First time with a bad off taste in finished syrup

[tgormley358]

I finished two gallons of syrup yesterday, my 6th or 7th batch this season which have all been great. I always taste the final product right out of my stainless 16"x16" flat filter canner when it's still warm, after bottling. I bottle directly from this rather than store and bottle later as I hear some do. I took a pretty good gulp of very clear, amber syrup, and didn't have an immediate reaction, but several seconds later a bad aftertaste which first struck me as sharp and I couldn't identify it right away but maybe in the category of a cleaning fluid like soap. I couldn't get this yuk taste out of my mouth for hours after. I brought it right to my wife and had her taste without saying anything to prompt her -- i just said could you taste this. She said it tasted good but it she did notice something, and i think her first description was like cardboard. She also said maybe a little soapy taste. I've since read multiple past posts here back to 2011 and 2014 on metabolized syrup, "buddy" sap and syrup, and other off tastes). I'm trying to figure out what i got, how it happened, and what to do with both the finished syrup and what's left in my pan (new 2x5 raised flue evaporator this year).

Starting from the end of the process and then back to sap collection and storage:
- I happened to take an opportunity to clean my syrup pan the Monday night before, for the first time this season. I had no reason to do this other than it seemed like a good time to do it. I drew off all syrup from the pan into a 2-gallon SS pot, and left it covered with a SS cover on the floor of my sugar shack. I started cleaning the pan with just hot water from the tap, and a sponge. I could feel a sticky layer of niter in the middle and final channel of the pan, so i tried a nylon brush. That didn't seem to help much, so i found some powdered pan cleaner I purchased last year from Bascom and used successfully in another evap. I let it sit, then scrubbed more. It wasn't all coming out but i didn't want to clean all night and figured some niter left on the bottom wouldn't be a problem, so i emptied it, rinsed with hot water, then filled it again and added baking soda, stirred, let it sit, and then sponged it all over the pan. I drained it, rinsed again twice, dried it with paper towels. I put it back on my evaporator that night, dumped my almost syrup back in, and boiled for 2 hours then went to bed. The next day everything looked cool from the night before. I had 75 gallons in my tank to boil. An hour later i was drawing off syrup, and had no indications from the smell of steam or the syrup drawing off, of any problem. Poured it into my flat filter, and started bottling into glass. After bottling just under 2 gallons with just maybe a cup left in the filter pan, I poured into a cup and that's when i got this bad taste. Never tasted it before. I smelled the filters and inside the pan -- same as the bad taste.

I wondered about the paper and felt filters. I'd cleaned the pre-filters a day earlier when i found them in a bag with a little mold in them. But I'd already used them to finish syrup after cleaning that day, and tasted it with no problems, so I can't believe they would be the source of the problem. But anyway my cleaning process was -- Soaked them in a 3 gallons of hot water with maybe a cup of bleach, then scrubbed them a bit and rinsed them three times in hot water. Like i said i used them after this and the syrup tasted fine, so it doesn't seem likely and I'm all but ruling it out.

So the potential problem sources at this point seem to be either the syrup pan cleaning i did monday night, or a problem with the sap i'd collected, or storage of the sap before boiling. The weather here in MA has been great lately, and I'm boiling daily from last friday through yesterday tuesday. This is mid-season here (started a month ago), so it's neither early nor late which this forum said is when metabolism usually happens. We did have two 65-70+ degree days in February, but it hasn't hurt my syrup and I don't see buds on the trees yet. Sap was a bit cloudy during that time but i've since boiled it all and finished the syrup which tasted great although cloudy. The last several days I've been collecting in a poly 210 gallon pickup tank, pumping up to 100 gallons into my SS head tank right after collection, and then boil within the next day.

Does this sound like metabolism? or caused by niter in the bottom my pan? Or something went wrong in my cleaning job? A combination? I can't figure it out, and wonder if i should drain and toss what i've got in my pans? So far i'm just setting aside the 2 gallons of this syrup. I've tasted the boiled sap in my flue pan and it seems fine. The almost syrup now in my syrup pan tastes questionable to me, like the same off taste, but my wife insists it tastes OK. Tonite i'm going to taste test the off tasting finished syrup against a prior bottling to be sure about the off taste. I'll let you all know what i find from that. Really appreciate any input on what to do with what's left in my pans, as the weather is still good and I hope to make another 10 gallons before the season's over.

[tgormley358]

...Sorry for the long post...I just know you all have good questions so thought i'd try to provide for most of what you'd likely ask.

[mainebackswoodssyrup]

Our first batch of 1.5 gallons from about 100 gallons sap was off flavor this year. Sap set through a 60 degree and 50 degree days for a total of 5 days. Smelled and tasted fine as sap and when boiling. Did the taste test at syrup and had a slight aftertaste. Your cardboard analogy comes to mind. It was slight but enough to go cooking grade. Hoping that was the fault of warm weather. We'll finish our next batch this weekend and boil some more of what we got this week. First time I remember not detecting it in the sap.

[cabinetcap]

Couple years ago I had similar issue. My syrup tasted almost like the felt filter smells when hot. Filter appx. 2 years old, cleaned and stored properly. I do a taste test before filtering and was fine, seem to pick up the taste after cone filter. My wife also said it was fine,but I know it was off. Since then i buy new filter every year. Not sure if thats your problem. Im in central ma, do not notice metabolism.

[Russell Lampron]

It's probably metabolism. I always taste my syrup before it goes into the canner. I have never had an off taste but if I did I would put it in 5 gallon plastic drums to be sold as commercial.

[tgormley358]

Well, i did a taste test last night of the off-tasting batch with an earlier batch that tasted good. The bad batch is definitely off. My wife says it tastes good except for a cardboard taste, but i still taste more of a sharp, acidic, chemical taste that sticks in my taste buds.

