Research On The Quality Of Tea Beverages Extracted And Blended By Different Water Property

Water is one of the key factors determining the quality of tea beverages, since 80 percent of the beverage is water. The paper compared the difference of physical and chemical properties of the five various water properties (distilled water, purified water, softened water, mineral water and tap water), studied the effect that different water properties take on the extraction and blending of tea drinks, analyzed the evolution of the liquor color, tea polyphenol, caffeine,catechins and sensory quality of tea drinks made of various water quality during the aging storage under the 40 0C incubator, and discussed the storage behaviour of tea drinks made of various water quality. The results are as follows:1 Research on Different water qualityIn the present study, distilled water, purified water, softened water, mineral water and tap water are provided as the materials to be tested with regard to their electric conductivity, hardness value and pH. The research shows: The hardness value of distilled water and purified water is lower than 0.01mg/L; their electric conductivity is low, with no notable difference. The hardness value of softened water is lower than 1mg/L, and its electric conductivity is low; there is no remarkable difference between softened water, mineral water and tap water in terms of electric conductivity. The hardness value of mineral water and tap water is fairly high; the difference between the two is remarkable, tap water ranking the highest with a hardness value of 34.08 mg/L and electric conductivity of 139.80μS/cm. The pH of distilled water and purified water (5.93 and 5.31 respectively) is low, rendering them acid water. The pH of softened water, mineral water and tap water is 7.10, 7.15 and 7.05 respectively, rendering them neural water; there is no remarkable difference in terms of pH among the three.2 Research on the effect of different water quality on the quality of tea beveragesGreen tea beverages, ice green tea beverages and ice black tea beverages are extracted and blended with different water and the effect of different water quality on the quality of tea beverages is studied. It shows: The difference of water quality has a remarkable effect on the brightness of green tea beverages and ice black tea beverages, while the effect on ice green tea beverages is unnoticeable.The tea beverages extracted and blended with distilled water and purified water has the highest degree of brightness, however a lighter color, so they fail to display satisfactorily the color of tea itself. Tea liquor in the cases of mineral water and tap water is oxidized due to the calcium and magnesium in them, thus a darker color; however, not sterilized yet, the tea liquor has not been oxidized seriously, so contrarily it displays the tea color better. The difference of water quality has no effects on the content of TP, caf, aa and catechins in tea beverages.3 Research on the effects of water quality on the storage characteristics of tea beveragesThe tea beverages extracted and blended with different water are stored in an incubator of 400C. The experiment shows: During storage, the brightness of tea beverages is growing lower while the color is growing darker. The colors of tea beverages made from distilled water and purified water stay fairly steady, with a minor change. Green tea beverages made from mineral water and tap water precipitate after a period of time. During storage, the content of TP and caf stays steady while the content of aa is on decline. The content of catechins drops, and the droping in the cases of tea beverages made from distilled water and purified water with a low electric conductivity is far less than the cases of the other three with a higher electric conductivity. Of all the five cases, tea beverages made from distilled water show the least degree of declining in terms of the catechins content, while tea beverages made from mineral water show the greatest degree of declining.4 Research on the effects of water quality on sensory quality of different tea beveragesTea beverages made from mineral water taste mellow, but the color grows dark and the liquor turns turbid after a period of time. Tea beverages made from distilled water are generally astringent, less refreshing, and taste less like tea. Tea beverages made from tap water has the worst quality, with noticeable disturbing taste. Tea beverages made from purified water and softened water have similar quality and do not precipitate during storage.In the case of ice tea beverages, water quality has a smaller effect on their sensory quality since tart and sugar are added in the process of blending. Comparatively speaking, the tea liquor of distilled water is tarter and it tastes astringent; while the tea liquor of mineral water tastes mellower and the taste stays steady during storage; and it is quite similar to the cases of purified water and softened water.5 Research on the effects of water quality on green tea beveragespH, electric conductivity and hardness value on water have a considerable impact on the brightness and color of green tea beverages. When the water's pH value goes beyond 7.5, the oxidization process is accelerated and the tea liquor takes on a brown look, which is not a favorable condition to display tea quality. The sensory quality of green tea beverages is on decline as the electric conductivity and hardness value go up. At the same time, the color turns yellow, the degree of brightness falls, and the tea liquor tastes astringent. The content of Ca ion, Fe ion, Al ion and Zn ion yields a fairly big impact on sensory quality. When the amount of the metals added is smaller than 5 ppm, tea liquor tastes mellow, the taste enhancement, and the astringent taste gets weaker. If the amount exceeds a certain value, it will be an unfavorable condition to the taste.6 Research on the effects of water quality on tea extractionWater quality has a remarkable effect on the brightness and color of tea liquor. The color of the tea liquor extracted from distilled water and purified water is yellowish green and bright; while the color of that extracted from mineral water and tap water is turbid and darker yellow; the situation of softened water goes between the two. Water quality has no remarkable effect on tea polyphenols, amino acid, caffeine, extracting yield of green tea liquor. Judging from the sensory quality of green tea liquor, it shows that the tea liquor extracted from distilled water smells lightly fragrant, and tastes astringent; the liquor extracted from purified water tastes mellow, with a bright yellowish color, similar to the case of softened water; the liquor extracted from mineral water carries a mellow taste and a rich fragrance with it, yet the color is darker; the tea liquor extracted from tap water has the worst quality, carrying a disturbingly rusting smell.