Is there a max. recommended concentration for RO?

[PerryW]

Is there a recommended RO concentration rate which should not be exceeded to produce good flavored syrup? I heard a fellow-sugarmaker talking about a nearby operation concentrating the sap to 18% and that customer's were complaining about bad tasting syrup. He apparently reduced his concentration rate for this season.

[maplwrks]

I concentrated to 25% alot this year---No complaints!! I think that he probably doesn't clean his RO or his rig well enough.....could just be NH syrup!!! ooops!!

[Tmeeeh]

If I remember right research project at UVM Proctor Maple made syrup from the same sap source on the same day and the sap was concentrated to different % sugar then boiled at the same time on identical evaporators side by side at the same time. The syrup was blind taste tested by experienced maple contest judges. The result again if I remember right was that the judges couldn't tell the difference between the samples.

I recollect that the highest % sugar sap used in this project was well below 20%.

There is an often repeated opinion that syrup made with RO has a "flat" taste or "doesn't taste like Maple syrup" if the syrup is boiled on a steam heated evaporator the problem is compounded because of the lower temperatures in the pan.

I would like to know what the truth is.

We RO to around 13% and fire the evaporator with wood. I think our syrup generally tastes fine. (We did make lots of Fancy syrup this year without a lot of flavor but the later season syrup we are making now has plenty of nice flavors)

[DrTimPerkins]

I would like to know what the truth is.

You can't handle the truth (with apologies to Jack Nicholson as Col. Nathan R. Jessup in A Few Good Men). :)

Actually, you had it pretty much right. The only detail I would add is that we did several boils (~5-7) each year over three different seasons, ranging from raw sap up to about 20% concentrate, sometimes boiling in as many as 4 identical evaporators (the place sure gets hopping when you've got 4 evaporators running at the same time). Not much difference in the syrup chemically, not much difference in taste (as judged by 20-30 experienced maple producers, regulators, researchers, packers, etc.). Of course they didn't know exactly what it was they were comparing either....the syrup was in opaque, unmarked bottles. There was a slight (but statistically significant) difference in color (RO syrup tended to be just a wee tad lighter, probably due to faster processing). As far as I am concerned, techno-syrup is a myth.

[DrTimPerkins]

OK....back to the original question.


Is there a recommended RO concentration rate which should not be exceeded to produce good flavored syrup?

You should always respect the capabilities of your machine. You can't buy a Yugo and drive it like a Porsche and expect it to operate well (or for long). In general, most regular ROs aren't real happy about concentrating more than about 4.7X the original starting sap concentration. Some machines can do more than that due to their design (boost pumps, serial concentration, etc.). Beyond that you have to run at fairly high pressures, and can damage the membrane if you aren't careful. So what some producers do is recirculate the sap/concentrate. The problem you run into by doing this is that every time the sap runs through the RO it heats up. So you have high sugar sap that is fairly warm.....you get VERY rapid microbial action, which results in darker syrup. If you don't process it quickly, it can ferment fairly fast, causing some off-flavor issues. It is better in that case to have a more capable/larger RO machine and do it all in one pass. So with a standard machine you can run in about the 8-10% range safely, with a machine with more bells and whistles maybe up to 15-16%, and with a high-powered properly designed machine, up to about 20%.

[PerryW]

I concentrated to 25% alot this year---No complaints!! I think that he probably doesn't clean his RO or his rig well enough.....could just be NH syrup!!! ooops!! Ha! good one!

I also suspect that the sugarmaker also could have blended later-season 2012 syrup (after the 80 degree weather) with lighter syrup to increase the amount of table syrup for the 2012 crop. I tried some blending but all it did was make my limited 40 gallons of Grade A syrup taste bad.

[PerryW]

(We did make lots of Fancy syrup this year without a lot of flavor but the later season syrup we are making now has plenty of nice flavors)

Yes this exactly described my 2013 crop (so far) and I do NOT use RO or vacuum. The first 40 gallons was ultra light w/ not a lot of flavor. (click on thumbnail below, my syrup is right-hand sample)

[sapman]

OK....back to the original question.

In general, most regular ROs aren't real happy about concentrating more than about 4.7X the original starting sap concentration. .


Dr. Tim, does that 4.7X refer to a single pass increase?

Thanks,
Tim

[Sunday Rock Maple]

Maplwrks --- just looked at your pictures, very nice setup!. Looks like your RO is the Turbo 3000 with two membranes from Lapierre --- are they MarkE8's? How many passes to get to 25%?