RO Question

[steve J]

So the last batch of sap I boiled the sugar percentage was 1.1. And at that percentage it takes 78 gallons to make one gallon of syrup. Needless to say not only did I burn thru wood but the syrup came out dark but tasted great. I also created a ton of niter sludge. My question is if I had an RO would that have produced a lighter color? and would I have created less sludge due to less boiling time?

[Potters3]

Maybe lighter always hard to guess on that one. Same amount of sludge would have made same amount of Syrup, just way less time and energy.

[DrTimPerkins]

My question is if I had an RO would that have produced a lighter color? and would I have created less sludge due to less boiling time?

Concentrating to less than 10 Brix tends to result in slightly darker syrup color (compared to boiling the same sap). As you go higher in concentration level above that, the syrup produced will get lighter.

No difference in niter though. The minerals are concentrated along with the sugar. Thus you make syrup faster AND make niter faster with increasing RO concentration.

[Ridge Creek]

Dr. Tim,
What causes this “phenomenon” with under 10 brix concentration resulting in darker syrup as compared to boiling same sap unconcentrated and not being as dark?

[DrTimPerkins]

Under about 8-10 Brix the amount of heating by pumps causes an increase in invert sugar levels, which results in increased syrup color development relative to boiling non-RO processed sap. Above that concentration, and progressively as you get higher in concentration, there is still some invert development, but that effect is offset by the reduced residence time for the liquid in the evaporator, which reduces the caramelization reaction that causes color development.

I hope that makes sense. It was initially a bit surprising to us as well (which is OK...we like head scratchers like this...gives rise to lots of interesting lunchtime conversations), until we measured the different sugars and calculated how long the sap/concentrate takes at different concentrations to transit the evaporator system.

[Ridge Creek]

So if I follow this logic, recirculating on an RO that can’t make a 10 plus brix on first pass could exacerbate this. We had very low sugar this year and had to recirculate to get 8-10. Makes sense why we had dark color yet not a robust taste. Thank you for this information, quite informative and interesting.

[maple flats]

I also have a Deer Run 250, while my lowest sugar % this year was 1.7%, I got amber even on my final boil, finishing off the pans. I ran the RO to get 7% on my first pass then recirculated and brought it up to 15%, then boiled. I do not know what the temperature was of the concentrate, I was busy packing syrup at the same time and did not check. As I finished off for final clean-up I was surprised to get Amber, my final cleanout is usually darker. During most of my season I got 2.0-2.1%, then the last week it fell to 1.9. then 1.8 and finished the last day at 1.7%.

[Mead Maple]

Biggest difference is the time it would NOT have spent in the pan, especially at 78 gallons worth of evaporation per 1 gallon of syrup.

If I cannot convince steve j via my weekly run up the road to visit in person, I’ll just have to rely on everyone else here on MT to help me convince him to put together an RO for next season!!



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[Russell Lampron]

I also have a Deer Run 250, while my lowest sugar % this year was 1.7%, I got amber even on my final boil, finishing off the pans. I ran the RO to get 7% on my first pass then recirculated and brought it up to 15%, then boiled. I do not know what the temperature was of the concentrate, I was busy packing syrup at the same time and did not check. As I finished off for final clean-up I was surprised to get Amber, my final cleanout is usually darker. During most of my season I got 2.0-2.1%, then the last week it fell to 1.9. then 1.8 and finished the last day at 1.7%.

When I make Amber I make most of it at 14% so I'm not surprised that you got Amber at 15%. Now that I can concentrate into the twenties I've learned that I can pretty much produce the color that I want at any point in the season by adjusting my concentration percentage up or down. I make the lightest syrup with the lower percentages and the darkest with the higher percentages. I made the lightest syrup of the season at 6% on Maple weekend and made the darkest, although it wasn't very dark at 23% a week later. The flavor followed the color too. The Golden taste like Golden and the Dark taste like Dark, basically the same flavor but the Dark is much more intense.