Title of Invention

"A PROCESS FOR THE PREPARATION OF COLD WATER SOLUBLE INSTANT TEA"

Abstract

The present invention provides a process for preparation of cold water soluble instant tea. said process comprising extracting black tea leaves with hot soft water substantially free of salts to provide a tea liquor containing tea solids and insoluble cream, separating the insoluble cream, concentrating and obtaining a concentrate containing about 5-15% tea solids, adding an alkali and calcium chloride, oxidizing the slurry, separating the insoluble solids therein, and collecting the supernatant, polishing and preparing cold-water soluble instant tea.

Full Text

COLD WATER SOLUBLE INSTANT TEA Field of Invention: The present invention provides a novel process for the production of improved cold water soluble instant tea. Specifically, the invention provides a tea extract which is completely and readily soluble in cold water and the beverage prepared has minimum turbidity. Background and prior art: Green tea leaves i.e those that have been freshly gathered and dried immediately or tea leaves that have been heat treated before drying and includes aqueous extracts of these leaves In each instance, the green tea has undergone substantially no fermentation to the black state. Black tea, on the other hand, is generally made from green tea leaves by subjecting tea leaves to a series of processing conditions such as withering, rolling or otherwise disintegrating, fermenting and firing. Rolling or other disintegration initiates the enzymatic reactions of fermentation, during which the characteristic color, flavor and aroma of black tea are developed. When the fermentation has progressed sufficiently, the tea leaves are fired ( i.e. dried). This arrests the enzymatic reactions and the resulting product bears the characteristic appearance of black tea. (Millin, D.J. & Rustidge, D W. (1967) Process Biochemistry 2 No. 6 page 9) Black tea extracts or infusions as known in the art, are normally produced by a hot water countercurrent extraction process. Such processes are described, for example, in U.S. Pat. Nos. 2,902,368, 2,912,334, 3,065,077 and.3,0_80,237, as well as other literature. On extraction of black tea leaves with hot water, an extract containing soluble as well as insoluble material is obtained. The insoluble portion is generally discarded and the soluble portion is concentrated to form a concentrated extract which frozen or dried to form a shelf-stable powder. The powder is reconstituted in cold or hot water, as the case may be and used as beverage. 2 During the process of extraction of black tea. the soluble portion of the extract itself contains certain tea solids which cause turbidity or cloudiness in the beverage or extract The turbidity is caused by tea material, which is generally referred to as "cream" Clouding is a serious obstacle to the preparation of a commercial tea concentrate and consumer acceptability. Much attention has been directed to the elimination of the turbidity or cloudiness which often manifests in the reconstituted beverage and wide variety of processes have been proposed to eliminate the cold-water insoluble materials which cause such cloudiness. One solution, for example, is to employ chemical or enzymatic agents to solubilize the insoluble components; to remove the cold-water insoluble materials or their precursors; or to extract the tea leaf in a manner such that the insoluble materials contributing to or resulting in cloudiness are leached from the leaf. In order to produce turbidity free, water soluble instant tea or tea extract, especially one which is soluble in cold water, the cream must be separated from the extract. This is accomplished conventionally using centrifugation or similar techniques. The cream solids thus separated are found to contain a substantial proportion of desirable tea color and typical tea astringency, and thus the supernatant remaining after centrifugation no longer contains these properties. Therefore, the 'tea cream' which is insoluble in cold water, is usually processed further. The additional processing may involve solubilization of the cold water instant tea cream using chemicals or enzymes The supernatant fraction obtained after treatment of the tea cream is recombined with the solubilized cream fraction, concentrated and dried to obtain beverage powder. The focus of the research on instant tea has been on improving clarity, yield of tea extract i.e. the supernatant obtained after processing tea cream because it reflects on the clarity of final product. 