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Recipe Quest: Shear-Thickening Starch Noodles

April 29th, 2013 · 17 Comments · Uncategorized

by Paul Adams

Last week, the landlord of this blog spotted an intriguing video online of a man in China making noodles.

Look at that. The guy’s got a big bowl of white non-Newtonian goo. When he smacks it or squeezes it, it’s as firm as clay, but when he leaves it alone, it’s fluid enough to drizzle through the holes in his colander. When he drips it into boiling water, it gels up into perfectly lovely, easy noodles. Rheology at work! Can we do that at home?

I tried mixing up a classic oobleckian starch slurry and dribbling it into boiling water. It didn’t hang together well in noodle shapes, and as soon as it hit the water, the starch dispersed and just made the water cloudy. Time for some internet research.

A critical clue came from EatingAsia, where a very appetizing article about a Sichuan treat indicates that the noodles in the video are not rice noodles, as the video caption has it, but familiar glassy noodles made with starch from sweet potatoes.

Sweet potato starch

Sweet potato starch noodles are also popular in Korean cuisine, where they’re called dangmyun and form the foundation of japchae, which I have for lunch at least a couple times a month.

Japchae is a popular dish. Surely the internet has recipes for making your own dangmyun at home, right? Well, not in English, as far as I can find. Every result for my “glass noodles from scratch” searches led off with “Ingredients: one pound dry noodles.” Thanks, English-language internet.

The closest I came was this page, which seems, as far as I can tell from the rather infelicitous translation from the Chinese, to be talking about the same thing:

raw materials: 5000 grams sweet potato starch, alum 35-40 grams, 125-130 grams of cooked qian paste.

Production:

1, the alum research into fine powder, add water, stir well made of 100 grams of alum water.

2, cooked qian paste into the basin, add sweet potato starch, water 2000 grams, alum powder moderately hard and soft water bunched up into groups inactive.

3, with a large aluminum scoop will be used to tool to plug into a soybean-sized hole in the powder group bailer installed, use the palm to make it into the group shot powder into the boiling water, drain lines, pot boiled, and then pick into the Serve cold in cold water floating “water noodles.”

After reading this over a few times, I made a lovely squishy-firm goo using sweet potato starch and alum. This one held together nicely in noodle shapes when I dripped it through a colander, but still, as soon as it hit the boiling water, it dispersed.

I was lacking the qian paste. From my smattering of Mandarin, I know that qián (钱) means ‘money’. Where was my money paste?

The original Chinese is on the same page, below the “English” version. Scrolling down, I found the actual Chinese character is 芡, romanized as qiàn: different tone, different word. It refers to the gorgon or foxnut plant (not to be confused with salep) whose starch is used as a thickener in Chinese cooking.

With no foxnut starch handy, I focused on the requirement that it should be cooked starch. A modicum of starch gelatinized by cooking would add some cohesiveness to the raw goo. Separately heating a portion of my sweet potato starch slurry turned it into a firm, rubbery, translucent off-white glob that reminded me of a giant glass noodle. Now we were on the right track.

It turns out that making fresh glass noodles at home is simple and fun. Why is that such a secret?

photo by Dan Nosowitz

photo by Dan Nosowitz

Update, May 5: in the comments, Hannes pointed out that in China it’s illegal to use alum in glass noodles. Alum is controlled in the EU as well, due to concerns about aluminum toxicity. Click the image at right to see what Kalustyan’s says. I have replaced alum with chitosan in the recipe below, a possible substitution I spotted in a Korean journal. Chitosan, like alum, has a positive charge in water, and it holds the starch network together very nicely. Most commercial chitosan is derived from shellfish, but there’s some made from mushrooms instead.


Drip Noodles

alum chitosan, 1% solution, available from winemaking suppliers
water
sweet potato starch

1. Fill a container with room-temperature water and dissolve alum into it. I only had an alum block, not alum powder, so I didn’t measure the exact quantity of alum that went into my water. But here’s how much it was: enough to drop the pH of tap water from 7.1 to 2.8. I’m not sure precisely what the alum is doing. It’s always used in homemade play-doh recipes, where it’s cited as a preservative but surely serves a textural purpose as well, stabilizing or strengthening the starch’s molecular network.

1. Fill a container with room-temperature water. For every liter of water, stir in 80 ml of chitosan solution. Much more than that and the noodle batter gets stretchy, and starts to become reluctant to drip.

2. In a mixing bowl, slowly stir some alumated chitosanated water into potato starch until it’s got a shear-thickening consistency kind of like the one in the video. It should scoop up cleanly in your hand and almost crumble when you squeeze it hard, but run fluidly out of your hand when you relax the pressure.

3. Put a small portion of the slurry in the top of a double boiler and cook it, stirring occasionally, until it firms up and starts to look translucent. This takes a few minutes.

4. By weight, make a combined goo of 5% cooked starch goo chunks to 95% raw starch goo slurry.

5. Smooth this goo in a blender till it’s uniform and creamy. It thickens with shear, remember, so the blender has a tough job. Add some more alumated chitosanated water if necessary.

