Oxidative Stabilities of Enzymatically Interesterified Fats Containing Conjugated Linoleic Acid

Abstract

Interesterified fat was produced from soybean oil (SBO) and palm stearin (PS) using two different weight ratios of substrates. Conjugated linoleic acid (CLA; 10 wt% on the weight of SBO and PS) was used as a functional fatty acid. Interesterification and acidolysis was simultaneously carried out to exchange fatty acids and incorporate CLA in the triacylglycerol (TAG) backbone, respectively, using immobilized lipase. Comparative study was carried out between interesterified fats and blends (before interesterification) for the quantification of physical properties (i.e., solid fat content, melting and crystallization behavior) and oxidative stability. In the interesterified fat 5.2–6.1 % CLA was incorporated in the TAG backbone. Blends showed higher solid fat content (SFC) and melting point than interesterified fat at each measured temperature. The Rancimat test was performed for the oxidative stability where the interesterified fat showed significantly lower induction time than physical blends. After the addition of antioxidants such as butylated hydroxytoluene (BHT), rosemary extract, tertiary butylhydroquinone (TBHQ), propyl gallate (PG), etc. into the interesterified fat, the induction time was significantly increased. On the other hand, different deacidification methods (alkaline, batch deodorized and short path distillation) were performed after interesterification to remove the free fatty acids. After deacidification, oxidative stability of alkaline deacidified sample showed significantly (P ≤ 0.05) longer induction time compared to short path distillation (SPD) and physically deacidified samples. In this study, interesterified functional fat that may have a potential functionality for the margarines and shortenings were produced and their oxidative stability was observed.