Manske? Curcumin? I really don't think so. Curcumin isn't even an alkaloid. By all means try 'salting out' the curcumin as salt will further reduce the already meagre solubility of turmeric in water. I'd suggest trying a test-tube sized sample first, so you don't trash all your turmeric with a load of salt. Better still, stick with the oil and pepper method.

To see if your precipitate might be mostly curcumin, dry it off and try dissolving a little of it in alcohol or vegetable oil. Curcumin should be completely soluble.

Also, curcumin reacts with boric acid to form a red compound, rosocyanine.

Canola oil is produced from GMO crops in many countries but not in Europe. The oil is functionally identical to non-GMO canola oil but google 'Percy Schmeiser' for more reasons to avoid GMO's.