Update: SWIM just learned that the defatting step refers to mixing the solvent with the acidic juice, shaking it and sucking up the solvent which now should contain the impurities and discarding it. How much solvent should be used for defatting ?
Alright defatting occurs when you add your non-polar (shellite, naptha, lighterfluid. hopefully not the last one its impure and the first two are dirt cheap) to your acidic soup after the boils. Your spice will be in the aqueous acidic layer (soup) as a salt and therefore won't be soluble in your non polar solvent so it will only pull fats and oils out not the goodies. The amount is up to you but it depends on batch size. 3 defats of 125ml would be good for 500g.
-Prepare an acidic solution with a pH of approx. 4
-Add the alkaloid-containing solvent and mix very thoroughly [mix gently]
-Separate solvent (alkaloids have now been removed and it contains only plant fats and oils)
-Basify the aqueous solution [that was previously acidic] to approx. pH 12 (it now contains your alkaloids)
-Add fresh non-polar solvent to aqueous solution
-Mix very thoroughly [stir gently]
-Remove non-polar solvent that now contains your alkaloids
-Evaporate or freeze-precipitate
benzyme wrote (in chat):
Defat the acidic phase with a completely nonpolar solvent, basify the acidic phase, use fresh nonpolar to extract, and dry the nonpolar over epsom salt. You pour the nonpolar solvent containing the alkaloids into a jar/beaker containing a thin layer of epsom salt this is to absorb any basic water that may have carried over into the nonpolar, and it grabs microemulsions. The nonpolar solvent pours off easily, you just rinse out the epsom salts with tap water. Evaporate, or freeze precipitate the nonpolar phase. That technique leads to a less resinous product.
What tek and at what stage are you defatting? If you have a separator then I suggest using hot sunflower oil. If just basting away then xylene or toluene as its much tidier to decant.