High Concentrate, Dark Syrup

[Amber Gold]

The past two season, we've been making an effort to concentrate higher, say mid-teens, on a regular basis. I do recirculate to get it there, but it's usually only for a couple hours from start of RO to boil time, so the sap's not sitting around and getting warm. We've also noticed our syrup color has darkened significantly...have been barely able to hit a medium before it drops down to a dark for a while. I hadn't put much thought into the cause just thinking that some years are darker than others. The syrup flavor is excellent, just darker than what it tastes. I'd like to go back to making some lighter grade syrup, but also don't want to concentrate less...more time boiling=more wood burned One solution is to install a bubblemaster, but I'd prefer not to build one or listen to another blower going (main reason). I know plenty of people are boiling in the teens and not using bubblers. Is there something I should be doing differently? Are there other options for lightening syrup?

On a side note, I've always recirc'd even when going to ~8%, and used to make lighter syrup. Also, the past two seasons, I've also noticed a lot of niter in the syrup pan float box...guessing this is correlating to niter in the flue pan and darker syrup.

Thanks for the help.

[eagle lake sugar]

Last year my first boil was April 6th. and we had nothing but dark and extra dark all season. Everyone in the area that I talked to had the same situation. I attributed it to such a late season, but maybe we're in for the same thing this year? It looks like I may have my first boil tomorrow so I guess I'll find out. I recirculated last year and sent it to my head tank at 12% to 14%. This year, I'm concentrating to around 6% into a tank and running it back through to 14%, I'm curious if I'll see a difference in syrup grade.

[doocat]

We started out recirculating in the big tank and over the last few years we have gone to two pass concentrating. High flow one pass to a concentrate tank, maybe to 5%. Then we recirculate for a short time and put up in the head tank at 15%. We have been making all light this year. Last year was darker syrup and the year before was all light throughout the season. Not sure if this helps but we feel it is more streamlined this way. We never put any concentrate back into the raw sap tank so when we decide to call it a night we just cook out the head tank.

[mellondome]

How often do you clean your pans? High concentrate will build up niter and sand faster. If not kept clean,it will make darker syrup.

[Amber Gold]

Thanks for the responses. I just have one sap tank to run sap/concentrate into before it goes to the feed tank. This year, like last year, was a lot of small runs which means short boils. This year though we've had a couple days of decent runs where we're firing for a few hours, but still can't get the grade into a medium. I wonder if it has something to do with only boiling once, maybe twice a week, so far this season.

Going on almost 100 gal of syrup and haven't cleaned the flue pan yet. I generally go about 300 gal on the syrup pan, but I also run the syrup pan through the filter press every night. Even at 300 gal, the syrup pan isn't bad at all.

[unc23win]

Interesting Josh I was always told that ROs make the syrup lighter (or at least get blamed for it) because of less cooking time. I know first hand that the longer the evaporator sits idle the darker the syrup in it gets, but sometimes it will get lighter again. For me I generally take a sample about draw #2 (to look at) for the day and then about draw #5 or 6 (the one I keep). Sometimes it is lighter on the second sample. I always thought that syrup was lighter some years than others because of the sap composition. I have heard of some who filter their flue pan to change gradient but I have never tried it.

[mellondome]

Short boils will make it dark as well due to being exposed to heat for long times.. start up and cool down.

[WESTVIRGINIAMAPLER]

Sitting in evaporator for week between boils won't help it either.

[ennismaple]

I thought I read somewhere (Dr Tim post?) that concentrating using RO will generally make lighter syrup but around 8% concentrate it will make slighter darker syrup because the heating effect of concentrating is not offset enough by the reduced boiling time.

[Brian Ryther]

did you wash your tubing before season? Sounds to me like a lot of dead yeast / bacteria build up left over from the tubing system. That would account for the sludge in the flue pan and the darker syrup.

