Usporedba udjela polifenola i metilksantina u vodenim i metanolnim ekstraktima čokolade

master's thesis

• Title (english): Comparison of the content of polyphenols and methylxanthines in water and methanol extracts of chocolates
• Author: Tea Gačina
• 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: 2011-09-29, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Posljednjih je godina posebno zanimanje znanstvenika usmjereno prema prirodnim antioksidansima i njihovoj ulozi u zaštiti ljudskog zdravlja. Čokolada je prema brojnim istraživanjima bogata biološki aktivnim spojevima, posebno polifenolima i metilksantinima. Cilj rada bio je odrediti udio polifenola i metilksantina u različitim kakaovim proizvodima te usporediti učinkovitost otapala (voda i 70 %-tni metanol) u svrhu ekstrakcije ispitivanih bioaktivnih sastojaka. Udjel ukupnih fenola, ukupnih flavonoida, ukupnih flavan-3-ola i ukupnih proantocijanidina određeni su spektrofotometrijskim metodama, dok je primjenom tekućinske kromatografije visoke djelotvornosti (HPLC) određen udjel pojedinačnih polifenola i metilksantina. Spektrofotometrijskom metodom određena je i ukupna suha bezmasna tvar kakaovih dijelova ispitivanih kakaovim proizvodima. Antioksidacijski kapacitet ispitan je primjenom dvije metode: reakcijom s 1,1-difenil-2-pikrilhidrazil radikalom (DPPH metoda) i 2,2'-azino-bis(3-etilbenzotiazolin-6-sulfonska kiselina) radikalom (ABTS metoda). Najveći udjel ukupnih fenola, flavonoida, flavan 3-ola i proantocijanidina određen je u kakaovoj masi, dok se u ostalim kakaovim proizvodima udjeli fenolnih spojeva smanjuju proporcionalno udjelu kakaovih dijelova. Veći udjel ukupnih fenola i ukupnih flavonoida određen je u metanolnim ekstraktima. Vodeni ekstrakti bogatiji su flavan-3-olima i proantocijanidinima. Veći antioksidacijski kapacitet karakterizira metanolne ekstrakte.

Abstract (english)

In recent years, special scientific interest has been directed towards natural antioxidants and their role in the protection of the human health. Chocolate is, according to the many researches, rich with active compounds, particularly polyphenols and methylxanthine. The aim of this study was to determine the proportion of polyphenols and methylxanthine in a variety of cocoa products and compare the effectiveness of solvents (water and 70% equity methanol) for extraction of the tested bioactive ingredients. The share of total phenol, total flavonoids, total flavan-3-ol and total proanthocyanidins were determined according to spectrophotometric methods, while the share of individual polyphenols and methylxanthine was determined by using high performance liquid chromatography (HPLC). With the help of spectrophotometric method was determined the total dry non-fat cocoa solids in tested cocoa products. The extracts were screened for their potential antioxidant capacity using two different radical scavenging methods: reactions with 1,1-diphenyl-2-picrylhydrazyl radical (DPPH assay) and with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS assay). The largest share of total phenols, flavonoids, flavan 3-ols and proanthocyanidins was determined in cocoa mass while in other cocoa products, shares of phenolic compounds reduce proportionately the share of cocoa solids. Higher share of total phenols and total flavonoids was determined in methanol extracts. Water extracts were richer in flavan-3-ols and proanthocyanidins. Higher antioxidant capacity characterised methanol extracts.

• Keywords: antioksidansi; čokolada; kakaovi proizvodi; metilksantini; polifenoli
• Keywords (english): antioxidants; chocolate; cocoa products; methylxanthines; polyphenols
• Language: croatian
• URN:NBN: urn:nbn:hr:159:791889
• Study programme: Title: Food Safety Management; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka upravljanja sigurnošću hrane (magistar/magistra inženjer/inženjerka upravljanja sigurnošću hrane)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-31 09:32:13