The goal here is to isolate the sugar from all other compounds in the juice. In this case, I'm using apple juice and grape juice. The sugar does not need to be edible, as it is being used to make r-candy. Boiling off the water from the juice doesn't work in this particular application, since the syrup is still contaminated with other compounds. I've tried mixing juice in denatured alcohol, and I didn't see any sugar precipitate (felt like a kid staying up all night waiting for Santa to come). Do y'all have any ideas?

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    $\begingroup$ Have you checked how a sugar factory works? Far as I remember, the most important tricks are Ca(OH)2, coagulants, filtration, and recrystalllisation. Possibly a bit of crystalline sugar as nucleation agent. $\endgroup$
    – Karl
    Dec 13, 2020 at 12:08
  • $\begingroup$ Hard to see why you are concerned with stuff from the fruits and not of denatured alcohol. My idea is to buy a pack of sugar and do a better use of the fruits. $\endgroup$
    – Alchimista
    Dec 14, 2020 at 11:52
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    $\begingroup$ @Karl I just did haha, I guess I'll need to do more research into that process. The only issue I can see myself running into is the centrifugal filtration process that's used to separate sugar crystals from molasses (I don't have a centrifuge, is there an alternative process I could use?). Also, is the Ca(OH)2 be added to balance the pH of the juice? $\endgroup$
    – squiddy
    Dec 14, 2020 at 20:19
  • $\begingroup$ The road to scientific success is paved with literature studies. :-)) $\endgroup$
    – Karl
    Dec 14, 2020 at 20:32
  • $\begingroup$ Let the sugar crystals grow until they are mm-sized, then use a sieve? Slow cooling might help, i.e. let the sugar crystallise at elevated temperature. Calcium hydroxide firstly inhibits the "inversion" (check wikipedia) of sucrose, that might not be relevant for you. The high pH also precipitates polyvalent ions, that's a first semester chemistry lab classic. The molasse is in the factory later neutralised again by CO2 (which comes from the inhouse production of Ca(OH)2 ), precipitating calcium carbonate again. $\endgroup$
    – Karl
    Dec 14, 2020 at 20:47


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