Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Beverage or beverage concentrate
Reexamination Certificate
1999-05-04
2001-07-31
Cano, Milton (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Beverage or beverage concentrate
C426S655000, C426S435000, C426S271000, C426S425000, C462S080000, C462S080000
Reexamination Certificate
active
06268009
ABSTRACT:
TECHNICAL FIELD
This application relates to a process for preparing green tea extracts having improved clarity and color. This application particularly relates to a process for preparing these green tea extracts involving treatment with a cation exchange material, followed by nanofiltration. This application further relates to beverages prepared with these green tea extracts.
BACKGROUND OF THE INVENTION
The extraction of tea material is well known in the art. For example green tea is typically extracted with hot or cold water to form a dilute extract containing soluble tea solids. This green tea extract can be concentrated to form a concentrated extract which is sold in frozen, refrigerated or dried form. This green tea extract can also be combined with other beverage ingredients such as fruit juice, nectar, etc., to provide beverages having at least some of the desired flavor and sensory characteristics of green tea
Green tea extracts initially contain high levels of unoxidized flavanols, especially monomeric catechins such as epicatechin, epigallocatechin, epigallocatechingallate and epicatechingallate that impart a desired taste quality (astringency) to the tea beverage. Unfortunately, these catechin components (molecular weight of from about 200 to about 500) can be oxidized to higher molecular weight polyphenols, especially the theaflavins and thearubigins, in the presence of other components in the extract. These other components include metal ions (especially calcium, magnesium, manganese, aluminum, zinc and iron), certain partially oxidized organic intermediates (especially quinones) that are formed when the green tea is initially extracted, and dissolved oxygen. These metal ions in the extract act as a catalyst, and along with the quinones and dissolved oxygen, convert the catechins to oxidized polyphenols that impart a less desirable, lingering astringency to green tea beverages.
These oxidized polyphenols that are formed by the oxidation of the catechins can interact and react with other materials in the green tea extract, such as caffeine, protein, pectins and/or metal ions, to form even larger and heavier complexes that eventually precipitate out. As a result, the tea beverage turns from the desired pale green color to an unappealing brown color over time. More importantly, the tea beverage becomes cloudy, turbid and develops a visible precipitate within a few days.
This discoloration and precipitation of complexed materials in tea containing beverages is not visually appealing. Some consumers consider such beverages to be distasteful and “old”. Moreover, where it is desired to provide “clear” beverages containing green tea, the fact that these green tea extracts can change color and become turbid is certainly undesirable.
Attempts have been made to remove these complexes from green tea extracts. These methods include changing processing conditions, especially temperature to cause precipitation, followed by centrifugation, filtration, and removal of the precipitate. Other methods include suspending and stabilizing the oxidized polyphenols. See for example, U.S. Pat. No. 4,051,261 (Jongeling) issued Sep. 27, 1977. Still other methods include using chemical and enzymatic agents to solubilize the insoluble components, or using solvents to extract the tea leaf, so that only the unoxidized catechins are extracted. Even after using these methods, the catechins will still be oxidized over time to the less desirable oxidized polyphenols. Also, when the green tea extract is incorporated into a beverage having non-tea materials such as juice, punch, and/or nectar, the beverage can turn an unappealingly brown color and can become “muddy” with time.
Another method that has been used to lower the level of oxidized polyphenols such as the theaflavins and thearubigins, and to increase the levels of desired catechins, as well as the desired amino acid theanine, is disclosed in U.S. Pat. No. 5,427,806 (Ekanayake et al), Jun. 26, 1995. In this prior Ekanayake et al process, green tea is extracted with an aqueous acid solution of erythorbic acid and/or ascorbic acid, plus citric acid. The acid extracted tea solution is then treated with gelatin and the resultant precipitate filtered out. This prior Ekanayake et al process removes some of the undesired oxidized materials as well as iron that can be present in the green tea extract. However, not all of the undesired components in the green tea extract are removed, including metal ions other than iron (e.g., calcium and magnesium), the theaflavins, and complexing components such as pectins and proteins. Accordingly, there is still a need for a process that can provide a green tea extract in which components contributing to oxidized polyphenols and other complexing components are minimized, reduced or removed so that the resultant extract has improved clarity and color over time.
DISCLOSURE OF THE INVENTION
The present invention relates to a process for producing a green tea extract having improved clarity and color over time. This process comprises the steps of:
a. providing a green tea extract that has been optionally, but preferably, obtained by:
(1) contacting green tea material with an aqueous acid solution comprising erythorbic acid, ascorbic acid, or mixtures of erythorbic and ascorbic acid, plus citric acid, to provide a first aqueous extract containing soluble green tea solids;
(2) separating the first aqueous extract from the residual green tea material;
(3) contacting the residual green tea material of step (2) with an aqueous acid solution comprising erythorbic acid, ascorbic acid, or mixtures of erythorbic and ascorbic acid, to provide a second aqueous extract containing soluble green tea solids;
(4) separating the second aqueous extract from the residual green tea material; and
(5) combining the first and second aqueous extracts to provide the green tea extract;
b. treating the green tea extract with an amount of a food grade cation exchange material effective to remove metal cations present in the extract;
c. contacting the treated extract with a nanofiltration membrane while the treated extract is at a temperature of from about 100° to about 140° F. (from about 37.8° to about 60° C.) to remove higher molecular weight components and to provide a filtered green tea extract as the permeate.
The present invention further relates to the filtered green tea extract obtained by this process. This filtered extract comprises, on a 1% soluble solids basis:
a. a mixture of catechins comprising:
(1) at least about 130 ppm of epicatechins;
(2) at least about 300 ppm of epigallocatechins;
(3) at least about 350 ppm of epigallocatechingallates;
(4) at least about 60 ppm of epicatechingallates;
b. at least about 50 ppm of theanine;
c. optionally, but preferably, at least about 450 ppm of caffeine;
d. about 10 ppm or less each of calcium, magnesium, manganese, aluminum, zinc and iron ions;
e. an absorbance of about 0.06 or less when measured at 600 nm;
f. optionally, but preferably, an absorbance of about 0.6 or less when measured at 430 nm
g. optionally, but preferably, a titratable acidity (TA) of at least about 0.1%.
The treatment of the green tea extract with the cation exchange material improves clarity by removing metal ions, especially calcium and magnesium ions, that can bind with pectin or proteins (or pectin-like or protein-like components) in the extract to form complexed molecules that can precipitate out and cause turbidity. Most importantly, this treatment with the cation exchange material gets rid of these metal ions as potential catalysts of the oxidation of catechins to oxidized polyphenols such as the theaflavins and thearubigins. In addition, where the cation exchange material is a strongly acidic cation exchange resin, hydrogen ions are added that minimize or reduce the need for additional acidity (e.g., adding edible acids) extract so that beverages prepared from this extract have a smooth, less tart, astringent taste.
The step of contacting the treated green tea extract with a nanofiltration membrane removes the lar
Bunger John Robert
Ekanayake Athula
Mohlenkamp, Jr. Marvin Joseph
Cano Milton
DuBois Philip
Mc Bride James F.
Roof Carl J.
The Procter & Gamble & Company
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