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, Faculty of 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 by comparing green tea made with Hakusan-Meisui mineral water and purified water, and ii) 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 amount of nutritional content and inorganic qualities were extracted from the exudate when compared 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 pure water, and the color was stronger. Though no changes were seen over time in pH, the number 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 maintenance was 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 than when 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
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