AU2023258713A1 - BLACK COFFEE BEVERAGE CONTAINING γ-AMINOBUTYRIC ACID - Google Patents

Abstract

Provided is a black coffee beverage in a neutral range with improved flavor. A black coffee beverage having a pH of 6.0-7.5 is made to contain γ-aminobutyric acid to yield a concentration of 60-800 mg/kg.

Description

DESCRIPTION

BLACK COFFEE BEVERAGE CONTAINING y-AMINOBUTYRIC ACID

TECHNICAL FIELD

[0001] The present invention relates to a black coffee beverage having a pH of 6.0 to 7.5.

BACKGROUND ART

[0002] Coffee beverages are highly palatable, and have been widely and habitually drunk

all over the world. Coffee beverages are provided to consumers in various forms, for

example, not only in forms directly provided at home or at restaurants (so-called regular

coffee) but also in the form of packaged RTD (ready to drink) coffee beverages at retail

stores or vending machines.

[0003] In general, regular coffee has pH of around 5 that is weakly acidic, and some types

thereof have a pH of less than 5. The pH of powdery coffee diluted with predetermined hot

water or water (so-called instant coffee) is also around 5. The sourness of coffee exhibits

the fruitiness derived from coffee fruits, and is one of the attractions of coffee that leads to

the freshness and the sharpness. Meanwhile, pH adjustors such as baking soda (sodium

hydrogen carbonate) are usually added to packaged black coffee beverages to adjust pH to

5.5 or more, preferably 6.0 or more in a neutral range, to suppress a decrease in the pHs of

the beverages accompanying the heat-sterilization or the long-time storage while the

beverages are warmed. This causes problems that not only a faint sharp sourness that

regular coffee has is lost, but also the saltiness, the sliminess, and the like derived from the

pH adjustor occur, and a coffee aroma is weakened. Accordingly, various packaged black

coffee beverages of which pH is adjusted to around 5.5 in a weakly acidic range so that the

pH is made as approximate to the pH of regular coffee as possible have been proposed.

Examples include a weakly acidic black coffee beverage with a pH of 4.6 to 6.0 to which a

very minute amount of sodium chloride is added (PTL 1) and a black coffee beverage with a pH of 5.3 to 5.7 reduced in the used amount of a pH adjustor using basic amino acids such as histidine and arginine (PTL 2).

[0004] Meanwhile, it has been reported thaty-aminobutyric acid (hereinafter abbreviated as

"GABA") participates in the sense of taste. For example, it has been reported that when

GABA was added to 0.01% acetic acid solution, the sourness was increased as compared

with the solution to which GABA was not added and that the strengths of the sourness in

citric acid solutions at 0.01% and 0.05% were not changed depending on whether GABA was

added to (NPL 1). It has been reported that GABA can be added to food and drinks such as

chocolate containing a raw material derived from cacao to improve the taste qualities of the

bitterness and the sourness (PTL 3). However, it has not been reported about the

improvement in the flavor of a coffee beverage, especially in a black coffee beverage having

a pH in a neutral range.

CITATION LIST PATENT LITERATURE

[0005]

PTL 1: JP 2012-100619 A

PTL 2: JP 2011-101625 A

PTL 3: JP 2007-6853 A

NON PATENT LITERATURE

[0006]

NPL 1: Mimasaka Daigaku/ Mimasaka Daigaku Tankidaigakubu Kiyo (Mimasaka

University/ Mimasaka University Junior College Department Bulletin), Vol.56, 9-14, 2011

SUMMARY OF THE INVENTION TECHNICAL PROBLEM

[0007] For packaged black coffee beverages to be stored for a long time at normal temperature or warmed condition, it is desired that their pH is adjusted to a neutral range if possible, from the viewpoint of the quality stability during storage. A problem is however that if the pH is adjusted to the neutral range, a satisfactory coffee flavor is reduced as described above. An object of the present invention is to provide a black coffee beverage having an improved flavor and a pH in a neutral range.

SOLUTION TO PROBLEM

[0008] The present inventors have earnestly examined to achieve the above-mentioned

object, consequently found that the incorporation of y-aminobutyric acid in a specified

amount can impart sourness peculiar to a coffee beverage to a black coffee beverage having a

pH in a neutral range, and the black coffee beverage having an improved flavor and having a

pH in a neutral range can be provided, and completed the present invention.

