The effect of added rosemary extract and olive leaf on oxidative stability of pumpkin seed oil

U ovom radu istraživan je utjecaj dodatka prirodnih antioksidanasa ekstrakta ružmarina (Oxy’Less® Clear, StabilEnhance® OSR) i ekstrakta maslinovog lista u udjelima 0,04% i 0,1% na oksidacijsku stabilnost bučinog ulja i djevičanskog bučinog ulja. Oksidacijska stabilnost ulja, sa i bez dodanog prirodnog antioksidansa, ispitivana je primjenom Oven testa. Rezultati testa prikazani su kao vrijednost peroksidnog broja nakon određenog vremena držanja uzorka pri temperaturi 63°C, odnosno tijekom četiri dana trajanja testa. Rezultat istraživanja pokazuje da veću antioksidacijsku aktivnost ima ekstrakt ružmarina Oxy’Less® Clear kod obje koncentracije u odnosu na ekstrakt StabilEnhance® OSR i ekstrakt maslinovog lista. Ispitivani prirodni antioksidansi dodani u udjelu 0,1% efikasnije štite ova ulja od oksidacije u odnosu na dodatak 0,04%. Primjena ekstrakta ružmarina StabilEnhance® OSR (0,04% i 0,1%) nije se pokazala uspješna u porastu stabilnosti bučinog ulja.This study researched the effect of added natural antioxidants rosemary extract (Oxy’Less® Clear, StabilEnhance ® OSR) and extract olive leaf, in dosage of 0.04% and 0.1%, on the oxidative stability of pumpkin seed oil and virgin pumpkin seed oil. The oxidative stability of oil, with and without added natural antioxidant, was evaluated using the Oven test conditions. The results are expressed as peroxide number value after keeping the sample for a certain period of time at temperature of 63°C, that is, within four days of the duration of the test. The result showed the highest antioxidant activity with rosemary extract Oxy’Less® Clear comparable to extract StabilEnhance® OSR and extract olive leaf in both concentrations. Tested natural antioxidants added in dosage of 0.1% protect these oils from oxidation more effectively than dosage of 0.04%. The application of rosemary extract Stabil Enhance® OSR (0.04% and 0.1%) has not proved successful in increasing the stability of pumpkin oil