6. Scoop some slurry into a colander with big holes and practice dripping it in long filaments. Add alum chitosanated water if it’s too sludgy, or a little raw starch if it’s too thin.

The holes in my colanders are pretty small, so I also tried just letting it drool off my fingertips, which is messy, juvenile fun. You can see in EatingAsia’s picture that the Sichuan cook’s colander has nice big holes. Soybean-sized holes, as it were.

7. Bring a deep pot of water to a gentle boil and drip in long, noodle-shaped strands of slurry.

8. Scoop the cooked noodles out of the boiling water after a minute or so and drop them into an ice water bath. Voila, glass noodles.

Toss them with sesame oil or spicy oil to help keep them separate.

Spicy Noodles

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17 Comments so far ↓

  • Alvin

    This is a clip of how rice noodle is being manufactured. As it turns out, what you said about a high pressure press is correct!

    Here’s a video clip I found using “米粉製作過程” as the keywords.
    http://www.youtube.com/watch?v=tQRLWWRek0o

    You podcast is inspirational! Keep up the good work!

  • schinderhannes

    Hi Dave,
    The magic of alum resides in the trivalent cat-ion of aluminum this can coordinate very well to negatively charged or polarized groups in macromolecule like starch and pectin’s (it can actually coordinate six groups around it).
    That is why it has astringent properties used in medicine (for cuts from shaving), more importantly it is used as a stabilizer for cut fruits to keep em look nice and fresh. (also for glacé fruit, btw the only application it is allowed for in the German food industry).
    I am not surprised that is also does miracles in stabilizing starch noodles.
    Sort of similar as the divalent calcium reacts with alginate.
    But aluminum is very controversial (at least in Europe)! The toxicity (especially of soluble) aluminum and its potential connection to degenerative diseases like Alzheimer are a big thing. (I tend to believe this is overhyped, but still: in patients with impaired renal function acute aluminum intoxication is known, so it is not totally benign.
    It seems that in industrial glass noodle there is always aluminum and some health advocate propose to avoid them for that exact reason….
    I tried to find an aluminum free glass noodle recipe and was successful: unfortunately it is in German written by an Expat in in China. He warns that it is a lot of work and that is why next to everybody buys his galls noodle but still it might be worth a try…..
    TTFN
    Schinderhannes

    Since I am a lazy bum I google translated this for you:
    ******
    • 2 pcs 5 – 6 L stainless steel pots, one with easily removable strainer (one for cooking, one for the cold water)
    • 1 stainless steel pot about 4 L (for the dough)
    • a nice pasta machine with 5 x 1 mm or 2 mm holes slots
    • a thick wooden spoon
    • 1,220 g mung bean starch or
    • 1100 g sweet potato starch and 120 g mung bean starch
    • 1 L of water
    • Thermometer
    The water is heated to 90 ° C and prepare a thin paste with 120 g mung bean starch. This is stirred at 90 ° C for 15 minutes.
    Then the paste is cooled to about 50 ° C, the residual strength is at work and the resulting dough kneaded for a further quarter of an hour.

    The starch paste is forced through the pasta machine* directly into boiling water, boiled for one minute and then immediately quenched with cold water. This is just only in portions.
    Then the noodles are well drained and dried on racks before you can break them.
    For preparation, you should never cook, but can only move according to long in the soup or hotpot.

    Googles translation is bad a nudel or spaetzle presse is this:
    http://de.wikipedia.org/wiki/Sp%C3%A4tzlepresse

    For those who can read it here is also the German version and a link to where i found it:
    Wenn Ihr Euch die Patzerei wirklich antun wollt – ich hab es ausprobiert und es funktioniert – braucht Ihr Folgendes :

    • 2 Stk. 5 – 6 L Edelstahltöpfe, davon einer mit leicht herausnehmbaren Siebeinsatz (einer für das kochende, einer für das kalte Wasser)
    • 1 Edelstahltopf ca. 4 L (für den Teig)
    • eine schöne Nudelpresse mit 5 x 1 mm Schlitzen oder 2 mm Löchern
    • einen dicken Kochlöffel
    • 1220 g Mungobohnenstärke oder
    • 1100 g Süßkartoffelstärke und 120 g Mungobohnenstärke
    • 1 L Wasser
    • Thermometer

    Das Wasser wird auf 90°C erhitzt und mit 120 g Mungobohnenstärke ein dünner Kleister bereitet. Dieser wird bei 90°C 15 Minuten lang gerührt.
    Dann kühlt man den Kleister auf ca. 50 °C, die restliche Stärke wird untergearbeitet und der entstandene Teig eine weitere Viertelstunde geknetet.

    Der Stärketeig wird durch die Nudelpresse direkt in kochendes Wasser gepresst, eine Minute gekocht und dann sofort mit kaltem Wasser abgeschreckt. Das geht halt nur portionsweise.
    Anschließend werden die Nudeln gut abgetropft und auf Ständern getrocknet, bis man sie brechen kann.

