The present invention relates to beverages containing a
high concentration of catechins but having improved taste with reduced bitterness
It is reported that catechins have effects, for example,
as an inhibitor against a rise in cholesterol level (Japanese Patent Application
Laid-Open (kokai) No. Sho 60156614), for reduction of a plasma cholesterol
level (Japanese Patent Application Laid-Open (kokai) No. Hei 6-80580) or
as an &agr;-amylase activity inhibitor (Japanese Patent Application Laid-Open
(kokai) No. Hei 3-133928). This suggests that tea beverages such as green
tea, black tea and Oolong tea have physiological effects. Journal of Agric. Food
Chem., 2000, 48, 4227 - 4232 describes the effects of heat processing and storage
on flavanols and sensory qualities of green tea beverage.
EP-A-0426230 discloses a process for isolating flavanols
from natural sources.
In order to gain such physiological effects of catechins,
an adult must take four to five cups of tea a day (The Food Industry, 35(14), 26-30(1992)).
There has accordingly been a demand for the development of a technique of mixing
a high concentration of catechins in a beverage. Tea beverages containing a high
concentration of catechins (Japanese Language Laid-Open Publication (PCT) No. Hei
11-504224, Japanese Patent Application Laid-Open (kokai) No. 2000-60427)
have however strong bitterness and astringency due to catechins, caffeine and tannin
extracted from tea (tea leaves) so that they are not preferred as a beverage.
As a conventional evaluation method of bitterness, known
is a method using quinine sulfate. According to an index as specified by the bitterness
evaluating method by using sulfate quinine (Equivalency Concentration Testing Method/Organoleptic
Test Handbook, ed. by Organoleptic Test Committee/JUSE, published by JUSE Press,
Ltd.), beverages having an index of 5 or greater are not suited for drinking owing
to intense bitterness. With regards to beverages having various catechin concentrations,
an index of those having a catechin concentration of 300 mg/500 mL exceeds 6, while
those having a catechin concentration of 900 mg/500 mL exhibits an index of 10 or
greater and in addition, has pungency.
A beverage increased in its catechin content to impart
it with physiological usefulness has accordingly strong bitterness and astringency
and is not suited for daily drinking.
As an agent for reducing this bitterness and astringency
peculiar to catechins, proposed are a cyclodextrin (Japanese Patent Application
Laid-Open (kokai) No. Hei 10-4919) and a bitterness reducing agent comprising
a natural polymer (Japanese Patent Application Laid-Open (kokai) No. Hei
3-164136, Japanese Journal of Taste and Smell Research, 6(3), 665-668, 1999). The
physiological action of catechins can be exhibited effectively by increasing their
intake amount. Beverages containing much catechins are inferior in taste, but forms
facilitating high intake of catechins is desired from marketability.
As a method for incorporating a large amount of catechins
in a beverage, proposed is a method of adding powdered tea leaves (Japanese Patent
Application Laid-Open (kokai) No. Hei 10-234301). In this method, however,
when powdered leaves are added at a high concentration, excessive existence of powders
in the beverage disturbs smooth throat-feel and leaves an uncomfortable taste in
the mouth. In addition, such a beverage provided after a distribution process have
precipitates of powdered tea leaves on the bottom of its container or their floats
on the surface of the beverage upon drinking. Such precipitates in a transparent
container, for example, PET bottle greatly damages its appearance and hence commodity
value. Moreover, in a beverage providing physiological effects, consumers must shake
or stir it upon drinking to disperse the powdered tea leaves uniformly.
A method of adding catechins in the dissolved form by making
use of a catechin preparation is proposed (Japanese Patent Application Laid-Open
(kokai) No. Hei 2-182176, Japanese Language Laid-Open (PCT) No. Hei 8-504591).
The dissolved catechins have bitterness and astringency. A beverage containing a
large amount of them has therefore intense bitterness and astringency and drinking
of such a beverage is rather a pain. Accordingly, daily or continuous drinking until
its physiological effects appear is impossible.
An object of the present invention is therefore to provide
a beverage containing a high concentration of catechins but having improved taste
with reduced bitterness and astringency.
The present inventor has found that when a watersoluble
polymer is added to a highly concentrated catechins beverage containing both of
non-epi-catechins and epicatechins of non-polymerized type at a specific ratio,
it is possible to obtain a beverage having a higher quality which is no longer affected
by bitterness and astringency.
