Proctor Research advice on eliminating metabolism really works

[heus]

On the U of Vermont Proctor site there is a paper by Dr. Tim and others about eliminating metabolic taste. I tried this with my last 5 gallons this season. It had a strange taste similar to wet cardboard. I followed the instructions and heated my syrup to 235 (thats fun with a 5 gal batch, lots of near foam-overs) and then added potable water slowly to bring it back to density. I was delighted to find that the cardboard taste is gone, and now the syrup has my favorite grade B taste. Im keeping it for myself.

[Gary R]

How the heck did they figure that one out?

[heus]

There is a research paper part 1 deals with how they found it part 2 looks at 4 attempts to eliminate it.

[Wardner in Tewksbury]

It had a strange taste similar to wet cardboard.

I'm glad I read this thread. I would have characterized the taste as similar to washing my socks in a sap bucket.

I only boil off two or three gallons of sap at a time. I have done it about ten times this season. I only make small batches of different candies but have never been satisfied with the taste. I thought my taste buds were not working properly. I left a sample tray down at the local garage and the owner said everybody liked it but it was way too sweet for seconds.

I hope my taps have another two gallons in them at this point. I will try the water dilution.

[jasonl6]

Do you have a link to the Article?

Jason

[DrTimPerkins]

Do you have a link to the Article?

Jason

Both are on the UVM Proctor Maple Research Center webpage located at http://www.uvm.edu/~pmrc/ in the "Recent Publications" area along the right edge of the page.

Direct links:

Metabolism Off-Flavor in Maple Syrup: Part I Identification
http://www.uvm.edu/~pmrc/off-flavor.pdf

Metabolism Off-Flavor in Maple Syrup: Part II Remediation
http://www.uvm.edu/~pmrc/off-flavor2.pdf

[DrTimPerkins]

How the heck did they figure that one out?

By understanding maple syrup chemistry. The papers describe the work. Doing it wasn't particularly cheap though. Each analysis costs $500-$1,000, and we had to do a bunch of analyses to narrow it down. This particular off-flavor compound, once identified, is volatile (evaporates) at a reasonably low temperature. By boiling the syrup to a very high density, it drives off (most of) the off-flavor compound. At the same time, the high temperatures form other "good" flavors to help mask the little off-flavor that remains. Dilute back to syrup and you're good to go. You end up with a very dark, strong-tasting syrup, but with far less metabolism off-flavor. Warning....your building and clothes and everything else around will have that off-smell when you're done until it dissipates.

[Kev]

Nice site Doc!
I read untill way too late last night though :D

[pelz]

i came across this post yesterday and it seemed to have paid off. my last batch of 2.5 gal smelled what i thought may be buddy, but it tasted good, but it stunk. what would i have to loose, i followed the recipe and the stink is gone, the taste improved, and didn't gain to much color. thanks a bundle!!

[Kev]

Doc you guys do a lot of great research! Thank You.

[Webbs Mills]

Just made some fudge with some slightly buddy syrup :razz:. After the preparation I didn't notice the buddy odor or unpleasant flavor in it. The high temps called for in the recipe accomplished the same thing.:cool:

[markct]

yea i was wondering about making candy from buddy syrup if it would have the same effect??

[PerryW]

yea i was wondering about making candy from buddy syrup if it would have the same effect??

I tried making candy from buddy syrup, not the metabolic tasting syrup, but the true buddy flavor. The candy tasted lousy.

[Webbs Mills]

Well I guess I'm unsure whether I had buddy sap or metabolic sap. I boiled 24 or so gallons of freshly collected hard maple sap last Saturday, maybe 4 gallons of which was kinda cloudy. It had a slightly "veggie" smell while cooking. The end product was sweet and mapley, but with some off flavor I can't describe. Next time I'll always ditch the cloudy sap. Funny how in my first season sugaring I went from making the best tasting syrup I've had to some of the worst.:razz:

[SeanD]

Doc,

Thanks so much for doing this. I have about 4 gallons that might be a worth while candidate for this process and it would be great to improve it. I'm glad the simple heating method was pretty effective because that's the only one I'll be able to do. Also, thanks for the safety tips about stirring and adding water. I did not know that.

Did the process have to last 3 hours to be effective or was that just how long it took to get to 240 in the canner?

Does the length of the boil or the temp. have to do with how strong the off flavors are?

I have to admit, I'm a little nervous about bringing that much syrup up to 240.

Thanks,
Sean

[killingworthmaple]

Very interesting reading. Thanks Dr. Tim so much for your work. The question that came to mind is, do you think using an RO and not boiling the sap as long as the old slower way increases the likelihood of off tasting syrup

[DrTimPerkins]

Very interesting reading. Thanks Dr. Tim so much for your work. The question that came to mind is, do you think using an RO and not boiling the sap as long as the old slower way increases the likelihood of off tasting syrup

Of producing off-flavors, definitely not. Of detecting off-flavors that happen to be there....maybe slightly. Less chance of detecting off-flavors when you make darker syrup....the increased flavor intensity can mask slight off-flavors.

[Big_Eddy]

So the question that came to my mind immediately was "what creates the metabolic taste" in the first place? What went wrong, what was different, what do we change in the process to avoid it?

I've had a couple of batches with an off flavour over the years - I think it is caused by letting "almost" syrup sit for a while (overnight) warm. Doesn't happen when it's cold overnight, and doesn't happen to finished syrup.

But I'm interested in what the research team thinks causes the metabolic off flavour.

[DrTimPerkins]

So the question that came to my mind immediately was "what creates the metabolic taste" in the first place? What went wrong, what was different, what do we change in the process to avoid it?
.

First off, what is referred to as "metabolism" by some people -- probably isn't true metabolism. What we mean by metabolism is typically early-to-mid season off flavor in otherwise good (often light-colored) syrup. Often you don't notice it much when making the syrup, but later on when you open the drum the taste is there.

The cause(s) are uncertain, but seem to be related to environmental conditions (weather, soil) and sometimes genetics of the stand. Very cold winters without thaws seems to produce more metabolism. The compound itself is a pyrazine, which forms from the action of nitrogen-rich amino acids in sugar solutions. So if those particular amino acids are abundant in sap, and haven't yet dissipated (no thaws), then we collect the pyrazine precursors in the early season. When boiled, they produce the particular compound with this objectionable flavor.

It is more common now because we collect in tubing. If in buckets, the precursors had some time to volatilize off, and didn't form the off-flavor. They can't volatilize in tubing, so end ups in the sap in the tanks, which we process quickly, forming the off-flavor.

No way to predict it. No way to get rid of it before you make the syrup. Often you don't even realize you have it until later. Some years it is very prevalent....most times it isn't. Almost impossible to blend out as it has a very low odor and taste threshold.

Buddy is definitely NOT the same off-flavor, although the way in which it forms is similar, just at the end of the season instead of the beginning. We haven't tried this process with buddy syrup (yet). Fermented or sour sap is also not the same thing.

[OneLegJohn]

Would "bubblers" in a sap tank aerate the sap enough to volatilize it? Kind of an accelerated bucket scenario?

[DrTimPerkins]

Would "bubblers" in a sap tank aerate the sap enough to volatilize it? Kind of an accelerated bucket scenario?

It would help, but probably not enough. We tried it.