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 A degrees 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 (a dagger H), peak temperature (T (P)) and transition range were observed. After short path distillation, interesterified fat (IF) was produced in which alpha-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/cm(2), respectively. After interesterification, short spacing at 4.6 disappeared or weakened, indicating that the predominant polymorphic form had changed from the beta form to the desirable crystalline structure of the beta' form.