Palm-based diacylglycerol (P-DAG) oils were produced through enzymatic glycerolysis of palm kernel oil (PKO), palm oil (PO), palm olein (POL), palm mid fraction (PMF) and palm stearin (PS). High purity DAG (83-90%, w/w) was obtained and compared to palm-based oils (P-oil) had significantly (P<0.05) different fatty acid composition (FAC), iodine value (IV) and slip melting point (SMP). Solid fat content (SFC) profiles of P-DAG oils as compared to P-oils had less steep curves with lower SFC at low temperature range (5-10°C) and the higher complete melting temperatures. Also, P-DAG oils in contrast with P-oils showed endothermic as well as exothermic peaks with higher transition temperatures and significantly (P<0.05) higher crystallisation onsets, heats of fusion, and heats of crystallisation. Crystal forms for P-DAG oils were mostly in the β form.
Optimum processing conditions on palm oil-based formulations are required to produce the desired quality margarine. As oils and fats contribute to the overall property of the margarine, this paper will review the importance of beta' tending oils and fats in margarine formulation, effects of the processing parameters -- emulsion temperature, flow-rate, product temperature and pin-worker speed -- on palm oil margarines produced and their subsequent behaviour in storage. Palm oil, which contributes the beta' crystal polymorph and the best alternative to hydrogenated liquid fats, and the processing conditions can affect the margarine consistency by influencing the solid fat content (SFC) and the types of crystal polymorph formed during production as well as in storage. Palm oil, or hydrogenated palm oil and olein, in mixture with oils of beta tending, can veer the product to the beta' crystal form. However, merely having beta' crystal tending oils is not sufficient as the processing conditions are also important. The emulsion temperature had no significant effect on the consistency and polymorphic changes of the product during storage, even though differences were observed during processing. The consistency of margarine during storage was high at low emulsion flow-rates and low at high flow rates. The temperature of the scraped-surface tube-cooler is the most important parameter in margarine processing. High temperature will produce a hardened product with formation of beta-crystals during storage. The speed of the pin-worker is responsible for inducing crystallization but, at the same time, destroys the crystal agglomerates, resulting in melting.
A study was carried out to compare the composition and thermal properties of lard (LD) and engkabang fat (EF) - canola oil (CaO) blend interesterified with Candida antartica lipase (C. antartica). A fat blend EF-4 (40% EF in CaO) was prepared and interesterified using C. antartica lipase at 60°C for different time intervals (6 h, 12 h and 24 h) with 200 rpm agitation. The fat blends before and after interesterification were compared to LD with respect to their slip melting points (SMP), fatty acid and triacyglycerol (TAG) compositions, melting, solidification and polymorphic properties. Result showed that the slip melting point (SMP) of the fat blend interesterified for 6 h was the closest to that of LD. The solid fat content (SFC) values of fat blends interesterified for 12 and 24 h were found to become equal to those of LD within the temperature range of 0 to 20°C. In addition, all three interesterified blends had SFC values similar to those of LD within the temperature range of 30-40°C. According to thermal analysis, the transition of the fat blend interesterified for 24 h appearing at -2.39°C was similar to the low melting thermal transition of LD and the transition of the fat blend interesterified for 12 h appearing at 26.25°C was similar to the high melting thermal transition of LD. However, there is no compatibility between LD and all three interesterified blends with regard to polymorphic behaviour.
The main goal of the present work was to assess the mechanism of crystallisation, more precisely the dominant component responsible for primary crystal formations and fat agglomerations. Therefore, DSC results exhibited significant effect on temperature transition; peak sharpness and enthalpy at palm stearin (PS) levels more than 40wt.%. HPLC data demonstrated slight reduction in the content of POO/OPO at PS levels less than 40wt.%, while the excessive addition of PS more than 40wt.% increased significantly PPO/POP content. The pNMR results showed significant drop in SFC for blends containing PS less than 40wt.%, resulting in low SFC less than 15% at body temperature (37°C). Moreover, the values of viscosity (η) and shear stress (τ) at PS levels over 40wt.% expressed excellent internal friction of the admixtures. All the data reported indicate that PPO/POP was the major component of primary nucleus developed. In part, the levels of PS should be less than 40wt.%, if these blends are designed to be used for margarine production.
The ability of palm oil (PO) to crystallize as beta prime polymorph has made it an attractive option for the production of margarine fat (MF). Palm stearin (PS) expresses similar crystallization behavior and is considered one of the best substitutes of hydrogenated oils due to its capability to impart the required level of plasticity and body to the finished product. Normally, PS is blended with PO to reduce the melting point at body temperature (37 °C). Lipid phase, formulated by PO and PS in different ratios were subjected to an emulsification process and the following analyses were done: triacylglycerols, solid fat content (SFC), and thermal behavior. In addition, the microstructure properties, including size and number of crystals, were determined for experimental MFs (EMFs) and commercial MFs (CMFs). Results showed that blending and emulsification at PS levels over 40 wt% significantly changed the physicochemical and microstructure properties of EMF as compared to CMF, resulting in a desirable dipalmitoyl-oleoyl-glycerol content of less than 36.1%. SFC at 37 °C, crystal size, crystal number, crystallization, and melting enthalpies (ΔH) were 15%, 5.37 μm, 1425 crystal/μm(2), 17.25 J/g, and 57.69J/g, respectively. All data reported indicate that the formation of granular crystals in MFs was dominated by high-melting triacylglycerol namely dipalmitoyl-oleoyl-glycerol, while the small dose of monoacylglycerol that is used as emulsifier slowed crystallization rate. Practical Application: Most of the past studies were focused on thermal behavior of edible oils and some blends of oils and fats. The crystallization of oils and fats are well documented but there is scarce information concerning some mechanism related to crystallization and emulsification. Therefore, this study will help to gather information on the behavior of emulsifier on crystallization regime; also the dominating TAG responsible for primary granular crystal formations, as well as to determine the best level of stearin to impart the required microstructure properties and body to the finished products.