Yonago Acta medica 2008;51:61–67

Elements and Physical Properties of Green Tea Decoction
using Hakusan-Meisui Mineral Water
Daisuke Houri, Shin-ichi Yoshioka*, Kenji Matsumoto†, Kunihiko Amikawa‡, Satoru
Tanaka‡ and Naoki Nagata‡
Division of Medical Environmentology, Department of Social Medicine, School of Medicine and*Department of Nursing Care Environment and Mental Health, School of Health Science, Tottori
University Faculty of Medicine, Yonago 683-8503, †Department of Regional Environment, Facultyof Regional Sciences, Tottori University, Tottori 680-8551 and ‡Tottori Health Service Association,
Tottori 680-0061 Japan

It has been said that when green tea is made using mineral water, the color is thicker
than when made with tap water, and the smell and taste are of a higher quality. This
study aimed i) to confirm whether there was a difference in the decoction elements bycomparing green tea made with Hakusan-Meisui mineral water and purified water, andii) to examine the preservation of the decoctions in terms of their quality retention effect.
The study found that when green tea was made using Hakusan-Meisui, a larger amountof nutritional content and inorganic qualities were extracted from the exudate whencompared with pure water. However, the quantity of vitamin C with Hakusan-Meisui
was lower than that of purified water. In addition, the amounts of vitamin C in decoctions using both cold and hot water were also lower. The color and turbidity of green
tea exudate made using Hakusan-Meisui by heating were higher than those of purewater, and the color was stronger. Though no changes were seen over time in pH, thenumber of bacteria or precipitation of either Hakusan-Meisui or pure water, the color,
turbidity and oxidation-reduction potential showed an uptrend in the heated green tea
decoction. In contrast to pure water, Hakusan-Meisui did not give off any rotten odor
or astringency after being preserved for 5 days, and the effect of its quality maintenancewas confirmed through a sensory evaluation of the decoction. The results of this study
indicated that when green tea is made using Hakusan-Meisui, the color is stronger thanwhen made with pure water, and the smell and taste are of a higher quality, as is generally said to be the case with mineral water.
Key words: decoction; dissolved oxygen; green tea; Hakusan-Meisui; oxidation-reduction potential

Since ancient times, green tea has been an indispensable part of Japanese traditional food culture. Nowadays, scientists recognize the utility
for living beings of green tea elements such as
catechins and polyphenol, and the effect of green
tea on health enhancement and disease preven-tion is increasingly attracting attention (Cabrera
et al., 2006; Khan and Mukhtar, 2007). Criticalfactors for tea include the drinking situation, elements of the decoction and a thorough tone studyof the taste and smell. These influence the flavor
directly and therefore the quality.

Abbreviations: EC, electrical conductivity; ORP, oxidation-reduction potential

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D. Houri et al.

Table 1. Method of analysis
Ingredientsrified water or Hakusan-Meisui. This paper also
reports on a preservation examination of green tea
exudate from purified water and Hakusan-Meisui
for a short term, and presents a comparative studyof the effects of quality maintenance.

Method of analysis

Water
Ordinary pressure ustulation method
ProteinKel Dahl nitrogen assay
Lipid
Acidolysis method
Carbohydrates 100 − (water + protein + lipid + ash)*
Ash
Direct ashing method
Mineral matter Ashing/ICP analysis method
Vitamin C
2,4-dinitrohydrazine method

Materials and Methods* ( ), percentages of water, protein, lipid and ash.
ICP, inductively coupled plasma.

Analysis sample
A sample of Hakusan-Meisui was collected on
January 7, 2005 (7:15 AM) from the water intake source (Kurauchi, Kurayoshi, Japan). It wasplaced in 1.5-L plastic bottles (5 bottles) and 5-L
polyethylene containers (2 pieces), then taken backto Tottori Health Service Association (Tottori, Japan) and analyzed.

However, the decoction of green tea changes tobrown over time, and this creates a problem forpreservation. It has been reported that autoxidation of catechin is promoted in a basic stronger
amino-acid although the pigmentation material isgenerated in the catechin, the green tea element,by oxidizing and polymerizing (Nakagawa, 1969).
In addition, it has been reported that discoloration
occurs in the decoction of tea according to thetemperature and moisture content when percolating, and that the enzyme contained in the tea
decoction exerts a great influence (Fukatsu et al.,1969).
Hakusan-Meisui is a famous type of mineralwater in the Daisen area of Japan, and is marketed as bottled drinking water. Hakusan-Meisui
is known as a mineral water with a low oxidationreduction potential (ORP) value. When used tomake green tea, the colors are stronger than thoseof regular water, and it is known to be excellent inquality as well as in smell and taste (Fujita, 2004).
We previously measured the mineral balance ofmineral water in 5 places in the Daisen region(Houri and Yoshioka, 2004), including HakusanMeisui, utlilizing the delicious water index andhealthy water index advocated by Hashimoto etal. (1985). In terms of results (delicious water index ≥ 2.1 and healthy water index ≥ 5.2), it can bereported for water classification that only Hakusan-Meisui was found to be delicious and healthy.
Green tea was also examined as to whether it differed in terms of nutritional content and physicalproperties when made from a decoction using pu-

Green tea decoction
Green tea was prepared based on the method
given in the supplementary note of the “Four Correction Food Composition Table (2000)” (Kagawa
Nutrition University Publishing Division, 2000).
In other words, 2 packs of green tea (5.7 g of tea
and 0.4-g pack of Japanese paper) were transferred to a beaker containing 430 mL of Hakusan-Meisui boiled to 90˚C which was then stirred
slowly, and left sitting for 1 min. The filtrate wasmade into a decoction. As a contrast, a similar
operation was carried out to obtain a decoctionof purified water (city water refined by the membrane filtration method, specific resistant value =1–10 MΩ•cm). In the same way, green tea decoctions using cold water were obtained and adjusted
using Hakusan-Meisui and purified water at 15˚C,left sitting for 30 min. Finally, to reconfirm theresults of the experiment, a similar operation was
carried out using Hakusan-Meisui and purified
water twice each, and the resulting decoctions
were adjusted.

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Hakusan-Meisui mineral water

Table 2. Comparison of nourishment ingredient of green tea of medium quality exudate by HakusanMeisui and pure water
Classification ofgreen tea*

Water Protein Protein Carbohydrates Ash
(g)
(g)
(g)
(g)
(g)

Mineral matter (mg)
Na
K
Fe
Ca

P

Vitamin C(mg)

Hakusan-Meisui†
Pure water†
Quantity ofingredient ratio‡

99.69
99.74

0.05
0.04

0
0

0.23
0.2

0.03
0.02

0.3
0.2

9.4
5.8

0.08
0.06

3.3
1.2

0.8
0.7

0.7
1.1

0.999

1.25

0

1.15

1.50

1.50 1.62

1.33

2.75 1.14

0.64* Green tea of medium quality exudate (90˚C, 1 min)† Each component is expressed as weight included per 100 g decoction.
‡ Ratio of Hakusan-Meisui when the assumed quantity of pure water exudate is 1.

immediately after cooling, 1 day later, 2 days laterand 5 days later. For the initial setting, the mouthof the stopper-equipped measuring cylinder containing the decoction was assumed to have been
open for 1 h, and preserved in a thermostatic bathset to 20˚C. In addition, the decoction was shaken
to a froth for a few seconds, then left sitting andobserved. The taste evaluation of the green tea
percolation liquid was carried out by 5 laboratory
technicians (3 men and 2 women).

Items, method and instruments used in theanalysis
Nutritional content analysis of the decoction
Moisture, proteins, lipids, carbohydrates, inorganic qualities (sodium, potassium, calcium, iron andphosphorus) and vitamin C (ascorbic acid) of eachexudate were analyzed by the method determinedin the Food Hygiene Inspection Indicators (Japan
Food Hygiene Association, 2005) (Table 1). The
amounts of vitamin C in the green tea decoctions
using cold water and hot water of both HakusanMeisui and purified water were obtained andcompared.