3 Aqueous extracts obtained from black tea contain substances, believed to be primarily polyphenols compounds and complexes of polyphenols compounds and caffeine, which arc responsible for the desirable organoleptic and aesthetic characteristics of the extracts These substances are readily soluble in hot water, i e , boiling water and at temperatures when the beverage is consumed hot, i.e., above about 60 degree C However, when the extracts are cooled to room temperature and below, these substances are, at most, only partially soluble in the water of the extract Thus, the cooled extracts have a "cloudiness" which occurs from these substances being in the form of solids in suspension and form precipitated sediment. The cloudiness, which is not aesthetically acceptable, is known in the art as "turbidity", and the solids, as said earlier are described as "tea cream". Various methods and means have been proposed, attempted and utilized in the art to provide extracts which have minimal turbidity in cold water, the most simple being cooling a hot water extract of black tea so that a precipitate will form. The solids then are removed from the extract by means such as filtration or centrifugation. However, it long has been recognised that such processes are unacceptable because removal of the solids from the extract not only eliminates valuable organoleptic and aesthetic components, but also results in valuable yield losses. One suggestion found in U.S. 3,163,539 is that after aqueous extraction of black tea leaves, the extract obtained be oxidized particularly under alkaline conditions, in the presence of oxygen. Then the resultant oxidized solubilized material is added back to the extract. Further, methods to treat separated tea cream under alkaline conditions also can be found in U.S. Pat. Nos.3,151,985 and 3,451,823 and in Canadian Pat. No. 927,189, the latter of which also discloses treating the oxidized cream with sulfur-containing compounds to obtain improved color characteristics. On the other hand, U.S. Pat. No. 3,787,590 suggests performing oxidation of tea cream in the absence of added alkali in a manner such the oxidation will take place at a pH 2 to about 3.5. 4 Other efforts in the art to reduce turbidity and improve clarity of black tea extracts include adding a pectinase enzyme preparation to aqueous black tea extracts which is said also to reduce foaming of instant water-soluble extracts prepared therefrom and also to improve color; treating the extracts with catechins, ( U.S 3,787,582_and U S. Pat. No. 4,680,193), adding a water-solubie caseinate to the extracts, as disclosed in European patent application Publication No. 0 11 772. It also has been disclosed that black tea leaf may be treated to prepare a product having greater solubility than conventional black tea extracts by treating the leaf with an enzyme solution containing tannase and at least one "cell wall digesting" enzyme, such as cellulase, pectinase,-papain or hemicellulase, as disclosed in U.S. Pat. No. 4,639,375. Thus, so far, most researchers have concentrated on improving yield reducing turbidity of tea product. Little or no attention has been paid to the quality of water used for tea extraction. It is a commonly known fact that the standard/quality of water is not same in all parts of world or even within the same country. Yet, so far, the Applicant has not come across any literature that describes the influence of the water used for tea extraction, on the final tea product. The applicant's studies reveal that the water used, its quality and its nature plays a crucial role and affects clarity of the final tea product. Most often water has calcium or magnesium ions. It does not affect the reaction when tea cream is processed, rather forms salts, precipitates or settles and sediments at bottom allowing clear supernatant to be found Often calcium has been added to remove haze eg. Schroeder US 2,891,866 recommends alkalinization of slurry. However, the prior art does not study the influence of water on cold tea. To fulfil this void, the Applicant provides improved cold water soluble instant tea and its method of preparation. 5 Objectives of the Invention: A general object of the invention is to provide improved cold water soluble tea product which is instantly soluble in cold water and has improved clarity Another object is to provide a cold water soluble instant tea which when reconstituted in cold water retains its organoleptic properties, its natural taste and flavour Yet another object is to provide cold water soluble instant tea product which has little or no unnatural contaminants and acceptable colour A further object is to provide a cost effective, simple and easy method for the production of cold water soluble instant tea product Yet another object of the invention is to provide improved cold water soluble instant tea having improved clarity Statement of the Invention: The invention provides a process for the preparation of cold water soluble instant tea, said process comprising a) extracting black tea leaves with hot soft water substantially free of salts to provide a tea liquor containing tea solids and insoluble cream, b) separating the insoluble cream from the tea extract, c) concentrating the tea liquor at about 70-90°C to obtain a concentrate containing about 5-15% tea solids, d) adding 5-12% w/w of an alkali to the concentrate at 80°C and maintaining the concentrate at 80°C, e) adding 0 025 to 1% of calcium chloride to the hot alkalinized concentrate and allowing it to stand for 20 to 30 minutes, f) oxidizing the slurry of step (e) by incubating it at 70-130°C for 20 to 60 minutes under constant agitation and