In the present invention, there is thus provided a beverage,
which comprises in the dissolved form the following non-condensed component (A),
another non-condensed component (B), and component (C):
- (A) non-epi-catechins,
- (B) epi-catechins,
- (C) water-soluble polymers; and has, per 500 mL of the beverage, these components
in amounts satisfying the following equations:
The term "catechins" as used herein means a generic name
of non-epi-catechins such as catechin, gallocatechin, catechin gallate and gallocatechin
gallate and epi-catechins such as epicatechin, epigallocatechin, epicatechin gallate
and epigallocatechin gallate.
The catechins to be used in the present invention are available
from a water extract or a hot water extract, to which an extracting assistant may
be added as needed, of green teas such as natural leaf tea, coarse green tea, refined
green tea, Tencha (green tea not powdered) and kiln-dried tea; semi-fermented teas
which are generically called "oolong tea", such as Ti guan yin, Sezhong, Huang jin
gui and Wu yi yan cha; and fermented teas called black teas such as Darjeeling,
Assam and Ceylon; each made from tea leaves available from species belonging to
Camellia spp. such as C. sinensis and C. assamica or.the Yabukita
variety, or hybrid thereof.
Tea is extracted by the conventional method such as extraction
under stirring. Upon extraction, an organic acid or organic acid salt such as sodium
ascorbate may be added to water in advance. A method of extracting in a socalled
non-oxidizing atmosphere while removing dissolved oxygen by boiling deaeration or
by feeding of an inert gas such as nitrogen gas may be used in combination. Instead
of extraction from tea leaves, a tea extract concentrate may be dissolved in water
or diluted with water, or a liquid extract from tea leaves and a tea extract concentrate
may be added together.
The term "tea extract concentrate" as used herein means
the concentrate of an extract obtained by extracting tea leaves with hot water or
a water soluble organic solvent. It is prepared, for example, by a method as described
specifically in Japanese Patent Application Laid-Open (kokai) No. Sho 59-219384,
Hei 4-20589, Hei 5-260907 or Hei 5306279. Commercially available products of it
include "Polyphenon" of Tokyo Food Techno, "Thea-furan" of Itoen, Ltd., "Sunphenon"
of Taiyo Kagaku Co., Ltd. and "Sunoolong" of Suntory Limited. As catechins, those
available from the other raw materials, column-purified products and chemically
synthesized products can also be used. The "tea extract concentrate" in the present
invention may be in various forms such as solid, aqueous solution and slurry. Examples
of the medium (which will hereinafter be called "liquid extract") in which a tea
extract concentrate is dissolved or with which it is diluted include water, carbonated
water and common tea extracts.
Since the content of condensed polyphenol increases with
the advance of the fermentation condition of tea leaves, the concentrate of a green
tea extract is particularly preferred among the concentrates of various tea extracts
to be added to water or a tea liquid extract.
In particular, combined use of a semi-fermented tea such
as oolong tea and a fermented tea such as black tea is preferred, because catechins-related
bitterness and astringency of the resulting beverage are alleviated further and
its platability is excellent even if catechins concentration is heightened.
The beverage of the present invention has catechins content,
that is, a total amount of Components (A) and (B) which are non-condensed and are
dissolved in water is 300 to 2500 mg, preferably 400 to 1300 mg, more preferably
500 to 1300 mg, especially 500 to 800 mg per 500 mL of the beverage. Amounts within
this range facilitate a high intake of catechins and, when a water-soluble polymer
is used in combination, facilitate exhibition of bitterness and astringency reducing
In the beverage, the catechins content in the total polyphenols
is 10 wt.% or greater, preferably 20 wt.% or greater, rightly after preparation.
The content sum of epigallocatechin gallate, gallocatechin
gallate, epigallo catechin is 30 to 98 wt.%, preferably 40 to 90 wt.%, in the total
catechins. When catechins are selected from epigallocatechin gallate, gallocatechin
gallate, epigallocatechin and gallocatechin, the resulting beverage has excellent
taste and is preferred. Here, at least one of epigallocatechin gallate, gallocatechin
gallate, epigallocatechin and gallocatechin is incorporated in the beverage, but
usually all of them are incorporated.
In tea leaves, most of catechins exist as epi-catechins,
but they change into their steric isomers, non-epi-catechins, by the treatment under
heat or with an acid or alkali.
A drastic lowering in melting point is recognized from
non-epi-catechins compared with epi-catechins, even if they have the same compositional
formula. In some compositions, a further lowering in melting point happens to occur,
depending on a mixing ratio of epi-catechins and non-epi-catechins. However, a functional
difference between them has hardly been studied yet.
