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What makes sugar white?

White sugar undergoes a series of processes before reaching us in its universally popular white granulated form.

White sugar is one of the most popular sweeteners used everywhere today from baked goods to beverages. Beginning its journey as a naturally yellow brown to brown colored raw solution extracted from sugar beet pulp or sugarcane, white sugar undergoes a series of processes before reaching us in its universally popular white granulated form.

The brownish colouration of the sugar solution increases during processing as a result of the enzyme-catalyzed and heat-induced procedures including the Maillard reaction between sugar and amino acids, enzymatic browning, caramelization and alkaline decomposition of sugars.

Highly customized ion exchange resins such as the Lewatit range from specialty chemical maker LANXESS enable the industrial sugar production industry to meet the tough colour intensity and other quality criteria of the food and beverage industry. These specialized resins have numerous applications during the process of creating pure-white granulated sugar including desalination and decolorisation of sugar solutions, the inversion (hydrolysis) of disaccharides, particularly saccharose, and for the treatment of diluted sugary solutions. For example, they can be used to desalinate whey, grape must and fruit juices or to remove unwanted, excess acid and bitterness from orange juice.

Decolorization with ion exchange resins complements traditional purification methods like crystallization, clarification through carbonatation and phosphatation, in which impurities are filtered off, and the affination of impurities from the crystal pulp (magma).  

Both mono and special heterodisperse resins are used in the sugar decolorization process. If the latter exhibit a low proportion of fine grain, they are also suitable for filtering concentrated and, therefore, high-viscosity solutions, e.g. syrups. This property is present per se with monodisperse resins enabling them to be regenerated. This is reflected in both the amount of time and water required by this process step. Thanks to the standardized length of diffusion paths, monodisperse resins require around 30 percent less cleaning water after the actual regeneration process – despite their high porosity.

Lewatit’s macroporous ion exchange resins based primarily on styrene polymers and cross linked via divinylbenzene units comply fully with food law requirements in many countries of the world. These act as absorbers  to efficiently bind color impurities, thus removing them from the sugar solutions. Absorber resins are superior to traditional activated carbon filters, particularly for solutions with only moderate coloring (< 1,000 ICU).

Not only is it far more time-consuming to regenerate these carbon filters, the regeneration process usually cannot be performed on-site, which generates extra costs and reduces the system’s productivity. In contrast, ion exchange resins charged with coloring molecules can quickly be readied for operation again by simply washing them with a saline solution on-site – and this procedure can be performed several times.

Lewatit ion exchange resins help realize higher sugar yields, cut waste and meet the increasingly strict quality requirements of the food industry. The long service life of the resins and their simple and cost-effective regeneration enables their profitable application in the process. Lewatit ion exchange resins sweeten the sugar making process by complementing and extending the process portfolio for industrial sugar production.