I built a new reverse osmosis system based on this design:
https://sites.google.com/site/mattat...osmosis-system

The concentrated sap does not appear to have an foul odor but does have a very slight yellow tint. however when you start boiling the concentrated sap it smells a little bit like seafood or "lobster water". When boiling raw sap if we get foam it resembles bubble bath. The concentrate almost immediately foams up with a very thick foam that is more like whipped cream.

I cant imagine the off smell being normal but maybe it is. We boiled it down to syrup and had a couple of people taste it and they say it seemed fine.

Any Idea what could be going on here? I have done 2 batches with RO and they both came out the same way.

Another issue somewhat related. I was under the impression that concentrating the sap would lighten the color of the syrup. However it still came out very dark the same as a batch we made just before using raw sap. We started at 2-3% and concentrated to about 8%.