The effect of antioxidants on the stabilization of the mixture of hazelnut oil and grape seed oil

Abstract

U ovom radu određena je oksidacijska stabilnost mješavine biljnih ulja. Ispitana je oksidacijska stabilnost mješavine hladno prešanog lješnjakovog ulja i hladno prešanog ulja koštica grožđa (70:30) bez dodatka antioksidansa, te sa dodatkom prirodnih i sintetskih antioksidanasa uz dodatak limunske kiseline. Parametri kvalitete ulja (peroksidni broj, slobodne masne kiseline) određeni su primjenom standardnih metoda. Prirodni antioksidansi koji su korišteni u ovom ispitivanju su: ekstrakt nara, ružmarina i kadulje, udjela 0,2 %, mješavina tokoferola udjela 0,2 % te eterična ulja konopljike, lavande, smilja, slatkog pelina i divlje mrkve udjela 0,05 %. Kao sinergist korištena je limunska kiselina udjela 0,01 %. Kao sintetski antioksidans korišten je propil galat u udjelu 0,01 %. Oksidacijska stabilnost mješavine ulja ispitivana je Oven testom na temperaturi od 63 ˚C tijekom 4 dana. Kroz rezultate ispitivanja prikazana je vrijednost peroksidnog broja za pojedinačni uzorak. Ekstrakt ružmarina pokazao je najbolju zaštitu mješavine ulja od oksidacije, dok ekstrakt nara i mješavina tokoferola ne pokazuju zaštitu mješavine ulja. Dodatkom eteričnog ulje smilja postignuta je najbolja zaštita mješavine ulja, dok podjednako dobru zaštitu pokazuju eterično ulja lavande i slatkog pelina. Limunska kiselina djeluje kao sinergist uz ekstrakt ružmarina zbog čega je postignuta najbolja zaštita mješavine ulja od oksidacijskog kvarenja.In this study the oxidative stability of mixture consisted of vegetable oils was determined. The oxidative stability of mixture of cold-pressed walnut oil and cold pressed grape seed oil (70:30) was tested without the addition of antioxidants, and with the addition of natural and synthetic antioxidants with added synergist citric acid. The oil quality parameters (peroxide number, free fatty acids) was determined by using standard methods. The natural antioxidants used in this study are: pomegranate extract, rosemary and sage extract, 0.2%, a mixture of 0.2% tocopherol and essential oils of hemp, lavender, immortelle, sweet wormwood and wild carrot 0.05%. As a synergist, the citric acid content was 0.01%. As a synthetic antioxidant, propyl galate was used in the share of 0.01 %. Oxidative stability of the oil mixture was tested by the Oven Test at a temperature of 63 °C for 4 days. The test results show the peroxide number for the individual sample. Rosemary extract showed the best protection of the oil blend from oxidation, while the pomegranate extract and tocopherol blend show no protection for the oil blend. The best protection of oil blend is achieved by the addition of essential immoretelle oil, while equally good protection is shown by lavender and sweet wormwood essential oils. The best protection against oil oxidation for this mixture of oils was by citric acid which acts as a synergist with rosemary extract