Influence of Screw Press Type and Pressing Process Parameters on the Utilisation of Pumpkin Seed Oil

Buča (Cucurbita pepo L.) je jednogodišnja biljka koja potječe iz Amerike, a sastoji se od mesnatog dijela ploda i koštice. Koštica može biti s ljuskom i bez ljuske. U ovom radu istraživan je utjecaj vrste pužnice i procesnih parametara na iskorištenje bučinog ulja. Proizvedeno je hladno prešano bučino ulje na kontinuiranoj laboratorijskoj pužnoj preši. Procesni parametri koji su se mijenjali prilikom prešanja su: frekvencija elektromotora, temperatura grijača glave preše i nastavak za izlaz pogače. Korištena su tri tipa pužnice s različitom dubinom navoja. Ispitani su osnovni parametri kvalitete ulja: slobodne masne kiseline, peroksidni broja, udio vode i udio netopljivih nečistoća. Analitički je određen udio ulja u bučinim košticama i pogači kako bi se odredila efikasnost proizvodnje ulja. Prešanjem bučine koštice kod veće temperature glave preše, manje frekvencije elektromotora i manjeg nastavka za izlaz pogače proizvedena je veća količina ulja. Primjenom pužnice dubine navoja 5 mm dobivena je veća količina ulja u odnosu na 8 mm i 10 mm.Pumpkin (Cucurbita pepo L.) is an annual plant that originate from America and it is made of pulpy part of fruit and pits. A pit can be with a husk or without one. The aim of this research was to analyze the influence of screw press type and process parameters on the utilisation of pumpkin seed oil. It was produced cold pressed pumpkin seed oil on continuous laboratory screw press. The process parameters, which were changed during the pressing process, are: the frequency of electric motor, temperature of the press heating head and nozzle size. There were used three screw press types with different thread depth. There were questioned the basic quality oil parameters such as free faty acid, peroxide value, water content and proportion of insoluble impurities. Oil extraction by Soxhlet method determined the proportion of oil in pumpkin seeds and cake so that it could be defined oil production efficiency. Analytically it was determined content of oil in pumpkin pits and nozzle so it could be determined oil production efficiency. With pressing pumpkin pit at higher press head temperatures, less frequency of electric motor and smaller nozzle size it was produced a larger amount of oil. Using screw press with thread depth of 5 millimeters it was gained a larger amount of oil in comparsion with 8 millimeters and 10 millimeters