Određivanje antioksidacijske aktivnosti kakao masa različita podrijetla DPPH i ORAC-metodama

master's thesis

• Title (english): Antioxidative activity determination of different origin cocoa liquor using DPPH and ORAC methods
• Author: Karmen Kurek
• Mentor: Jasna Vorkapić-Furač (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Cell Technology, Application and Biotransformations); Zagreb
• Defense date and country: 2007-02-02, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Kakao zrno, je prema brojnim istraživanjima, bogato antioksidantima i to polifenolima [(-)- epikatehin, (+)- katehin i procijanidini]. U ovom su radu istraživanja provedena na kakao masama različita podrijetla. U odmašćenim su kakao masama kvantitativno određeni ukupni polifenolni spojevi Folin-Ciocalteau reagensom, a njihova je antioksidacijska aktivnost određena DPPH- i ORAC-metodama. Antioksidacijska aktivnost u odmašćenim kakao masama veća je u uzorcima koji imaju veću koncentraciju polifenola. Vrijeme 50 %-tne inhibicije DPPH˙ najmanje je u uzorku koji sadrži najviše polifenola. ORAC-metodom je utvrđeno da je antioksidacijska aktivnost veća u uzorcima koji sadrže višu koncentraciju polifenola i najduže sprječavaju pad intenziteta fluorescencije. U lipofilnom dijelu kakao masa istražena je antioksidacijska aktivnost također ORAC-metodom, koja je prilagođena za rad u nevodenim medijima. Utvrđeno je da je antioksidacijska aktivnost spojeva topljivih u lipofilnom dijelu znatno manja od onog u odmašćenom dijelu. Dobivene vrijednosti su približno jednake za sve uzorke.

Abstract (english)

According to research data cocoa bean is a rich source of antioxidants due to polyphenols [(-)-epicatechin, (+)-catechin and procyanidins]. In this study research was made with cocoa liquor of different origin. In defatted cocoa liquor total amount of polyphenols was determined using Folin-Ciocalteau reagent. Their antioxidative activity was defined with DPPH and ORAC methods. Antioxidative activity of defatted cocoa liquor was higher in samples with higher total amount of polyphenols. Inhibition time of 50 % DPPH radical activity was the least in samples that contain the highest amount of polyphenols. By ORAC method it was determined that samples with higher total amount of polyphenols have had higher antioxidative activity and longer inhibition of fluorescence intensity. In lipophilic part of cocoa liquor antioxidative activity was studied using ORAC method, which was adjusted for measurement in non-aqueous solutions. It was determined that antioxidative activity of compounds dissolved in lipophilic solutions was less than in the defatted ones. The values obtained were similar for all the samples.

• Keywords: antioksidacijska aktivnost; DPPH-metoda; kakao masa; ORAC-metoda; polifenoli
• Keywords (english): antioxidative activity; cocoa liquor; DPPH method; ORAC method; polyphenols
• Language: croatian
• URN:NBN: urn:nbn:hr:159:718682
• Study programme: Title: Biotechnology; specializations in: Biochemical Engineering; Course: Biochemical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: diplomirani inženjer biotehnologije; smjer biokemijsko inženjerstvo (diplomirani inženjer biotehnologije; smjer biokemijsko inženjerstvo)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-09-06 10:45:33