Optimization of walnut oil production

Orah je danas širom svijeta poznat kao funkcionalna hrana. Prilikom proizvodnje ulja važno je postići optimalne uvjete procesa kako bi se postigao što veći prinos. U ovom radu orahovo ulje je dobiveno postupkom prešanja i ekstrakcijom supekritičnim CO2. Analizirani su sljedeći parametri: temperatura zagrijavanja glave preše (70, 85 i 100 °C), frekvencija elektromotora (20, 30, 40 Hz) te veličina otvora glave pužne preše za izlaz pogače (8, 10, 12 mm) te su prilikom provedbe eksperimenta dobiveni optimalni parametri za provedbu ekstrakcije ulja. U dobivenom ulju određeni su sljedeći parametri kvalitete: peroksidni broj, slobodne masne kiseline, netopljive nečistoće, udio vlage u ulju, jodni broj, saponifikacijski broj, p-anisidinski i totox broj. Zaostalo ulje iz pogače, nakon hladnog prešanja pri optimalnim uvjetima, ekstrahiralno je pomoću superkritičnog CO2 s ciljem potpunog iskorištenja ulja. Sadržaj tokoferola u ulju dobivenom prešanjem i ulju dobivenom ekstrakcijom supekritičnim CO2 je određen i uspoređen.Walnut is recognized worldwide as a functional health food. In the walnut oil production it is very important to find an appropriate method to recover the oil from seeds. Walnut oil in this study was obtained by pressing the seeds followed by extraction with supercritical CO2. The effects of pressing temperature (70, 85, 100 °C), frequency (20, 30, 40 Hz) and nozzle size (8, 10, 12 mm) in pressing experiments on oil recovery and oil temperature were monitored. The optimal calculated pressing condition within the experimental range of the variables studied was determined. In obtained walnut oil the following parameters were analyzed: peroxide value, free fatty acids, insoluble impurities, moisture content, iodine value, saponification value, p-anisidine value and Totox value. The residual oil from pressed cake obtained at optimal conditions was extracted with CO2 with the aim of complete oil recovery. Content of tocopherols in walnut oil obtained by screw pressing and oil extracted by supercritical CO2 were compared