[0009] The present invention includes, but not limited to, the following aspects.

[1] A black coffee beverage, containing y-aminobutyric acid at 60 to 800 mg/kg and having a pH of 6.0 to 7.5.

[2] The black coffee beverage according to [1], wherein a content of furfuryl acetate is

2.0 pg/kg or more.

[3] The black coffee beverage according to [1] or [2], wherein the beverage is a

packaged beverage.

ADVANTAGEOUS EFFECTS OF INVENTION

[0010] The present invention can provide a packaged black coffee beverage having a

satisfactory flavor, even though the beverage has a pH of 6.0 or more in a neutral range.

DESCRIPTION OF EMBODIMENTS

[0011] (Black coffee beverage)

The present invention solves a problem caused by adjusting the pH of regular coffee

that has an acidic liquid property to a neutral range to package the coffee. The targets of the present invention are black coffee beverages having a pH in a neutral range. The black coffee beverage as used herein refers to a coffee beverage containing no dairy products.

Although, in general, milk-containing coffee beverages also have a liquid property in a

neutral range, a faint sharp sourness is not emphasized in milk-containing coffee beverages

unlike black coffee beverages, and milk-containing coffee beverages are not therefore

targeted. The black coffee beverage may be of a sugar-free type to which no sugar is added,

or may be of a sugared type, containing sugars. The degree of sweetness is preferably 1 or

less, and further preferably no sugars are added from the viewpoint of enjoying the effect of

the present invention more. The degree of sweetness as used herein is an index indicating

the strength of sweetness, and is the relative ratio of the sweetness to the sweetness of 1% by

mass sucrose (200C) defined as 1. The amounts (concentrations by mass) of the sweetness

components contained in the beverage are converted into sucrose equivalent amounts based

on the relative ratios of the sweetnesses of the sweetness components to the sweetness of

sucrose defined as 1, and the sucrose equivalent amounts of all the sweetness components

contained in the beverage can be subsequently totaled to calculate the degree of sweetness of

the beverage. The relative ratios of the sweetnesses of various sweetness components to the

sweetness of sucrose defined as 1 can be calculated from a well-known sugar sweetness

conversion table (McMurry Organic Chemistry (7th edition) page 988).

[0012] The coffee beverage as used herein is a beverage mainly containing roasted coffee

bean extract. Specifically, the amount of roasted coffee beans contained per 100 g of the

coffee beverage is preferably 1 g or more, more preferably 2.5 g or more, and further

preferably 5 g or more in terms of raw beans. With respect to the raw bean conversion

value, 1 g of roasted coffee beans shall be equivalent to 1.3 g of raw coffee beans (described

in Kaitei-shinpan Soft Drinks (Soft Drinks Revised New Edition), supervised by Japan Soft

Drink Association, published by Korin, December 25, 1989, page 421).

[0013] The type of the coffee beans to be used for the black coffee beverage of the present

invention may be any type. Examples of the cultivated tree species include Arabica species,

Robusta species, and Liberica species. Example of coffees include Mocha coffee, Brazil coffee, Colombia coffee, Guatemala coffee, Blue Mountain coffee, Kona coffee, Mandheling coffee, and Kilimanjaro coffee. The coffees can be used alone or as a blend of two or more.

In the present invention, coffee beans are roasted to produce roasted coffee beans, the roasted

coffee bean is subjected to extraction to provide a roasted coffee bean extract, and the roasted

coffee bean extract is used for the beverage. The coffee bean extract as used herein includes

liquid extract of coffee bean, and powder prepared by drying the liquid extract and pulverized

the dried extract. The coffee bean extract can be produced by an ordinary method. The

method for roasting coffee beans may be any method. The roast temperature and

environment are not limited, and an ordinary method can be adopted. Furthermore, the

method for extraction from the roasted coffee beans may be any method. Examples include

a method involving coarsely, medium, or finely grinding the roasted coffee beans, and

subjecting the obtained ground beans to extraction with water or warmed water (0 to 100°C)

for 10 seconds to 30 minutes. Examples of the extraction method include dripping,

siphoning, boiling, jetting, a continuous style, or the like.