circulation, 6 g) adjusting the pH of the oxidised slurry to 5.3 by adding an edible acid, h) separating the insoluble solids therein, and i) collecting the supernatant of step (h) to obtain a tea extract and polishing the same by centrifugation, j) preparing cold-water soluble instant tea by concentrating and drying the supernatant of step (i). In an embodiment, the ratio of water to tea leaves is 10 1 to 30.1. In another embodiment, the water in step (a) is soft water substantially free of calcium or magnesium salts. In yet another embodiment, black tea leaves are extracted with hot soft water at 50 to 95°C. In another embodiment, the insoluble cream is separated by filtration or centrifugation In yet another embodiment, the alkali in step (e) is selected from sodium hydroxide or potassium hydroxide. In another embodiment, the amount of alkali added is 5 to 12% w/w on tea solids. In still another embodiment, the amount of calcium chloride added is 0.025 to 1.0%. In another embodiment, the edible acid is selected from citric acid, fumaric acid, maleic acid and tartaric acid. In an embodiment, the amount of edible acid added is 5 to 15% w/w of tea solids In another embodiment, the concentrate obtained in step (j) is incorporated with additives acceptable in the food and beverage industry such as cola concentrate. According to this invention, first, a hot water extract of black tea is prepared. The prior art at this step, recommends the use of hard water or any other water, without regard to its quality. Contrary to these teachings, in the present invention, soft water substantially free of salts is used for extraction of black tea. The reason for use of soft water is that Novel such soft water has little or no salts. Salts, if present, affect the clarity of the final product. Extraction is effected at temperature about 50-65°C, preferably at 55-60 C. The tea liquor obtained contains tea solids and insoluble cream. The insoluble cream is separated from the liquor by methods such as filtration or centrifugation. 7 Subsequently, the liquor is concentrated. It must be ensured that the concentration is effected in such a manner that 'haze' does not remain in the final product This achieved by concentrating the liquor to the extent that minimum amount of solids are left thereafter. It is "advantageous to effect concentration at elevated temperature of 70-90°C so that only 5-15% of tea solids remain. In a preferred embodiment, the concentrate may contain 8 to 10% of tea solids. The concentrate is now hot and cannot be processed as such. It must be cooled from 5 to 10°C, preferably 7 to 10°C. The insoluble cream, if any, is separated from the concentrate by filtration or centrifugation. At this juncture, alkali is added. The amount of alkali added may be 5 to 12% w/w. The alkali may be selected from sodium hydroxide or potassium hydroxide. Subsequently, the alkalinized concentrate is heated to about 70 - 90°C. When such temperature is attained, calcium chloride is added. The amount of calcium chloride added is about 0.025 to 0.50%. If more calcium chloride added, then too much of haze remains in the final product. If less calcium chloride is added, turbidity remains in the final product. Therefore, the optimum amount which may be added to the concentrate is about 0.01 to 1% wt./v. It is advantageous to add alkali at 80°C in one shot. Upon such addition, slurry is formed. The slurry is then incubated at a temperature of 70-130°C for 20 to 60 minutes, preferably 30-40 minutes under constant agitation and circulation. The heat generated enables oxidation of tannins in the tea slurry. The temperature at this juncture is maintained at 80°C. A higher temperature is not preferred Prolonged duration of heating for complete oxidation at temperature greater than 130°C also not preferred due to the risk of irreversible denaturation of tannins. The pressure at the time of oxidation of the slurry is atmospheric. 8 In the process of the invention, there is no need to add any oxidizing agent as suggested in US Pat. No. 3,950,553 The degree of oxidation of tannins is readily observable as color of the slurry darkens The change in color (in the oxidized extract) due to oxidation of tannins is from reddish to dark brown In the art so far, this oxidised extract has been subjected to decolonzation (optional), chilled to precipitate unoxidized tannins and the solution of decolorized cold water soluble tannins are separated from the precipitate . Supernatant is combined with cold water soluble extract and tea is prepared. The applicant observed that if such process is followed, the turbidity remains and the natural properties of tea are lost. Further, it is the finding of the applicant that the oxidised tea slurry obtained has a very high pH and if used for further processing, the natural properties of tea will be lost. Therefore, it is necessary to adjust the pH. This is accomplished by the addition of an edible acid such as citric acid, tartaric acid, fumaric acid or maleic acid, since it is easily available and is best as far as preservation, and other organoleptic properties are concerned. It