title: Effect of different brewing times on soluble oxalate content of loose-packed black teas and tea bags.
abstract: Because of the postulated role of increased dietary oxalate intake in calcium oxalate stone formation, the effect of different brewing times on soluble oxalate contents of loose-packed black tea and tea bags was studied. The oxalate content of 25 different samples of loose-packed black teas after brewing at 5, 10, 15, 30, and 60 min and of ten brands of tea bags after infusion for 1, 2, 3, 4, and 5 min was measured by enzymatic assay. The oxalate concentration resulting from different brewing times ranged from 4.3 to 6.2 mg/240 ml for loose-packed black teas and from 2.7 to 4.8 mg/240 ml for tea bags. There was a stepwise increase in oxalate concentration associated with increased brewing times.
authors.affiliation: Nutrition Research Centre, Faculty of Health and Nutrition, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Mahdavi
authors.forename: Neda
authors.initials: N
authors.lastname: Lotfi Yagin
authors.forename: Michael
authors.initials: M
authors.lastname: Liebman
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Nikniaz
mesh_terms: D001628:Beverages / Q000032:analysis*; D010070:Oxalates / Q000032:analysis* / Q000652:urine; D013662:Tea / Q000737:chemistry*; D013997:Time Factors
chemical_list: D010070:Oxalates; D013662:Tea