4. Purification of diffusion juice

There are several reasons why the feed juice must be purified before concentration and crystallization.

• The filtrate is black, grayish, and opalescent in appearance. It contains suspended particles to which flakes of coagulated protein material adhere, and it is difficult to filter these particles because they clog the filters, and the filtered liquid would not be clear.

• The diffusion juice has a pH of approximately 6 when measured at 20 °C. However, when heated, its pH drops significantly, leading to the hydrolysis of sucrose and the production of reducing sugars (Figure 2 ), which in turn degrade to form coloring compounds....