Water wouldn't get into the syrup, so that's not a concern.

However, while it has a high sugar content, maple syrup is low-acid. I don't know how that plays out in terms of food safety, as I haven't found anything regarding home canning for the hobby producer.

All the resources I've checked (Extension resources like Ohio State and Vermont) do suggest 1) freezing or 2) open-kettle, which was surprising.

Their instructions are to bottle hot syrup (180 degrees) in sterilized jars, filling almost to the very top to assure a good seal. Vermont suggests storing jars on their sides.

So it looks as if your 1 1/2" headspace is the culprit as getting a good seal open-kettle is hard enough without having that volume of air in the jar.

You might want to check these sources yourself as I'm not any kind of expert on maple syrup. If you search for something like canning maple syrup site:.edu that will bring up only educational sites, which generally will be more reliable.

Also check publication dates or revision dates on any Extension documents.

Carol

Thank you for your response, Carol.

I don't think there is any food safety issue when syrup goes bad -- at least, I've never heard of any. It tends to do one of two things -- at times, a mold grows on top. THAT definitely goes down the drain. Other times, it gets contaminated with yeast, and actually turns into mead, or the equivalent thereof, or goes all the way to vinegar. Which, while I personally wouldn't use it that way, shouldn't be toxic.

I had a little type above regarding the headspace -- I only leave about half an inch.

I may try a boiling water bath for a batch and see.

What I do now is the "open kettle" method. Its funny, really, that I pour boiling hot syrup (and remember, this stuff is 219 to 221 degrees on my candy thermometer), put on a lid that came out of hot water, put on a band, flip upside down, all while wearing heavy potholders because its so incredibly hot, and mold or yeast spores somehow survive in some of those jars. Either my technique is flawed or these things are real survivors.

I actually like the idea of freezing it, except for the fact that freezer space is always an issue for me. But, I may make room for some of it.

I also might just take a couple of batches it all the way to maple sugar, which shouldn't be a storage issue if done properly -- cool and dry and it should keep for several years.

Maple sugar is a viable option and would definitely require less space.

I've seen maple syrup mold even under refrigeration. My guess is it's too low a brix - i.e. you can get the syrup to boiling when you bottle it up, but if the sugar level isn't high enough (approx. 66-67% sugar), there's probably enough water in the mixture to contribute to spoilage. In other words, it's kind of like low-sugar jam, more prone to spoilage as the sugar content isn't sufficient to bind the water.

So a boiling temperature per se isn't sufficient to assure longevity. There are other factors at play. You'd need to be sure your maple syrup gets to 7.1 degrees above boiling to assure sufficient water has been evaporated out. Then you can drop the temp before bottling.

Just a guess.

Carol

Are your jars sterilized before you fill them? Also, if you're not reducing the syrup enough, there isn't enough sugar/there is too much water and it will spoil.

Most people here just use plastic bottles, no problem as long as the syrup is 190-200 F when you pour it in. Sounds like you're not reducing it enough.

I do maple sirup and the way I understand it, is that there is a safety concern if it is not concentrated enough. It is low acid. It can be measured with a hydrometer and I actually invested in one because I do bath mine and it sits on a shelf. It is quite safe in the fridge for a reasonable long amount of time (but I'm not sure of how long, right off hand) and the jars can be frozen quite successfully for long-term.

It sounds like we're all coming from the same place - make sure the sugar concentration is sufficiently high.

The sources I read say 180 degrees is a good bottling temperature (in sterile containers) but like jelly it has to reach that magical viscosity and sugar level before it's good long-term. Then it can be cooled somewhat before putting up.

Carol

Yup, I do sterilize the jars first.

We shall see what 2011 brings. Thanks all for your input.

Just an update - we went to largest syrup producer in the state (not far from us), I didn't ask specifically about mold but he said in tour that they get the syrup to 7.1-7.3 degrees above boiling water (so check your altitude but 219-220 sounds right). High-sugar sap at beginning of season doesn't take long to turn to syrup, lower-sugar end of season takes longer so it turns out more brown. But they use a hydrometer to check brix - want it 66-67% sugar. Too much sugar and it crystalizes, to little sugar and it's not legal maple syrup (and I guess it molds, b/c he said they boil the sap the day it's collected, and collect it every day, b/c the high water content is hospitable to bacteria and he doesn't want the bacteria eating all the sugar!).

My mom's neighbor was making a batch on her woodfired evaporator last night, again she gets it to 219, puts it right into hot sterilized jars (doesn't let it cool much I guess - she wasn't jarring it when we were there), inverts them. Doesn't BWB but says that you don't want to allow much headspace at all, fill it right up to the top (?) then invert. But she only makes about 5 gallons a year, donates it to church for pancake supper in April so it doesn't get stored long. I imagine she keeps some for herself (3 gallons or so, she gave us about 12 oz in exchange for jars and blackberry jam), but maybe she refrigerates it. Mu mom just poured it into an almost-empty quart of store-bought (pure, not fake!) syrup in the fridge so she could give back the jar today, so I don't know how it would keep.

"-- at times, a mold grows on top. THAT definitely goes down the drain. "

I skim the mold off and re-boil the syrup.