Can I eat... Puffy cornbread mix?
April 29, 2020 11:00 PM   Subscribe

Bob's Red Mill brand cornbread mix. Sold in a plastic bag. Unopened. Best by July 2019. Has been in the freezer for... 2 years? Took it out a few days ago and discovered the package was fully puffed up with air. How do I know if it is safe to eat?

It contains baking soda and baking powder, so maybe that caused the puffiness over time? But I've also heard other mixes like Bisquick can be really unsafe if you go well past their date.
posted by rouftop to Food & Drink (7 answers total)
Normally I'd say puffed up food packaging indicates bacterial activity, and it should be discarded. However, bacteria need moisture to live on, and also can't live at freezer temperatures. But I have another theory...

Was it fully puffed up with air when you took it out of the freezer, or only after you warmed it up?

Because when you put it in there, all the air in the bag got smaller, creating a partial vacuum. If the seal on the bag is even slightly imperfect, over two years maybe new freezer air got sucked through it to replace it. In that case, when you warm it up again, that air would expand and would no longer fit comfortably inside the package, causing it to swell out
posted by aubilenon at 11:12 PM on April 29, 2020 [10 favorites]

If it was in the freezer, it seems very unlikely to me that it's unsafe. If it wasn't puffy there and became puffy when you took it out, my guess is that the cold air still trapped in the bag expanded as it warmed. The baking soda/powder may have become less effective, however, so it might be a good idea to add a bit more if you decide to use it.

As far as other such mixes go, the idea that they are unsafe past the date is mostly about whether they pick up mold or other things from the environment, from what I can tell. If it was stored sealed in the freezer, you shouldn't have a problem.
posted by Aleyn at 11:13 PM on April 29, 2020 [4 favorites]

I'd guess that the air in the original pre-freeze package had a modicum of water vapor content. On freezing that would frost up and form bigger crystals. On defrost those crystals would melt and be more like a localized wet. When the baking powder got a concentrated dose of wet from the melt (instead of just a bit of water vapor in the air) it some of it activated.

I doubt it's unsafe from being bought and frozen. But the freezing / thawing cycle may have messed with the wet-activated bits of the mix.
posted by zengargoyle at 1:16 AM on April 30, 2020 [5 favorites]

Good food can’t become unsafe in the freezer, ever.
Even the highly conservative USDA says: Food stored constantly at 0 °F or below will always be safe.

Use it and enjoy but be prepared for the quality to suffer a bit. Worst case is if it doesn’t rise at all, but you can still crumble it into soups of stews.
posted by SaltySalticid at 4:55 AM on April 30, 2020 [6 favorites]

I had puffy larabars, and when I searched, I found out someone else had contacted the manufacturer via Twitter, and they knew exactly what had gone wrong (and advised against eating them). So you could always contact the company and ask.
posted by FencingGal at 6:31 AM on April 30, 2020

I would not think twice about baking and eating this. As SaltySaltacid said, the quality can suffer but the food will be safe. Worst case scenario is it tastes gross (it may taste like the inside of your freezer now!) and you throw it out.
posted by fiercecupcake at 7:22 AM on April 30, 2020

I think it's just going to taste it worth it?
posted by biscuits at 11:25 AM on April 30, 2020

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