Influence of the degree of unsaturation of vegetable oils on textural properties of oleogels

V okviru magistrske naloge smo pripravili oleogele iz sončničnega, oljčnega, žafranikinega, lanenega olja in olja oljne ogrščice. Oljem smo določili maščobnokislinsko sestavo in jodovo število z namenom, da ugotovimo, kako nenasičenost olja vpliva na teksturne lastnosti oleogelov. Teksturni lastnosti, ki smo ju določili, sta trdota in lepljivost. Oleogele smo pripravili tako iz svežih kot iz močno oksidiranih olj in iz olj z dodatkom rožmarinovega izvlečka. Kot oleogelator smo uporabili čebelji vosek pri 1,5 %, 2 %, 3 %, 5 % in 7 % (w/w). Ohlajali smo jih po treh različnih postopkih in jih izpostavili različnim pogojem skladiščenja, da bi ugotovili, kako vsebnost voska, temperatura ohlajanja in shranjevanja vplivajo na teksturne lastnosti oleogelov in sposobnost vezanja olja (OBC). Ugotovili smo, da na teksturne lastnosti oleogelov in OBC vplivajo vsebnost čebeljega voska, temperatura ohlajanja in skladiščenja oleogela in vrsta olja. Preiskovani oleogeli so termoreverzibilni. Stopnjo oksidiranosti olj in oleogelov smo spremljali z določanjem peroksidnega števila. Rožmarinovim izvlečkom v olju oz. v oleogelu smo določili tudi antioksidativni potencial. Dodatek antioksidanta, kljub temu da preprečuje lipidno peroksidacijo v oleogelu, oslabi 3D mrežo oleogela in s tem vpliva na teksturne lastnosti. Ugotovili smo tudi, da trdna struktura oleogelov upočasni lipidno peroksidacijo v oleogelu in ohrani antioksidativni potencial rožmarinovega izvlečka.In this master\u27s thesis oleogels were prepared from sunflower, olive, safflower, linseed and rapeseed oil. In order to find out how oil unsaturation degree affects the oleogels texture properties, fatty acid composition and iodine value of oils were determined. Texture properties measured included firmness and stickiness. Oleogels were made from fresh and highly oxidized oils as well as from oils with added rosemary extract. Beeswax was used as oleogelator at 1.5%, 2%, 3%, 5% and 7% (w/w). Oleogels were subjected to three different cooling processes and to different storage conditions in order to determine how oleogelator amount, the cooling and storage temperature affect the oleogels texture properties and oil binding capacity (OBC). We found out that the texture properties and OBC of oleogels are influenced by the beeswax content, the cooling and storage temperature, and oil type. The investigated oleogels are thermoreversible. The degree of lipid peroxidation in oils and oleogels was monitored by the peroxide value. The antioxidant potential of rosemary extract in oil and in oleogel was determined. The addition of the antioxidant, despite the fact that it prevents oxidation of oil in the oleogel, weakens the 3D structure of oleogel and so affects the texture properties. We also found out that the solid structure of oleogels slows down lipid peroxidation in the oleogel and preserves the antioxidant potential of rosemary extract