title: The major factors influencing the formation of sediments in reconstituted green tea infusion.
abstract: The effects of Ca(2+), caffeine and polyphenols on the formation of reversible tea sediments (RTS) and irreversible tea sediments (IRS) in green tea infusion were studied. Adding Ca(2+) (2 mmol/l) was found to increase the formation of RTS by 8% and IRS by 92%, while adding chelating ions of Na2EDTA significantly decreased the amount of RTS by 14.6%, but not the amount of IRS. Under acid conditions, Ca(2+) combined with oxalic ions to form indissoluble oxalate that is the principal constituent of IRS, despite the existence of the chelating ions. Decaffeination largely inhibited the formation of RTS (73%) and IRS (60%), even in the presence of Ca(2+). The amount of sediment could be reduced by removing polyphenols using polyvinyl-polypyrrolidone. The results suggest that sediment formation in green tea infusions can be inhibited by lowering the concentration of Ca(2+), caffeine or polyphenols.
authors.affiliation: Tea Research Institute, Chinese Academy of Agricultural Sciences; Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture, 9 South Meiling Road, Hangzhou 310008, China; Institute of Food Chemistry, Zhejiang Gongshang University, 149 Jiaogong Road, Hangzhou, Zhejiang 310012, China.
authors.forename: Yong-Quan
authors.initials: YQ
authors.lastname: Xu
authors.affiliation: Institute of Food Chemistry, Zhejiang Gongshang University, 149 Jiaogong Road, Hangzhou, Zhejiang 310012, China.
authors.forename: Xiong-Fei
authors.initials: XF
authors.lastname: Hu
authors.affiliation: Hangzhou Vocational and Technical College, 68 Xueyuan Road, Hangzhou 310018, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Tang
authors.affiliation: Tea Research Institute, Chinese Academy of Agricultural Sciences; Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture, 9 South Meiling Road, Hangzhou 310008, China.
authors.forename: Yong-Wen
authors.initials: YW
authors.lastname: Jiang
authors.affiliation: Tea Research Institute, Chinese Academy of Agricultural Sciences; Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture, 9 South Meiling Road, Hangzhou 310008, China.
authors.forename: Hai-Bo
authors.initials: HB
authors.lastname: Yuan
authors.affiliation: Institute of Food Chemistry, Zhejiang Gongshang University, 149 Jiaogong Road, Hangzhou, Zhejiang 310012, China. Electronic address: qizhendu@126.com.
authors.forename: Qi-Zhen
authors.initials: QZ
authors.lastname: Du
authors.affiliation: Tea Research Institute, Chinese Academy of Agricultural Sciences; Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture, 9 South Meiling Road, Hangzhou 310008, China. Electronic address: yqx33@126.com.
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: Yin
mesh_terms: D000143:Acids / Q000737:chemistry; D002110:Caffeine / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D028241:Camellia sinensis / Q000737:chemistry*; D011232:Chemical Precipitation; D010070:Oxalates / Q000737:chemistry; D028321:Plant Preparations / Q000737:chemistry*; D059808:Polyphenols / Q000737:chemistry; D013662:Tea / Q000737:chemistry*
chemical_list: D000143:Acids; D010070:Oxalates; D028321:Plant Preparations; D059808:Polyphenols; D013662:Tea; D002110:Caffeine; D002118:Calcium
keywords: Ca(2+); Caffeine; Irreversible sediment; Polyphenols; Reversible sediment