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Vitamin C content in dried and brewed green tea from the US retail market
Author(s) -
Somanchi Meena,
Phillips Katherine,
Haile Ermias,
Pehrsson Pamela
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.956.8
Subject(s) - black tea , green tea , camellia sinensis , food science , nutrient , brewing , health benefits , vitamin , vitamin c , toxicology , traditional medicine , business , chemistry , medicine , biology , horticulture , biochemistry , organic chemistry , fermentation
Background Tea is the most consumed beverage after water in the world. Of the three main types of teas, namely black, oolong and green tea, the latter has been associated with a variety of health benefits, including cancer prevention, cardiovascular health, oral health and others, attributed to antioxidants activity as well as specific phytochemicals and nutrients it contains. Vitamin C is an essential nutrient, with a recommended daily intake of 60 mg, and higher intakes have been associated with numerous health benefits. Green and black tea are made from the leaves of Camellia Sinensis but green tea is less processed than black tea. Vitamin C concentrations exceeding 250 mg/100g have been reported in the unbrewed leaves, based on scientific literature for mostly Japanese green tea. Different cultivars and processing and brewing methods could significantly impact vitamin C in tea as consumed, and data on vitamin C in green tea available in the U.S. retail market are lacking. The goal of this study was to assess the vitamin C content of retail green tea bags in the U.S. retails market. Methods Sampling was done according to the National Food and Nutrient Analysis Program (NFNAP), which identifies top consumed products and implements a nationwide sampling based on market share. Samples of three brands were collected from each of the 12 locations. Samples from these 12 locations were composited randomly into pairs giving rise to six analytical samples. Six selected local samples of green tea bags were steeped in 230 ml of distilled hot water at 70°C, for two and four minutes and analyzed along with the corresponding unbrewed leaves. Vitamin C was determined as total ascorbic acid and dehydroascorbic acid, HPLC with UV detection. Certified reference materials and in‐house prepared control materials were included in each analytical batch. Results The brewed tea contained <0.5 mg of vitamin C/100g, except for one local sample that contained 1 mg/100g; brewing time did not affect the results. Vitamin C in the unbrewed leaves ranged from < 3 to 178 mg/100g (mean 45.5; median 28.1). Conclusion Although this study did not screen all brands of green tea or possible brewing methods, the consistently negligible vitamin C in brewed tea suggests that the high vitamin C content in tea leaves should not be considered to transfer into the beverage as typically consumed in the U.S.