What causes sap to turn "buddy" and off-flavor?

[DrTimPerkins]

I wouldn't call whats going on now buddy, but its probably some metabolism going on. With all of the syrup being so light this year, any off flavors will come through. Darker syrup, being more strong, tends to shade out and kill the off flavor, at least up until a certain point. Pretty much happens every year. Rileysugarbush gives a very good analysis.

All correct, but for more clarity, "metabolism" off-flavor is different from tree metabolism (the ramping up of growth processes). Metabolism tends to occur in early-season and in light-flavored syrups, and tends to go away with time. Often (unless it is very pronounced) you won't even notice it until you open up a drum of early-season syrup and reheat it. It is kind of a popcorn, musty-like flavor, and extremely difficult to blend out (very low taste threshold detection limit for many people...whereas some can barely taste it). Buddy off-flavor tends to occur very late in the season, and is often found in dark syrup, but can also occur in light syrup. The two factors (syrup color and buddy off-flavor) come from different things, so they aren't always associated.

Very frequently there is a "pre-bud" stage where there is just the tiniest hint of buddy off-flavor. It is caused by the tree metabolism, but is not called "metabolism" off-flavor. People will sometimes say "chocolatey" or "tootsie-roll" flavor", and you can tell when you start to get that "sweat-sock" odor in the sugarhouse at the end of the season. Metabolism is also known as "woody", but is not at all the same as "buddy" either in flavor, timing, or cause. If someone says metabolism at the end of the season....they mean buddy. As Mark says, in darker syrup it is more difficult to discern until it gets stronger. In lighter syrup you can taste it more.

[canaanmaple]

Very frequently there is a "pre-bud" stage where there is just the tiniest hint of buddy off-flavor. It is caused by the tree metabolism, but is not called "metabolism" off-flavor. People will sometimes say "chocolatey" or "tootsie-roll" flavor", and you can tell when you start to get that "sweat-sock" odor in the sugarhouse at the end of the season. Metabolism is also known as "woody", but is not at all the same as "buddy" either in flavor, timing, or cause. If someone says metabolism at the end of the season....they mean buddy. As Mark says, in darker syrup it is more difficult to discern until it gets stronger. In lighter syrup you can taste it more.

I just ran into this myself. Figured since there was no sign of even buds or swelling, I was fine.... Well the syrup is slightly off enough that I probably won't sell or give away as syrup, but cook with instead. The first perceptions were chocolaty hints, but now I know it's that pre-bud stage smell. The steam seemed to be more off than the taste of the syrup after I let it settle out via gravity filtration. Oddly, it's the lightest syrup of the season too, and my syrup seemed to have gotten lighter as the year progressed.... (unless it could be from increasing evaporation efficiency)

[DrTimPerkins]

Oddly, it's the lightest syrup of the season too, and my syrup seemed to have gotten lighter as the year progressed.... (unless it could be from increasing evaporation efficiency)

Sometimes near the very end and it is warm you can run into an unusual situation where the syrup gets lighter. What the heck? It is actually a good example of the complexity of maple sap/syrup chemistry. When there is a lot of microbial action, the sap can get very acidic. When sap is boiled, as it is concentrated the minerals get more concentrated too, and eventually precipitate out as niter. Niter is primarily calcium and malic acid -- malic acid...as in what gives apples the tart flavor...same compound is in maple sap. As the calcium-malate is getting more concentrated, the syrup gets more and more alkaline. Some very interesting reactions happen in the liquid during this "alkaline degradation phase", which along with caramelization of sugars (mainly invert sugars) due to heat, form color and flavor. BUT...if the sap starts out very acidic, it may never get to the "alkaline degradation phase", thus color and flavor formation is retarded. You end up with a very flat, light-colored and mild-flavored syrup. Occasionally it can also be sour and have a weird mouth feel (almost fizzy). It isn't because of much of anything you did, it is merely that there was a lot of microbial action in the sap.

[mspina14]

It is caused by a suite of amino acids released by meristems (mainly buds) in conjunction with bud swelling.

So as the leaf buds are starting to swell, the tree releases a suite of amino acids into the sap that causes "buddy" flavor?

What role do these amino acids play in the health of the tree? Are they necessary for the tree to create leaves?

Just wondering about the timing of all this. Like why doesn't the tree release these amino acids during the time of the year when we collect sap?. Or maybe they're present but not in the same concentration?

Thanks

Mark

[DrTimPerkins]

So as the leaf buds are starting to swell, the tree releases a suite of amino acids into the sap that causes "buddy" flavor?

That is correct. Both the types and levels of amino acids change over the season, and a different suite of amino acids is associated with bud swell, budbreak, and leaf growth.

What role do these amino acids play in the health of the tree? Are they necessary for the tree to create leaves?

Amino acids place a variety of roles in tree function. Yes....they are necessary for leaves to grow.

Just wondering about the timing of all this. Like why doesn't the tree release these amino acids during the time of the year when we collect sap?. Or maybe they're present but not in the same concentration?

There are amino acids (and minerals, and organic acids, and hormones....lots of things) in sap during the time we collect sap, but the mix and concentrations change. Not all amino acids are associated with buddy off-flavor.