title: Irreversible sediment formation in green tea infusions.
abstract: The formation of irreversible tea sediment (IRS) and its chemical components in green tea infusions were investigated. The results showed that the amounts of IRS in the green tea infusions from various tea cultivars ranged from 0.10 to 1.47 mg/mL. The amount of IRS was influenced remarkably by the chemical components in the green tea infusion. Principal component analysis and regression analysis indicated that gallated catechins, Mn, Ca, caffeine, Na, and (-)-gallocatechin gallate (GCG) were the principal components. IRS (mg/mL) = -4.226 + 0.275 gallated catechins + 79.551 Na + 7.321 Mn + 21.055 Ca + 0.513 caffeine - 0.129 GCG (R2 = 0.697). The contents of the main chemical components in the reversible tea sediment (RTS) and IRS were markedly different, especially the minerals. Large amount of minerals participated in the formation of irreversible green tea sediment. The amount of IRS increased with the extraction temperature.
authors.affiliation: Key Laboratory of Machining and Quality Control of Tea and Beverage Plants, Ministry of Agriculture, Tea Research Inst. Chinese Academy of Agricultural Sciences, 9 South Meiling Road, Hangzhou 310008, China. yqx33@126.com
authors.forename: Yong-Quan
authors.initials: YQ
authors.lastname: Xu
authors.forename: Gen-Sheng
authors.initials: GS
authors.lastname: Chen
authors.forename: Qiu-Shuang
authors.initials: QS
authors.lastname: Wang
authors.forename: Hai-Bo
authors.initials: HB
authors.lastname: Yuan
authors.forename: Chun-Hong
authors.initials: CH
authors.lastname: Feng
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: Yin
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002110:Caffeine / Q000032:analysis* / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D006358:Hot Temperature; D018515:Plant Leaves / Q000737:chemistry*; D059808:Polyphenols / Q000032:analysis; D012044:Regression Analysis; D013662:Tea / Q000737:chemistry*; D014131:Trace Elements / Q000032:analysis
chemical_list: D000596:Amino Acids; D059808:Polyphenols; D013662:Tea; D014131:Trace Elements; C417940:gallocatechin gallate; D002110:Caffeine; D002392:Catechin