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The question was prompted by running out of suitable sized plastic boxes for some home-made hummus, so I used a couple of old jam jars. This was for freezing, but it got me thinking.

I assume a simple recipe of cooked chickpeas, tahini, garlic, lemon and spices, such as this one from Felicity Cloake at the Guardian (which happens to be the recipe I roughly follow).

Hummus is normally sold refrigerated, but is there any (safety) reason why it couldn't be canned? Obviously any form of canning means that the final product gets cooked, but the chickpeas are already cooked and the other ingredients shouldn't suffer too much (the garlic will mellow, for example). Ideally I'd think of water-bath canning, but I'm not sure if the pH is low enough. Pressure canning would also be interesting but only in an academic sense as I'm not equipped for it.

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No, it is not safe to can hummus, even with a pressure canner. The problem is that it has a paste consistency, and the temperature has trouble penetrating through the middle of the jar. No safe home canning process has been established which can consistently reach the required temperatures.

You can buy canned hummus, but that's no contradiction. Home pressure canners operate at nominal 10 PSI, while industry has access to different equipment.

Some people go around the problem by canning everything that goes into the hummus whole - so a jar of chickpeas, seaseme seeds (not the ready tahini!), spices and lemon juice in liquid. They stick a blender into the can after they open it, to make their hummus. That's a safe practice, since you can can chickpeas on their own.

  • To my mind the last paragraph defeats the object -- it ceases to be portable if you have to take a blender with you. But different solutions for different people I suppose. Does canning normally rely on convection? – Chris H Nov 5 '18 at 13:29
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    @ChrisH In pressure canning, you rely on the fluid phase of the food to get hot enough to heat each solid chunk individually, just like in a soup. So you certainly have convection happening in jars of, say, canned beans, besides the conduction. For pureed items, the viscosity prevents convection (or atl least slows it down a lot). There is research which has created whitelists of pureed items which are safe to pressure can, like some tomato sauces, because they produce known viscosity and the processing time has been measured to be sufficient. I have never found such recipes for hummus. – rumtscho Nov 5 '18 at 14:09
  • Thanks, the point about suppressed convection in pastes was what I was thinking of. Conduction will of course get there in the end but then you've effectively pressure-cooked the outer layers of the food, so it's probably ruined by the time it's provably safe. – Chris H Nov 5 '18 at 14:17

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