Oxidative stability and total phenols of olive oil from authentic Croatian olive varieties - Oblica, Buhavica, Lastovka and Drobnica in the period of early and late harvest. : bachelor thesis

Maslinovo ulje je samo po sebi prehrambeno vrijedna i zdrava namirnica, međutim danas postoje maslinova ulja lošije i bolje kvalitete, što ovisi o samom načinu uzgoja masline, berbe i prerade. Nezasićene masne kiseline koje se nalaze u maslinovom ulju, od kojih je najzatupljenija jednostruko nezasićena oleinska kiselina, osjetljive su na djelovanje kisika i povišene temperature. Maslinovo ulje sadrži prirodne antioksidanse, fenolne tvari, koje usporavaju proces oksidacije. Stoga je vrlo važno da se pravilnom preradom maslinovog ulja i pravim trenutkom i tehnikom berbe sačuva što veća količina ukupnih fenola u ulju i time se postigne bolja prehrambena vrijednost i otpornost ulja na oksidaciju. Poznato je također da kvaliteta maslinovog ulja, odnosno udio ukupnih fenola ovisi o samoj sorti masline, području na kojem se uzgaja i periodu berbe. Tako su masline koje rastu na višim nadmorskim visinama i u područjima sa velikom količinom vlage siromašnije sa fenolnim spojevima. U ovom radu analizirani su uzorci ekstra djevičanskog maslinovog ulja proizvedeni od četiri sorte autohtonih hrvatskih maslina; Oblice, Buhavice, Lastovke i Drobnice u periodu rane i kasne berbe. Analizirana je oksidacijska stabilnost te ukupni fenoli i uspoređene su vrijednosti ovisno o sorti i periodu berbe. Iz dobivenih rezultata vidljivo je da oksidacijska stabilnost i udio ukupnih fenola uvelike ovise o sorti i o periodu berbe. Općenito je dokazano da je maslinovo ulje dobiveno od maslina u ranom periodu berbe znatno otpornije na oksidaciju i sadrži veće količine ukupnih fenola.Olive oil is a nutritionally valuable and healthy ingredient, however there are olive oil with better and worse quality, which depends on the very way of olive growing, harvesting and processing. Unsaturated fatty acids found in olive oil, the most absorbed single-unsaturated oleic acid, are sensitive to oxygen activity and elevated temperatures. Olive oil contains natural antioxidants, phenol substances, which are slowing down the oxidation process. Therefore, it is very important that olive oil is properly processed at the right time with right harvesting technique to save as much as posible the amount of total phenol in oil, thereby achieving better nutritional value and oil resistance to oxidation. It is also known that the quality of olive oil, that is, the share of total phenol depends on the olive variety itself and the area where the harvest is grown. So are the olives growing at higher altitudes and in areas with a high degree of humidity poorer with phenol compounds. In this paper was investigated oxidative stability of samples of olive oil produced from four varieties of Croatian olives: Oblice, Buhavice, Lastovke and Drobnice in the period of early and late harvest. The oxidation stability of the oil was determined by the Rancimat method in the early and late harvest period, and the total phenols in oils was determined by a rapid spectrophotometric method. The results show that oxidation stability and the total phenols depend largely on varieties and on the harvest period. It has generally been shown that olive oil obtained from olives during the early harvest is significantly more resistant to oxidation and contains higher amounts of total phenols