J. of Supercritical Fluids 72 (2012) 305–311 Contents lists available at SciVerse ScienceDirect The Journal of Supercritical Fluids jou rn al h om epage: www.elsevier.com/locate/supflu Chemometric analysis of tocopherols content in soybean oil obtained by supercritical CO 2 Stela Joki ´ c a , Senka Vidovi ´ c b,∗ , Zoran Zekovi ´ c b , Sanja Podunavac Kuzmanovi ´ c b , Lidija Jevri ´ c b , Branimir Mari ´ c c a University of Josip Juraj Strossmayer in Osijek, Faculty of Food Technology Osijek, Franje Kuhaca 20, 31000 Osijek, Croatia b Faculty of Technology, University of Novi Sad, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia c SGS Beograd Ltd, SGS Serbia Multilab, Danila Kiˇ sa 20, 21000 Novi Sad, Serbia a r t i c l e i n f o Article history: Received 4 September 2012 Received in revised form 22 October 2012 Accepted 22 October 2012 Keywords: Tocopherols Soybean oil Supercritical extraction Chemometric analysis a b s t r a c t The objective of this work was to evaluate the concentration of tocopherol isomers in different fractions of soybean oil obtained at different extraction process conditions. GC–MS analysis shown that the total content of tocopherols in the collected fractions were in the range from 31.74 to 1410.55 mg total toco- pherols/kg of extract, depending on investigated extraction conditions. By selecting the relevant process conditions of supercritical extraction, as well as by fractionation, it is possible to obtain soybean oil with different mass concentrations of tocopherols. Chemometric analysis was applied on different tocopherols isomers to model the relationships between the contents of different tocopherols isomers in soybean oil. The linear regression method was used to derive the significant models for predicting the tocopherols contents. To confirm the predictive power of the models, predicted contents of total tocopherols were calculated by using derived models and compared with the experimental values. High agreement between experimental and predicted values, obtained in the validation procedure, indicated the good quality of the models. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Vegetable oils are mixtures of minor and major lipid compo- nents. There are several techniques available to extract oil from oily seeds, and industrial extraction is commonly carried out through mechanical pressing followed by solvent extraction. Hexane is the most used solvent for the extraction of oil from oily seeds. How- ever, this procedure can result in the production of undesirable residues. The oil can undergo oxidative transformations during the removal of the solvent which can cause deterioration of the oil qual- ity [1]. The extraction of vegetable oils with supercritical CO 2 is alternative for conventional extraction method in which solvent free extracts are obtained in relatively mild conditions which avoid thermal degradation, thus making it the ideal solvent for natural products. Also, this process enabled a high selectivity and control capability of dissolving the desired components in the supercritical fluid by changing pressure and temperature, and easy removal of the solvent from extract. Furthermore, CO 2 is generally recognized as safe for the use in food production and processing. This energy ∗ Corresponding author at: Tehnoloˇ ski fakultet Novi Sad, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia. Tel.: +381 214853731; fax: +381 21450413. E-mail address: senka.curcin@yahoo.com (S. Vidovi ´ c). efficient process belongs to the “clean technology” because there are no secondary products harmful to the environment [2–8]. In fractional extraction, where fractions are collected as a function of time throughout the extraction, the dynamic nature of extracts can be used to affect separation [9]. Isolation of minor lipid components from complex lipid mix- tures is receiving increased attention due to their biological activity and health benefits [9,10]. Increasing consumer demand for “natu- ral” products has put on focus alternative processing technologies such as supercritical extraction because is more selective than the conventional one. The amount of valuable compounds is more than few times higher in the extracts obtained with supercriti- cal CO 2 [11,12]. Extraction of vitamin E from natural sources has received increasing interest due to the high antioxidant activity. ˛-Tocopherol is the most important lipid-soluble antioxidant in human body. The major antioxidant function of vitamin E in the human body is the protection of unsaturated fatty acids in cell membranes [13]. Chemometric analysis is undoubtedly of great importance in modern sciences. It means performing calculations on measure- ments of chemical data. Chemometric techniques are applied to explain both descriptive and predictive problems in experimental life sciences, especially in chemistry and biochemistry. In descrip- tive applications, properties of chemical systems are modelled with 0896-8446/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.supflu.2012.10.008