Results
Nutritional content analysis of the decoctions

Physical properties of Hakusan-Meisui and purified water
Both Hakusan-Meisui and pure water (200 mLeach) were put in 200 mL measuring cylinders
equipped with stoppers. For both of these, pH,dissolved oxygen, electrical conductivity (EC) and
ORP were measured i) before heating, ii) during
heating at 90˚C, iii) 1 min after being heated, iv)
2 h after being heated and v) 5 h after.

When green tea was made using Hakusan-Meisui,its degree of nutrition and inorganic exudate element were found to be greater than those for purewater for all items except vitamin C (Table 2).

Table 3. Quantity of vitamin C of medium quality green tea exudates with cold water andheated water (mg/100 g)

Physical properties of the decoction and changes in sensory evaluation over time
The exudates were left to sit until room temperature, and then 200 mL of each was put in a measuring cylinder equipped with a stopper. This wasthen heated for 1 min at 90˚C. Evaluations of pH,
taste, ORP, number of bacteria, color, turbidity
and the presence of precipitation were carried out

Cold water

Heated water Exudation
ratio†(15˚C, 30 min) (90˚C, 1 min)

Hakusan-Meisui
Pure water
Quantity ofingredient ratio*

2.0
2.4

0.7
1.1

0.83

0.64

0.35
0.46

* Ratio of Hakusan-Meisui when the assumed quantity ofpure water exudate is 1.
† Vitamin C of exudates with heated water/with cold water.

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D. Houri et al.

Table 4. Properties of matter change of Hakusan-Meisui and pure water by heating
Item
		
pH		
		
Dissolved oxygen (mg/L)
		EC(µs/cm)
		
ORP
(mV)
		

SampleHakusan-Meisui
Pure water
Hakusan-Meisui
Pure water
Hakusan-Meisui
Pure water
Hakusan-Meisui
Pure water

Before 		 After heating for 1 min at 90˚Cheating
Immediately after After 2 h
After 5 h
8.3 (10˚C)
6.1 (18˚C)
1.6
10
193
4.0
–164
62

8.3 (23˚C)
6.1 (22˚C)
4.4
5.8
194
5.7
62
150

8.3 (22˚C)
6.1 (22˚C)
5.4
6.6
199
2.6
105
144

8.3 (20˚C)
6.2 (20˚C)
5.7
6.6
194
2.6
108
160

EC, electrical conductivity; ORP, oxidation-reduction potential.

Table 5. Properties of matter change of medium quality green tea exudate of Hakusan-Meisui andpure water by heating
Item

pH		
		
Color
(degree)		
Turbidity(degree)
		
ORP
(mV)
		
Presence of sediment				
General bacteria (cfu/mL)		Classification of		
After heating for 1 min at 90˚Cmedium quality
Immediately after After 1 day
After 2 days
green tea exudate
Hakusan-Meisui
Pure water
Hakusan-Meisui
Pure water
Hakusan-Meisui
Pure water
Hakusan-Meisui
Pure water
Hakusan-Meisui
Pure water
Hakusan-Meisui
Pure water

6.7 (20˚C)
5.7 (20˚C)
1200
770
48
47
38
75
None
None
0
2

6.7 (22˚C)
5.7 (22˚C)
1500
820
87
40
47
71
None
None
0
1

6.6 (21˚C)
5.7 (21˚C)
1400
760
86
35
54
96
None
None
0
1

After 5 days
6.3 (20˚C)
6.1 (21˚C)
1600
860
91
84
85
70
None
None
0
1

ORP, oxidation-reduction potential.

When compared with purified water, the amountof vitamin C of the Hakusan-Meisui decoction
made with both cold and hot water was low, registering at 0.83 (for cold water) and 0.64 (for hot
water) (Table 3). The proportion of vitamin C
content in the hot water decoction compared tothe cold water decoction was 0.35 for HakusanMeisui, and 0.46 for purified water.