[0014] The neutral range of pH of the black coffee beverage as used herein means that the

pH of the beverage at 20°C is 6.0 or more. The pH is preferably 6.1 or more, more

preferably 6.2 or more, further preferably 6.3 or more, and particularly preferably 6.4 or more,

from the viewpoint of quality stability during storage. The pH is preferably lower from the

viewpoint of a remarkable effect of the present invention. The upper limit of the pH is

therefore around 7.5, preferably 7.3 or less, more preferably 7.0 or less, and further

preferably 6.8 or less. In the present invention, y-aminobutyric acid (hereinafter abbreviated

as "GABA") is added to increase a fruit-like sourness of which the black coffee beverage

having a pH adjusted to this neutral range is likely to be short and that is unique to coffee.

Although the addition of GABA to even a black coffee beverage having a pH of less than

6.0 increases the sourness, it is unpreferable because the sourness is not a fruit-like sourness

unique to coffee but a stimulating strong sourness like acetic acid, and may have an adverse

influence on the flavor.

[0015] ApH adjustor is used for adjusting the pH of the black coffee beverage of the present invention. As long as the pH adjustor is a substance to be dissolved in water to exhibit alkalinity, any pH adjustor may be used. Specific examples include baking soda

(sodium hydrogen carbonate), sodium carbonate, potassium carbonate, sodium hydroxide,

potassium hydroxide, trisodium phosphate, and tripotassium phosphate.

[0016] (y-Aminobutyric acid (GABA))

The present invention improves the flavor of the black coffee beverage having a pH

adjusted to a neutral range by addingy-aminobutyric acid (GABA). The improvement of

the flavor as used in the present invention refers to the action of imparting sourness that is

likely to be short at a pH in the neutral range and is peculiar to coffee beverages, and means

that the flavor becomes a flavor more similar to that of weakly acidic regular coffee,

specifically a taste to which a faint sharp sourness is imparted, than in the case where GABA

is not added.

[0017] GABA is a type of amino acid widely contained in vegetables, fruits, cereals,

fermented food, and the like. The GABA as used for the present invention may be derived

from anything, and for example, GABA extracted from vegetables, fruits, or cereals, GABA

produced by fermentation, or GABA obtained by organic synthesis are usable. It is

preferable to use purified product containing GABA at 80% by mass or more, preferably

% by mass or more, and more preferably 90% by mass or more, from the viewpoint of

minimizing influence on the flavor of the beverage itself. The purified product can be used

in various forms of a solid, an aqueous solution, slurry, and the like. Examples of

commercial purified GABA that include GABA 100% Pure Powder (APLUSVITA, INC.)

and ORYZA GABAR Extract HC-90 (Oryza Oil & Fat Chemical Co., Ltd.).

[0018] In the present invention, GABA is added to the black coffee beverage so that the

concentration of GABA in the beverage is 60 mg/kg or more, preferably 100 mg/kg or more,

further preferably 150 mg/kg or more, and particularly preferably 200 mg/kg or more. The

content of GABA in the beverage is preferably 800 mg/kg or less, more preferably

700 mg/kg or less, and further preferably 600 mg/kg or less. The content of GABA can be

measured with an amino acid analyzer.

[0019] (Other components)

The black coffee beverage of the present invention preferably contains furfuryl

acetate. Furfuryl acetate is a fragrance component known as a ripe fruit-like flavor

component. In the present invention, the addition of GABA imparts or increases a faint

sourness of which the black coffee beverage having a pH adjusted to a neutral range is likely

to be short. It has been found that if the coffee beverage contains furfuryl acetate in a

specified amount, a sourness that is imparted/increased by GABA and is peculiar to the

coffee beverage is further felt as a fruit-like natural sourness unique to coffee. The furfuryl

acetate content in the black coffee beverage of the present invention is preferably 2.0 pg/kg

or more, more preferably 5.0 pg/kg or more, further preferably 7.0 pg/kg or more, and

particularly preferably 10 pg/kg or more. The upper limit of the furfuryl acetate content is

preferably 200 pg/kg or less and more preferably 100 pg/kg or less. The furfuryl acetate

content can be quantified by gas chromatography-mass spectrometry (GC/MS analysis

method). The furfuryl acetate may be added as a component derived from coffee beans

(coffee bean extract, ground coffee beans, and the like) or as a flavoring component.

