 in varying percentages, depends
upon the condition of SCF CO2 pressures, and to some extent the temperature. o The tea aroma dissolves in water, and water dissolved aroma saturates the SCF
CO2, in varying percentages along with the caffeine dissolved water and saturates
SCF CO2 in varying percentages depending upon the SCFE CO2 pressure and
temperature. o SCFE CO2 saturates with water dissolved caffeine and water dissolved aroma
fractions to be separated under different process conditions of pressure and
temperature. o SCFE CO2 is highly lipophillic and dissolves moieties and to some extent surface
pigments of tea.



238-che-2004-claims duplicate.pdf

238-che-2004-claims original.pdf



238-che-2004-description(complete) duplicate.pdf

238-che-2004-description(complete) original.pdf


238-che-2004-form 1.pdf

238-che-2004-form 19.pdf

238-che-2004-form 26.pdf

238-che-2004-form 3.pdf

Patent Number 205659
Indian Patent Application Number 238/CHE/2004
PG Journal Number 26/2007
Publication Date 29-Jun-2007
Grant Date 09-Apr-2007
Date of Filing 18-Mar-2004
Name of Patentee J.RAGHUNATH RAO
Applicant Address 6-3-663/G, 1st FLOOR, INNOVATIVE HOUSE, PUNJAGUTTA, HYDERABAD 500 082
# Inventor's Name Inventor's Address
PCT International Classification Number A 23 F3/36
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA