Note: Descriptions are shown in the official language in which they were submitted.
FIELD O:F THE INVENTION
~ his invention relates to tea compositions having
improved color and flavor and to a process for preparing such
compositions. ~ore particularly, the invention is directed
to tea compositions containing added aluminum in a form and
an amount effective to provide a tea infusion having enhanced
color and flavor characteristics.
BACKGROUND OF THE INVENT ION
The crop harvested from the tea plant, Camellia
sinensis, comprises young leaf (green leaf) shoots which consist
essentially of two or more leaves and the unopened terminal leaf
bud or tip. This crop when suitably processed results in the
various types of tea of commerce. For instance, black leaf tea
is generally made by subjecting the plucked leaves (green leaf)
to a series of traditional processing steps including (1)
withering, (2) disintegration of the leaves by rolling, macerat- -
ing or otherwise bruising the withered leaf to release the juices
and enzymes, (3) fermentation (enzymatic oxidation) to develop
the characteristic color and flavor, the latter including taste
and aroma, of black tea, and (~) firing or drying, to deactivate
~the enzymes which catalyze fermentation. The extent of the
fermentation varies in commercial practice, from black to various
gradations between green and black. Partially fermented tea is
known as "oolong" tea~ An infusion of dried black leaf in hot
water provides a li~uor ha~ing a color ranging from gray to
golden to brown to ros~ pink in hue and exhibiting various de-
grees of brightness. It is generally considered that a bright
orange-red or red color is most desirable, but this depends on
the intended market for the tea. It is known that the color
and flavor o~ a black tea infusion are influenced by the
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nature of the aforesaid processing steps. Another factor which
also affects- the color and flavor is the nature of the original
green leaf from which t~e tea is manufacturedt as determined by
the type of plant locality and conditions under which the tea
is grown. Factors such as the country of origin, soil condi-
tions, rainfall and other climatic variations all have a bearing
on the quality of the tea, and variations may occur not only
from one locality to another, but also from one season to an-
other for tea grown at the same location~
Similar considerations apply to the quality of the
various instant black teas which conventionally are manufactured
by extracting the water-soluble ingredients produced during
black leaf ~ea manufacture and forming by known techniques hot
or cold water-soluble concentrated tea extracts or tea powders.
Optionally, it is known to produce such extracts or powders
from green tea extract by slurry fermentation or by non-enzy-
matic chemical conversion. Again, because of variability of the
starting tea and the nature of the processing, the control of
tea color and flavor is difficult. The determination of quality
of the tea tends to be a subjective assessment by the tea
taster. From these considerations, it will be appreciated that
there is a long-felt need for being above con~eniently to modify
the organoleptic qualities of black tea, particularly from the
standpoint of enhancing the color and flavor attributes thereof.
As used in the present application, the term l'tea" is
intended to mean leaf tea (unless otherwise specified, black or
oolong), aqueous extracts and infusions of tea and tea composi-
tions produced therefrom in either liquid or powder form and
whi~h are hot water-soluble or cold water-soluble and fractions
thereof.
It is known that the color of an infusion of black
tea is provided b~ the oxidation of polyphenols. These colored
3487~
oxidation products may be divided into two classes, theaflavins
and thearubigins. The former may be separated from the latter
by extraction of an aqueous extract of tea with ethyl acetate,
the theaflavins being extracted into the ethyl acetate.
Characteristically, the theaflavins impart a yellowish color to
a tea infusion which may approach a bright orange-red color in
concentrated solution, whereas thearubigins impart a reddish-
brown color. The total color of the tea is related to the sum
of the theaflavin and thearubigin contents and, hence, to
strength, whereas brightness is primarily an expression of the
propor-tion of the color due to the theaflavins. In a given
black tea infusion, if the thearubigin value is high and the
theaflavin value low, the tea is considered dull. If the levels
of both the theaflavins and thearubigins are low, then the tea
is thin and gray. To achieve the normally preferred bright
orange-red or red color, it is believed that the tea should
contain an average thearubigin content and a high theaflavin
content.
It is also known that the tea plant is an aluminum
accumulator and the aluminum content in the plucked leaves from
the naturally occurring tea plants is generally within the
range of from 200 to 1000 ppm by wei~ht (dry basis) as compared
with 50 to 100 ppm in other plant species. The stated aluminum
content is normally also present in black and oolong teas. The
role of aluminum in the metabolism of the tea plant has been a
matter of some speculation without resolution. The effect of
variations in the amount of aluminum accumulated in the leaf
on tea infusions has not been known.
SUMMARY OF THE INVENTION
Surprisingly, and in accordance with the present in-
vention, it has now been found that the color and flavor of a
black or oolong tea infusion may be enhanced, improved and
modified by the addition of a suitable aluminum compound to th~
tea leaves prior to plucking or to the tea composition during
any stage of the manufacturing or make-up o the tea from
plucking to the point of consumption. Thus, in accordance
with this invention, there is provided a tea-containing
composition comprising black or oolong tea having incorporated
therein added aluminum compound in a combined form and in an
amount effective to provide a beverage having enhanced or
modified color and flavor relative to the same tea beverage
without said added aluminum compound.
The invention also provides a process for preparing
an enhanced or modified tea composition, which comprises
treating black or oolong tea or instant tea at any stage during
its manuacture or infusion, or by spraying or coating of the
tea leaves prior to plucking, with a suitable aluminum compound
in an amount effective to provide an enhancement or mod~fica-
tion in color and flavor characteristics of the final tea
~everage.
In another embodiment the invention provides a process
for improving the color and flavor of a non-decaffeinated
beverage consisting essentially of tea which comprises adding
an effective color- and flavor-enhancing amount of a non-toxic
aluminum salt to said beverage or a precursor thereof at any
stage during or prior to the manufacture and preparation of
said beverage. In a preferred embodiment the aluminum salt is
a water-soluble aluminum salt selected from the group consist-
ing of aluminum sulfate, aluminum chloride, potassium aluminum
sulfate, aluminum nitrate, sodium aluminate and potassium
aluminate. In a further preferred embodiment such a process
is provided wherein said beverage contains an instant tea and
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during said manufacture and preparation green tea is slurry
fermented and said water-soluble aluminum salt is added at the
beginning of fermentation, or preparation green tea is
fermented and an extract of the fermented green tea is prepared.
In another aspect the present invention provides a
process for improving the color and flavor of a decaffeinated
beverage consisting essentially of tea, the tea component of
which is a black or oolong tea prepared by fermentation of
green tea, which comprises adding an effective color and flavor
enhancing amount of a non-toxic aluminum salt to the green tea
from prior to plucking to during fermentation.
In still another embodiment the invention provides
a tea-containing composition comprising black or oolong leaf
or instant tea having incorporated therein added aluminum
compound in an amount effective to provide a beverage having
improved color and flavor relative to the same composition
without added aluminum compound.
These and other features and advantages of the present
invention will become more readily apparent to those skilled
in the art from a consideration of the following detailed
description and the appended claims.
DETAI1ED DESCRIPTION
-
By enhanced or modified color a~d flavor characteris-
tics is meant characteristics which are enhanced or modified
to provide a more desirable tea as compared to a less desirable
tea as determined by an e~perienced tea taster. The enhanced
characteristics achieved by the present invention include
increased redness, intensity of redness and brightness and
improved flavor for both milk containing and non-milk tea. The
beneficial results of the invention may be realized with any
black or oolong tea.
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In performing the process of the present invention,
the tea is treated with a non-toxic, suitably reactive aluminum
compound, preferably a water-soluble aluminum compound. Various
water-soluble aluminum salts have substantially the same effect
in the color and flavor enhancement of the tea composition and,
for example, aluminum sulfate, aluminum chloride, potassium
aluminum sulfate, aluminum nitrate and the like may be suitably
employed. Also, solutions of sodium aluminate or potassium
aluminate may be used. A particular source of aluminum is the
ash produced from the combustion of mature tea leaves having a
high aluminum content. It has been reported that mature leaves
may contain up to 17,100 ppm aluminum based on the dry weight
of leaf. Although such leaves are not suitable for ordinary
tea production, they can prove useful as a source of aluminum
for the process of the present invention. Depending on the
stage of addition, the aluminum compound may be added in various
forms, for example, as a powder or as an aqueous solution.
The amount of aluminum added to the tea is that
amount sufficient to impart to the tea product the desired
color and flavor. However, in certain cases, tea products
with more than the normal redness and brightness are needed,
for example, when such small amounts of instant teas are used
in liquid or dried compositions that only a very light color is
contributed to the overall compositions by the tea. In addi-
tion, such compositions are usually consumed at low pH values
~as would occur with added lemon~ which further lightens the
tea color. In such cases, the color of the tea is often not
sufficiently dark for desired appearance of the beverage and
thus needs to be ausmented. It is an advantage to achieve the
desired darkenlng by the process of the present invention rather
than by the addition of food colorings.
~)94~7~L
Thus, the amount of aluminum compound to be added to
any particular tea will depend upon the inherent color and
flavor properties of the starting material and the color and
fLavor properties desired. secause of wide variations in inher-
ent organoleptic characteristics, it is not possible to fix
definite limits on the amounts of aluminum addition. However,
based upon experiments with selected teas, the addition of
aluminum (as aluminum sulfate) in an amount from 60 to 4,800
ppm, preferably from 60 to 1000 ppm, of aluminum by weight,
based upon the dry weight of the total tea solids, has been
found to be suitable to provide an appropriate modification of
color and flavor, the actual amount used within these ranges
being dependent upon the characteristics of the initial start-
ing material and the characteristics desired in the final
product.
The reaction of the tea with aluminum proceeds at
almost any temperature, such as, at room temperature or at
elevated temperature (e.g., boiling). The reaction proceeds
readily at pH values of about 3.3 to 7Ø Increasing the pH
of a tea brew containing added aluminum generally increases the
depth of the red color.
As stated previously, the aluminum may be added to
the tea at any stage during its manufacture. It has been un-
expectedly found that if the aluminum compound is added before
or during fermentation, for example, in the case of air
fermentation, by spraying the leaf with an aqueous solution
of the aluminum compound, the time needed to bring the color
and flavor of the fermenting tea to the point at which fermen-
tation is considered complete is thus reduced.
This speed-up of color and flavor development in
fermentation resulting from the process of the present inven-
tion is particularly useful in certain teas where the time to
complete the fermentation is so long that the color becomes dull
with the flavor being adverseIy affected. Also, in the case of
batch processing, reduction of the fermentation time reduces
the number of fermentation trays, or skips, or any fermentation
equipment needed, thereby reducing the capital cost in a tea
factory.
The aluminum compounds used as additives in the present
invention may be applied in liquid form at any stage during the
manufacture of any black or oolong tea product or may be added
in dry form to the tea or the water for brewing or dissolving
the tea at the point of consumption. Such aluminum compounds
may even be ad~ed to the green tea leaves prior to plucking as
by spraying or coating in dry or liquid form. The leaves are
then picked with the aluminum compound adhering to or absorbed
; into the leaves. However, there are specific points during the
manufacture of each product where the addition is most conven-
ient or where the best conditions for maximum control of the
reaction exist. For example r in the case of the manufacture of
black leaf tea, the aluminum is most conveniently added just
after the disintegration step, l.e., cutting or rolling of the
leaf, is completed and just before fermentation commences. For
slurry fermented tea, the addition may be directly to the slurry
at the beginning of fermentation. Treatment of cold water-
soluble tea may be before or after cold water solubilization.
When leaf tea is extracted for immediate consumption in
a teapot or cup, the tea liquor is usually extracted in three to
six minutes, although longer times are sometimes used. However,
in the manufacture of commercial instant teas, the extraction or
heating time will be much longer, depending on the manufacturing
method. It is known that when leaf time is extracted for long
periods, the color of the brew becomes dark and dull and the
brightness and redness are lost. The process of the present
39~371
invention improYes the color and flavor of beverages made from
tea solids obtained by extracting at high temperatures for long
periods of time. Even spent tea leaf from instant tea manu-
facture, which when further extracted yields a raw tasting and
colorless liquor, may be treated by the process of the present
invention to provide a composition which will yield a palatable
beverage of desirable color and flavor.
Black tea compositions produced by the process of the
present invention from certain teas provide infusions up-graded
to the distinctive reddish-orange or red color and corresponding
superior flavor of desired teas. The improvement in the color
is particularly noticeable when the infusion is made up with
milk. Furthermore, the reddish color of the tea/milk infusion
is intensified when the pH of the infusion is increased.
It has further been discovered that the reddish color
attributable to the added aluminum is not extracted from a water
infusion of the tea by ethyl acetate. Also, the ethyl acetate
extract of a hot water infusion o a tea treated by the process
of the present invention is lighter in color then a similar
extract of the untreatsd tea, which indicates a lower theaflavin
content in the treated tea (orange-yellow theaflavins are ex-
tracted by ethyl acetate). This further indicates that the added
aluminum reacts with at least some of the theaflavins present
in the original tea. This is additionally substantiated by the
fact that the color of teas with a very low initial theaflavin
content is not improved by the process of the present invention
to the same extent as teas having a higher theaflavin content.
The following examples are given merely as illustrative
of the present invention and are not to be considered as limiting.
~11 of the taste tests on hot tea were done by expert tea tasters
using standard methods.
7~
EXAMPLE 1
A hot water-soluble tea (non-decaffeinated) having a
yellowish-brown color with milk was dissolved in hot water at a
solids concentration of 0.6% by weight and divided into five
portions of 240 ml. To each portion was added 5 ml. of milk.
To four of the samples were added increasing levels of aluminum
sulfate. One had no added aluminum. The amounts added and the
observations made on the appearance of each sample are recorded
below.
Sample ppm added Aluminum Appearance with
number (based on ~based on milk
weight of beverage
tea solids) volume)
1. (Control) 0 0.00 Yellowish-brown
2. 60 0.09 Slightly redder and
brighter than 1.
3. 120 0.18 Redder and brighter
than sample 2.
4- 180 0.27 Redder and brighter
than samples 2 and 3.
5. 240 0.36 Rosiest red color;
brightest with an
appearance of strength.
EXAMPLE 2
An instant tea powder (non-decaffeinated), which in
beverage form with milk added thereto was yellow-brown and light
in color, was dissolved in hot water at a solids concentration of
0.6~ by weight. The dissolved sample was divided into slx por-
tions of 240 ml., and 5 ml. of milk was added to each. Various
aluminum compounds were added to all the samples except one
(a control), and visual observations were made.
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Aluminum ion
Form of (ppm based on Observations
Aluminum Added dry sol-ids-) on appearance
1. None (control) 0 Yellow-brown, Dull
2. Aluminum 100 Red, Bright
sulfate solution
3. Aluminum 100 Red, Bright
chloride solution
4. Aluminum 100 Red, Bright
nitrate solution
5. Aluminum 100 Red, Bright
potassium sulfate
solution
The samples with added aluminum were all redder and
brighter than the control with no aluminum added. There was no
discernible color di~fererence between the samples containing
the various added aluminum compounds.
EXAMPLE 3
Hot beverages (280 ml.~ were made using standard meth-
ods from several brands of hot water soluble instant teas and
black teas (all non-decaffeinated) and 5 ml. of milk was added
to each. To one-half of each o~ the samples was added a solu
tion of aluminum sul~ate so that each had 100 ppm aluminum
based on total tea solids. Each of the tea beverages with added
aluminum was compared with the other half of the same beverage
; to which no aluminum had been added. All the samples to w~ich
aluminum had been added were redder and brighter than the con-trol
samples, the actual intensity of redness and degree of bright-
ness varying from sample to sample.
EXAMPLE 4
A hot water-soluble, non-decaf~einated instant tea
powder (which when reconstituted exhibits a yellow-brown milk
color) was dissolved in water at a solids concentration of 40%
by weight and divided into three batches. The first batch was
used as a control~ To each of the others was added aluminum
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sulfate to provide lO~ and 500 ppm, respectively, of aluminum.
The three batches were then spray-dried in a commercial spray
drier. The resulting powders were examined after dissolution
in water at a concentration of 0.6~ by weight solids with an
appropriate amount of milk added thereto.
