Effect of Chemical Refining Steps on the Some Micro and Macro Element Content and Quality Parameters in Corn Oil

Abstract

In this study, it was aimed to determine some element contents and some quality properties and to compare these parameters at each stage in the chemically refining process of crude corn oil. Color (lovibond tintometer), free fatty acidity, peroxide values and fatty acid compositions were determined in the samples of corn oil taken from consecutive stages of chemically refining. Also, the content of elements (Na, Mg, K, Ca, Fe, Pb, Cd, Ni, Mn, Zn, Co, Cr, P, Cu) was analyzed, by using inductively-coupled plasma-mass spectrometry (ICP-MS) and inductively-coupled plasma-optical emission spectrometry (ICP-OES) after microwave digestion. The color (Lovibond tintometer), free fatty acidity and peroxide values in the chemically refining process varied between 2.7-16, %0.09-2.12, 10.95-1.08 mEqO2/kg, respectively. Oleic, linoleic and linolenic acid contents changed between 30.486-30.580%, 54.339-54.703% and 0.972-0.993%, respectively, in the chemically refining stages. While no trans fatty acids detected in crude corn oil and after degumming-neutralization step, very low amount of trans oleic acid (0.040%) and total trans linoleic acid (0.132%) was detected in bleached corn oil. The total trans fatty acid content little more increased in the last stage of the chemically refining. However, total trans fatty acid content of refined corn oil was < 0.3%. It was clearly seen that Na, Mg, K, P, Ca, Mn, Fe, Pb, Ni, Cr, Cu element contents decreased significantly at the end of the chemically refining process. Although Cd, Co and Zn elements were determined in crude corn oil, these elements were not detected in the refined corn oil. The results obtained showed that the chemically refining process effected some of the quality properties of corn oil and especially the changes in the element contents.