Chemists, re: brown, sticky residue

Crystals captured in the filter, and well-washed with fresh EA, are unlikely to have much, if any, contamination (hence my obsession with collecting them in the filter rather than the residue).   For me, the water washed evaporate is another matter.

One component of the brown, sticky residue that earlier ended up in my evaporate has an acidic “taste”, presumably Citric that was  undissolved or “loosely bound” to other molecules.  If citric acid is part of the residue, could lime also be in there? Could these be contributing to the brown, sticky?

I’ve done some fresh EA washes, dried the filtrate, and then warm water washed the filter & filtrate, finding in some cases small chalklike white chunks that don’t stain orange/red in marquis.