is also used by bottlers eventually in the final tea product. The amount of citric acid added may be 5 to 15% wt/v. With the addition of citric acid, the pH is brought down from 5.0 -5 8. The acidified product thus obtained is now cooled and chilled. It is pumped into a precipitation tank which is kept at 2 to 4°C with slow agitation. This allows the concentrate to settle. The extract is kept thus for 2 hours or more so that the calcium salts and other insolubles acids will settle at the bottom leaving behind a clear supernatant The supernatant thus obtained is drawn out without disturbing the sediment. The feed is then subjected to the step of centrifugation. Centrifugation can be achieved using any conventional apparatus. However, factors such as amount of liquid used, density of the liquid, the temperature of the centrifuge, speed of the centrifuge and the time cycle determine how much clarity can be imparted to the supernatant/centrifuge. For best results, the centrifuge may have a specific density of 1.80µ/g and the product 9 temperature may be within the range of 20-30°C. The speed of the centrifuge may vary from 1000 -1500. The time cycle may be 600 litres/hr to 900 ltr/hr. This process will result in a clear supernatant. The haziness and cloudiness observed so far in prior art is unexpectedly reduced. The haziness, as said earlier is due to the presence of insoluble materials and are not removed by ordinary extraction techniques. It is therefore, essential to perform the sequence of steps as recited in the foregoing paragraphs Optionally, the natural tannins may be utilized to decolorize the oxidized tannins. In this instance, however, after removal of natural tannins, the resultant supernatant of oxidized tannins is combined with an appropriate solution containing "the normally cold-water soluble fraction of extractable tea solids. This combination is ordinarily made in a proportion such that the reconstituted extract has approximately the same ratio of solubles to tannins as is found in normal tea extracts. Where desired, however, the reconstitution may be performed so as to yield extracts in which the normal ratio between tannins and other solubles is altered. In this manner, variation in the aroma and flavor of the eventual tea beverage may be effected so as to suit particular consumer desires The subsequent processing for the production of a tea product in the form of a powder or extract may be performed in accordance with the prior art techniques. Accordingly, the reconstituted extract may be dried, for example, by spray drying. Alternatively, the reconstituted extract may be frozen and then freeze-dried. It is additionally desirable, prior to drying, to concentrate the reconstituted extract to facilitate the drying step. Concentration may be performed by well-known means such as freeze concentration or vacuum evaporation of the reconstituted extract.- It is most preferred that concentration be performed so as to obtain a solution having a solids concentration within the range of from about 20 to 60%, the particular optimum concentration being dependent upon the drying technique actually utilized. 10 In order more clearly to describe the nature of the present invention, specific examples are hereinafter described. It should be understood, however, that this is done solely by way of illustration and thus is not limitative of the ambit of the invention or the appended claims Example - Cold Water Soluble Instant Tea Powder. Method: - Conducted in Pilot Plant. A tea extract was prepared by mixing soft water boiled to 85°C with black tea, with water to tea ratio of 10:1. Residence time of 20 mts., was given for brewing at 80°C. The slurry was filtered using a filter cloth and twice extracted to reasonable normal operating conditions. The extract thus obtained had 4-5% tea solids. An already solublised tea cream solution was blended to this on 10% w/w basis. The extract was evaporated in a mini centrifugal evaporator to obtain tea 8% solids. The evaporated extract at 8% solids was boiled to 90°C using a mini tubular heater. The contents were collected in an open tank. Potassium hydroxide was added in diluted form. This was again circulated for hour when at this temperature, 0.25% w/w CaCb was added to the mixer. The contents were again boiled by fasting through the mini heater with straw on the shell side. Citric acid was added when the contents were hot and pH lowered to 5.3. The solubilised extract at pH 5.3 was chilled in a heat exchanger (outer shell with chilled water) to 4°C and allowed to settle in an open vessel for 2 hours at 4°C. Thereafter, the chilled extract was fed to a centrifuge at the rate of (600 litres/hr or 10 ltrs/mt). The centrifuged liquor was evaporated again to 6% solids and spray dried in mini spray drier using co-current nozzle atomization. The resultant product is absolutely sparkling in raw chilled hard water with ideal colour characteristics for an iced tea beverage. Method - conducted as a laboratory trial. 