Sour Sap/Syrup?

[Amber Gold]

I skipped a day boiling to do RO maintenance, and when I boiled again last night, the syrup was coming off the evaporator kind of foamy (really the best way to describe it because it didn't look like a stream of syrup), the syrup temps were all over the place, and the grade lightened up from 35% to 57% during the boil. It was definitely off-flavored, but I need to try it again to tell you what it tasted like. The sap was definitely cloudy, but it didn't look too bad. The buds look OK. Tanks get cleaned after every collection. Sap temp was in the 50's going through the RO on the first pass, high 50's on the second pass. Concentrate didn't sit around.

Long and short, I'm trying to figure out if the off-flavor is from sour sap (or something else), if I should keep collecting, and will the bad syrup get pushed out of the evaporator and start making good syrup again? Sap flows just haven't been good this year, so I'll be stuck boiling every other day to get enough sap to process. I'm not interested in continuing to make bad syrup, but interested if things will come back around. This week's temps look good with nights around 30F and days in the 40/50.

Thanks

[Sugarmaker]

I would recommend keep making syrup. It may change back to better syrup. It may have been on the edge of ropey syrup. At least thats what it sounds like to me.
Regards,
Chris

[DrTimPerkins]

If the sap run is low and it moves very slowly in the tubing system (or sits in the bucket for a while), it can ferment and turn sour. Let it run on the ground for a bit and clean your tanks.

When/if the sap starts running well again, let it flush out the tubing a bit, then start collecting again. You might have to dump the pan contents and resweeten the pans if it was real bad.
Concentrate and boil a little (after the tubing system is flushed out a bit) and taste it. If it still is off-flavored...probably time to stop. If not...you're back in business.

[maple flats]

I had a similar situation 9 days ago, sap 2 days old, and warmer than desired, sap got up to 51 degrees. Then during the boil I had to shut down to clean the front pan. during the cleaning I did not drain the pre-heater or the cold sap float box. When we restarted, about 1 hr. later, as the concentrate had been in the pre-heater and that float box worked it's way to the draw off channel everything changed in a hurry. I made ropy syrup, it plugged the piping from the draw off box and the auto draw solid. As it cooled it got hard like hard candy, what did flow at the beginning of the problem thru the auto draw, into the draw off tank it set up hard on the bottom of the draw off tank.
We ended up dumping the rest of the sap we had, then concentrate, the contents in the evaporator and what had made it into the draw off tank. Then we washed everything, tanks, RO entire evaporator, all piping, the auto draw valve and the draw off tank. Then we collected fresh sap and resumed making good syrup.
One thing we now do but had not done before is as we shut down the preheater and the cold sap box get drained, then dumped into the still boiling flue pan, then we let the float box refill from the flue pan. That way it has boiled and killed any bacteria rather than setting for awhile at the perfect temperature for bacteria to multiply rapidly.

[CampHamp]

One thing we now do but had not done before is as we shut down the preheater and the cold sap box get drained, then dumped into the still boiling flue pan, then we let the float box refill from the flue pan. That way it has boiled and killed any bacteria rather than setting for awhile at the perfect temperature for bacteria to multiply rapidly.

I think that’s a good strategy. I pump the float 20 times or so by hand to mix the new sap into the flue pan when I shut down (I open both intake tubes first to get a faster heat exchange).

[Amber Gold]

Thanks for the quick input everyone.

Dave, crazy that it changed that quickly! At shutdown, I drain both the preheater and float box and dump them into the flue pan.

The woods tank was pumped pretty much dry and cleaned at yesterday afternoon's pickup.

It's a lot of work to drain/clean the evaporator during the week. Usually something I reserve for the weekend.

With sap flows at 1/2gpt/day or less, I may just call it. A lot of work for maybe 1-2 more boils before we're back in the 60's this weekend, and the season's likely over.

In the future, is there a way to tell if the sap is sour before A. I collect it, or B: I boil it?

[DrTimPerkins]

In the future, is there a way to tell if the sap is sour before A. I collect it, or B: I boil it?

A) No, but if it is barely trickling in for several warm days, I'd suspect it might that way.
B) Not really...unless you want to measure the pH or fermentation level...and even then, it wouldn't tell you precisely.