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master's thesis
Određivanje udjela kafeina u čaju
Zagreb: University of Zagreb, Faculty of Food Technology and Biotechnology, 2008. urn:nbn:hr:159:613537
Baljak, Ana
University of Zagreb
Faculty of Food Technology and Biotechnology
Department of Food Engineering
Laboratory for Chemistry and Technology of Carbohydrates and Confectionery Products

Cite this document

Baljak, A. (2008). Određivanje udjela kafeina u čaju (Master's thesis). Zagreb: University of Zagreb, Faculty of Food Technology and Biotechnology. Retrieved from https://urn.nsk.hr/urn:nbn:hr:159:613537

Baljak, Ana. "Određivanje udjela kafeina u čaju." Master's thesis, University of Zagreb, Faculty of Food Technology and Biotechnology, 2008. https://urn.nsk.hr/urn:nbn:hr:159:613537

Baljak, Ana. "Određivanje udjela kafeina u čaju." Master's thesis, University of Zagreb, Faculty of Food Technology and Biotechnology, 2008. https://urn.nsk.hr/urn:nbn:hr:159:613537

Baljak, A. (2008). 'Određivanje udjela kafeina u čaju', Master's thesis, University of Zagreb, Faculty of Food Technology and Biotechnology, accessed 19 November 2024, https://urn.nsk.hr/urn:nbn:hr:159:613537

Baljak A. Određivanje udjela kafeina u čaju [Master's thesis]. Zagreb: University of Zagreb, Faculty of Food Technology and Biotechnology; 2008 [cited 2024 November 19] Available at: https://urn.nsk.hr/urn:nbn:hr:159:613537

A. Baljak, "Određivanje udjela kafeina u čaju", Master's thesis, University of Zagreb, Faculty of Food Technology and Biotechnology, Zagreb, 2008. Available at: https://urn.nsk.hr/urn:nbn:hr:159:613537

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Metadata
TitleOdređivanje udjela kafeina u čaju
Title (english)Determination of caffeine content in tea
AuthorAna Baljak
MentorDraženka Komes (mentor)
GranterUniversity of Zagreb
Faculty of Food Technology and Biotechnology
(Department of Food Engineering)
(Laboratory for Chemistry and Technology of Carbohydrates and Confectionery Products)
Zagreb
Defense date and country2008-12-18, Croatia
Scientific / art field,
discipline and subdiscipline		BIOTECHNICAL SCIENCES
Food Technology
Abstract
Čaj je posljednjih godina postao najpopularnije piće upravo zbog svog sastava i njegovog utjecaja na zdravlje. Uz flavonoide, vitamine i minerale, najvažniji sastojak čaja je alkaloid kafein. Cilj ovog istraživanja bio je odrediti udjele kafeina u 7 različitih vrsta čajeva: bijeli, žuti, zeleni, oolong, crni, maté i prženi maté čaj. Udjeli kafeina određeni su primjenom četiri različite metode: ekstrakcija s kloroformom, mikro-metoda, metoda s olovnim acetatom i metoda tekućinske kromatografije visoke djelotvornosti (HPLC-PDA). Antioksidacijski kapacitet čajeva, kao i ekstrahiranog („sirovog“) kafeina, određen je primjenom dvije metode: reakcijom s 2,2'-azinobis(3-etilbenzotiazolin-6-sulfonska kiselina) radikalom (ABTS metoda) te reakcijom s željezo(III)-tripiridiltriazin (Fe3+-TPTZ) kompleksom (FRAP metoda). Primjenom sve četiri metode, najveći udjel kafeina određen je u bijelom čaju, dok je maté i prženi maté čaj karakteriziran najmanjim udjelom kafeina. Rezultati mikro-metode i metode s olovnim acetatom dobro koreliraju s rezultatima HPLC metode.
Abstract (english)
In recent years, tea became one of the most popular beverages of the world, mainly due to the compounds it contains and its influence on human health. Along with flavonoids, vitamins and minerals, the most important tea substance is the alkaloid caffeine. The aim of this study was to determine the content of caffeine in 7 different types of tea: white, yellow, green, oolong, black, maté and roasted maté tea. The content of caffeine was determined by using four different methods: extraction with chloroform, micro-method, method with lead-acetate and high performance liquid chromatography method (HPLCPDA). The antioxidant capacity of teas as well as of the extracted („raw“) caffeine was determined by using two methods: reactions with 2`-azino-bis(3-ethylbenzothiazoline-6- sulfonic acid) radical (ABTS assay) and Ferric reducing antioxidant power (FRAP assay). By applying all four methods, the highest content of caffeine was determined in white tea, whereas maté and roasted maté tea were characterised with the lowest content of caffeine. The results of the micro-method and the method of lead-acetate have a good correlation with the results of HPLC method.
Keywords
Keywords (english)
Languagecroatian
URN:NBNurn:nbn:hr:159:613537
Study programmeTitle: Food Technology; specializations in: Food Engineering
Course: Food Engineering
Study programme type: university
Study level: graduate
Academic / professional title: diplomirani inženjer prehrambene tehnologije; smjer prehrambeno inženjerstvo (diplomirani inženjer prehrambene tehnologije; smjer prehrambeno inženjerstvo)
Type of resourceText
File originBorn digital
Access conditionsAccess restricted to students and staff of home institution
Terms of useLicence In copyright icon
RepositoryRepository of the Faculty of Food Technology and Biotechnology
Created on2017-08-31 10:43:07

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