I like to make noodle soups. Chicken noodle, pho, k'tieu, soba, and so on; there are many different types of noodle involved. In every case, if the soup goes into the fridge, the noodles absorb all the broth fairly quickly. Typical fixes for this include:

  • cook the noodles separately and add to the soup when serving;
  • freeze the leftovers;
  • eat all the soup right away!

But when I buy canned soup from the grocery store, the noodles are never blown up and they don't seem to blow up even after opening the can and leaving summer in the fridge.

What is the secret? Is it a special kind of noodle, something about the broth or a heavy duty industrial preservative at work?

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    @Unheilig note that "healthy or not" is completely off topic here. Different people have different feelings about current food industry practices, but debating them ends in nothing but flamewars. And talk of "natural" vs "chemical" makes no sense under any consistent definition of the words anyway. So, I'm deleting the debate here. – rumtscho Dec 16 '14 at 22:44
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    What's your ultimate goal here - just to know what companies do, to preserve noodle soups without canning, or to home-can noodle soups? – Cascabel Dec 16 '14 at 23:10
  • @Jefromi Mainly curiosity. Figuring out a way to keep noodles from blowing up in leftover soup without going through the trouble of freezing or canning would be great, but I expect it may not be feasible for a home cook. – Air Dec 17 '14 at 4:27


I've been looking up canning, as I suspected it had much to do with the process of noodles not absorbing all the water. I've found this tangentially related post and quoting:

You CAN can pasta yourself. It is not difficult but, like the commercial caners [sic] you will need to make sure it is high acid (they add flavorless citric acid) but using a red tomato sauce works just as well.

I have also found this very interesting set of ideas:

The idea is simple and genius: combine par-cooked noodles, a bit of vegetable base, some raw sliced veggies, and a few seasonings inside a jar.

Partial cooking

On an article about partial cooking which has some good ideas on par-cooking. I suspect this, combined with the above factors, as well as vacuum-sealed canning, is what allows for noodles, and vegetables/potatoes, to not absorb all the liquid.

Dig deeper

If you wish to dig deeper, I have found a scientific paper by American Association of Cereal Chemists specifically on the topic of liquid absorption by noodles:

Noodles. V. Determination of Optimum Water Absorption of Flour to Prepare Oriental Noodles

  • The acid makes sense -- for some items (eg, potatos & onions), they won't soften when they're cooked in too acidic of a liquid. – Joe Dec 25 '14 at 11:38
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    I strongly disagree with the quoted claim that citric acid is "flavourless". It's the citric acid that's entirely responsible for the sour component of the taste of citrus fruits. – David Richerby Apr 10 '15 at 15:41

I had the same question tonight. After looking at the ingredients of Campbell's Chicken Noodle Soup, I'm guessing that using an egg noodle instead of pasta might be part of the answer. Another part, possibly in addition to the citric acid already mentioned, is the sugar in the broth. Sugar pulls water to itself, making it important in preserving jams and jellys. That action would hold some of the liquid in the broth and out of the noodles. Salt does the same thing. Maybe that's why canned soup is so high in both sugar and salt.

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