Production Of Palm Oil And Effect Of Heat On It

Thesis Overview

<p> <b>1.1 INTRODUCTION</b></p><p><b>1.0 BACKGROUND STUDY&nbsp;</b></p><p>Palm oil is an edible oil derived from the fruits of the oil palm Elaeis guineensis (Siew, 2002). Palm olein is one of the major palm oil products that domestically and industrially used as cooking/frying oil. The functions of frying oils are to transfer heat to cook foods and to produce characteristics of fried-food flavor. The major advantage of palm olein is its high stability during frying that produced minimum amount of breakdown products in an acceptable level. Study conducted by Azmil and Siew (2008) shows that palm oil, single-fractionated palm olein and doublefractionated palm olein were more stable than high oleic sunflower oil after 80 hours of heating at 180 °C. These palm products also produced lower amount of free fatty acids, polar and polymer compounds, as well as preserved higher smoke points and tocols content. However, palm olein tends to crystallize at low temperature that limits its usage in temperate countries. In spite of various nutritional studies, palm olein is not well considered as a recommended choice due to its higher saturation content. Against this factor, there is a need to reduce its saturation content, so as to enhance its versatility in applications for market penetration in cold countries as well as cater to market trends. Generally, the saturation content of palm olein can be reduced by multistage fractionation of palm olein. However removal of saturation in palm olein is difficult due to the difficulty in controlling the crystallization of palm olein (Gijs et al., 2007a). Other than that, blending palm olein with other soft vegetable oils such as canola oil, cottonseed oil, rice bran oil, sunflower oil, soybean oil etc 2 is implemented to reduce the saturation level of palm olein and for frying purposes in temperate countries (Razali and Nor‟aini, 1994). In fact, blending of palm olein may also enhance the stability and frying performance of the oil. In this study, palm olein is modified by enzymatic interesterification and dry fractionation to reduce the saturation content of the oil. Enzymatic interesterification enables interchange of acyl groups between and within triacylglycerols (TAGs) at specific positions to form new TAG species that have high melting TAGs, PPP and PPS. These saturated TAGs that causes the crystallization of palm olein, can be removed as stearin during fractionation. Two sn-1,3 specific immobilized lipases; Lipozyme® TL IM (Thermomyces Lanuginosa) and Lipozyme® RM IM (Rhizomucor Miehei) are selected as biocatalysts for interesterification in solvent-free system (Appendix A and B). Palm olein has been chosen as the feedstock due to its higher unsaturation content compared to palm oil. Two types of new palm oil products can be derived from this study; the low saturation palm liquid oils and the respective stearin fractions. 1.2 The Objectives of the Studies The main objective of the studies was to prepare pure palm-based products with low saturation, via enzymatic interesterification of palm olein with iodine value (IV) of 62 follow by dry fractionation, as well as to characterize the physicochemical properties of the products. Besides, the efficiency of the lipases; Rhizomucor Miehei (Lipozyme® RM IM) and Thermomyces Lanuginosa (Lipozyme® TL IM) in the interesterification reaction will also be looked into. Optimization of the interesterification reactions and dry fractionation will also be carried out. 3 1.3 Chemical Properties of Palm Oil Palm oil consists of mostly glyceridic materials with some non-glyceridic materials in trace amount (Chong, 1994). TAG is the most abundant glyceridic component in palm oil which comprises of triesters of high aliphatic acids or fatty acids, while monoacylglycerol (MAG) and diacylglycerol (DAG) are the minor glyceridic components in palm oil. The chemical structures of partial acylglycerols (MAG and DAG) and TAG were shown in Figure 1.1. <br></p><p> TAGs are esters formed from glycerol acylation of three fatty chains, while acylation with one or two fatty chains formed partial acylglycerols (MAG and DAG). The hydrocarbon chains in the ester group, R could be varied in terms of carbon number and the chemical structure (bend structures for unsaturated fatty acids) (Chong, 1994). The physicochemical properties of the oil could be due to the types of fatty acid presence, and the manner in which fatty acids combine to form various TAG molecules (Naudet, 1996). In general, the hydrophobic nature of oil is due to the long fatty acid chains in the glyceridic materials. 2-monoacylglycerol (β) 1-monoacylglycerol (α) 3-monoacylglycerol (α’) 1,3-diacylglycerol 1,2-diacylglycerol 2,3-diacylglycerol Triacylglycerol 4 The Fatty Acids Composition of Palm Oil For palm oil, the fatty acids composition falls within a very narrow range from twelve to twenty carbon number, with a balanced fatty acids composition between saturation and unsaturation (Berger, 2001). Table 1.1 shows the common name, systematic name, shorthand name of fatty acids presence in palm oil and its fatty acid composition. In most vegetable oils, the sn-2 position fatty acids of TAGs are preferentially occupied by unsaturated fatty acids such as oleic acid and linoleic acid. Saturated fatty acid (SFA) (e.g. palmitic acid) is found in the sn-2 position of animal fats TAGs for instance lard, tallow etc (Naudet, 1996). Although palm oil contains high quantity of SFA, the sn-2 position fatty acids in the TAGs is preferably occupied by unsaturated fatty acids (mainly oleic acids) (Naudet, 1996; Nor Aini and Noor Lida, 2005). <br></p><p> Table 1.1 Common name, Systematic name, Shorthand name of fatty acids in palm oil and its fatty acid compositions (Sean, 2002; Siew, 2002)&nbsp;</p><p>Common name    Systematic name    Shorthand     FAC</p><p>&nbsp;Lauric Dodecanoic&nbsp;</p><p>12:0 0.1-0.4 Myristic Tetradecanoic 14:0 1.0-1.4 Palmitic Hexadecanoic 16:0 40.9-47.5 Palmitoleic Cis-9-Hexadecenoic 16:1ω7 0-0.4 Stearic Octadecanoic 18:0 3.8-4.8 Arachidic Eicosanoic 20:0 36.4-41.2 Oleic cis-9-Octadecenoic 18:1ω9 9.2-11.6 Linoleic cis-9, cis-12, Octadecadienoic 18:2ω6 0-0.6 Linolenic cis-9, cis-12, cis-15-Octadecatrienoic 18:3ω3 0-0.4 <br></p>