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Why does pure maple syrup need to be refrigerated afer opening?

The stuff is like gold..........I know.

I purchase a large container (for a small fortune mind you) and transfer it to a pourable container so that the family does not over-pour on their breakfast plate. Usually, the larger container holds about twice the smaller so there's often actually 2 containers of syrup in the fridge.

But..........for some reason, the last person to fill the pour-able container put the 1/2 empty jug back in the pantry by mistake. I have no idea how long it had been there so begrudgingly, I had to pour it all out.

The family all argued that since it smelled and looked fine, it should be OK. I showed them all the "refrigerated after opening" label but also questioned what is in pure maple syrup to go bad??

I stuck by my philosophy "when in doubt.......throw it out" but am curious if anyone has the answer??

(PS. there was no swelling or expansion of the container and did not make a "release of gas" sound when opened)

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  1. It doesn't have sufficient sugar in it to keep it from getting moldy. But if it's not moldy it's gonna be fine.

    2 Replies
    1. re: Will Owen

      What Will says. And even if it has some growth on top, you can skim it, boil it, skim again whatever floats, and the rest will be fine. Oh well.

      1. re: Will Owen

        If it gets mold on the surface, skim it off with a spoon, no big deal.

      2. I kept it in the pantry for years, then I had a gallon of it go moldy. I now store it in the fridge.

        1 Reply
        1. re: pikawicca

          I keep mine in the fridge now too, due to a mold incident with the last third of a bottle. It didn't look moldy but it sure smelled it. It's expensive but it's so worth it.

        2. As others have said, you can store it at room temperature, but it may go moldy. But if you find some white stuff on the top, you can skim it off, boil and strain the syrup, and still use it.

          1. The Maple Syrup Cookbook cautions against long-term storage in a tin container, because the tin can impart a metallic flavor to the syrup, and may rust. It suggests refrigerating in glass, and freesing in glass for longer-term storage (over 6 mos.), since plastic is air-permeable so can affect taste. As already mentioned, if there is mold it should be strained out, then the syrup boiled and rebottled in clean glass.

            1. The short answer is because microorganisms like bacteria and mold like dark, sweet, room temperature things.Maple syrup has no "preservatives", which actually are agents to prevent the microorganisms growth. And just because you can't see discoloration or smell anything doesn't mean it isn't there - it takes lots of the critters to make a visible spot. Sorry to waste the syrup but you did the right thing. (Too many years as a nurse to ignore contamination questions.)

              1. Because it crystalises... and grows green stuff! I assume that refrigerating it slows down both undesirable processes. They do say that the mould is harmless, and once it's scooped out the rest of the bottle is still good to go.

                PS. It's a real shame that you threw the rest of the container out before you asked about it! It would have been perfectly good still.

                1 Reply
                1. re: Kajikit

                  If the mold is allowed to develop it destroys the flavor. If it's got just a few spots on the surface you can strain it and then heat it to a simmer, let it do that for a bit, then cool it. The way to correct crystallization is the same as with honey: set the bottle (uncapped) in a pan of water, bring the water just to a boil, and leave it there for a while.

                2. I have never stored maple syrup (pure or otherwise) in the fridge, and I have never had it go bad.

                  2 Replies
                  1. re: FitMom4Life

                    You've been lucky. With the price of maple syrup these days, I'm taking no chances.

                    1. re: FitMom4Life

                      Only happened to me once, about 25 years ago, that was all it took to teach me a lesson.

                    2. all I know is that I pay a pretty penny for the real stuff and I would *WEEP* in despair if it grew any mold...so it's easy for me to follow the darned directions and keep it in the fridge!!!! I only buy 9 ounces at a time but it's pretty expensive!

                      1. I came back from Canada with a half gallon. I never put it in the fridge, just stored it at room temperature (which could get pretty hot in the summer).. I had it two years, and it tasted perfect every time I used it. I definitely got my money's worth!