[0020] As described above, the beverage of the present invention contains roasted coffee

bean extract, the pH adjustor, and GABA. As long as the beverage departs from the

expected object of the present invention, other components, namely components to be

generally blended into the black coffee beverage, for example, an antioxidant, a quality

stabilizer (an emulsifier, a thickening stabilizer, and the like), flavorings, and sweetness

components such as sugars can be appropriately added.

[0021] (Packagedbeverage)

Since the beverage of the present invention has a pH in the neutral range, the

beverage has a relatively satisfactory quality stability even if the beverage is stored at room

temperature for a long period. Accordingly, the beverage is suitably provided as a packaged

beverage that may be stored for a long term. The packaged beverage refers to a product

wherein a container is filled with the beverage and closed with a lid. As the container, an

ordinary packaging container such as a molded container containing polyethylene terephthalate as the main component (so-called PET bottle); a metal can, a paper carton combined with metal foil or a plastic film; and a bottle can be exemplified.

[0022] Heat sterilization may be performed for storage at room temperature for a long

period. As the conditions for the heat sterilization treatment, for example, a method that can

obtain an effect equivalent to that of conditions stipulated by the Food Sanitation Law in

Japan can be selected. Specifically, the temperature is 60 to 150°C, preferably 90 to 150°C,

and more preferably 110 to 150°C, and times in the ranges of 1 second to 60 minutes,

preferably 1 second to 30 minutes, depending on the temperature can be selected. In more

detail, if a heat-resistant container (a metal can, glass, and the like) is used as the container,

retort sterilization (110 to 140°C, one to several dozen minutes depending on the

temperature) can be performed. If a non-heat-resistant container (a PET bottle, a paper

carton, and the like) is used as the container, for example, a prepared liquid can be subjected

to ultra-high-temperature short-time sterilization (UHT sterilization: 110 to 150C, one to

several dozen seconds depending on the temperature) with a plate heat exchanger beforehand,

cooled to a certain temperature, and then sterilely filled into the non-heat-resistant container.

Since the expected effect of the present invention is remarkably exhibited, the black coffee

beverage heat-sterilized under severe heating conditions at a temperature of more than 100°C

is a particular suitable aspect of the present invention.

[0023] The beverage in the container may have any volume, for example, 150 to 1000 mL,

and preferably around 160 to 600 mL.

(Production method)

The black coffee beverage of the present invention can be produced in the same way

as common black coffee beverages except that GABA is blended as one of the raw materials.

That is, the black coffee beverage is produced by a process including a step of mixing the

roasted coffee bean extract with GABA to prepare a preparation liquid, and a step of blending

a pH adjustor to adjust the pH of the final beverage to 6.0 to 7.5. If the beverage is a

packaged beverage, the process includes a step of filling the coffee preparation liquid into a

container, and a step of heat sterilization. In the process for producing a packaged beverage including the heat sterilization step, the pH is reduced by heat sterilization. The pH of the packaged beverage can be controlled by measuring beforehand how much pH is reduced by heat sterilization, and adjusting the pH of the preparation liquid before the heat sterilization.

In order to obtain the black coffee beverage having a pH of 6.0 to 7.5 after the heat

sterilization, the pH of the preparation liquid before the heat sterilization may be usually

adjusted to around 6.5 to 8.0. The production method preferably includes a step of adjusting

the content of furfuryl acetate in the beverage to 2.0 pg/kg or more.

EXAMPLES

[0024] Hereinafter, details of the present invention will be described specifically by

showing Experiment Examples, but the present invention is not limited thereto. The

numerical ranges as used herein are described as numerical ranges that shall include the end

points thereof unless otherwise specified.

[0025] <Measurement of GABA content>

A sample liquid was collected and centrifuged, and the supernatant thereof was

treated with 0.02 N hydrochloric acid to obtain the treated supernatant. The treated

supernatant was filtered through a cylinder with a 0.45 pm filter, and this was quantified with

a fully automatic amino acid analyzer (available from JEOL Ltd., JLC-500/V) to measure the

GABA content.

