C: Food Chemistry JFS C: Food Chemistry Properties of High-Oleic Palm Oils Derived by Fractional Crystallization M.R. RAMLI, W.L. SIEW, AND K.Y. CHEAH ABSTRACT: High-oleic palm oil (HOPO) with an oleic acid content of 59.0% and an iodine value (IV) of 78.2 was crystallized in a 200-kg De Smet crystallizer with a predetermined cooling program and appropriate agitation. The slurry was then fractionated by means of dry fractionation at 4, 8, 10, 12, and 15 ◦ C. The oil and the fractionated products were subjected to physical and chemical analyses, including fatty acid composition, triacylglycerol and di- acylglycerol composition, solid fat content, cloud point, slip melting point, and cold stability test. Fractionation at 15 ◦ C resulted in the highest olein yield but with minimal oleic acid content. Due to the enhanced unsaturation of the oil, fractionation at relatively lower crystallization temperature showed a considerable effect on fatty acid composi- tion as well as triacylglycerol and diacylglycerol composition of liquid fractions compared to higher crystallization temperature. The olein and stearin fractionated at 4 ◦ C had the best cold stability at 0 ◦ C and sharper melting profile, respectively. Keywords: crystallization, crystallizer, fractionation, high-oleic palm oil, olein and stearin fractions Introduction H ydrogenation, interesterification, blending, and fractionation of oils and fats are modification methods frequently used to achieve a target quality fat-based product or process improvement. During these modifications, the physical and chemical properties of the starting oils and fats may change (Zaliha and others 2005). Among all, fractionation is one of the most commonly applied, es- pecially for palm oil modification. It is a totally reversible process and is carried out in 2 stages. The process involves crystallization followed by separation or filtration (Timms 2005). The degree of fractionation can be controlled according to the applications of fi- nal products. In palm oil, the liquid fraction from the fractionation process is used as a frying medium, whereas the solid fraction is a higher solid fat content component and suitable for margarines and shortening formulations. Applications of high-oleic oils are increasing as they provide higher stability required in food products. Research has demon- strated that the oxidative stability of high-oleic canola oil is twice the stability of regular canola oil (Corbett 2007). Apart from stabi- lizing the frying oil, high-oleic oils are also utilized in the prepara- tion of snack food for potato chips frying or spraying to enhance mouth-feel and palatability. Beside food applications, high-oleic oils could also be used for nonfood applications. Oleic acid is one of the most important and versatile oleochemicals derived from oils and fats (Bhat 1989). Palm oil is among the vegetable sources of this monounsaturated fatty acid. The vegetable-based high-oleic oils can be further processed through transesterification to pro- duce products such as polyurethane. Other nonfood applications of high-oleic oils include cosmetic formulations and use as vegetable- based lubricant. MS 20070564 Submitted 7/20/2007, Accepted 12/01/2007. Authors Ramli and Siew are with Analytical & Quality Development Unit, Product De- velopment & Advisory Services Div., and author Cheah is with Milling & Processing Unit, Engineering & Processing Division, Malaysian Palm Oil Board, Nr 6, Persiaran Inst., Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia. Direct inquiries to author Ramli (E-mail: roddy@mpob.gov.my). The objective of this study was to examine the physicochemical properties of high-oleic palm oils and its fractionated products in a pilot plant experiment. Better understanding of the products gives early information on suitable applications. In addition, the data on a pilot plant production scale are very useful during commercial scale-up. As compared to laboratory experiments, pilot scale gives the most realistic information required for commercialization. Materials and Methods Materials High-oleic palm oil (HOPO) was produced at the High-Oleic Pi- lot Plant, Malaysian Palm Oil Board (MPOB) Head Office, Selangor, Malaysia. The pilot plant production of the oleic-enhanced palm oil was carried out in-house, as comprehensively described elsewhere (Muhamad Roddy and others 2007). All chemicals used were of an- alytical grade. Fractional crystallization Refined HOPO (120 kg) with free fatty acid (FFA) of 0.05% was fed into a 200-kg double-jacketed De Smet crystallizer. It was first heated and agitated to 70 ◦ C for 2 h to eliminate any nuclei present in the oil. The oil was then cooled gradually according to a pre- determined cooling program. The agitation was between 10 and 30 rpm. The cooling program and agitation rate were controlled by a Wizcon Programmable Controller (De Smet, Brussels, Belgium). The crystallization temperature was set at 15, 12, 10, 8, and 4 ◦ C. The slurry was then subjected to physical separation by means of dry fractionation. A Yabuta (Hyogo, Japan) filter press was used for filtration. The filter press consists of filter membrane plates and fil- ter chamber plates. Prior to filtration, the filter press was chilled to an almost similar temperature to the slurry’s temperature to avoid deformation of crystals and minimum crystal damage during fil- tration. Filtration was carried out with the assistance of a volumet- ric pump. The slurry was first fed into the filter press with a min- imum pressure rate of 0.5 bar/min. The filling period was 10 min with a maximum pressure of 2.5 bars. After the maximum pressure C140 JOURNAL OF FOOD SCIENCE—Vol. 73, Nr. 3, 2008 C  2008 Institute of Food Technologists doi: 10.1111/j.1750-3841.2007.00657.x Further reproduction without permission is prohibited