The milk color of the control sample was yellowish-
brown. That of the sample containing lO0 ppm aluminum had the
desired redness and brightness. The milk color of the sample
containing 500 ppm aluminum was more deeply red and brighter
than tea is usually expected to be. Upon tasting, it was found
that the samples containing the aluminum had more flavor,
specifically described as more strength, than the control sample
containing no added aluminum.
EXAMPLE 5
Several batches of macerated green leaf in an aqueous
slurry at a weight ratio of 20 parts of water to l part of tea
leaf (on a dry basis) were fermented with an air stream evenly
dispersed throughout the slurry. The-batches were allowed to
ferment for 35 minutes. Aluminum sulfate (in an amount provid-
ing 200 ppm aluminum on a dry leaf basis) was added to each
batch at different stages in the manufacture of dried instant
hot water-soluble tea (non-decaffeinated) from the fermented
tea slurries. The process points at which the aluminum was
added are shown in the Table below. The visual observations
made on appearance of the beverages made from the powders are
recorded in the Table.
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Point of Observations on Appearance
addition of
_uminum without milk wit'h milk
1. At no point Turbid, Yellow Yellowish-brown, Dull
(Control) Thin
2. Before Clearer, Red Red, Bright, Thick
fermentation
3. After fermenta- Clearer, Red Red, Bright, Thick
tion, before
hot extraction
4. After hot extrac- Clearer, Red Red, Bright, Thick
tion, with leaf
still present
5. After removal of Clearer, Red Red, Bright, Thick
spent'leaf
6. After concentra- Clearer, Red Red, Bright, Thick
tion to 4~ solids
The appearance of the samples with added aluminum was
very similar at whichever point the addition was made. In all
of these experiments, the appearance of the samples with added
aluminum was more attractive than the control sample with no
added aluminum.
EXAMPLE 6
To demonstrate the effect of the addition of aluminum
sulfate during the manufacture of black tea (non-decaffeinated),
'~ the following experiment was performed in a commercial black
tea factory.
By the use of atomizing spray apparatus, solutions of
aluminum sulfate were applied to the CTC cut leaf being conveyed
into fermentation tubs (each with a capacity of holding 50 kg.
of cut leaf). Two levels of aluminum sulfate were employed,
using the same amount of sprayed liquid (containing 4~ and 8%
aluminum, respectively). Controls without added aluminum were
subsequently processed in the same way as the experimental
samples. The tubs containing the experimental samples and con-
trols were attached to an air supply and allowed to ferment.
~.o~
The following Table shows the amounts of aluminum added to the
experimental samples and the length of time required to complete
fermentation according to the factory's standard way of judge-
ment (by color and aroma).
SamplesAluminum added Time to complete
(ppm based on dry fermentation
weight of tea)
Control 1 0 72 minutes
Experimental 1 190 ppm 60 minutes
Control 2 0 78 minutes
Experimental 2 380 ppm 38 minutes
The batches were then fired in the normal way. Samples
were brewed in the standard manner for evaluating teas (includ-
ing addition of milk), and the following observations made on
appearance and taste.
Sample Observation
Control l Red, Bright, Brisk, Raw
Experimental l Slightly redder, Brighter, More mature
Control 2 Red, Bright, Brisk, Raw
20~ Experimental 2 Redder, Very Bright, Mature
Importantly, the samples containing the added aluminum,
and having much shorter fermentation times than normal in this
particular black tea factory, did develop a normal or better
than normal tea color, and~yielded brews which were mellower or
more mature than the fresh, con~entionally made tea which had a
raw taste.
XAMPLE _
~everal commercial and experimental cold water-soluble
instant teas (non-decaffeinated) were dissolved in water at 0.4%
solids concentration. To each tea was added 100 ppm aluminum
(as aluminum sulfate). Each had a control sample with no added
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aluminum for comparison. Visual observations were made on the
beverages in transparent glasses, and also in white cups with
4 ml. of milk added to the heverages. All the samples contain-
ing the added aluminum were slightly darker and redder than
their controls when viewed in transparent glasses. When viewed
in white cups with milk the differences were accentuated. The
samples containing aluminum all had significantly more redness
than the samples without added aluminum when evaluated with
milk added thereto.
