Decolorization of Lactose-6-Phosphate Solutions Using Activated Carbon

Abstract

Sugar phosphorylation has many applications that can be used to develop dairy and food products. During the phosphorylation process, the color of the solution turns into a dark color. The dark color causes many challenges and limitations in using phosphorylation products. The dark color could cause unpleasant color changes in the products, so it is important to remove that color. Activated carbon has been utilized for decades to remove the dark color and improve the appearance of solutions such as sugar syrup and wastewater. This methodology is cheap and environmentally friendly. The objectives of this study were to develop a method to phosphorylate α-lactose monohydrate and milk permeate and to remove the dark color of solutions. The compositional characteristics of the solution, such as pH, total solids, and color parameters (L*—lightness; a*—redness; and b*—yellowness), were examined at different stages (seven stages) of washing the solutions. α-lactose monohydrate and MPP solutions were diluted with distilled water with a ratio of 1:2.2. Activated carbon was mixed with the solutions and left for 5 min at room temperature. Subsequently, the solutions were filtered. These steps were repeated seven times until there was a transparent (colorless) solutions. The experiment was repeated using three different batches of lactose and milk permeate solutions. Both solutions’ pH and total solids decreased with an increase in the number of washings with activated carbon. The International Commission on Illumination (CIE) L*a*b* scale was studied. The L* of the initial solutions was lower than that of the final solutions. However, the a* and b* of the initial solutions were higher than the final solutions. The total color difference (∆E) was calculated for both solutions. ∆E decreased with an increase in the number of washings with activated carbon in both solutions. We conclude that activated carbon can be used to remove the dark color that results from the phosphorylation process.