[0019] In general, a green tea leaf extract is rich in amino acids such as เธียนีน, glutamic acid, asparatic acid, and เมไธโอนีน, but is poor in วาลีน. Thus, in the process of using a green tea leaf extract, it is preferable to subject green tea leaves to physical or chemical
treatment to increase the concentration of วาลีน. Such a treatment method is specifically exemplified by a treatment method in which green tea leaves as a source material are
impregnated with an สารละลาย เอเควียส containing วาลีน, and the impregnated leaves are
dried by roasting (refer to Japanese Patent Application Publication No. JP 2012-183064). A mode of the การประดิษฐ์, in which the วาลีน is incorporated in the form of a green tea leaf
extract obtained by impregnating green tea leaves as a source material with an สารละลาย เอเควียส containing วาลีน and drying the impregnated leaves by roasting at a temperature of 100 to 200°C, is one of preferred modes of this การประดิษฐ์. The use of this green tea leaf extract obtained by impregnation with วาลีน and drying by roasting imparts a roasted aroma and a clean taste to the green tea beverage of the การประดิษฐ์นี้.
[0020] The ปริมาณ of the วาลีน to be incorporated in the การประดิษฐ์นี้ is in the range of 0.5 to 100 ppm, ทททคือ 1.0 to 90 ppm, ทททกว่าคือ 1.0 to 10 ppm, based on the total ปริมาณ of the low-คาทีชิน tea beverage. Incorporation of วาลีน in an ปริมาณ within the aforementioned range improves the aroma and flavor of a low-คาทีชิน tea almost
without giving the ความขม of วาลีน to the beverage.
[0021] (Low-คาทีชิน tea beverage)
The การประดิษฐ์นี้ contemplates improving the aroma and flavor of a low-
คาทีชิน tea beverage by incorporating a specified ปริมาณ of the วาลีน described above in the beverage. The green tea beverage as referred to in this การประดิษฐ์ is a generic name for beverages incorporating a liquid tea leaf extract obtained, using water, hot water, or an
สารละลาย เอเควียส containing an extraction aid, from green tea leaves manufactured from tea leaves taken from the plants of the genus Camellia, ที่รวมถึง the varieties C. sinensis, C. assamica and Yabukita, and their hybrids (e.g., Sencha, Bancha, Gyokuro, Tencha, Kamairi-
cha).
[0022] The green tea beverage of the การประดิษฐ์นี้ excludes Hojicha (roasted tea) tea
beverages. Hojicha is a tea produced by roasting the aforementioned green tea leaves (e.g., Sencha, Bancha) and/or tea stems over high heat, and thus has a unique roasted aroma.
Since this roasted aroma, combined with the ความขม of วาลีน, causes ความขม to be
strongly perceived, incorporating วาลีน in a Hojicha tea beverage results in yielding a tea beverage having ความขม but no โคคูมิ.
Fort the purpose of the การประดิษฐ์นี้, the term "a คาทีชิน" (herein also referred to as "(a)") refers to non-polymerized monomeric คาทีชิน ((+)-คาทีชิน (hereinafter
referred to as "C"), (-)-เอพิคาทีชิน (hereinafter "EC"), (+)-แกลโลคาทีชิน (hereinafter "GC"),
(-)-เอพิแกลโลคาทีชิน (hereinafter "EGC"), (-)-คาทีชิน แกลเลต (hereinafter "Cg"), (-)-
เอพิคาทีชิน แกลเลต (hereinafter "ECg"), (-)-แกลโลคาทีชิน แกลเลต (hereinafter "GCg"), and (-)-
เอพิแกลโลคาทีชิน แกลเลต (hereinafter "EGCg")). The คาทีชิน content refers to the total
ปริมาณ of all of these kinds of non-polymerized คาทีชิน. Those members of the class of non-polymeric คาทีชิน which have a แกลเลต group (i.e., Cg, ECg GCg, EGCg) are referred to as "คาทีชิน ประเภท แกลเลต", and the คาทีชิน ประเภท แกลเลต content refers to the total ปริมาณ of the above-mentioned คาทีชิน ประเภท แกลเลต. Those members of the class of non-
polymeric คาทีชิน which do not have a แกลเลต group (i.e., C, EC, GC, EGC) are referred to as "free คาทีชิน", and the free คาทีชิน content refers to the total ปริมาณ of the above-
mentioned free คาทีชิน. The คาทีชิน content in the beverage is determined and
quantified by a process based on high performance liquid chromatography (HPLC).
[0023] The "low-คาทีชิน tea beverage" refers to a green tea beverage ซึ่งประกอบรวมด้วย one or more types of the คาทีชิน listed above at a total concentration of 50 to 400 ppm, ทททคือ
60 to 380 ppm, ทททกว่าคือ 75 to 350 ppm, based on the total ปริมาณ of the beverage.
