Utjecaj vrste deguminacije na reološka svojstva sirovog suncokretovog ulja | Influence of degumming type on rheological properties of crude sunflower oil

Croatian. Deguminacija ulja je postupak uklanjanja nepoželjnih negliceridnih sastojaka iz sirovog ulja kao što su fosfolipidi, lipoproteini, proteini i drugi spojevi koji uzrokuju visoke rafinacijske gubitke i umanjuju stabilnost ulja te utječu na senzorska svojstva ulja. Cilj ovog rada je istražiti utjecaj vrste deguminacije (vodena, kiselinsko-vodena, elektrolitima) na reološka svojstva sirovog suncokretovog ulja dobivenog metodom prešanja te izračunavanje prinosa i gubitka ulja tijekom raznih vrsta deguminacije ulja. Istraživan je utjecaj postupka odvajanja nastalog fosfolipidnog taloga od degumiranog ulja (centrifugiranje, lijevak za odjeljivanje) na reološka svojstva ulja. Uspješnost deguminacije ulja praćena je određivanjem reoloških svojstava degumiranog ulja i kvalitativnim sadržajem fosfora u degumiranom ulju. Mjerenja reoloških svojstava degumiranog ulja provedena su rotacijskim viskozimetrom primjenom sustava koncentričnih cilindara pri temperaturi 23 oC. Reološki parametri određeni su primjenom Newtonovog zakona. Rezultati istraživanja pokazuju da su svi ispitivani sustavi imali Newtonovski karakter. Postupak degumiranja utječe na reološka svojstva ulja te na udio zaostalih fosfolipida u ulju. Deguminacijom sirovog ulja otopinom elektrolita (NaCl) postiže se veća efikasnost uklanjanja fosfolipida iz ulja (manja viskoznost ulja, manji udio zaostalog fosfora u ulju). Vodenom deguminacijom u sirovom suncokretovu ulju zaostaje veći udio fosfolipida jer se ne izdvajaju nehidratibilni fosfolipidi iz ulja. Odvajanjem taloga fosfolipida iz degumiranog ulja postupkom centrifugiranja postižu se bolji rezultati nego primjenom lijevka za odjeljivanje tijekom 24 sata.

English. Oil degumming is a treatment of eliminating undesirable non- glyceride components from crude oil such as phospholipids, lipoproteins, proteins and other compounds that cause high refination loses, decrease stability and affect sensory properties of the oil. The aim of this paper is to explore the influence of type of degumming (water, acid-water, electrolyte) on rheological properties of crude sunflower oil obtained by pressing method and calculation of the yield and loss of oil during various types of degumming processes. The effect of removal of the appearing sediment of phospholipids from degummed oil (centrifuging, pouring funnel) on rheological properties of oil was researched. Efficiency of oil degumming was monitored by determining rheological properties of degummed oil and qualitative phosphor content in oil. Measurements of rheological properties of degummed oil were performed using rotational viscometer at 23 oC. Rheological parameters were determined by the Newton law. The results of the research have shown that all the investigated systems had Newtonian characteristics. Degumming process influences the rheological properties of oil and the amount of phospholipids retained in the oil. Degumming of crude sunflower oil with electrolyte solutions (NaCl) results in better efficiency in removal of phospholipids (lower viscosity and phosphorus content in oil). Water degumming in crude sunflower oil retained higher amount of phospholipids, because non- hydratable phospholipids are not separated from the oil. Better results are achieved by removing phospholipid sediment from the degummed oil by the centrifugation procedure than by using a pouring funnel during a 24 hour period.