[0026] <Measurement of pH>

100 mL of a sample liquid was measured into a 200-mL beaker, the temperature was

adjusted to 20°C, and the pH was measured with a pH meter (available from HORIBA, Ltd.,

HORIBA pH meter F21).

[0027] <Method for analyzing aroma components>

A 20-ml glass bottle with screws (18 mm in diameter, available from GERSTEL

K.K.) was charged with 5 ml of a sample liquid and tightly sealed with a metal lid with a

septum made of PTFE (available from GERSTEL K.K.), and the aroma components were

extracted by solid phase microextraction (SPME). The quantification was performed by the standard addition method using the peak area detected in the EIC mode of GC/MS. The used instruments and the conditions will be shown below.

[0028]

• SPME fiber: StableFlex/SS, 50/30 pm DVB/CAR/PDMS (available from Merck KGaA)

• Fully automatic volatile component extraction/introduction apparatus: MultiPurpose

Sampler MPS2XL (available from GERSTEL K.K.)

• Preliminary warming: at 40°C for 5 minutes

• Stirring: Not stirred

• Volatile component extraction: at 40°C for 30 minutes

• Time for desorbing volatile components: 3 minutes

• GC oven: GC7890A (available from Agilent Technologies, Inc.)

• Column: VF-WAXms, 60 m x 0.25 mm i. d. df= 0.50 pm (available from Agilent

Technologies, Inc.)

• GC temperature conditions: 40°C (5 minutes) -> 5°C/minute -> 260°C (11 minutes)

• Carrier gas: Helium, 1.2 ml/minute, constant flow rate mode

• Injection: Splitless

• Inlet temperature: 2500 C

• Mass Spectrometer: GC/MS Triple Quad7000 (available from Agilent Technologies, Inc.)

• Ionization method: El (70 eV)

• Measurement method: Scan measurement or Scan and SIM simultaneous measurement

• Scan parameter: m/z: 35 to 350

[0029] Experiment 1 Preparation of GABA-containing black coffee beverage (1)

As the test beverage, a commercial plastic bottled sugar-free black coffee beverage

(type: coffee) (raw materials: coffee (coffee beans (Brazil, Ethiopia, and others))/flavoring) is

used. This black coffee beverage had a pH of 5.7, and contained furfuryl acetate at a

content of 20 pg/kg.

[0030] To this beverage was added an aqueous sodium hydroxide solution (100 times

diluted solution) to prepare a black coffee beverage having a pH of 6.4. y-Aminobutyric acid (GABA) (at a purity of 99% or more) was added to this black coffee beverage having a pH in the neutral range so that the contents of GABA were 30 to 800 mg/kg, and

GABA-containing black coffee beverages were prepared. These beverages were sensorily

evaluated for the strength of sourness at a pH of 6.4 using a GABA-free beverage as a control.

Six special panelists evaluated the beverages on the following scale of one to five with the

strength of the sourness of the GABA-free black coffee beverage at a pH of 6.4 (control)

evaluated as 1 point and the strength of the sourness of a black coffee beverage before NaOH

was added (pH: 5.7, GABA content: 0 mg/kg) evaluated as 3 points.

[0031] <Sensory evaluation criteria>

1 point: The sourness is scarcely felt (equivalently to the control).

2 points: The sourness is slightly felt as compared with a control.

3 points: The sourness is moderately felt (equivalently to a commercial beverage)

4 points: The sourness is slightly clearly felt.

5 points: The sourness is strongly felt.

Table 1 shows the evaluation results of the six special panelists a to f. It was

proved that the incorporation of GABA at a content of 60 mg/kg or more increased the

sourness, depending on the GABA content. The quality of the sourness was also evaluated

on a scale of one to two based on the following evaluation criterion:

(+):The sourness is comfortable and satisfactory as a fruity sourness during drinking.

(-):The sourness is uncomfortable and unpleasant during drinking.

If the GABA content was 60 to 600 mg/kg, all the six panelists evaluated the sourness as +

(comfortable sourness). If the GABA content was 800 mg/kg, only one panelist felt

uncomfortable. The above suggested that the upper limit value of GABA was around

800 mg/kg, preferably around 600 mg/kg.

[0032] The strength of the aroma was also evaluated on a scale of one to three on the

following evaluation criteria:

(-): An aroma is weakly felt as compared with that of the control.