(Table 4). On the other hand, pure water did notshow any change after heating for pH, while thevalues of dissolved oxygen and EC fell, and thevalue of ORP rose.
Changes over time of decoctions using
Hakusan-Meisui and purified water
There were virtually no changes over time in bacteria, pH or precipitate in the green tea decoctions
made with either Hakusan-Meisui or purified water. However, for green tea made with HakusanMeisui, the color, turbidity and ORP showed an
uptrend (Table 5). Furthermore, when the decoction was shaken to frothing for a few seconds,

Physical properties of Hakusan-Meisui andpure water after heat-treatment
The values of pH and EC of Hakusan-Meisui after heating showed almost no change. However,the values of dissolved oxygen and ORP rose64Hakusan-Meisui mineral water

Table 6. Sensory evaluation of taste by state of preservation of exudate
Item

Classification of Dismedium quality penser
green tea exudate 		After heating for 1 min at 90˚C
Immediately
after

After 1 day

After 2 days

After 5 days

Taste Hakusan-Meisui
1
Taste is thick,
Taste of normal tea Taste of normal tea
			but mellow					2Mellow taste
Taste weaker thanTaste weaker				
the day before
than at first		3
Mellow taste
Taste weaker thanTaste weaker				
the day before
than at first		
4
Thick taste
Thick taste
Thick taste		
5Thick taste
Thick taste
Thick taste

Smell of tea

Pure water
1
Strong bitter taste		
2Strong bitter taste		
3
Bitter taste		
4
Bitter taste
				
		
5
Bitter taste				

Bad smell
Smell of putrescence
Depressing smell
Depressing smell

Slightly bitter taste
Bitter taste
Bitter taste
Taste weaker than
Hakusan-Meisui
Taste weaker than
Hakusan-Meisui

then left sitting, the bubbles in purified water
disappeared after a few seconds. In contrast, for
Hakusan-Meisui, there was a larger amount of theeffervescence and this took a longer time to disappear.
As for the taste of the decoction and sensory
evaluation concerning odor, the taste of HakusanMeisui weakened as time passed from an initial
evaluation of “mellow though thick”, changing toan ordinary smell after 5 days (Table 6). In contrast, pure water had a more astringent taste thanat the beginning. As time passed, the taste andastringency gradually weakened, then changed toa “rotten odor” after 5 days.

Slightly bitter taste
Bitter taste
Bitter taste
Taste weaker than
Hakusan-Meisui
Taste weaker than
Hakusan-Meisui

Smell of roasted tea
Normal smell of tea
Normal smell of tea
Smell of roasted tea

Depressing smell 		

while the color was stronger, as well. In terms of
sensory evaluation, as time passed, the pure water
began tasting bitter and gave off a putrid odor. In
contrast, Hakusan-Meisui was evaluated with a“mellow but thick” taste over 5 days.
When the mineral water was used and extracted, it was found that the dissolving ability
was strong, and that there were differences in
the color and density of the taste (Fujita, 2004).
Moreover, it was determined that mineral water
has an extraction power which draws out the tasteof the ingredient, and that the extracted material
contains a large number of glutamic acids thatseem to be umami elements (Murata, 2004). It
was found that the results obtained in the present
study concerning sensory evaluation and amountof nutritional content confirmed previous reports.
In the article on “tea” in Heibonsha’s “GreatWorld Encyclopedia” (Kawashima, 1981), it statesthat “While it is safe to make tea with soft water,using hard water can slightly improve the taste”.
In analyzing the taste of tea, it is said that there
is a strong relationship between amino acid (asthe taste ingredient) and catechins (as the bitterness element). The taste of the green tea decoction extracted from Hakusan-Meisui was thickDiscussion
In this study, a higher degree of nutritional content and inorganic qualities were found in green
tea exudate extracted using Hakusan-Meisuimineral water when compared with pure water.
The only element which was found to be lower
than pure water was vitamin C. Moreover, thecolor and turbidity of the heated Hakusan-Meisui
exudate were higher than those for pure water,65

