Metabolism

[tpathoulas]

Calling Dr. Tim or others with way more experience than me.
I am curious about metabolism. I recently read that not cooking sap long enough causes metabolism. I also read that metabolism is caused by the sap the trees are producing. I made some syrup last year that tasted good except it had a little off flavor that would linger on my palate after swallowing. The syrup also was clear when hot after filtering but as it cooled it became cloudy with sediment that settled to the bottom after a couple of months. Would somebody please provide a simplistic(if possible) definition of metabolism and best way to avoid it, inless it is solely from the trees?
Thanks

[raptorfan85]

Metabolism is from the trees. There's nothing you can do about it. It's not something that you can filter out or boil off. It will smell like old socks while boiling it. If you get sap the has metabolism the only thing you can do is dump it or maybe make sugar or candy with it.

[Goatogether]

Speaking of this... We ran 20 gallons thru our small arch when it came off last week. We gather it in a 275 g tote that held simple syrup at one time. I should also mention that our operation is new, with new lines and equipment, and newly tapped 150+ trees.so we took the 20+ gallons and ran it thru the prefilter of our RO and passed it thru our concentrate tanks and into the evaporator, so we were able to check for leaks and fix them. Boiled it down, got it down to an amount we could do on the finishing pan. My sugarin* partner boiled it down to the heavy side, testing thick at 72 brix. We added some distilled water and got it to 68.5 and called it good. Ran it thru our homemade vacuum filter and put it in a couple of containers for testing. What we came out with is that it has little to none maple flavor. It’s color and clarity are beautiful, it’s a nice reddish amber and tests right at Grade A Amber Rich, 59% Tc. When you taste it, right at first, on the front of the tongue you get a slight taste that could be brown sugar, super light molasses, maybe very very light burnt or plastic essesnce? It’s only there for a second, and when you really think about it or keep following up with it, seems something in the molasses family. The texture, mouthfeel and viscosity is all good. Brix right at 68.5. We used the Off Flavors kit that UVM sent out, and tasted the Sour Sap sample. It did have some similarities to that, but no after taste, nothing that lingered on the tongue, just that first second of taste on the tongue. I don’t know if you all might have some feedback, but we didn’t add defoamer, the sap was fresh. I did notice that the finishing pot had 2 black egg sized scorch marks on the side of the round pot. I wasn’t there to know how big of a flare up or how long it took to make that mark on the pot, but could that cause the slight off-ness? It took quite a bit to scrub it off...ANY ANY help would be appreciated! Ellen

[Super Sapper]

Metabolism is caused by chemicals produced by the trees. My experience is that is tastes fine while hot off the evaporator but after is cools down it has a terrible aftertaste. The sock smell while cooking is more with buddy syrup.

[buckeye gold]

My experience is metabolism usually occurs early in the season and will go away. It can be slight or bad, with various after taste. Mine has always had a metallic or plastic taste that lingers. The only way to fix it is make candy or sugar or you can take the syrup to 245 degrees and readjust the density with distilled water to 68.5 brix. The responsible chemicals gas off at 240-245. Your not doing anything wrong, just a natural thing. For the cloudyness, you'll just have to filter an extra time. Some years there's a real fine grain to the nitre

[DrTimPerkins]

If you get sap the has metabolism the only thing you can do is dump it or maybe make sugar or candy with it.

Metabolism is from certain types of nitrogenous amino acids in trees that occur rarely. Some bushes seem to be more prone, but sometimes it occurs regionally. It appears to be associated with certain weather that occurs in some winters. Typically it is an early-season phenomenon. No way to tell (easily) if it is in the sap. Frequently people will make syrup they think is fine, but when they open the drum later they will smell/taste it. The intensity can be lessened by a certain process, which simultaneously producing more "good" flavor compounds. The process makes the syrup darker though. Different people have very different taste/smell sensitivities to the off-flavor.

It will most likely still be present in candy or sugar. Some of the worst candy I've ever had was metabolized. Just awful.

Any chance that you've fertilized your woods or have a lot of crop fields nearby where they heavily fertilize (with nitrogen)?

More info at:
https://mapleresearch.org/pub/m0209metabolismoffflavorpart1/
https://mapleresearch.org/pub/m1009metabolismoffflavorpart2/

[Goatogether]

Thanks for the feedback everyone. No fertilizer nearby. I went thru our 275 gal totes that we use for gathering and did see some leftover simple syrup that was stuck in a glump in a corner. Could that have caused it? I got it cleaned out, but could that have been it I wonder?

[tpathoulas]

Thanks all for sharing your knowledge. Our bush is part of a 120 acre pasture. It is heavily fertilized by 175 black angus in the summer and fall. we do have crop fields on the north boundary. My in-laws do use fertilizer but the majority of our trees are 100 yards away. Some are closer. Again, thanks for the info.

[blissville maples]

Metabolism is caused by chemicals produced by the trees. My experience is that is tastes fine while hot off the evaporator but after is cools down it has a terrible aftertaste. The sock smell while cooking is more with buddy syrup.

Yes, dirty sock or pukey smell is due to sour sap. I've had great experience with this from using plastic sap tanks that can't fully be emptied, and it WILL only happen at the end of season.....you can smell it in the sap prior to boiling

Taste the sap, sometimes this can be an indicator of what the syrup will become.

Do you use ro? Wonder the effect on flavor of not rinsing all soap or acid out??