The influence of the process parameters and the addition of antioxidants on the utilization and stability of plum kernel oil

Abstract

Koštica šljive je nusproizvod prehrambene industrije iz kojeg se prešanjem može dobiti jestivo ulje, a njegova konzumacija može smanjiti rizik obolijevanja od kroničnih bolesti. Koštice šljive pribavljene s područja Slavonije i Baranje prešane su na pužnoj preši te je dobiveno sirovo ulje. Sedimentacijom i filtracijom dobiveno je hladno prešano ulje koštice šljive kojemu su određeni osnovni parametri kvalitete: peroksidni broj, slobodne masne kiseline, udio vode i udio netopljivih nečistoća. Prilikom prešanja ispitivao se utjecaj procesnih parametara: temperature zagrijavanja glave preše, veličina otvora glave preše i frekvencija elektromotora na iskorištenje ulja. Ispitan je i utjecaj dodatka antioksidansa na oksidacijsku stabilnost ulja primjenom Testa održivosti na 98 °C. Korišteni su prirodni antioksidansi ekstrakt zelenog čaja, ekstrakt ružmarina i eterično ulje primorskog vriska te sintetski antioksidans oktil-galat. Rezultati pokazuju da ispitivani procesni parametri hladnog prešanja utječu na iskorištenje ulja. Dodatkom prirodnih antioksidanasa postignuta je bolja zaštita ulja od oksidacijskog kvarenja, nego dodatkom sintetskog antioksidansa. Eterično ulje primorskog vriska imalo je najbolji antioksidacijski utjecaj.Plum kernel is byproduct of the food industry which can be used to produce edible oil through pressing. Also, its consumption is associated with reduced risk of chronic diseases. Kernels from territory of Slavonia and Baranja were used for production of oil. Raw oil was produced by using screw pressing and cold-pressed oil was obtained by sedimentation and filtration. Quality parameters such as peroxide value, free fatty acids, moisture content and insoluble impurities were determined. Aim of this study was to examine the influence of process parameters: press head temperature at cake exit, size of the press head hatch and electromotor frequency on the utilization of oil. Oxidative stability of oil with added antioxidants was determined by the Test of sustainability at 98°C. Natural antioxidants such as green tea extract, rosemary extract, winter savory essential oil and synthetic antioxidant octyl gallate were used. Results showed that natural antioxidants have greater protection of oil in comparison to synthetic antioxidants. Winter savory essential oil had the best antioxidant effect