Recently I realized that traditional 3-4 mil plastic vacuum bags actually permitted a lot of water to pass through the bag, resulting in dried fruit becoming rubbery. A small bag of dried fruit would suck in a couple of grams of water over just a few weeks!
I decided to try packing dried fruit in 5 mil mylar bags to see what would happen. By the numbers mylar food bags should permit very very little water or oxygen to enter the bag. (Each bag had some desiccant packs and an oxygen absorber in it too.)
Let's see what happened.
This is not an attack on your favored storage method.
After 3-4 months the amount of bag weight gain that I saw was very low, 0.0 g to 0.2 g. My scale is only accurate to 0.1 g at best though, meaning that it's hard to say how much water ingress there actually was.
I looked at a combination of impulse sealed bags and bags packed at 70% vacuum in a chamber vacuum sealer. Some of the bags were big, some were small. Basically, half the bags showed no change or a tenth gram loss in weight, and the other half showed 0.1 - 0.2 g gain in weight. But what was interesting was that most of the bags that showed a weight gain were the big bags. That suggests to me the weight gain really is due to water ingress, since the bigger bags would allow more water to pass in due to larger surface area. Then again, perhaps the nature of my scale is that its own error is nonlinear.
I used these mylar bags: https://www.amazon.com/gp/product/B0BNK1MLWG
This sealer: https://www.amazon.com/gp/product/B07RRQBKQC
These desiccant packs: https://www.amazon.com/gp/product/B01MPYB16J
The oxygen absorber came with the mylar bags so I threw one in since I had them.
To actually seal the bags, I ignored the ziplock strip, sealing below it--I have seen leaks from the ziplock seams so I just cut it off. I did 3 separate seals with the impulse sealer... Probably overkill, but hey, why not.
With the weight gain pretty much being within the realm of instrumental error, even on bags that were sealed with a cheap impulse sealer, I see the results as good news so far.
Of course, maybe a year from now these bags will have gained grams of water and be full of rubbery fruit. I'll post followups down the line.
-------------------- We have not succeeded in answering all our problems. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things. -- Earl C. Kelley
Things I really wish I knew when I started // Vacuum sealer discussion thread // Shroomery gif zoo
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