What makes syrup spoil? what did i do wrong?

[ninety6]

I had my first try at maple tapping last year -- Question? My last batch of last winter, boiled over fire outside, then finished in a pot on the stove.. probably around 8 pints, i put in canning jars with metal lids. It had a few bits of ash in it from the fire. I had a few other jars boiled inside on the stove completely (smaller batches). They self-sealed the lids as they cooled. It was delicious maple syrup when put in the jars. ALL of it -every jar- turned near-black and had a terrible taste/small after 4-6 weeks (stored at room temperature in a dark cabinet). Clearly spoiled. Maybe soured/fermented? Even a couple I had in the fridge.

What went wrong? How do i prevent that this year? (though sap flow so far is much less than last year, I may not have much...)

Here's more details: I have 3 decent maple trees, 5 total taps. i was collecting with plastic taps and tubes into gallon milk jugs. I'd collect it every 2-4 days and boil down what i had on the stove. Great tasty syrup, generally a 40:1 to 45:1 ratio. I'd strain (metal collander, not filter) it, boil it, and be done. Boiled to 217 degrees. Put in jars (initially syrup jars, then glass canning jars). when we were eating it as fast as we made it (within a week or 2) we never noticed any problems. (I did not filter sap or syrup, so we regularly had some niter at the bottom).

I did notice towards the end of the season the milk jugs had a couple spots of presumably tiny bits of mold, as did the tubes. Would have thought boiling would have killed any mold, so i wasn't too concerned.

I did some searching on the internet, but couldn't really find anything about syrup spoiling. Just thinks about how it shouldn't spoil, or if mold grows on it to pick it off and maybe re-boil it. I didn't have anything growing on the syrup. Just black in color.

Thank all!

Collecting in food grade white buckets this year, and will be cleaning them occasionally.

[MapleCamp]

Sounds like it was not finished, I go to 219.

[Goggleeye]

I would agree - not finished. Everything you described - the ash, mold spots in the milk jug, not the best filtering, all describe my first year, but I took my syrup to 219 or a little past. To make a long explanation short, if you get your syrup to 219 or past, it can't spoil, with the exception of mold growing on top. Once you hit that 219 point, the sugars are so concentrated, the water activity is reduced to the point that bacteria and yeast can't reproduce.

[tcross]

get a hydrometer and you will never have spoiled syrup again. if it is finished to the right consistency it'll keep for a very very long time. just going off of temperature will not always get you "finished" syrup! My syrup finishes at different temperatures pretty much daily/each boil! anywhere from 218 to 222

[buckeye gold]

My syrup finishes at different temperatures pretty much daily/each boil! anywhere from 218 to 222

This true. The only thing you done wrong is not go far enough. I second the motion to get a hydrometer. Don't worry, you have a lot of sap coming. I'm an hr east of you and the main season is just starting. When did you tap? If your going to go by temperature alone go to 220 and you'll be safe. You'll have more nitre but it won't spoil. If nothing else filter it through a Tee shirt

[ninety6]

Thanks all! Sounds like a pretty good concensus that i really just needed to boil it down just a tad further. Thinking now i think i did go to 219 last year -- i used the number all over google, which looking now is 219, i just remembered wrong when posting. however, if my cheap amazon thermo was even 1% off, then i didn't go far enough. I'll look into a hydrometer -- open to recommendations for an accurate/affordable one.

I will aim for a couple more degrees this year with everything and see how it goes!

I tapped in 2020 and 2021 on January 1. I know it's a little early, but i had a buddy that recommended it. Last year, I had pretty decent sap throughout January, and it boomed in February to probably double or more of January....

I know it's been a dryer winter than last year -- does that affect sap quantity much? or really just the temperatures?

Thanks!

[ecolbeck]

That one won't work. You definitely want one specifically for maple syrup as it is far more dense than beer wort. Have a look at this one:

https://smile.amazon.com/Maple-Syrup-Hydrometer-Moisture-Calibrated/dp/B07D6W3MBR/ref=sr_1_3?dchild=1&keywords=hydrometer+maple&qid=1611880159&sr=8-3

[ninety6]

That one won't work. You definitely want one specifically for maple syrup as it is far more dense than beer wort. Have a look at this one:

https://smile.amazon.com/Maple-Syrup-Hydrometer-Moisture-Calibrated/dp/B07D6W3MBR/ref=sr_1_3?dchild=1&keywords=hydrometer+maple&qid=1611880159&sr=8-3

Thanks for the quick response! I realized that pretty quickly and deleted my post before i saw your response. I ordered a syrup-specific one and watched a youtube video on using it. pretty simple. Hopefully better luck for me this year!

[ecolbeck]

I think the other thing you might look into is getting a hydrometer cup to perform the measurement in. Again, it's an added expense, but doing the job with the right tools is better in the long run. No more spoiled syrup. Another thing to be aware of is that density is affected by temperature and the measurements on the hydrometer are made at specific temperatures. There are charts for temperature corrections. It can get a little tricky managing the moving parts but you'll get the hang of it.

[ninety6]

I ordered the cup too!

I really am curious if i boiled to 217 or 219 last year. I do remember checking boiling water temp, and my thermometer registered right at 212, and i new i had to go 7 degrees higher. I may have just made a mental mistake with the last few batches. no telling.

Should be on track this year. Looking forward to trying again! A friend of my wife just bought a big wooded lot so maybe next year we can do some more tapping - need to get out there and check out their trees this summer!

[berkshires]

So assuming for the moment that you did go to 219, your syrup (or nearly-syrup - sometimes 219 is not quite to syrup) would not have gone bad so fast. Maybe you did go to 219, and there is another possibilty:


i put in canning jars with metal lids. It had a few bits of ash in it from the fire. I had a few other jars boiled inside on the stove completely (smaller batches). They self-sealed the lids as they cooled.

Check the inside of the lids of those jars. Do you see any sign that the plastic coating on the lid failed, and the metal rusted? A tiny bit of metal getting into it could absolutely turn it black and nasty. I've seen that happen, especially if the jars were used for something acidic before like tomatoes or fruit.

Gabe