D. Houri et al.

and mellow. It was found that, as a mineral water,
Hakusan-Meisui has excellent dissolution andextraction powers which draw out the taste of theingredients.
In this study, changes over time in EC and
ORP were measured for the physical properties ofwater. As for the water, the greater the number ofelectrolytes, the less the electrical resistance therewas. Conversely, the fewer the electrolytes, thegreater the resistance there was. As a result, EC
is widely used as an index to determine the electrolytic concentration of water. Hakusan-Meisui
showed a higher degree of EC than purified water,which implies a greater quantity of electrolytes.
Moreover, the hardness of Hakusan-Meisui is 25.8
mg/L, which is known to be high compared withthe hardness (13.0 mg/L) of city water (Houri and
Yoshioka, 2004). It is also said that the bitternessof tea is related to the amount of tannin it contains. In the present study, although the amountof tannin was not measured, it was supposed that
Hakusan-Meisui suppressed the leaching of tannin related to bitterness because its EC was higher
and its hardness greater than purified water, thus
giving it a mellow taste, and extracting a large
amount of umami elements.
In general, the moisture content of fresh tea
leaves is 20% to 25% and the solid contents 75%
to 80%. About 40% of the solid content is watersoluble, and this contains catechin, amino-acid,caffeine, saccharide, saponins, minerals, VitaminC, etc. When shaken to a froth for a few seconds,
then left sitting, a large amount of effervescence
was produced by Hakusan-Meisui and this did notdisappear easily. In contrast, for the decoction using purified water, the bubbles disappeared in justa few seconds. Thus, it seems that the HakusanMeisui decoction contains a large amount ofsaponins. In terms of nutritional content, whencompared with purified water, a larger number of
elements with nutritional content and inorganics
were extracted from the Hakusan-Meisui decoction, except for vitamin C. Moreover, the amountof vitamin C in the green tea decoctions using
both cold and hot water was also low. The green

tea exudate for Hakusan-Meisui was 6.7 while its
pH registered 8.3 with slight alkalinity. In contrast, the exudate for pure water was 5.7 while its
pH was acidic at 6.1. Because vitamin C showsan unstable degree of alkalinity, it was judged,
based on pH differences, that there was a difference in the amount of vitamin C in HakusanMeisui and pure water.
At present, tea beverages in plastic bottles
can easily be bought and consumed from retailstores. As a result, the preservation of tea exudates is very important. In the present study, thepreservative effect of green tea decoctions extracted from Hakusan-Meisui and purified water
were examined. As for the properties of heatedgreen tea exudate, no changes over time wereseen in either Hakusan-Meisui or pure water for
pH, number of bacteria or precipitation, althoughcolor, turbidity and ORP showed an uptrend. It
is thought that this originated from the effects ofatmospheric oxygen and carbon dioxide in the air
at the time of cooling. Moreover, in the green tea
exudate of pure water, bacteria were detected andputrescence advanced to the stage where a rotten
odor appeared after 5 days. It was thought thatthe foul smell was caused by organisms in the
purified water decoction, in particular proteins
which were decomposed by bacteria. In contrast,with Hakusan-Meisui, no putrid odors were produced even after 5 days of storage. It was judged,
therefore, that Hakusan-Meisui has a greater preservative effect than purified water.
The present results indicate that when green
tea is made using Hakusan-Meisui, the colors arestronger than when made with pure water, and thesmell and taste are of a higher quality, as is generally said to be the case with mineral water. However, it cannot be said that the unique qualities ofHakusan-Meisui have been fully clarified. One
reason is that no analysis has yet been made of thelarge amounts of catechins and polyphenols contained in green tea made with Hakusan-Meisui.
It is also necessary to carry out comparisons withother mineral waters.

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Hakusan-Meisui mineral water

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Nippon Shokuhin Eisei Kyokai; 2005 (in Japanese).
7 Kagawa Nutrition University Publishing Division.
Yontei Shokuhin Seibunhyou. [Food Composition
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8 Kawashima S. Sekai Daihyakka Jiten [Heibonsha
World Encyclopedia.] Tokyo: Heibonsha; 1981. p.
181–186 (in Japanese).
9 Khan N, Mukhtar H. Tea polyphenols for healthpromotion. Life Sci. 2007;81:519–533.
10 Murata T. Tadashii Mizu No Hanashi [Truth aboutwater.] Tokyo: Hamano Publishing; 2004. p. 210 (inJapanese).
11 Nakagawa M. The effect of amino acids and otherseveral substances on the autoxidation of catechins.
Chagyo Gijutsu Kenkyu 1969;38:26–32 (in Japanese).

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Received June 20, 2008; accepted August 20, 2008
Corresponding author: Daisuke Houri, PhD

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