Udjel polifenola i antioksidacijski kapacitet različito pripremljenih ekstrakata yinzhien čaja

master's thesis

• Title (english): Polyphenol content and antioxidant capacity of different made extracts of yinzhien tea
• Author: Ivana Prčić
• Mentor: Draženka Komes (mentor)
• Granter: University 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 country: 2009-07-03, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Čaj je jedan od najčešće konzumiranih napitaka u svijetu. Osim zbog svoje ugodne arome i specifičnog okusa, popularan je i zbog pozitivnih zdravstvenih učinaka. U radu su ispitivani ekstrakti žutog čaja pripremljeni iz rinfuze, filter vrećice i kuglice za ekstrakciju tijekom različitog trajanja ekstrakcije (3, 5, 10, 15 i 30 minuta). Vodeni i 75%- tni etanolni ekstrakti iz rinfuze pripremljeni su klasičnom ekstrakcijom i ekstrakcijom u ultrazvučnoj kupelji. Ukupni fenoli i flavonoidi određeni su metodom s Folin-Ciocalteu reagensom, a antioksidacijski kapacitet metodama: FRAP (reakcija sa željezo(III)-tripiridiltriazinom), ABTS (reakcija s 2,2'azinobis(3-etilbenzotiazolin-6-sulfonska kiselina)), DPPH (reakcija s 1,1-difenil-2-pikrilhidrazil). Najveći udio ukupnih fenola određen je u 50%- tnom etanolnom ekstraktu žutog čaja pripremljenom iz kuglice za ekstrakciju, a najmanji u 100%- tnom etanolnom ekstraktu iz filter vrećice. Najveći antioksidacijski kapacitet ima 75%- tni etanolni ekstrakt čaja iz kuglice, a najmanji 100%- tni etanolni ekstrakt žutog čaja iz filter vrećice. Određeni su visoki koeficijenti korealacije između udjela ukupnih fenola i flavonoida te između udjela ukupnih fenola i antioksidacijskog kapaciteta.

Abstract (english)

Tea is one of the most commonly consumed beverages throughout the world. Beside the attractive aroma and specific taste, its popularity is also a result of its potentially health-promoting properties. Yellow tea was determined in loose leaf form, filter bag and tea ball and they were extracted during different time of extraction (3, 5, 10, 15 and 30 minutes). Total polyphenol and flavonoid content was determined using Folin-Ciocalteu’s reagent as well as antioxidant capacity that was determined by: FRAP (reaction with iron(III)tripyridyiltriazine), ABTS (reaction of 2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) and DPPH (reduction of (1,1-diphenyl-2-picrylhydrazyl) assay. The highest polyphenol content has shown ethanol extract (50%) of tea in tea ball but the lowest has shown ethanol extract (100%) of tea in filter bag. The highest antioxidant capacity has shown ethanol extract (75%) of tea in tea ball, but the lowest capacity has shown ethanol extract (100%) of tea in filter bag. A significant linear correlation was confirmed between total polyphenol and flavonoid content, also between total polyphenol content and antioxidant capacity.

• Keywords: antioksidacijski kapacitet; Camellia sinensis; polifenoli; žuti čaj
• Keywords (english): antioxidant capacity; Camellia sinensis; polyphenols; yellow tea
• Language: croatian
• URN:NBN: urn:nbn:hr:159:176947
• Study programme: Title: 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 resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-08-30 09:09:50