Question on RO-ing

[TapTapTap]

I'm looking to set up a hobby RO that came with the used evaporator we bought last year. The evaporator is a Leader 30"x10' with a raised flue pan. My question on RO-ing is how the concentrated sap effects the production through the rig. As i understand it, the rig will evaporate about the same volume of concentrate as raw sap. Therefore, if the RO-ing doubles the sugar then a single sap molecule moves through the evaporator twice as fast as a molecule in raw sap. And, that also means that the concentration of sugar as it enters the syrup pan is also double which means a lot more cooking of the sap molecule occurred in the flue pan.

It seems somewhat surprising that RO-ing to higher concentrations doesn't loose more taste.

Am I understanding this correctly?

[maple flats]

Taste testing by professional tasters have shown no loss of flavor.
Thru your evaporator you will get twice as much syrup per hour if you RO to double the sugar percent. Tell us about the RO, with a 2.5x10 it will likely do better than double the sugar % in the sap because it would be rare for an evaporator that size to be matched with a real small RO, but certainly possible. Do you have the manual for the RO? Who made it and what size is it? Do you have a model number?

[DrTimPerkins]

We've done a lot of research on this, starting with modest RO concentration to 8%, then going to 15, 25, and most recently, we've looked at HyperBrix/High Brix concentration.

http://www.uvm.edu/~pmrc/Effects%20of%20RO%20on%20syrup%20-%20van%20den%20Berg%202015.pdf

The physical and chemical reactions in the evaporator that result in syrup color and flavor happen fairly quickly. Yes, you can always make syrup darker by heating it longer (different subject), but if you're working efficiently already, then RO won't have a real substantial effect on flavor or color.

[Potters3]

You have it correct double the % sugar going in go. Same evaporation from evaporator, draw off twice as much syrup, with no difference in taste, just a lot less fuel used to drive the evaporator. We have been careful not to affect flavor as we sell mainly in jugs abd want to make sure customers order more then once from us. Last season we boiled mainly 14 to 16% sap and it still taste like when we boiled 2%.

[TapTapTap]

Thanks for the input.

And, yes I agree that the hobby RO isn't matched well to the evaporator. The previous owner claimed that the RO output for a single pass matched the evaporator input but I'm a little skeptical that I can make it work seamlessly - Obviously I must be pushing the evaporator harder than he had!)

[DrTimPerkins]

To add to my previous comment, if you're concentrating to <10 Brix, you're more likely to make slightly DARKER syrup using an RO. Above 10 Brix the syrup can get lighter, but the flavor doesn't change appreciably -- or at least not enough to be detected by taste panels (made up of people experienced with maple flavor).

[Russell Lampron]

Thanks for the input.

And, yes I agree that the hobby RO isn't matched well to the evaporator. The previous owner claimed that the RO output for a single pass matched the evaporator input but I'm a little skeptical that I can make it work seamlessly - Obviously I must be pushing the evaporator harder than he had!)

The output of the RO can be adjusted to match the input of the evaporator by adjusting the concentrate flow. I would say that the previous owner wasn't lying. The higher the concentrate flow is adjusted to, the lesser amount of water will be removed so the concentrate percentage will be less but it is possible to match RO output to evaporator usage.

[wnybassman]

To add to my previous comment, if you're concentrating to <10 Brix, you're more likely to make slightly DARKER syrup using an RO. Above 10 Brix the syrup can get lighter, but the flavor doesn't change appreciably -- or at least not enough to be detected by taste panels (made up of people experienced with maple flavor).

Last year was my first year using an RO, and it wasn't bought until well into the season. I had the opposite happen for me. I was boiling .8 to 1.0% for long hours producing dark syrup right from the start, then I bought the RO the first week of March. Well, you can see what happened after I started running 8% into the evaporator. In my 20 years of doing this, I never had a dramatic lightening of color like this mid season. Perhaps it was conditions, but it seems awfully coincidental it was the same time I started ROing.

19000

[raptorfan85]

Wnybassman, what are the percentages on the bottles? Just curious.

[maple flats]

I'll take a guess, they look like they could be the % of light transmission based on what a Hanna Checker says. That is a great way to grade syrup, it takes lots of guess work ( deciding if the sample is lighter, equal to or darker than a temporary grade sample bottle is) out of grading.
If that's the case 75% or more is Golden, 50% to 74% is Amber, 25% to 49% is dark and less than 25% is very dark. In all cases the flavor must be representative for that grade

[johnallin]

In my 20 years of doing this, I never had a dramatic lightening of color like this mid season. Perhaps it was conditions, but it seems awfully coincidental it was the same time I started ROing.

19000

While I don't doubt that an RO will make lighter syrup, in this case it may have been the conditions.

It was March 20-21 this year that we made the lightest syrup of the season. It made no sense at all; we went from dark to light, then progressively got darker again. I've not seen that in 13 years, but it was fairly common around here in NE Ohio last year. That is certainly some nice looking syrup you made there.

[wnybassman]

I'll take a guess, they look like they could be the % of light transmission based on what a Hanna Checker says. That is a great way to grade syrup, it takes lots of guess work ( deciding if the sample is lighter, equal to or darker than a temporary grade sample bottle is) out of grading.
If that's the case 75% or more is Golden, 50% to 74% is Amber, 25% to 49% is dark and less than 25% is very dark. In all cases the flavor must be representative for that grade

That is it exactly :)

[wnybassman]

While I don't doubt that an RO will make lighter syrup, in this case it may have been the conditions.

It was March 20-21 this year that we made the lightest syrup of the season. It made no sense at all; we went from dark to light, then progressively got darker again. I've not seen that in 13 years, but it was fairly common around here in NE Ohio last year. That is certainly some nice looking syrup you made there.

Thanks, and conditions could very well have been the case. It sure didn't make any sense though lol

[DrTimPerkins]

It was March 20-21 this year that we made the lightest syrup of the season. It made no sense at all; we went from dark to light, then progressively got darker again. I've not seen that in 13 years, but it was fairly common around here in NE Ohio last year. That is certainly some nice looking syrup you made there.

That can happen some years, and is more related to the seasonal patterns. Interestingly it is related to the extremes.

It could just be higher flows after a freeze resulting in a good ice scrubbing and flushing of lines, resulting in better sap quality and lighter syrup.

Alternatively, it can arise from excessive fermentation in the lines and poor sap quality. While the sap can look terrible, the fermentation lowers the sap pH so much that there is less "alkaline degradation" that happens during evaporation (and less niter formed), so the syrup ends up lighter (it doesn't always taste the greatest).

In the first case the season may keep going for a while with the syrup light, then progressively dark again. In the latter case, the season is probably close to being done.

Another possible explanation is that you changed something else along with adding the RO...better filtering perhaps or the sap was processed faster. Either of those could result in lighter syrup and are not a direct result of the RO, but rather are indirect effects.