Formiranje epoksi masnih kiselina tijekom fotooksidacije i autooksidacije biljnih ulja

master's thesis

• Title (english): Evolution of epoxy fatty acids during photo- and autoxidation of vegetable oils
• Author: Tamara Ciko
• Mentor: Dubravka Škevin (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Oil and Fat Technology); Zagreb
• Defense date and country: 2014-09-29, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Nutrition

Abstract

Cilj ovog rada bio je određivanje primarnih i sekundarnih produkata lipidne oksidacije, tj. hidroperoksida, konjugiranih diena (CD) i triena (CT) te epoksi masnih kiselina (EFA) nastalih u biljnim uljima procesima autoksidacije i fotooksidacije. CD i CT su određivani spektrofotometrijski, dok je za određivanje stupnja oksidacije i nastalih hidroperoksida mjerena peroksidna vrijednost (PV). Epoksi masne kiseline su analizirane plinskom kromatografijom pomoću plameno-ionizacijskog detektora. Nakon 54 dana mjerenja stupnja oksidacije u smjesama biljnih ulja, pokazalo se kako je više primarnih i sekundarnih produkata nastalo procesom fotooksidacije budući da se reakcije odvijaju brže u usporedbi s autoksidacijom. Kako su polinezasićene masne kiseline podložnije autoksidaciji i fotooksidaciji, veća koncentracija epoksi masnih kiselina nastalih iz tih kiselina je određena u smjesama koje su sadržavale veći udio linolne i linolenske masne kiseline. Također se pokazalo kako porast PV te koncentracije CD, CT i EFA ovisi o stupnju nezasićenosti.

Abstract (english)

The objective of this thesis was to determine primary and secondary oxidation products, namely hydroperoxides, conjugated dienes (CD) and trienes (CT) and epoxy fatty acids (EFA) formed in vegetable oils during photo- and autoxidation. CD and trienes CT were determined spectrophotometrically, whereas the peroxide value (PV) was measured to determine the extent of oxidation and hydroperoxides formed in oil blends. Additionally, EFA were analyzed by gas chromatography. After monitoring the extent of photo- and autoxidation in vegetable oil blends for 54 days, the results showed that more primary and secondary oxidation products formed during photo-oxidation, indicating that photo-oxidation proceeded faster than autoxidation. Moreover, higher contents of EFA arising from unsaturated fatty acids were determined in blends rich in linoleic and linolenic acid, demonstrating that PUFA were highly susceptible to both photo- and autoxidation. In addition, increase in PV, CD, CT and EFA levels was related to the degree of unsaturation.

• Keywords: autoksidacija; epoksi masne kiseline; fotooksidacija
• Keywords (english): autoxidation; epoxy fatty acids; photo-oxidation
• Language: croatian
• URN:NBN: urn:nbn:hr:159:000357
• Study programme: Title: Nutrition; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra nutricionizma (magistar/magistra nutricionizma)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-02 07:57:41