Non-epi-catechins are available by heating an aqueous solution
of one of green tea, semi-fermented tea or fermented tea or an aqueous solution
of the concentrate of a tea extract at 40 to 140°C for 0.1 min to 120 hours.
Alternatively, the concentrate of a tea extract having
a high non-epi-catechin content may be used. They may be used either singly or in
It is preferred that Component (A) is incorporated in an
amount of 70 to 2250 mg, preferably 140 to 2250 mg, especially 140 to 1880 mg, per
500 mL of the beverage. Amounts within this range accelerate the effects of a water-soluble
polymer for reducing bitterness and astringency.
The Component (A)/Component (B) weight ratio is 0.25 to
9.0, preferably 0.43 to 9.0, more preferably 0.43 to 5.67, especially 0.54 to 5.67.
Weights ratios falling within this range accelerate the taste improving effects
brought by the addition of a water-soluble polymer.
As the water-soluble polymers serving as Component (C)
in the present invention, any of the water-soluble polymers usable as food additives
can be employed. Examples include gum arabic, alginic acid, carrageenan, agar, xanthan
gum, gelatin, tamarind seed polysaccharide, furcellaran, locust bean gum, branched
dextrin, polydextrose and caboxymethyl cellulose, with preferred examples being
gelatin, branched dextrin, polydextrose and carboxymethyl cellulose (CMC). From
the viewpoint of smooth throat-feel upon drinking, polydextrose and carboxymethyl
cellulose are particularly preferred.
Water soluble polymers contained in natural products are
Water-soluble-polymer-containing natural products usable
in the present invention include fruits such as blueberry and mandarin orange, vegetables
such as dried gourd shavings, Japanese radish, burdock, jew's mallow, Brussels sprouts,
spinach, corn and soybean sprouts, cereals such as wheat and rice, beans such as
red bean, soybean and pea, seaweed such as dried kelp, brown algae and brown seaweed,
mushrooms such as Shiitake, Enokidake, Maitake, Matsutake and eringii, and teas
such as refined green tea, natural tea leaves, oolong tea and black tea. From the
viewpoint of smooth throat-feel upon drinking, fruits, vegetables and teas are particularly
preferred, with the teas being most preferred.
When the above-exemplified natural product is used, the
water-soluble polymer in a beverage is quantitatively determined, for example, by
isolating it from the beverage by solvent fractionation and reprecipitation, by
treating the beverage with a specific enzyme and then conducting the similar operation,
by GPC, by hydrolyzing the beverage and then subjecting the hydrolysate to gas chromatography,
by separating the other components from the beverage by thin-layer chromatography
and causing color development of the remaining polymer component by using a reagent,
or by near infrared spectroscopy after conversion into a dried product.
Upon incorporation, the water-soluble polymer may be not
only in the powder form but also in the solution or suspension form.
The weight ratio of the water-soluble polymer content (C)
to the catechin content (A)+(B), that is, a quotient obtained by dividing the water-soluble
polymer content by the catechins content ((C)/(A)+(B)) is 0.05 to 10, preferably
0.05 to 5, more preferably 0.08 to 2. At a weight ratio within the above-described
range, a beverage has smooth throatfeel upon drinking and effects for alleviating
the astringency of the beverage are sufficient.
The mechanism of action of the water-soluble polymer has
not yet been revealed, but it is presumed that it suppresses adsorption of catechins
to the bitterness receptor portion of the taste bud cell on the tongue or it adsorbs
to the taste bud cell itself. It is presumed that the water-soluble polymer forms
a weak association with catechins via a hydrogen bond or the like, thereby suppressing
the contact of catechins to the bitterness receptor portion.
The pH of the beverage at 25°C is preferably adjusted
to 3 to 7, more preferably 4 to 7, especially 5 to 7 from the viewpoints of taste
and chemical stability of catechins.
The beverage of the present invention preferably has a
haze of 40 or less, more preferably 20 to 0.1, especially 15 to 0.3 in consideration
of the commodity value in appearance and material quality of the container wherein
the haze is measured by using a commercially available haze measuring apparatus
at 25°C. In addition, a trouble of uniformly mixing the components upon drinking
can be saved within such a haze.