EXAMPLE 8
Black leaf tnon-decaffeinated) was extracted at a 20:1
weight ratio of water (at 95C.) to tea. The extract was con-
centrated to 6~ solids and divided into 2 portions of 10 gallons
each. To one portion was added 1000 ppm of aluminum in the form
of aluminum sulfate; to the other portion no aluminum was added.
Both portions were then chilled to 2C. and centrifuged in a
continuous, automatically desludging disc type centrifuge. The
clarified portions were spray-dried in a pilot plant size spray
dryer. The insoluble portions were chemically solubilized by a
conventional method, well known in the art. The chemically
solubilized liquors were then chilled to 2C., centrifuged to
remove any remaining insoluble material, and spray-dried in the
pilot plant size spray dryer.
Three parts of clarified dry solids and one part of
solubilized solids were admixed to form each set of samples.
The samples were dissolved in water at 7C., and at 0.43% by
weight solids concentration. The sample containing aluminum
was clearer in solution, had a more balanced taste and was redder
both without and with milk (5 ml. unhomogenized cow's milk) than
the sample without added aluminum.
_XAMPLE 9
A number o~ samples of tea were evaluated for color
8~
as described herein. Each sample of 10 gm. of black tea leaf
(non-decaffeinated) was infused in ~00 ml. of boiling water.
Each infusion was stirred for 5 seconds after one minute and
again after two minutes. 20 ml. of milk was added after three
minutes. After 4.5 minutes each infusion was strained into a
cell for measuring, in a Hunter Laboratory Color Difference
Meter, A/B values which were read after five minutes. Some of
the samples were control samples containing no added aluminum
and other samples contained added aluminum according to the
invention where the addition (as aluminum sulfate) had been
made either before or after fermentation. The fermentation
times and the color values obtained are shown in the following
Table:
Sample No. Added Addition Fermentation A/B
aluminum (Before or Time values
(ppm) after (minutes)
fermentation)
:
1. --- ---- 70 0.76
2. 760 before 70 0.92
; 3. 530 after 70 0.85
4. 360 before 40 0.86
5. 180 before 60 0.79
6. 740 before 30 0.88
7. ~ --- 70 0.79
8. ---- -- - 70 0.74
9 ~ 70 0.71
The A/B values, which represent the red/yellow ratios
on the Hunter scale, give an indication of the redness of the
sample, the higher the A/B value the redder the color.
The Control Sarnples 1, 7, 8 and 9, all of which re-
quired a fermentation time of 70 minutes, gave color values vary-
ing from 0.71 to 0.79, showing that variations may occur due to
different fermentation conditions. But significantly, all the
* Trade Mark - 16 ~
~3~71
control samples had lower values than the samples with added
aluminum for similar fermentation times, whether the aluminum
was added before (Sample 2) or after (Sample 3) fermentation.
Even for a low level addition of aluminum (Sample 5)
the highest color value obtained in the control samples was
achieved at a shorter fermentation tirne.
The results in the above Table clearly demonstrate
that the process of the present invention provides teas having
increased redness with respect to untreated teas and also pro-
vides a reduction in fermentation time to achieve the same or
increased redness in teas as that of similar untreated teas.
EXAMP~E 10
To show the effect of altering the pH of a solutionof a hot water-soluble tea (non-decaffeinated) containing added
aluminum, a dried tea extract was dissolved at 0.4% by weight
concentration in hot water. To this solution was added 500 ppm
aluminum (as aluminum sulfate based on the dry weight of the tea).
The pH of the tea solution was 4.5. The pH was then adjusted
both towards the alkaline and acid side, and the following
observations made.
pH of solution Observati_
without milk with milk on color
3.3 3.9
4.0 4.7
4.7 5.4 increasing
5.5 5.9 redness
6.0 6.3
6~5 6.6
7.0 6.6 \
30EXAMPLE 11
-
To show that the formation of red color in tea with
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added aluminum is related in a large degree to the ethyl acetate-
soluble fraction of tea, and that the red color may be formed by
adding aluminum to this fraction, the following experiment was
performed.
