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?

  • 1
    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
    Commented Dec 16, 2014 at 23:10
  • @Cascabel 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
    Commented Dec 17, 2014 at 4:27

4 Answers 4


Canned noodle soup manufacturers use alkaline noodles that can include the following ingredients:

  • Hylon (High-amylose corn starch): reduces swelling and cooking loss.
  • MTGase (Microbial transglutaminase): affects solubility and hence gelation, emulsification, foaming, viscosity and water-holding capacity, which all depend on protein solubility.
  • Alkaline salts (9:1 sodium and potassium carbonate): affect the flavour and texture of the noodles, and makes them feel slippery in the mouth and on the fingers. The alkaline salts can produce white or yellow noodle colour.

Initially the pH of commercial alkaline noodles, depending on the salts used, is typically within the range of 9 to 11. After retort processing, the formation of acidic Maillard reaction products during heating in the presence of reducing sugars will cause the pH to fall to approximately 7 to 8.5. The pH fall and the attainment of yellow colour in alkaline noodles containing Hylon is caused (in part) by amino acids (lysine and glutamine) which are involved in cross-linking reactions.

Reference: https://onlinelibrary.wiley.com/doi/full/10.1002/fsn3.667



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
    Commented Dec 25, 2014 at 11:38
  • 5
    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. Commented Apr 10, 2015 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.


They use a high alkaline noodle…. It has a “slippery” coating to it when cooked… that coating eliminates the ability of broth absorption into the noodle.

  • 1
    interesting. Do you have any references to back your answer up?
    – Luciano
    Commented Jan 11, 2022 at 10:01
  • 1
    Concur. This seems pretty speculative at best. How are alkalinity and "slipperyness" connected?
    – gnicko
    Commented Jan 13, 2022 at 23:45

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