The Influence of Cold Pressing Parameters of Evening Primrose Seeds on Oil Production

Cilj ovog rada je ispitati utjecaj procesnih parametara hladnog prešanja sjemenki noćurka s kontinuiranom pužnom prešom na iskorištenje ulja. Prije prešanja određen je udio ulja u sjemenkama noćurka i udio vlage. Prešanjem sjemenki noćurka dobivena su tri proizvoda: sirovo ulje, uljni talog i pogača. Prilikom procesa prešanja mijenjali su se procesni parametri: veličina nastavka za izlazak pogače (8 mm, 10 mm, 12 mm), temperatura grijača glave preše kod izlaza pogače (90 °C, 100 °C, 110 °C) i frekvencija elektromotora (25 Hz, 30 Hz, 40 Hz). Nakon završetka prešanja provedeno je prirodno taloženje u trajanju 21 dan dobivenog sirovog ulja, a potom vakuum filtracija. Na proizvedenom hladno prešanom ulju noćurka određen su osnovni parametri kvalitete: peroksidni broj, slobodne masne kiseline, udio vode i udio netopljivih nečistoća. Metodom po Soxhlet-u određena je količina ulja u sjemenkama i zaostalog ulja u pogači kako bi se odredila efikasnost proizvodnje hladno prešanog ulja noćurka.The aim of this master thesis is to examine how different process parameters of cold pressing of evening primrose seeds with continuous screw press influence oil utilization. Before pressing, the oil content in the primrose seeds (21,50 %) and moisture content (6,90%) were determined. By pressing primrose seeds, three products were obtained: crude oil, oil sludge and cake. During the pressing process, process parameters were changed: extension that regulates the size of the opening press head (8 mm, 10 mm, 12 mm), temperature of the press heating head at the outlet of cake (90 °C, 100 °C, 110 °C) and the frequency of electric motors (25 Hz, 30 Hz, 40 Hz). After pressing has finished, natural sedimentation of 21 days and vacuum filtration were conducted on crude oil. Basic quality parameters of produced cold-pressed primrose oil were determined: peroxide number, free faty acids, water content and the proportion of insoluble impurities. Based on Soxhlet method, the amount of oil in the seeds and the residual oil in the cake were determined in order to define the efficiency of the production of cold-pressed evening primrose oil