Utjecaj otapala i duljine trajanja ekstrakcije na antioksidacijska svojstva žutog čaja

master's thesis

• Title (english): Effect of solvents and time of extraction on antioxidative properties of yellow tea extracts
• Author: Martina Juričko
• 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: 2009-07-02, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Čaj se dobiva od biljke Camellia sinensis i jedan je od najpopularnijih napitaka širom svijeta. Znanstvena istraživanja su pokazala da konzumiranje čaja zbog prisutnih polifenolnih sastojaka može smanjiti rizik od pojave različitih bolesti, posebice karcinoma i srčanih oboljenja. Cilj ovog rada bio je odrediti ukupne fenole, neflavonoide i flavonoide te antioksidacijski kapacitet žutog čaja ekstrahiranog pri različitim uvjetima. Uvjeti ekstrakcije uključivali su: različito vrijeme ekstrakcije (3, 5, 10, 15, 30 min) i različita otapala (voda, 10%-tni, 25%-tni, 50%-tni i 100%-tni etanol) koji su se primjenili na čaj u rinfuznom obliku, filter vrećici i kuglici. Udio ukupnih fenola, flavonoida i neflavonoida određen je reakcijom s Folin-Ciocalteau reagensom. Antioksidacijski kapacitet je određen primjenom tri metode: reakcijama s željezo(ІІІ)-tripiridiltriazinom (FRAP) te radikalima 2,2'-azinobis(3- etilbenzotiazolin-6-sulfonskom kiselinom) (ABTS) i 2,2- difenil-1-pikrilhidrazilom (DPPH). Na osnovu dobivenih rezultata može se zaključiti da je najveći udjel polifenola ekstrahiran produljenom ekstrakcijom čaja u rinfuznom obliku. Kao najučinkovitije otopalo za ekstrakciju pokazao se 50%-tni etanol.

Abstract (english)

Tea is made of a plant Camellia sinensis and it is one of the most popular baverages worldwide. Scientific studies have indicated that polyphenolics compounds present in tea may reduce the risk of a variety of illnesses, including cancer and coronary heart diseases. The objective of this dissertation is to determine the total content of phenols, non-flavonoids and flavonoids as well as the antioxidant activity of yellow tea extracts in different conditions. Conditions of extraction were: different extraction time (3, 5, 10, 15, 30 min) and different solvents (water, 10%, 25%, 50% and 100% ethanol) which were applied on tea in loose form, bagged form and tea infuser. The content of total phenols, non-flavonoids and flavonoids was determined by using a reaction with the Folin-Ciocalteau reagent. Antioxidant activity was determined by using reactions with iron(ІІІ)tripyridyltriazine (FRAP), and radicals 2,2'-azinobis(3-ethylbenzothiazoline-6- sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH). The obtained results showed that tea in loose form after prolonged extraction has the greatest proportion of phenol compounds. 50% ethanol was the most effective solvent for extraction.

• Keywords: antioksidacijski kapacitet; Camellia sinensis; fenolni spojevi; žuti čaj
• Keywords (english): antioxidant activity; Camellia sinensis; phenolics compounds; yellow tea
• Language: croatian
• URN:NBN: urn:nbn:hr:159:877594
• 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 10:21:04