Karakterizacija in oksidativna stabilnost konopljinega, arganovega, chia olja in olja granatnega jabolka ; Characterization and oxidative stability of hemp, argan, chia and pomegranate seed oil

V magistrski nalogi smo preverjali oksidativno stabilnost arganovega, konopljinega, chia olja in olja granatnega jabolka. Oljem smo določili maščobnokislinsko (MK) sestavo, gostoto in viskoznost ter iskali povezavo med fizikalnimi lastnostmi in oksidativno stabilnostjo. Vzorcem olja, staranim 1 do 14 dni pri 60 °C, smo določali koncentracijo primarnih in sekundarnih produktov oksidacije ter antioksidativni potencial (AOP). Oksidativno stabilnost olj smo določili tudi z metodo rancimat. Ugotovili smo, da so vsa analizirana olja sestavljena pretežno iz nenasičenih MK. Med gostoto in viskoznostjo smo ugotovili obratno sorazmerje. Za konopljino, arganovo, chia, oljčno in repično olje smo ugotovili skladnost med MK sestavo in jodnim številom. Tako primarni kot sekundarni produkti oksidacije so s časom staranja naraščali. Noben osnovni vzorec olja ni presegal zakonsko dovoljene meje za peroksidno število (PŠ) in proste MK. Med konjugiranimi dieni in PŠ smo ugotovili linearno odvisnost, tako PŠ in para-anizidinsko število pa sta linearno odvisna od vsebnosti večkrat nenasičenih MK. AOP olj je s časom staranja padal. Med AOP in PŠ smo ugotovili obratno sorazmerje – večje kot je PŠ, manjši je AOP. Olja z višjo vsebnostjo nenasičenih MK so imela krajši indukcijski čas, določen z metodo rancimat. Rezultati instrumentalne metode se skladajo z ugotovitvami, dobljenimi z metodo staranja. ; The masters thesis aimed to test the oxidative stability of argan, hemp, chia seed and pomegranate seed oil. The oil's fatty acid composition, density and viscosity were determined and checked for a correlation between the physical qualities and oxidative stability. In the oil samples the chemical analyses of primary and secondary products of oxidation and antioxidative activity (AA) after ageing at 60 °C from 1-14 days were carried out. Furthermore, the oxidative stability was determined with the rancimat method. All analysed oils were predominantly composed of unsaturated fatty acides (UFA). The research found an inverse correlation between density and viscosity. Additionally, positive correlation between unsaturated fatty acids content and iodine value in hemp, argan, chia seed, olive and rapeseed oil was found. Primary as well secondary products of oxidation increased with time of ageing. No non-ageed oil exceeded the legally admitted limit for peroxide value (PV) and free fatty acid content. A linear correlation between conjugated dienes and PV was found. There was also a positive correlation between content of UFA and para-anisidine value as well as PV. AA decreases with time of ageing. There is an inverse correlation between the AA and PV – the higher PV, the lower AA. Oils with higher UFA content showed shorter induction time determined with rancimat method. The results of this method were in compliance with the findings acquired with the ageing method.