The influence of the rosemary addition on the oxidative stability and the bitterness of virgin olive oil during storage

U ovom radu ispitivana je održivost i gorčina djevičanskog maslinovog ulja tijekom skladištenja, ovisno o udjelu dodanog ružmarina, kao i načinu dodavanja. 2,5 i 7% suhih listića ružmarina u jednoj seriji su samljeveni, macerirani u ulju i odfiltrirani, dok su u drugoj seriji dodani integralni listići koji su ostali u ulju tijekom skladištenja. Određivani su osnovni parametri kakvoće (slobodne masne kiseline i peroksidni broj), udjel klorofila, indeks boje, udjel fenolnih spojeva i intenzitet gorčine (IG). Panel grupa je senzorski ocijenila gorčinu i preferenciju prema pripremljenim uzorcima. Uzorci u kojima su listići macerirani i odfiltrirani, imali su bolju održivost od uzoraka s integralnim listićima. Povećanje udjela dodanih listića nije značajno utjecalo na održivost. Tijekom skladištenja u svim uzorcima smanjivao se indeks boje, udjel klorofila i fenola, jedino su o-difenoli u uzorcima s integralnim listićima nakon 30 dana skladištenja rasli. Intenzitet gorčine određen spektrofotometrijski, bio je uglavnom u korelaciji s udjelom fenola i senzorski određenom gorčinom. Na gorčinu je kod maceriranih listića utjecao udjel dodanih listića, dok kod cijelih listića udjel nije imao značajniji utjecaj. Testovima preferencije uzorci s maceriranim listićima bili su najlošije ocijenjeni na početku skladištenja, a uzorci s cijelim listićima na kraju skladištenja.The oxidative stability and the bitterness of the virgin olive oil during storage in their dependence on the added rosemary, as well as on the way it was added, were investigated. 2,5 and 7% of the dry rosemary leaves were grounded, macerated in oil and then filtrated as the first batch and as the second batch were used integral leaves which were left in oil during storage. Basic quality parameters were then determined (free fatty acid content and peroxide value), as well as chlorophyll content, color index, the total phenol content and the intensity of bitterness. Panel group evaluated the bitterness and the preference of the samples prepared by tasting them. Samples in which the leaves were macerated and filtrated had better oxidative stability than those with integral leaves in them. Increasing the addition of leaves did not influence the durance significantely. During storage time, color index, the chlorophyll content and the total phenol content decreased in all the samples but o-diphenols in samples which contained integral leaves increased after 30 days of storage. The intensity of bitterness determined by spectrophotometric method mostly correlated with the phenol content and the bitterness that was sensorically determined. In samples with macerated leaves, the addition of leaves had an influence on the bitterness while it did not have any significant influence on the samples with integral leaves. When it comes to preference tests, the samples with macerated leaves showed as the worst samples at the beginning of storage and the samples with integral leaves showed as the worst at the end of storage