Sugar solidification

Solidification. Production of a product in a form suitable for use and acceptable to the consumer also may be an objective of a crystallization process. For example, the appearance of sucrose (sugar) varies with local customs, and deviations from that custom could lead to an unacceptable product. A final crystallization may thus be called for to bring the product appearance into compliance with expectations. 

In crystallization from the melt, as in the freezing of water or the solidification of molten sugar, the liquid phase is one component and temperature alone is the determining factor in whether or not crystallization will take place. 

Eutectic point (Tc) A single point on a temperature concentration phase (or state) diagram for a binary solution (e.g., water and sugars or salts) where the solution can exist in equilibrium with both crystalline solute and crystalline solvent. Under equilibrium conditions, cooling at Te results in simultaneous crystallization of solvent and solute in constant proportion and at constant temperature until maximum solidification has occurred (based on Fennema, 1996). 

If a 20% fructose solution is selected. Young [17] shows in diagram (Fig. 2.63), that pure ice freezes out from this mixture at appr. -2.5°C this is a result of the known phenomenon of freezing point reduction in solutions. The freezing-out of pure ice, however, causes an increase in the sugar concentration and thus a further freezing point depression. This continues until a mixture of ice and fmctose dihydrate is present at -10°C. This lowest common solidification point is called eutectic point . 

Triboluounescence and crystallolununescence are exhibited by many ordinary substances Sugar crystals, for example, when crushed in the dark, emit light The same is the case with crystals of uranium nitrate. The process of solidification of a melted substance is also in some cases (eg-, fused silver) accompanied by light emission. 

In preparing crystals of any substance, one of two methods is used either the substance is melted and then slowly cooled, when crystals are formed, as in the case of ice, or the substance is dissolved and then the solvent evaporated, when the material may come out of solution as crystals, as in the case of crystallizing sugar from water solution. In the case of rhombic sulphur the first method can not be used, because crystallization must take place below the transition temperature, which in turn is below the solidification temperature of liquid sulphur. The second method must therefore be resorted to and evaporation carried on below 96°. For preparing monoclinic crystals the first method is suitable, since this form is stable directly below the solidification temperature of the liquid. 

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