(): The strength of the aroma is the same as (equivalent to) that of the control.

(+):The aroma is strong as compared with that of the control.

If the GABA content was 60 to 800 mg/kg, all the six panelists evaluated the strength as±.

That is, even the incorporation of GABA did not change the aroma.

[0033] [Table 1] Panelist Panelist Panelist Panelist Panelist Panelist GABA content a b c d e f mg/kg (Not added) mg/kg 1 2 2 2 2 2 100 mg/kg 3 3 3 3 2 3 200 mg/kg 3 3 3 3 3 3 600 mg/kg 4 4 4 3 4 4 800 mg/kg 4 5 5 4 5 5

[0034] Experiment 2 Preparation of GABA-containing black coffee beverage (2)

GABA-containing black coffee beverages were prepared in the same way as in

Experiment 1 except that the amount of sodium hydroxide blended was changed to adjust the

pH to 7.3 or 6.2. These beverages were sensorily evaluated for the strength of sourness

using the GABA-free beverage having a pH in the neutral range as a control in the same way

as in Experiment 1.

[0035] Tables 2 and 3 show the results. In all the black coffee beverages having a pH in

the neutral range, the effect of increasing a fruity sourness was able to be confirmed. This

effect of increasing fruity sourness was more remarkable at a pH more approximate to 6.0.

It is considered that, at a pH more approximate to around 6.0, fruity aroma like furfuryl

acetate is more easily perceived, and the sourness is still more strongly perceived in

combination of sourness felt from the aroma and sourness as taste due to GABA.

[0036] [Table 2] pH 7.3 Panelist Panelist Panelist Panelist Panelist Panelist a b c d e f GABA Strength of sourness 2 2 5 2 2 2 content Quality of sourness + + + + +

+ 200 mg/kg Aroma + + + + +

+

[0037] [Table 3]

pH 6.2 Panelist Panelist Panelist Panelist Panelist Panelist a b c d e f GABA Strength of sourness 4 4 4 2 4 4 content Quality of sourness + + + + +

+ 100 mg/kg Aroma + + + + +

+ GABA Strength of sourness 4 4 4 3 4 4 content Quality of sourness + + + + +

+ 200 mg/kg Aroma + + + + +

+

[0038] Experiment 3 Preparation of GABA-containing black coffee beverage (3)

As a test beverage, a commercial canned sugar-free black coffee beverage (type:

coffee) (raw material: coffee (coffee beans (Brazil, Ethiopia. and others))) that was different

from those in Experiments 1 and 2 was used. The pH of this black coffee beverage was 5.8,

and the furfuryl acetate content was 1.5 pg/kg. A GABA-containing black coffee beverage

having a pH of 6.2 was prepared in the same way as in Experiment 2 and sensorily evaluated.

Table 4 shows the results. It was confirmed that the addition of GABA increased the

sourness. In comparison with the beverage prepared in Experiment 2 and having a GABA

content of 200 mg/kg, the effect of increasing the sourness tended to be more strongly

perceived in the beverage in Experiment 2, containing a large amount of furfuryl acetate.

[0039] [Table 4]

pH 6.2 Panelist Panelist Panelist Panelist Panelist Panelist a b c d e f GABA Strength of sourness 4 4 4 3 3 3 content Quality of sourness + + + + + +

200 mg/kg Aroma + + + + + +

[0040] Experiment 4 Preparation of packaged black coffee beverage (1)

Medium roasted coffee beans (place of origin: Guatemala, L value: 20) were ground,

and hot water having 9 times the mass of coffee beans was used for extraction to perform

extraction at 80°C with an extractor. A steaming time of 3 minutes was provided in the

middle of the extraction step. When the mass of extracted hot water collected was around

3 times the mass of the coffee beans, the extraction was finished. After the extraction, the

extract liquid was subjected to centrifugal separation treatment and membrane filtration, and

this was around 3 times diluted to obtain roasted coffee bean extracted liquid having a Brix of

1.2% and a pH of 5.4. y-Aminobutyric acid (GABA) (at a purity of 99% or more) was

added to this roasted coffee bean extracted liquid so that the contents of GABA were 30 to

