2022Thesis or dissertation
Sabina Večeřová
Digital Repository (National Repository of Grey Literature)
The theoretical part of the thesis “Substances of tea” describes the history of tea, characteristics, cultivation of tea plants, leaf picking, preparation of tea, technological processing, chemical composition and the effects of tea on human health. In the practical part was to determine polyphenol levels spectrophotometrically and by HPLC caffeine content in ten varieties of tea (green, white, black, pu erh and matcha) using two different temperatures (70 °C, 90 °C) while being steeped for five minutes. Polyphenol levels ranged between 15,10 mg/g (sample of black tea Black Gunpowder using 70 °C temperature) to 126,92 mg/g (sample of matcha Wolfberry using 90 °C). Most samples varied significantly (p < 0,05) depending on the temperature. Content of polyphenols in mentioned tea varieties is as follows: matcha > white tea > green tea > pu erh > black tea. Caffeine content ranged between 8,57 mg/g (sample of green tea China Gunpowder while using 70 °C) to 27,97 mg/g (sample of white tea Guangxi Bílé peří while using 90 °C). Most samples showed significant difference (p < 0,05) depending on the temperature used. Matcha tea showed significantly higher caffeine content than other varieties. The effect of two different temperatures on the colour of the tea infusion was determined spectrophotometrically. The most sensory acceptable was white tea China OP using 70 °C temperature.
Abstract text comes from PubMed, OpenAlex or Europe PMC and belongs to the authors and publisher.
Study type
Chemical / analytical
Measuring what is in matcha, or how to detect it.
Assigned automatically from the title, abstract and subject terms.
Topics
Matcha is a main subject here (named in the keywords).
Sabina Večeřová. (2022). Obsahové látky v čaji. Digital Repository (National Repository of Grey Literature).
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