    Für die Zubereitung sollte man sie nie kochen, sondern nur entsprechend lange im Hotpot oder der Suppe ziehen lassen.

    http://www.chefkoch.de/forum/2,69,527845/Selbstgemachte-Glasnudeln.html

    • Paul Adams

      Makes sense — cooking the dough would make it hang together, but it would lose the awesome non-Newtonian drippiness.

      I wonder if there’s an aluminum-free ingredient that could work the same ionic magic.

      • Blaine

        It’s not like there is elemental aluminum in alum. I’d be way more concerned about eating sodium and chlorine than aluminum… And salt doesn’t scare me.

  • schinderhannes

    Hi Paul

    I only now realize you wrote the post (after Dave saw the video….)

    True, your recipe is an amzing example of thixotropy and prolly great for show cooking. (Once in a while some Aluminum won’t be too bad I presume.
    I wonder if bivalent Calcium (maybe with some added acid) does the trick as well. Iit cannot be the sulfate salt, though. That is gypsum and totally insoluble.
    The only trivalent ion in your body is iron. but that would make brown noodles with an off metallic taste.
    Hannes

  • Bronwyn

    Aren’t those two recipes actually very similar except for the alum? In the original one in the post a small portion of the starch is cooked in a small portion of the water to make a thick goo, which is then mixed with the remaining water and starch, whereas the one translated from German has a small portion of the starch cooked with all the water to make a thin goo, then is cooled and the rest of the starch added. The net result should be pretty much the same: a mixture of a little cooked and a lot of uncooked starch in water. With and without alum.

    • Paul Adams

      You have a point, Bronwyn! I didn’t notice that only a portion of the starch is cooked in Hannes’s recipe. But it has to be mung bean starch, apparently. Perhaps that compensates for the tendency of the sweet potato starch to fall to pieces without alum present.

      • schinderhannes

        The main portion is added at ca. 50°C (ca.120F), so some swelling of that starch also occurs.
        This is prolly the reason why the dough has to be forced thru a spaetzle press rather than dribbling it.

        But apart from that I totally agree that there are interesting similarities between the recipees and maybe you can find a fuzed version that omits alum and still exhibits this amazing thixotropy…

  • schinderhannes

    Hi Paul
    I dont want to sound too schoolmasterly,
    but I did some more search on the internet:

    Alum is illegal in the production of glass noodle in China. (Some ruthless crooks also use worse stuff like lead based bleaches to make glass noodles from corn starch…)

    read: http://www.shanghaidaily.com/article/print.asp?id=402015

    also this might be of interest:
    http://en.wikipedia.org/wiki/Cellophane_noodles
    The section on health concerns is´interesting.
    142 mg AL per kg of noodles are above the EU health limits. I bet you were higher than that…
    Maybe you should mention some of this in a disclamer at the end of your article in case people don´t read the comments. (Sort of a cover your asss operation.)
    Best regards
    Hannes

    • Paul Adams

      I like it when you’re schoolmasterly!

      “manufacturers illegally used potash aluminum to make noodles stronger and chewier” — if I were in China I’d be in prison.

      Alum is (still?) pretty commonly used in pickle recipes here too.

      I’ll stick in a disclaimer. I’m going to try an alum-free recipe this weekend.

      • schinderhannes

        Interesting!

        Alum in pickles, never heard of that in Germany, but google reveald there are also old German recipes asking for it.
        anyways if also found this: http://www.pickyourown.org/picklesFAQs.htm

        The section on crunchy pickles and alum reads:

        Here’s what the USDA says about using alum in pickling:

        Firming agents

        Alum may be safely used to firm fermented pickles. However, it is unnecessary and is not included in the recipes in this publication. Alum does not improve the firmness of quick-process pickles. The calcium in lime definitely improves pickle firmness….

        So if cucumbers and glass noodles are realted (clearely they are) maybe lime (clacium source) is really worth a try….

        Hannes

  • schinderhannes

    Congrats Paul,

    for modifining thie awsome recipe so now it is also safe on top of being amazing.

    I´ll have to find the ingredients asap in Germany and try it out.

    BTw: I will use a spatzle lid normally used to push spacle dough thru with a scraper to make specia knoepfle spaetzle. I bet the holes are just right:

    http://www.amazon.com/Kuchenprofi-Spaetzle-Scraper-Stainless-Steel/dp/B000NLLG7C/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1367917987&sr=1-1&keywords=spaetzle+lid

    Best Regards
    Hannes

  • Gustavo Henrique Ostermann

    Use tapioca (starch extracted from Manioc)… to make translucid, stronger and chewier noodles. ;)

    Brazilian use it to make the most amazing (and chewier) cheese bread (“pão de queijo”).

  • Tim Lin

    The referenced Chinese website seems to indicate that the cooked paste is simply prepared by mixing hot water with the potatoes starch until it resembles glue. Perhaps the double-boiler can be omitted this way, saving a step?

    • Paul Adams

      That sounds like it would work. You can also prepare a large batch of the cooked paste, which keeps OK if it’s tightly wrapped in the fridge, and just add bits of it to batches of raw paste as needed.

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