The beverage happens to be turbid owing to the tea leaf
powder added thereto or mutual action between the beverage component with catechins
or polyphenol oxide produced by oxidation of catechins. Even without addition of
tea leaf powder, mild filtering conditions upon preparation of a tea liquid extract
from tea leaves permit fine leaf powder to be mixed in the beverage, resulting in
The beverage of the present invention can be put on the
market as is or a variety of catechins-containing beverages can be provided by mixing
it with another beverage component such as juice as well as tea such as green tea,
black tea or oolong tea. For example, the beverage can be added as needed to soft
drinks such as carbonated beverages, juice-extract-containing beverages, vegetable-extract-containing
juices, near-water drinks, sports beverages and diet drinks.
To the beverage of the present invention, additives not
adversely affecting the tea-derived component can be added. Examples of such an
additive include antioxidants, perfumes, organic acids, organic acid salts, inorganic
acids, inorganic acid salts, inorganic salts, colorants, emulsions, preservatives,
seasonings, sweeteners, acidifiers, juice extracts, vegetable extracts, nectar extracts,
pH regulators and quality stabilizers. They may be used either singly or in combination.
Their content may be 0.01 to 0.15 % by weight.
As a container for packing the beverage, ordinarily employed
ones such as molded containers (so-called PET bottles) composed mainly of polyethylene
terephthalate, metal cans, paper containers lined with a metal foil or plastic film
and bottles can be used. Here, the beverage means a beverage not requiring dilution.
The beverage of the present invention is prepared, for
example, by filling a container such as metal can with the beverage, and then if
possible, subjecting it to flash heating under conditions as specified by Food Sanitation
Law. When the container is not suited for retort sterilization, for example, PET
bottle or paper container, employed is a method of sterilizing the beverage under
similar conditions to the above-described ones, for example, at high temperature
for short time by a plate type heat exchanger, cooling it to a predetermined temperature
and then, filling it in the container. Under sterile conditions, another ingredient
may be filled in a container having the beverage already filled therein. It is also
possible to sterilize by heating under acidic conditions and then return the pH
to neutral under sterile conditions; or to conduct flash heating under neutral conditions
and then returning the pH to acidic under sterile conditions.
By incorporating a high concentration of catechins, increasing
the content of non-epi-catechins and adding further a water-soluble polymer, the
beverage of the present invention having reduced bitterness and astringency can
Measurement of the amount of catechins in a beverage
By using a high-performance liquid chromatograph ("Model
SCL-10AVP) manufactured by Shimadzu Corporation and equipped with a packed column
for an octadecyl-introducing liquid chromatograph, "L-Column TM ODS (4.6 mmo x 250
mm: manufactured by Chemicals Evaluation and Research Institute), a beverage was
subjected to a gradient method at the column temperature of 35°C. As mobile
phase liquid A and liquid B, a distilled water solution containing 0.1 mol/L of
acetic acid and an acetonitrile solution containing 0.1 mol/L of acetic acid were
used, respectively. Measurement was conducted under the conditions of a sample injection
amount of 20 µL and an UVdetector wavelength of 280 nm.
Measurement of turbidity of the beverage
By using a haze & transmittance meter ("Model HR-100")
manufactured by Murakami Color Research Laboratory Co., Ltd., haze (H) was measured
at 25°C one minute after the beverage was charged in a glass cell (optical
path length: 10 mm, width: 35 mm, length: 40 mm).
Components used in Examples
(1) Catechin preparation
Commercially available catechin preparation A having a
catechins content of 77% by weight, of which non-epi-catechins content is 6.9% by
weight (product of Itoen).
Commercially available catechin preparation B having a
catechins content of 86% by weight, of which non-epi-catechins content is 13.60
% by weight (product of Tokyo Food Techno).
Commercially available catechin preparation C having a
catechins content of 34% by weight, of which non-epi-catechins content is 9.5% by
weight (product of Tokyo Food Techno)
(2) Tea extract
Oolong tea extract
Ion exchanged water was added to oolong tea leaves, followed
by extraction at a water/leaves ratio by weight of 25 at 90°C for 5 minutes.
The extract was filtered through a No. 2 two-ply paper filter and the filtrate was
lyophilized. Catechins content: total catechin 21.3% by weight of which non-epi-catechins
contetnt is 2.1% by weight.
Green tea extract
Ion exchanged water was added to green tea leaves, followed
by extraction at a water/leaves ratio by weight of 25 at 70°C for 5 minutes.
The extract was filtered through a No. 2 two-ply paper filter and the filtrate was
lyophilized. Catechins content: total catechin 30.2% by weight of which non-epi-catechins
content is 1.03% by weight.
(3) Water-soluble polymer
Water-soluble polymer A
Ion exchanged hot water was added to natural tea leaves,
followed by extraction at a water/leaves ratio by weight of 25 at 90°C for
5 minutes. The extract was filtered through a No. 2 two-ply paper filter and the
filtrate was lyophilized to obtain a solid substance. 500 mL of a 20% aqueous solution
No. 2 two-ply paper filter and the filtrate was lyophilized to obtain a solid substance.
500 mL of a 20% aqueous solution of the resulting solid substance was added dropwise
to 2L of 95% ethanol under stirring. After completion of the dropwise addition,
stirring was continued for 30 minutes. The reaction mixture was allowed to stand
and then the supernatant was removed. After addition of 1L of 95% ethanol to the
residue and stirring, the mixture was allowed to stand and then, the supernatant
was removed. This procedure was repeated three times. Through a No. 2 two-ply filter
paper, the residue was filtered and a solid remaining on the filter paper was collected.
It was dried at 50°C, whereby a dry product was obtained. In accordance with
the method as described in Journal of Japanese Society of Nutrition and Food Science,
46(3), 244(1993), 3 g of the dry product was treated with an enzyme and reprecipitated,
the precipitate was filtered through a No. 2 filter paper and the solid content
on the filter paper was designated as the amount of water-soluble polymer A.
Water-soluble polymer B
After addition of ion-exchanged hot water to natural tea
leaves and extraction of the resulting mixture at a water/leaves ratio by weight
of 25 at 90°C for 5 minutes, the extract was filtered through a No. 2 two-ply
filter paper. The filtrate was lyophilized, whereby a solid substance was obtained.
A 2.0 g portion of the solid substance was charged in a beaker and dissolved with
150 ml of a phosphate buffer. The phosphate buffer was obtained by dissolving 48
g of sodium dihydrogenphosphate, 20 g of ascorbic acid and 1 g of EDTA2Na in 1L
of water and then adjusting the pH of the resulting solution to 3.9 with sodium
hydroxide. The resulting solution of the sample was centrifuged at 3000 rpm/min
for 15 minutes at 4°C. After removal of the precipitate, the residue was transferred
to a dropping funnel. Extraction was conducted three times with 450 mL of mixture
was allowed to stand still for at least 24 hours. Under a nitrogen atmosphere, the
resulting aqueous phase was distilled to completely remove the solvent. The aqueous
phase was dialyzed through a membrane ("Dialysis Membrane 27", product of Wako Pure
Chemical Industries) for 6 days. Lyophilization was conducted after completion of
the dialysis, whereby water-soluble polymer B was obtained.
To 800 g of ion-exchanged water, the dried tea extract
and commercially-available catechin preparation B were added in predetermined amounts
as shown in Table 1, followed by the addition of the water-soluble polymer, and
polytextrose in an amount as shown in Table 1. They were dissolved uniformly. After
addition of 0.3 g of sodium ascorbate, an adequate amount of a 5 % aqueous sodium
bicarbonate solution was added to adjust the mixture to pH 6.2. Ion-exchanged hot
water was further added to give the total amount of 1000 g.
Examples 2 to 9 and comparative examples 1 to 4 Following
the procedures as described in Example 1 except by using the individual components
as shown in Table 1 in the amounts as shown in Table 1, further beverages were obtained.
The taste of the beverages was evaluated by a panel of
4 experts in accordance with the following method.
Since bitterness and astringency of the beverage came from
a plurality of components or components of different dissolution states, evaluation
was made in three stages, that is, immediately after putting it in mouth (initial
stage of drinking), having it in their mouth for several seconds (middle stage of
drinking) and immediately after swallowing (latter stage of drinking).
Evaluation was made based on the following criteria:
- [6+]: pungent with severe bitterness and astringency
- [5+]: having severe bitterness and astringency
- [4+]: having strong bitterness and astringency
- [3+]: having bitterness and astringency
- [2+]: having a little strong bitterness and astringency
- [1+]: having slight bitterness and astringency
Beverages of Comparative Examples 1 to 4 were not suited
for customary drinking because their bitterness level was 3+ or greater, while those
of Examples 1 to 9 were suited for customary drinking because they had weak bitterness
and astringency and smooth throat-feel upon drinking.
The beverages of the present invention contain a high concentration
of catechins, and at the same time, have improved taste with alleviated bitterness
and astringency and have smooth throat-feel upon drinking.