Physicochemical Properties of Lipase‐Catalyzed Interesterified Fat Containing α‐Linolenic Acid

Two substrate blends (8:6:6 and 6:6:9, by weight) of anhydrous butterfat (ABF), palm stearin (PS), and flaxseed oil (FSO) were interesterified by immobilized lipases. The reaction was carried out in the absence of solvent at 60 °C for 24 h in a 1-L tank stirred-batch type reactor. In terms of equivalent carbon number (ECN) of triacylglycerol (TAG), the areas of ECN 36-38 (from FSO) and ECN 48-50 (from PS) decreased during the interesterification while ECN 42–46 increased with increasing reaction time. As interesterification time increased, the decreased enthalpy (∆H), peak temperature (T P) and transition range were observed. After short path distillation, interesterified fat (IF) was produced in which α-linolenic acid contents (ALn, mol%) of the 8:6:6 and 6:6:9 IF were 15.7 and 21.7%, respectively. Tocopherol, cholesterol and phytosterol contents in each IF were significantly reduced after short path distillation. In this study, hardness of 6:6:9 IF and 8:6:6 IF were 217 and 800 g/cm2, respectively. After interesterification, short spacing at 4.6 A disappeared or weakened, indicating that the predominant polymorphic form had changed from the β form to the desirable crystalline structure of the β′ form.