New insight into scale inhibition during tea brewing: Ca^(2+)/Mg^(2+) complexing and alkalinity consumption  

作　　者：Linjun Li Jinsuo Lu Heliang Pang Zhiqiang Zhang Jing Yang Pengpeng Li Xiaoyu Yan Miaomiao Fan 

机构地区：[1]School of Environmental and Municipal Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China [2]Shaanxi Key Laboratory of Environmental Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China [3]State Key Laboratory of Green Building in West China,Xi’an University of Architecture and Technology,Xi’an 710055,China

出　　处：《Journal of Environmental Sciences》2023年第2期901-914,共14页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 51978558);the National Key Research and Development Program of China (No. 2019YFD1100102-04);the Chemical Institute of Chemical Industry of Shaanxi Normal University,Open Project of State Key Laboratory of Urban Water Resource and Environment (No. ES202121)

摘　　要：Scale not only affects the taste and color ofwater,but also increases the risks of osteoporosis and cardiovascular diseases associated with drinking it.As a popular beverage,tea is rich many substances that have considerable potential for scale inhibition,including protein,tea polyphenols and organic acids.In this study,the effect of tea brewing on scale formationwas explored.It was found that the proteins,catechins and organic acids in tea leaves could be released when the green tea was brewed in water with sufficient hardness and alkalinity.The tea-released protein was able to provide carboxyl groups to chelate with calcium ions(Ca^(2+)),preventing the Ca^(2+)from reacting with the carbonate ions(CO_(3)^(2-)).The B rings of catechins were another important structure in the complexation of Ca^(2+)and magnesium ions(Mg2+).The carboxyl and hydroxyl groups on the organic acids was able to form fivemembered chelating rings with Ca^(2+)and Mg^(2+),resulting in a significant decrease in Ca^(2+)from 100.0 to 60.0 mg/L.Additionally,the hydrogen ions(H^(+))provided by the organic acids consumed and decreased the alkalinity of the water from 250.0 to 131.4 mg/L,leading to a remarkable reduction in pH from 8.93 to 7.73.It further prevented the bicarbonate(HCO_(3)^(-))from producing CO_(3)^(2−)when the water was heated.The reaction of the tea constituents with the hardness and alkalinity inhibited the formation of scale,leading to a significant decrease in turbidity from 10.6 to 1.4 NTU.Overall,this study provides information to help build towards an understanding of the scale inhibition properties of tea and the prospects of tea for anti-scaling in industrial applications.

关 键 词：Scale inhibition Tea brewing CHELATION Hardness ALKALINITY 

分 类 号：TS272[农业科学—茶叶生产加工]