[Amber Gold]

I forgot that both this year and last year were both a lot of short boils, and concentrating higher isn't helping things. I was thinking that concentrating higher was leading to darker syrup, but maybe it's just been the nature of these past two seasons. I do need to take the time the wash and clean the flue pan. Maybe that'll bring the grade up a bit.

Hey Brian, m I've never washed the tubing. Pull taps under vac. Tubing is mostly clean even after five years, and the first bit of sap gets dumped.

[TRAILGUY]

going from 2 1/2 to 9 one pass. never add concentrate to raw sap. only boiled 3 time this year sweeten pans, 1 gallon amber last 4 1/2 gallons amber but lighter. Poor job on tube cleaning replace some . Have not cleaned pan yet. completely drain all concentrate every time and flush with a little raw sap. Buyer waiting for dark

[Amber Gold]

Do you think sap depth would impact the grade? The previous owner ran it 0.75" in the flue pan and I think 1.5" in the syrup pan, and I've done the same. I used to run the old Grimm at 1" and 1.25" and made light syrup.

Drained the flue pan last night. Sludge like niter layer on the pan, but not baked on. It'll come right off with a permeate soak and a hose. Filtered syrup and it has color, so caramelizing sugars. Been so long since I've boiled without an RO, not sure if this is typical or not...forget if some caramelization occurs in the flue pan or if it's all in the syrup pan.

Thanks again.

[nymapleguy607]

This sounds like complete bass ackward logic but have you tried to run the evaporator at a lower stack temp? I have an arch very similar to yours and I know they will put out tons of heat, perhaps too much in your case. If you are blasting the pans with too much heat perhaps that is why you are getting so much carmalization in the flue pan, there just isn't enough water in the sap to keep the sugars cool and not carmalizing. Maybe by not hitting the pans with as much heat it would keep the sap from coloring in the flue pan.

[maple2]

Letting sap sit around even for a day or two, tends to make darker syrup.

[GeneralStark]

did you wash your tubing before season? Sounds to me like a lot of dead yeast / bacteria build up left over from the tubing system. That would account for the sludge in the flue pan and the darker syrup.

I suspect there are several factors at play here, but I think Brian is onto something. I made dark robust my first and second boil this year and I didn't run sap on the ground the first run. I do rinse my tubing at the end of the season with 50/50 water vinegar mix, but there is still lots of slime that comes down the lines. Last year I made nothing but fancy (even with the wrong GD sample) until the very end of the season with a brand new tubing system. Perhaps due to the slow onset of the season, the tubing has been slower to rinse?

Last night I made the first golden delicate of the season, 60 gallons in, everything else has been amber rich after the first 5 dark gallons. It came close to GD for a day but then went a bit darker for a bit and now up to GD. I think in my case this has been related to boiling infrequently and sap sitting in the pans,and alternating between boiling raw sap and 9-10% concentrate. Now that the season is really here I suspect I will be consistently concentrating so it will be interesting to see how the grade evolves.

The length of time the sap is stored is certainly a factor as well, and the temp. the concentrate is brought up to by recirculating. I assume you have a temp. gauge on your ro so how high is the temp going?

I suspect that after you clean the pans, now that the season is going and the tubing is likely rinsed, your grade will lighten up. If not, I would suggest buying a glucometer and reading this study if you have not already.

http://www.centreacer.qc.ca/uploaded/Publications/109_En.pdf

[Amber Gold]

When recirc'ing, the sap temps have been staying below 40 degrees. I don't pay too much attention to it, but will confirm tonight.

Grade is back up to almost an amber rich after the rinse. Last night, I tried running the syrup pan shallower, but found out the float bottoms out during a draw and almost had a situation. Now I remember why I run it about 1.5" deep.

At this point, if there was any old sap in the lines, it's long been cleaned out. We collected 1gpt from morning to late afternoon pickup...it was running pretty good yesterday:)

Stack temps. I keep them around 700-750 degrees during a firing cycle. I add more bottom air to maintain this range. When temps drop below 650, I add more wood. Generally getting about 15 min load times.