Chemical Interesterification Research Paper

2.3.2.2 Chemical Interesterification

Chemical interesterification is the process to redistribute the component of fatty acid and glycerol ions to form new gylcerolester with the presence of sodium methoxide as a catalyst. Chemical interesterification is also known as directed interesterification since this reaction is directed to produce a particular type of glyceride (O’Brien, 2009). This process is conducted at mild temperature with a range between 20°C to 100°C. O’Brien (2009) states that only catalyst that is active at low temperature is effective. Besides, he also states that the rate of random rearrangement is crucial since the trisaturated glycerides can precipitate as fast as they are produced in the liquid phase. According to Norizzah

The first factor is a degree of unsaturation of fatty acid. Unsaturated fatty acids mean that fatty acids have at least one or more double bonds. The higher the degree of unsaturation or number of double bonds, the lower the melting point of the fats and oils. The second factor is the length of carbon chain of fatty acid molecule. The longer the carbon chain of saturated fatty acid, the higher the melting point. Isomeric forms of fatty acids also affect the melting point. Fatty acid in cis form has lower melting point compared to fatty acid in trans form. Next, the polymorphism of the fat also can affect the melting point. β’ crystal form has high melting point compared to α form but lower than β form. Lastly, the factor that affects the melting point of fat is a molecular configuration of triacylglycerol (TAG). Simple TAG has sharp melting point compared to TAG

(2010), different structure of crystal will have different physical characteristics, thus can alter the use of the chemical. The physical characteristics that may be differ include solubility, density, melting point, colour, size and shape of the crystal. In term of stability, β’ is more stable than α but less stable than β. β’ crystal form is suitable for margarine, shortening and bakery products because it gives smooth texture, shiny surface and good meltdown properties. Meanwhile, β will gives hard texture, loss of spreadibility, brittle and unpleasant product. To test the polymorphism of the fat, X-ray diffraction technique can be used. This technique will determine the crystalline unit dimension as well as the subcell structure (Buldo,