11 100 gms. of extractable black tea was mixed with 1000 cc of soft water at 90°C and heated in hot plate so that the temperature is raised to 85-95°C. The mixed slurry is allowed to brew for 20 minutes and thereafter extracted using a muslin cloth and then filtered through a sieve to remove particles. The extract received was around 4% in concentration. Solubilised cream powder already prepared and kept out of insoluble tea cream in a manner as explained under in the earlier example is mixed with the filtered extract at the rate of 10% but in diluted form a 10% concentration. This was pre-evaporated in rotary evaporator under partial vacuum to achieve 8% concentration. The concentrated extract (8%) is heated to 85°C and KOH is added into the extract to raise the pH to 4.0. This is boiled again and retained at 85°C. To this solution 0.025% CaCl2 on w/w basis is added and again re-heated. The CaCl2 added solution is allowed to remain at the same temperature on the hot plate for 30 mts. And thereafter neutralize to pH 5.3 by adding citric acid. The pH corrected solution is chilled in the refrigerator to 2°C and 1- mts. drawn and filled to calibrated test tubes to be spinned on a bench centrifuge. The speed is set at 3500 rpm and time of spinning is 20 mts. Refection were 1 ml but compact in nature. The supernatant was collected and 40 mts. made up. This was rotary evaporator which works under vacuum and is an idle laboratory equipment to produce powder similar to spray dried powder. The powder was dissolved in 4°C chilled raw hard water of 140 ppm and was found very clear in clarity as compared to the control sample without addition of the calcium chloride. Simultaneously, a bland sample was run by treating in the above manner as a control sample. The only difference of not adding the calcium salt. The control sample was hazy when dissolved in 4°C raw chilled water is when compared to the Cacl2heated extract liquor mentioned above. A comparison table is attached for reference. The results obtained from the pilot plant trial and laboratory trials had identical results. 12 WE CLAIM: 1 A process for the preparation of cold water soluble instant tea, said process comprising a) extracting black tea leaves with hot soft water substantially free of salts to provide a tea liquor containing tea solids and insoluble cream, b) separating the insoluble cream from the tea extract, c) concentrating the tea liquor at about 70-90°C to obtain a concentrate containing about 5-15% tea solids, d) adding 5-12% w/w of an alkali to the concentrate at 80°C and maintaining the concentrate at 80°C, e) adding 0 025 to 1% of calcium chloride to the hot alkalinized concentrate and allowing it to stand for 20 to 30 minutes, f) oxidizing the slurry of step (e) by incubating it at 70-130°C for 20 to 60 minutes under constant agitation and circulation, g) adjusting the pH of the oxidized slurry to 5 3 by adding an edible acid such as hereindescribed, h) separating the insoluble solids therein, and i) collecting the supernatant of step (h) to obtain a tea extract and polishing the same by centrifugation, j) preparing cold-water soluble instant tea by concentrating and drying the supernatant of step (1) 2 A process as claimed in claim 1, wherein the ratio of water to tea leaves is 10 1 to 30 1 3 A process as claimed in claim 1, wherein the water in step (a) is soft water substantially free of calcium or magnesium salts 4 A process as claimed in claim 1, wherein black tea leaves are extracted with hot soft water at 50 to 95°C 5 A process as claimed in claim 1, wherein the insoluble cream is separated by filtration or centrifugation 6 A process as claimed in claim 1, wherein the alkali in step (e) is selected from sodium hydroxide or potassium hydroxide 7 A process as claimed in claim 1, wherein the edible acid is selected from citric acid, fumaric acid, maleic acid and tartaric acid 8 A process as claimed in claim 1 or 7, wherein the amount of edible acid added is 5 to 15% w/w of tea solids. 9 A process as claimed in claim 1, wherein the concentrate obtained in step (j) is incorporated with additives acceptable in the food and beverages industry such as cola concentrate 10 A process for the preparation of cold water soluble instant tea substantially as hereindescribed and illustrated. The present invention provides a process for preparation of cold water soluble instant tea. said process comprising extracting black tea leaves with hot soft water substantially free of salts to provide a tea liquor containing tea solids and insoluble cream, separating the insoluble cream, concentrating and obtaining a concentrate containing about 5-15% tea solids, adding an alkali and calcium chloride, oxidizing the slurry, separating the insoluble solids therein, and collecting the supernatant, polishing and preparing cold-water soluble instant tea.

Documents:

00340-cal-2002 abstract.pdf

00340-cal-2002 claims.pdf

00340-cal-2002 correspondence.pdf

00340-cal-2002 description(complete).pdf

00340-cal-2002 form-1.pdf

00340-cal-2002 form-18.pdf

00340-cal-2002 form-2.pdf

00340-cal-2002 form-26.pdf

00340-cal-2002 form-3.pdf

00340-cal-2002 form-5.pdf

00340-cal-2002 letters patent.pdf

00340-cal-2002 reply f.e.r.pdf