One hundred ml. of a 0.5% solution of dried black tea
extract (non-decaf~einated) was extracted with 100 ml. of ethyl
acetate. The ethyl acetate layer was then extracted with a 2.5%
solution of freshly made sodium bicarbonate solution, which was
discarded, and then the ethyl acetate was evaporated to leave a
dry orange colored residue. The residue was dissolved in 100
ml. of distilled water and 1000 ppm (on dry basis of the resi-
due) of aluminum (as aluminum sulfate) was added to the aqueous
solution, which changed its color from yellow-orange to an
intense red. This solution was shaken with 100 ml. of ethyl
acetate, and upon separation of the layers it was noted that the
ethyl acetate had not extracted any color from the aqueous
fraction.
EXAMPLE 12
Fifty grams of old, mature tea leaves (with about 75
. .
by weight moisture) were ashed. The ash was then extract~d with
10~ ml. of hot water, decolorized with activated charcoal and
filtered to obtain a clear colorless solution.
When 0.2 ml. of this solution was added to an instant
tea brew (non-decaffeinated) with a yellowish color, the
beverage became markedly redder, showing that the ash from
mature tea leaves (which are known to contain large amounts of
aluminum) does indeed contain material which will cause forma-
tion of red color in tea.
EXAMPLE 13
-
To show that the precursors for color reaction with
aluminum are not present in unfermented tea material the follow-
ing experiment was performed~ Fresh green leaf was macerated
- 18 -
as in normal black -tea (non-decaffeinated) manufacture and
immediately extracted with boiling water to yield an extract
with approximately 0.3% solids. To this extract was added 500
ppm (by weight of dry tea leaf) of aluminum (as aluminum sul-
fate). A non-decaffeinated oolong tea and a black tea (Kenya)
were extracted in the same way as the green leaf. To each of
the extracts made from dry teas was added 500 ppm of aluminum
in the form of aluminum sulfate. The observations made are
shown below:
Extract Color observations
No aluminum With 500 ppm aluminum
Fresh green leaf Green Slightly greener
Oolong tea ~ellow and Markedly more red
slightly red
Black tea (Kenya) Red Markedly more red
EXAMPLE 14
In this Example the effect of added aluminum on teas
of various geographic origin, method of manufacture and grade
was investigated.
Each tea (non-decaffeinated) was brewed by infusing
5.6 g. of leaf in 280 ml. of boiling water for 6 minutes in
accordance with standard practice. The liquors were divided
into two equal portions and 500 ppm (based on the dry weight
of the tea) of aluminum (as aluminum sulfate) was added to one
of each of the portions. The samples were first classified
into five categories of color (from very light to very dark)
without added aluminum and then rated for color improvement with
added aluminum, in terms of increased redness and brightness,
without and with milk (5 ml.).
The results are shown in the following Table and the
optical density (at ~60 MN) of the fractions extracted with
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ethyl acetate (sodium bicarbonate washed~ from each of the teas
without added aluminum was determined as shown in the Table.
Color
improve-
Optical Density Color men-t by
of Ethyl Acetate without aluminum
Extract without added twithout
added aluminum aluminum and with
Tea Type (O.D. at 460 MN) milk)
_
1. South Indian CTC 0.16 light moderate
Fannings yellow
2. Uganda CTC Dust 0.64 very moderate
dark
3. Tanzania CTC PF 1 0.65 dark very
marked
4. Malawi CTC PF 0.29 average slight
5. Turkish Orthodox 0.055 very slight
PF light
yellow
6. Indonesia Orkhodox BOP 1 0.22 average moderate
7. Kenya Orthodox BOP 0~38 average marked
8. Sir Lanka Orthodox 0.21 average moderate
BOP
9. USSR Orthodox BOP 0.05 very slight
light
yellow
The invention being thus described, it will be
obvious that the same may be varied in many ways. Such varia- ~;
tions are not to be required as a departure from the spirit
or scope of the invention, and all such modifications are in-
tended to be included within the scope of the following claims.
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