2. Materials and methods
2.1. Sampling
Thirteen brands of margarines widely consumed in Serbia were
purchased in supermarkets in Belgrade, Serbia. All margarines
were produced in our country, by the following factories: Vital
(Vrbas), Dijamant (Zrenjanin), 365 Delhaize (Belgrade) and
Polimark (Belgrade). In order to fulfill the EuroFir criteria, four primary
samples of each margarine, purchased in different stores at
intervals of 3 months, were acquired for the experiment.
Expiration date of all margarines was at least one month after
the date of analysis. Samples were stored at 4 C until they were
homogenized and analyzed.
2.2. Fatty acid extraction and methylation
Fatty acids were extracted as previously described in other
research (Alonso, Fraga, & Juarez, 2000). The samples (100 mg)
were dissolved in 3 ml of hexane, and then 0.1 ml of 2 M methanolic
potassium hydroxide was added. The mixture was stirred for
1 min and left for 15 min. The hexane fraction containing FA
methyl esters (FAMEs) was used for further analysis. All samples
were determined in duplicate.