ABSTRACT:Changes in DSC melting properties of palm oil (PO), sunflower oil (SFO), palm kernel olein (PKOo), and their blends in various ratios were studied by using a combination of blending and chemical interesterification (CIE) techniques and determining total melting ( ∆H f ) and partial melting ( ∆ H i°C ) en- thalpies. Blending and CIE significantly modified the DSC melt- ing properties of the PO/SFO/PKOo blends. PO and blends con- taining substantial amounts of PO and PKOo experienced an in- crease in their DSC ∆ H f and ∆ H i°C following CIE. The DSC ∆ H f and ∆ H i°C of PKOo, blends of PO/SFO at 1:1 and 1:3 ratios, and all blends of PKOo/SFO significantly decreased after CIE. The DSC ∆ H f and ∆ H i°C of SFO changed little following CIE. Random- ization of FA distribution within and among TAG molecules of PO and PKOo led to modification in TAG composition of the PO/PKOo blends and improved miscibility between the two fats and consequently diminished the eutectic interaction that oc- curred between PO and PKOo. Paper no. J11380 in JAOCS 83, 739–745 (August 2006). KEY WORDS:Chemical interesterification, DSC melting and partial melting enthalpies, palm kernel olein, palm oil, sunflower oil. Most native fats and oils have limited applications in their un- modified forms, imposed by their TAG and FA compositions. To widen their use, they may be modified by blending, frac- tionation, interesterification (IE), hydrogenation, or combina- tions of these processes (1). Changing the natural physical characteristics of a fat or oil offers greater functionality for a large number of product formulations (2,3). Blending is the simplest modification. As requirements for fat products become more sophisticated, however, there are correspondingly fewer ways that appropriate specifications can be met by simply blending natural fats and oils. Other modifi- cation techniques need to be used for one or more of the blend components to meet product specifications at the lowest cost (3). Hydrogenation of polyunsaturated vegetable oils is cur- rently less appealing because of evidence that trans FA have adverse nutritional effects (4,5). IE has received much atten- tion in the edible oil industry as an alternative method to prove the physical properties of fats and oils. IE involves interchanging FA within and between TAG m ecules that make up fats and oils and leads to an increase ber of TAG types. Thus, important physicochemical proper such as melting and crystallization behaviors of the fats an oils, are modified. The precise effect of IE on the propertie fat and oil depends very much on the type of starting mate that is subjected to IE. For instance, the m.p. and solid fat tent of a high-melting fat would be reduced when it is inte esterified (IEed) with a liquid oil (2). Two types of IE are c rently in commercial use, i.e., chemical (CIE) and enzyma (EIE). CIE and random EIE using nonspecific lipases lead random distribution of FA on the TAG (6). In contrast, in u a 1,3-specific lipase, only the FA in the 1,3-positions shifted; the 2-position is unchanged. Preservation of the 2 sition means that a more natural fat is produced and resu the production of a much smaller absolute number of TAG compared with CIE and random EIE. Generally, EIE has c tain advantages over CIE, such as milder reaction conditio and regiospecificity (7), and is currently a cost-effective al native to CIE (8). Palm oil (PO), an important edible oil source for the foo industry, tends to crystallize as β′ and therefore is an attractive option for the production of yellow fat spreads. For the pr tion of such products, however, PO is normally combined other fats and/or oils because PO alone does not result in ucts that melt quickly on the palate (9,10). Hence, PO may blended and/or IEed with a lauric fat that contains short- a medium-chain FA and/or a liquid vegetable oil to give blen with improved melting properties. Lauric fats are often us one component of a blend to provide a broader spectrum o chain lengths, to provide a concentrated source of saturat to achieve both goals. A liquid vegetable oil is always used provide a source of unsaturated FA (3). The aim of the present work was to investigate the effec of blending and CIE on the melting behavior of PO, sunflo oil (SFO), palm kernel olein (PKOo), and blends thereof in ious ratios. The melting behaviors of the oils/fats and thei blends were studied by using their DSC melting thermogr The DSC melting thermogram gives valuable information the melting profile of fats, e.g., on how they melt in the m during mastication. It can also be used to monitor the phy Copyright © 2006 by AOCS Press 739 JAOCS, Vol. 83, no. 8 (2006) *To whom correspondence should be addressed at Product Development and Advisory Services Division, Malaysian Palm Oil Board, No.6 Persiaran In- stitusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia. E-mail: nlida@mpob.gov.my DSC Study on the Melting Properties of Palm Oil Sunflower Oil, and Palm Kernel Olein Blends Befo and After Chemical Interesterification Noor Lida Habi Mat Dian*, Kalyana Sundram, and Nor Aini Idris Malaysian Palm Oil Board (MPOB), Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia