Does Using an RO change the flavor of the Syrup Produced?

[TuckerMike]

Sorry if this is a recycled post. I did a search and haven't come up with an answer to my question...so here goes:

I bought an RO this year and start using it half way through the season. Previous to using the RO my wife loved my syrup. Now, she says the flavor has changed and doesn't like it as much (...or maybe at all)

The RO was not new and the membrane was stored in a solution of Meta-Bisulfate. I rinsed the membrane a lot before using it. At least 50 gallons, maybe more.

My theory is that the sugars in the sap don't stay in the arch nearly as long (6-8% concentrate) and are not caramelizing as much. I went from 3hrs per gallon to producing 1.25 gallons per hour using the RO. The syrup produced is definitely lighter with less robust of a flavor.

I can see what she means in that the flavor has changed, but I don't think it tastes bad, just different.

Thanks for your feedback.

[crashmjsapman]

It sounds to me as if you did not put enough water through the membrane when rinsing. we put 1000 gallons through our new ones this spring before we we used them for sap. but they also were 8 inch membranes. i would recommend washing and rinsing with the recommended amount of water. In previous posts of this there is no significant change in your syrup taste.

[WestfordSugarworks]

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

No.

But taste is so subjective and we will convince ourselves something tastes different when we know it was produced in a different way. So does it really taste difference to you and her? Yes. But if you do a scientific study like the one attached you will find no difference.

Another thing to keep in mind is that you've had the RO only for one season and season to season variation could be causing your perceived difference in taste. Or another factor could be changing things.

[maple flats]

How many gallons an hour RO did you get. If it was stored in a preservative, you need to run a soap wash then a cold permeate rinse for the same amount as the RO does in an hour. If it is a 250 GPH, use 250 gal of permeate. When you have no permeate yet, use soft well water or municipal water, but let it set vented for 2-3 days to vapor off the chlorine.
If it was not stored in a preservative it may have funky all thru it, you might need a new membrane.
An RO if run according to manufactures instructions an cleaned properly will not change the taste.
What make RO is it? What size?

[TuckerMike]

The RO I have is made by Memtek. It was modified, at some point, from a 21" membrane to a 4x40" membrane. It passes 100gph through the membrane at 500psi.

I was not told I had to wash the membrane first, just rinse it, so hopefully that is not the source of issue. I've put about 1500gal of sap through it this year and the taste didn't change over time. I rinse the membrane with about 50gal of permeate after each run. I'm new to the RO world, but I would think if the membrane had residual storage solution in it, that taste would fade over time.

The meta-bisulfate solution it was stored in was very apparent when I opened the tube, so I doubt there is any funky stuff that was growing on the membrane. I do have soft well water, so I can definitely do an extended rinse on the membrane. But unfortunately my season is over, so I don't think there's much testing I can do this year. I should probably run a few hundred gallons of straight well water through it and see if the concentrate or permeate lines produce any off-flavors.

There definitely is a difference in taste. I'm not going to say it is a bad taste, just different from what we produced prior to introducing the RO.

Any other suggestions?

[DaveB]

I feel like this topic was discussed from about every angle in another thread...deja vu I guess.

I know syrup flavor can change from season to season and even during the season. Last year we made some of the best tasting syrup I've ever had but this year it is different. The approach I would take is to look at all the variables. Since you started the year without the RO, does that syrup get the stamp of approval but syrup after that does not? Like others have mentioned, were the membranes properly cleaned? I've read several posts from producers who said that affected their flavor.

Personally, after having read the studies on the matter I would look at factors outside of the RO itself.

[TuckerMike]

I feel like this topic was discussed from about every angle in another thread...deja vu I guess.

Sorry for re-hashing an old topic...I tried finding other threads that spoke to this topic, but didn't find what I was looking for. If you know the link to the thread you referenced in your replay, please share it. Thanks.

I know this season's sugar content has been lower than last year. My wife thinks the non-RO syrup from earlier this year tastes better. I know that is very subjective. Just trying to get a plausible explanation and possibly find out a cause for off-flavors in case I'm inducing some.

Thanks again for the feedback.

[maple flats]

The off taste is from an issue with the membrane, a clean membrane does not affect the taste. I suggest you contact MES, they will help you get the membrane right, they are good folks and easy to work with. When you run the 50 gal of permeate thru after running the RO, how do you have the flows set? On my RO I need to balance the flows so both flow meters are essentially equal in GPM. Watch the scales, if they are not the same, you want equal concentrate and permeate flow. With both meters using the same scale that is easy, but some RO's have a different flow meter on each with the concentrate a finer scale and the permeate a more course scale. At any rate, when flushing with permeate run2 time, once for 5-6 minutes pushing the sweet into the head tank to boil, then flush for 10 minutes minimum on recirculate, sending both the concentrate flow and the permeate flow back to the wash tank. At that point, do what MES tells you, my RO is bigger but a more basic RO, so they may not be cleaned the same.
One thing mine requires at first of season, is that I run a cold water flush for at least 30 minutes, sending both flows to drain, then I fill the wash tank with clean hot water (113F max) add soap (use what MES says) and then do a 10-15 minutes wash cycle, followed by a cold rinse for 10 minutes. Then I change to pre-filter and it is ready to go.
If you want send me your email to: dave@cnymaple.com and I'll send you a copy of my manual and my proceedure. You must however realize the our RO's are made by different companies and the membranes are not the same. While my method works extremely well on my RO, it may not be right for your RO. I think the main point I finally ended up using in cleaning my membranes is that, except for the time prescribed to push the sweet to the head tank, I extend all other times. If the manual says 10 minutes on a step, I do 15 sometimes 20, then on mine after the wash cycle it says to run a cold permeate rinse for 5 minutes, I usually do 10-20 minutes. Then be sure to change the pre-filter.
I do not do a daily acid wash or soap wash, I just clean in season with permeate, heated to 113F in the wash cycle followed by a old permeate rinse for 10 minutes or more. If MES tells you otherwise, you will be smart to follow their instructions.
Good luck, and do not give up on the RO.

[TuckerMike]

Thanks Dave. The instructions for my RO have me close both valves, for concentrate and permeate, when doing the rinse. So the flow meters are out of the flow path during the rinse. I do extend the times that my manual says for doing the rinse, but certainly I could extend them more.

My issue with going back to the mfg. is that the original membrane is no longer installed. I'm not sure who did the mod from 21" to 40" membranes, so I'm sort of on my own as to what to do. I hate to "start over" with a new membrane, given the cost, but maybe that's my best option to make sure the membrane isn't the cause.

[VT_K9]

I believe Dave has the correct answers. The membranes should have been washed and rinsed or better rinsed, washed, and then rinsed again. We have a 250. We use about 100 gallons for the first rinse. Wash. Then rinse with the other 150. We do a wash cycle at the beginning of each year and try to have an longer rinse cycle at the end of the year prior to the storage solution. Our membranes are tested by CDL and they are above 100%.

You maybe in the market for new membranes.

Mike

[maple flats]

The membranes are likely savable, send them for professional cleaning. Lapierre, CDL and maybe others do it for far less than a new membrane.

[DrTimPerkins]

I agree. Send the membranes in for professional cleaning and testing. They'll be able to either clean it as best possible, or recommend replacement.

It is likely that the initial lack of washing/rinsing of preservative and then inadequate washing/rinsing during the season contributed to your off flavor. So the answer to your original question is yes, in your case RO did change the flavor of the syrup produced, but only because of self-inflicted issues.

Think of an RO membrane like a dishcloth in your sink. It's exposed to a lot of stuff during use. If you keep using it and are really good about rinsing it off each day, then it'll stay reasonably fine for quite a while. If you don't rinse it after each use, then it'll start to stink (due to microbial growth on the cloth), and you'll need to use a lot of clean water and really rinse it extremely well to get it back to just being OK, but it'll still stink a bit each time really fast as it is used. The other approach is to wash it either every now and then or even daily to keep it as clean as possible. If you never wash it....it is going to really stink and will not get your dishes very clean (your concentrate will stink, your RO will run slowly, and your syrup will taste bad).

[mellondome]

With that much sap through them, any"junk" is long gone from the membrane. But going from dark syrup before the ro to much lighter syrup with the ro.... there will be a big flavor difference. Not directly caused by the ro, but because the syrup is not spending as much time in the pans. Part if the reason for the new grading system is to incorporate taste. If she likes the flavor of darker syrup, cut some with water and reboil.

[Haynes Forest Products]

My 7" Mark 1 cost $225.00 last year for a cleaning and comes back with a report and new U cup gasket. My RO saved me around $4500.00 in fuel expenses and hundreds of hours in boiling time.

[wiam]

Guess I don’t see putting cost of professional cleaning into a 4” membrane that can be replaced for a little over $200. If I was the only one to have run it maybe but not if previous use is unknown.

[n8hutch]

I was thinking the same thing.

[Russell Lampron]

Guess I don’t see putting cost of professional cleaning into a 4” membrane that can be replaced for a little over $200. If I was the only one to have run it maybe but not if previous use is unknown.

My thought exactly. I usually get 2 or 3 seasons out of my 4" membrane and just buy a new one when I can't get it clean enough anymore.

[TuckerMike]

Thanks for all the replies. I did rinse the membrane after each use and permeate flow always returned back to its initial flow of 1.2 to 1.4gpm (with 0.5gpm concentrate).

I haven't had any complaints about the taste, other than my wife, but since I don't know the history of this membrane, I think for "insurance" purposes I'll just buy a new membrane and start afresh next year.

[wiam]

Thanks for all the replies. I did rinse the membrane after each use and permeate flow always returned back to its initial flow of 1.2 to 1.4gpm (with 0.5gpm concentrate).

I haven't had any complaints about the taste, other than my wife, but since I don't know the history of this membrane, I think for "insurance" purposes I'll just buy a new membrane and start afresh next year.

Are you making sure the pressure is the same when checking flow? You also need to correct flow for temperature. The more permeate you can rinse with the better.

[TuckerMike]

I adjust pressure each time I adjust either the permeate or concentrate flow. I check it regularly throughout the run.

I'm not sure what you mean by correcting the flow for temperature. I didn't read that in the manual. Can you explain what that is?

[Michael Greer]

Insisting that the RO does not change flavor is like saying there's no difference between light and dark syrup. Let's all reel that rhetoric back a bit and work on this man's particular problem.

[DaveB]

Insisting that the RO does not change flavor is like saying there's no difference between light and dark syrup. Let's all reel that rhetoric back a bit and work on this man's particular problem.

The majority of the posts are doing just that. That discussion was practically beat to death in another thread.

[GeneralStark]

Insisting that the RO does not change flavor is like saying there's no difference between light and dark syrup. Let's all reel that rhetoric back a bit and work on this man's particular problem.

It seems to me that his problem may be with his wife's particular flavor preferences. Like most things in sugaring we will likely never know what's going on in his situation unless we can all taste the syrup and see exactly what he did to make the syrup.

I will say however that not washing a membrane with an unknown history at the beginning of the season is certainly not the best idea. Dr Tim summed up why that is very adequately.

[wiam]

It seems to me that his problem may be with his wife's particular flavor preferences. Like most things in sugaring we will likely never know what's going on in his situation unless we can all taste the syrup and see exactly what he did to make the syrup.

I will say however that not washing a membrane with an unknown history at the beginning of the season is certainly not the best idea. Dr Tim summed up why that is very adequately.

I will definitely agree. My first ro (used) I was told by a dealer to rinse with rated flow. I made 2-17 gallon drums of fancy color syrup. Nastiest syrup I ever had in my mouth. Washed and was fine after that.

[TuckerMike]

I will definitely agree. My first ro (used) I was told by a dealer to rinse with rated flow. I made 2-17 gallon drums of fancy color syrup. Nastiest syrup I ever had in my mouth. Washed and was fine after that.

THAT is what I am worried about. I am new to using an RO and followed the instructions given by the seller. I'm thinking that maybe I should have washed the membrane before using it, just to be safe. I'm fairly confident that I properly rinsed it after each use....but if it started out out funky, rinsing would not have been enough.

I had some other folks do a taste test today and they didn't seen anything wrong with the syrup flavor that came from the RO. That tells me my wife's interpretation could be very subjective. However, to be safe, I may just buy a new membrane and start over.

Again, thanks for all the input...and sorry if this is a re-hashed post.

[hawthwood]

I had a guy evaporating my sap for six years that used RO.
The syrup was good, but this year it was done the traditional way on a 2x4 continuous flow pan, without RO,
The flavor, is a lot different, more "maple" flavor. Call me crazy, but I'll never go back to RO processed syrup. The new "fast" ways of a lot of things aren't always better.

[wiam]

I adjust pressure each time I adjust either the permeate or concentrate flow. I check it regularly throughout the run.

I'm not sure what you mean by correcting the flow for temperature. I didn't read that in the manual. Can you explain what that is?
Lot of good info here. What I’m referring to is benchmarking your membrane. And where I buy membranes.
https://www.mapleexperts.com/membranes/

[Cedar Eater]

I'm not sure what you mean by correcting the flow for temperature.

The reading on a flowmeter is scaled for a particular liquid at a specific temperature. In this case, it's probably for water at 60F. The reading will be inaccurate for concentrate (because it's not pure water) and for permeate (unless the temperature is 60F). So there are calculations that tell you what to set the flowmeter to in order to get a temperature or density corrected flow rate.

[TuckerMike]

Lot of good info here. What I’m referring to is benchmarking your membrane. And where I buy membranes.
https://www.mapleexperts.com/membranes/

Thanks Wiam. That website was helpful.

[Super Sapper]

The flow shown on the meter should be accurate no matter what the temp. Temp. correction for benchmarking would be for different flow velocity at different temp. If you benchmark your membrane at 45 degrees and get a certain flow rate you would have less of a flow rate at a lower temperature as it is harder to push through the membrane but would still indicate a clean membrane. I do not know the correction factor for temp in a membrane but would think it is somewhat different for each type of membrane. Temperature and pressure are the 2 variables you need to either match or compensate for.

[wiam]

Thanks Wiam. That website was helpful.
Correction table on that site is for MES membranes the table in Lapierre’s literature is quite different. But a lot of membrane info there.

[GeneralStark]

I had a guy evaporating my sap for six years that used RO.
The syrup was good, but this year it was done the traditional way on a 2x4 continuous flow pan, without RO,
The flavor, is a lot different, more "maple" flavor. Call me crazy, but I'll never go back to RO processed syrup. The new "fast" ways of a lot of things aren't always better.

How does one define "the traditional way", and how can you be certain that it was the use of an ro that lead to the change in flavor you describe?

[Haynes Forest Products]

When it comes to cleaning and rinsing you machine its like brushing your teeth and then sipping a fine wine YUK. Next time rinse your mouth out real nice with water and take a few moments and then try it.