I'm trying to get as pure citric acid as possible from a mandarin. It's not because I desperately need citric acid, but because I want to achieve this.
I started by grating the mandarine and filtering the juice. After filtering overnight, I was left with slightly yellow liquid. I heated it while avoiding boiling and I reduced the volume to 50%. When volume was reduced, the solution started to become saturated and crystals appeared. At this point, I stopped.
Now, I'm looking for a way to remove sugar from the solution, as this is the most annoying part. It's sticky.
When crystals appeared while I was boiling the solution, I came to think, that perhaps that could allow to separate sugar. Citric acid has solubility in water 1477.6 g/L (20 °C), while sugar has 2000 g/L (25 °C). Wikipedia unfortunately doesn't provide values for the same temperature.
From the above it seems that I can have more sugar dissolved than citric acid. I think that means that citric acid will crystallise first. Does it work like this? Are the crystals I've produced the citric acid crystals?
Is there another way to separate the compounds? Does something react with sugar to produce precipitate that can be filtered?