Tristearin melting point

Saturated fats like the tristearin in beef fat have higher melting points than the unsaturated fats in vegetable oils like trilin-olein or trilinolenin. 

Polymorphism means many bodies. Having determined the melting point of tristearin in... 

Monotectic mixtures arise when the individual components have similar melting points, molecular volumes and polymorphic forms. Figure 17.12(a) represents a possible phase diagram for monotectic mixtures. A typical monotectic solution occurs when SSS is mixed with SOS. Lutton (1955) determined that the a form was present and associated with limited solid solution formation, and contrasted with the a forms of other glyceride mixtures that formed continuous solid solutions (Rossell 1967). It was found, for this system, that tristearin incorporates about 50% of the SOS into a solid solution on the other hand, SOS incorporates very little SSS into a solid solution. 

The existence of a substance in two or more forms, which are significantly different in physical or chemical properties, is known as polymorphism. The difference between the forms arises firom different modes of molecular packing in the crystal structure of certain triglycerides. Certain pure or mixed fatty acid triglycerides may show as many as five different melting points. Each crystal system has a characteristic melting point, x-ray diffraction pattern, and infrared spectrum. For example, tristearin can exist in three polymorphic forms with melting points of 54.7, 63.2, and 73.5°C. 

Fats and oils often show multiple melting points. As an example, tristearin has three melting points at 52°C, 64°C and 70°C, because fats and oils solidify in more than one crystal form this property is known as polymorphism. Crystallization of fats and oils occurrs in two stages of nucleation and growth. 

Domb presents an example of liposphere encapsulation of tetracaine/tristearin microparticles having a size of less than 38 pm. The particles were suspended in molten ethyl stearate containing lecithin at 40°C. The melting point of tristearin is 65 to 72°C, so the microparticles remained solid during liposphere preparation. Warm phosphate buffer was added and the formulation was mixed and cooled. The resulting lipospheres had a particle size of 50 pm [1],... 

The melting points and values of heat of fusion of mixed palmitic stearic acid triglycerides compared to tripalmitin and tristearin are given in Table 8.26. 

The fatty acid composition of the triacylglycerols determines their physical nature. Those with a high proportion of low-molecular-weight (short-chain) and unsaturated acids have low melting points. Thus, tristearin is solid at body temperature whereas triolein is liquid. 

The lower melting points of triglycerides rich in unsaturated fatty acids are related to differences in three-dimensional shape between the hydrocarbon chains of their unsaturated and saturated fatty acid components. Shown in Figure 26.1 is a space-filling model of tristearin, a saturated triglyceride. In this model, the hydrocarbon chains lie parallel to each other, giving the molecule an ordered, compact shape. 

Stearin (Tristearin) can be prepared from tallow by crystallisation from a solution in ether, forming small crystals which have a bright pearly lustre. The melting point of stearin appears to undergo changes and suggests the existence of distinct modifications. When heated to t55 G. stearin liquefies with increase of temperature it be- comes solid, and again becomes liquid at C. If this liquid be further heated to 76 G., and allowed to cool, it will not solidify until 55" G. is reached, but if the liquid at 71 G° G. be allowed to cool, solidification will occur at 70" C,... 

Tristearin has a melting point of 72 °C. Based on this information, would you expect triarachadin to be classified as a fat or as an oil ... 

Tristearin was supplied by Cremer Oleo GmbH Co. KG and commercially available rapeseed oil was purchased from a local shop. The used tristearin has a melting point of 72 °C. Both triglycerides were used without further treatment. Polyethylene glycol 400 was purchased from Sigma Aldrich, while polyethylene glycol 2000 and 6000 were provided by Clariant. PEG 400 is liquid at room temperature, whereas PEG 2000 and 6000 are solids with melting points of... 

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