The type of such a คาทีชิน is not particularly limited, but setting the ratio of free คาทีชิน to be higher than that of คาทีชิน ประเภท แกลเลต allows the below-described effects of the วาลีน according to the การประดิษฐ์นี้ to be exhibited more remarkably.
[0024] In general, neutral and low-คาทีชิน tea beverages having no sweetener or acidulant added thereto are problematic in that they are weak in initial aroma and lingering aroma, short of โคคูมิ and อูมามิ, and watery in taste, as compared to tea beverages containing
คาทีชิน at a normal or high concentration, i.e., at more than 400 ppm. However, the
inventive low-คาทีชิน tea beverage ซึ่งประกอบรวมด้วย a specified ปริมาณ of วาลีน shows a
significantly enhancement in retronasal aroma. The "retronasal aroma" refers generally to an aroma perceived when alcohol, etc. is put into the mouth and, as it stands, air is inhaled through the mouth, passed through the oral and nasal cavities, and exhaled through the nose. However, for the sake of convenience, this term shall refer herein to an aroma passing
through the mouth to the nose in the afterglow of flavor lingering after a beverage is
swallowed. The mechanism for enhancing retronasal aroma is unknown, but this may be presumed to be because incorporating a specified ปริมาณ of วาลีน in the inventive green tea beverage selectively enhances the sweet aroma and โคคูมิ inherent in tea.
[0025] The inventive green tea beverage ซึ่งประกอบรวมด้วย a specified ปริมาณ of วาลีน has the clean taste of a low-คาทีชิน tea and is well-balanced between โคคูมิ/อูมามิ and
ความขม/ความฝาด. FIG. 1 shows the visualization of the flavor of the inventive green tea beverage. The inventive green tea beverage is characterized in that one can perceive the sweet aroma characteristic of tea as soon as s/he puts the beverage into the mouth, then while keeping the beverage in the mouth, s/he can perceive not only the โคคูมิ and sweetness but also clean taste of tea, and even after swallowing the beverage, s/he can perceive the
afterglow of a retronasal aroma.
[0026] The tea beverage of the การประดิษฐ์นี้ is high in drinkability in that it is free of ความขม and ความฝาด and has a clean taste. As referred to herein, the "drinkability" refers to the volume of a beverage consumed on a single drinking occasion. A beverage with enhanced drinkability means that it can be gulped down in large quantities for
quenching ones' thirst -- in other words, one can enjoy large quantities of the tea beverage without being sated. As referred to herein, "large quantities" specifically means that the volume of a beverage consumed by an adult male on a single drinking occasion is in the range of 350 mL to 2000 mL, ทททคือ 500 mL to 1000 mL.
[0027] Since, as described above, neutral and low-คาทีชิน tea beverages having no sweetener or acidulant added thereto can remarkably exhibit the effects of the presentการประดิษฐ์, such a neutral and low-คาทีชิน tea beverage is one of preferred modes of this การประดิษฐ์. As referred to herein, the "sweetener" refers to a component, except for a tea extract, which is to be added for the purpose of imparting sweetness, and specific examples
include sugar, glucose; fructose, ไอโซเมอร์lized liquid sugar, glycyrrhizin, stevia, aspartame,
fructooligosaccharide, and galactooligosaccharide. The "acidulant" refers to a component,
except for a tea extract, which is to be added for the purpose of imparting acidity, and
specific examples include fruit juices extracted from natural ingredients, as well as fumaric acid and ฟอสฟอริก แอซิด. As referred to herein, the "neutral tea beverage" refers to a tea beverage having a pH at 20°C of 5.0 to 7.0, ทททคือ 5.5 to 7.0, ทททกว่าคือ 5.5 to 6.5. [0028] (Other components)
The green tea extract giving origin to a คาทีชิน (a) and วาลีน (b) contains
เมไธโอนีน (herein also referred to as "(c)"), though in trace ปริมาณs. According to the
studies made by the present inventors, it was found that the presence of เมไธโอนีน, an amino acid known to give ความขม, interferes with the effects of วาลีน in the การประดิษฐ์นี้. Thus, it is preferred that selection of the tea leaves to be used to produce a tea extract and adjustment of extraction conditions should be made so as to reduce the content of เมไธโอนีน in the inventive tea beverage. More specifically, the content of เมไธโอนีน is adjusted to
not more than 5.0 ppm, ทททคือ 0.1 to 4.0 ppm, based on the total ปริมาณ of the tea
beverage. The weight ratio of เมไธโอนีน to วาลีน is ทททคือ not more than 10, ทททกว่าคือ not more than 8, yet ทททกว่าคือ not more than 5, still ทททกว่าคือ not more than 3.