On preventing sugar-coated tablets from browning

The phenomenon of browning occurs gradually in the white sugar-coating layer (comprised of sucrose, talc, and powdered acacia) when the coating is applied on a large scale. We found that this phenomenon is negligible on sugar-coated tablets when they are prepared on a small scale. The smoothing layer prepared on a small scale is nearly as opaque as the subcoating layer. Conversely, the smoothing layer produced on a larger scale is semitransparent. In large-scale operations, the conditions required to make the smoothing layer opaque were established, and it was demonstrated that this method can restrict the browning phenomenon. It is considered that the nitrogen-containing contaminants in powdered acacia may react with heat-inverted sucrose (the Maillard reaction) to make brown substances in the smoothing layer and that the opaque appearance of the layer conceals the color accumulation of the brown substances in the smoothing layer and therefore restricts the browning phenomenon.