I have a new plan though, based on input from a sugaring friend in town with many more years of experience. He tasted it tonite and said it didn't taste metabolic, but it is off. He couldn't quite identify it, but when i explained that I had cleaned the syrup pan just before boiling that night monday, using a powdered pan cleaner to loosen up the niter, and that I still didn't get all the niter out, he said he thinks maybe some residue of the cleaner got stuck in the remaining niter, and that's what caused the off taste. Thankfully he also suggested cleaning my pans again using permeate from his RO, so i've filled the pan several inches with 7-8 gallons of it and leaving it over night. He thinks it'll be loosened up enough to remove the niter by tomorrow, so i can boil tomorrow night. I'm hoping he's right.

The directions on the pan cleaner container are rubbed out so i can't read them, but if i'm not mistaken you're supposed to mix it in and heat to a boil in the pan being cleaned, vs. just using hot water which I poured from my tap monday night. Lessons learned. Hope i can report back soon that all's well. Meanwhile, i'm deciding whether to toss the bad stuff, or use it for cooking, or make sugar. Selling it commercial probably isn't an option since i only have 2 gallons of it. Live and learn...

[buckeye gold]

This seems to be a year with more metabolism and I think that is what you have. I started out with some metabolism in my early syrup, but it cleared and made some of the best syrup later on. I wholesaled mine to a guy that new what he was getting, it still makes good BBQ sauce and cooking additive. Proctor Maple Center has an article on resolving metabolism and it's causes. I read the article and to summarize it: heat your syrup to 238-240 and have distilled water ready to bring it back to proper density. The extra heat gases off the responsible chemical compound. I never tried it, but I will in the future if I have metabolism. I assume you have to add the water before it starts to cool or you'll have Maple caramel.

[DrTimPerkins]

Proctor Maple Center has an article on resolving metabolism and it's causes.

http://www.uvm.edu/~pmrc/Off-flavors...metabolism.pdf
http://www.uvm.edu/~pmrc/off-flavor.pdf
http://www.uvm.edu/~pmrc/off-flavor2.pdf

I read the article and to summarize it: heat your syrup to 238-240 and have distilled water ready to bring it back to proper density. The extra heat gases off the responsible chemical compound. I never tried it, but I will in the future if I have metabolism. I assume you have to add the water before it starts to cool or you'll have Maple caramel.

The process both helps to remove (volatilize) the responsible off-flavor compound, and develop stronger (darker) good-flavor compounds. It will reduce the off-flavor to some degree. With light-metabolism it can do a good job. With heavy metabolism it reduces and masks it somewhat, so repeated boiling/water addition is necessary to get the off-flavor to a low enough level to be acceptable. Be aware, because the compound responsible for the poor flavor (dimethylpyrzine, a naturally-occurring compound) is detectible (by many, but not people) at very low threshold concentrations, that simply mixing good-tasting syrup in with metabolized syrup will likely just produce more bad-tasting syrup. It is a real bugger to blend this flavor out.

You don't want to walk away from the boiling pot when you do this. The density is so high that it can go to black char very quickly.

A similar process has been developed for buddy. Many people confuse the two (metabolism and buddy). An off-flavor kit demonstrating the difference between the three common natural off-flavors (buddy, metabolism, sour sap) has been developed by UVM Maple Extension, and is available through some maple associations.

[Sugarmaker]

Dr. Tim has great information.
After reading OP I think you have done your best to list the possible causes.
My first guess would have been buddy, but you say your only mid way in the season, so then I would guess metabolic. Which can occur at any time in the season not just the end.
You should be able to smell the metabolic (off aroma) in the finished cold syrup.
If your filters are in question (moldy) replace them and also check syrup taste before and after filtering next time. I had this issue once and the wife caught it pretty quick. I thought the filters were still OK they were not.
I think you have done a good job with your analysis of the issue.
Let us know about next batches. Smell the steam while boiling too, it may have a indication of a off flavor.
I would not think the cleaning process caused this, but keep a open mind.
Regards,
Chris

[tgormley358]

Thanks - i've read through Dr. Tim's articles on things to do with metablized syrup. They are helpful, having a studied source of knowledge is a huge help in addition to everyone's individual experience here. This saga continues and at least for me isn't reaching a clear conclusion, but i'll report what i've found since a couple days ago, when i tried soaking in permeate water over night. That was thursday, so yesterday i checked it out after 20 hours and saw some loosening up but not a lot. I fired it up to give it some heat to help along, to a low boil for just 20 minutes or so, then let it sit a couple hours. Again some of it came off but there's still a pretty dark niter stain in two of three syrup pan channels (see picture attached).photo of niter in pans March 18.jpg

With some improvement i boiled new sap yesterday to see if the off taste would go away. I had left the boiled sap in the flue pan, so i opened the valve to flood the syrup pan with that, and fired it up. For a few hours i was feeling confident with steam aromas, but after 5 hours when I starting shutting it down for the night I took a whiff and thought i smelled the same thing as in the off taste syrup. I haven't tasted it yet, but i fit is, then i haven't really narrowed it down further -- either it's something in the syrup pan (my local sugaring buddy thinks) or it's metabolism as most on this forum seem to think.

I took one more step today, took a gallon of new sap from my head tank and boiled it inside on the stove. My observation and my wife's is this is good syrup like i've been making since last month, so this seems to be helpful info indicating the problem is in the pans -- right? In addition, the color is a fairly typical medium brown, vs. the color of the off taste syrup i made monday, and what's in my syrup pan now is more amber, a hint of reddish in it.

At this point i'm going to continue boiling and see what i get, and if it's still off tasting then either make sugar with it or pack it as bulk commercial.