800 mg/kg. Furfuryl acetate was added, sodium hydrogen carbonate (pH adjustor) was

further added so that the pH was 6.8, and the mixture was well stirred to prepare preparation

liquids. After UHT sterilization at FO = 4 or more, 500-mL plastic bottle containers were

sterilely filled with these preparation liquids to produce black coffee beverages packaged in

the plastic bottles. A black coffee beverage packaged in a plastic bottle was produced as a

control in the same way except that GABA was not added. These black coffee beverages

contained 5.6 g of roasted coffee bean extract in 100 g of the beverages in terms of raw

coffee beans, and had a Brix of 1.2 to 1.3%, a pH of 6.4, and a furfuryl acetate content of

7.5 pg/kg in the beverage.

[0041] Five special panelists sensorily evaluated the obtained plastic bottled black coffee

beverages. The panelists evaluated whether each presented pair of beverages had a

difference in the strength of sourness and which beverage felt sourer if the beverages had the

difference. Table 5 shows the results. More than half of the panelists estimated that the

addition of GABA to the black coffee beverages having a pH in the neutral range (pH 6.4) at

a content of 60 mg/kg or more in the beverage strengthened the sourness. If GABA was

added at 100 mg/kg or more, all the panelists estimated that the sourness was strengthened.

This sourness was similar to a refreshing fruity sourness that the roasted coffee bean

extracted liquid (pH 5.3, pH adjustor-free) had. If the GABA content in the beverage was

800 mg/kg, one panelist estimated the sourness was strange and different from a fruity

sourness, it was therefore suggested that the upper limit of the GABA content was preferably

around 800 mg/kg. Many panelists estimated that an increase in sourness improved a poor

sharpness of the aftertaste (poor saltiness and poor sliminess) due to the pH adjustor.

[0042] [Table 5]

Evaluation (of sourness) Number of those who The number of those who Number of those who GABA content estimated that there was estimated that the control estimated that no difference from the GABA-containing control wassourer product was sourer mg/kg (Not added) mg/kg 4 0 1 mg/kg 2 0 3 100 mg/kg 0 0 5 200 mg/kg 0 0 5 600 mg/kg 0 0 5

[0043] Experiment 5 Preparation of packaged black coffee beverage (2)

Medium roasted coffee beans (place of origin: Ethiopia, L value: 18) were ground

and fed into an extractor, and hot water at 98°C was sprayed for extraction. The extracted

liquid was rapidly cooled to around 20°C to obtain roasted coffee bean extracted liquid

having a Brix of 1.4% and a pH of 5.2. To this roasted coffee bean extracted liquid was

added the finely ground roasted coffee beans at a concentration of 10 g/kg. y-Aminobutyric

acid (GABA) was further added so that the content of GABA was 300 mg/kg. Sodium

hydrogen carbonate (pH adjustor) was added so that the pH was 7.0. The mixture was well

stirred to prepare a preparation liquid. This preparation liquid was filled into a 190-ml can,

air in the headspace was substituted with nitrogen gas, and the can was immediately sealed.

The prepared liquid was heat-sterilized at 115°C for 20 minutes and cooled to produce a

black coffee beverage packaged in the can. As a control, a black coffee beverage packaged

in a can was produced in the same way except that GABA was not added. These black

coffee beverages contained furfuryl acetate at a concentration of 75 pg/kg, and had a Brix of

1.4% and a pH of 6.8. The obtained canned black coffee beverages were sensorily

evaluated in the same way as in Experiment 4. Table 6 shows the results. All the panelists

estimated that the incorporation of GABA increased a refreshing sourness peculiar to coffee.

[0044] [Table 6] Evaluation (of sourness) Number of those who The number of those Number of those who estimated that there was who estimated that the estimated that GABA content no difference from the control was sourer GABA-containing control product was sourer mg/kg (Not added) 300 mg/kg 0 0 5

Claims (3)

1. A black coffee beverage, comprising y-aminobutyric acid at 60 to 800 mg/kg and

having a pH of 6.0 to 7.5.

2. The black coffee beverage according to claim 1, wherein a content of furfuryl

acetate is 2.0 pg/kg or more.

3. The black coffee beverage according to claim 1 or 2, wherein the beverage is a

packaged beverage.