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I have food grade lye (sodium hydroxide) from pretzel making and I want to make chewy noodles, either ramen or Chinese noodles. Many of these recipes call for lye water or kansui.

I have found many resources about making your own kansui from baking soda (for example Can I substitute baking soda for kansui powder?), but none that start with lye.

I've found that kansui has a pH of about 12.6 and sodium hydroxide (NaOH) has a pH of 14. Using a pH calculator, I should get a pH of 12.6 with 0.04 moles of NaOH in 1 liter of solute (water). That's 1.5 grams per liter. (It has been a while since high school chemistry so please jump in here if I'm making a massive mistake)

Is this a valid approach to making lye water or kansui? What might I be overlooking?

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  • Your calculations look about correct - however, remember that some of the OH- will be used up in the reaction when making the kansui, so at 0.04 mol/l you will probably deplete this quite rapidly, meaning that the pH will rise rapidly and not end up with the effect you want.
    – bob1
    Mar 23, 2021 at 2:04

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80% potassium carbonate, 20% sodium bicarbonate at some concentration https://omnivorescookbook.com/kansui is likely to behave very differently than your sodium hydroxide. Kansui is probably strongly buffered, while your pH is likely to wander. That sort of thing is liable to wreck recipes. I'd find a good how-to online, and make the stuff right.

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    Also note that phosphate salts are often added to kansui in order to keep the solution stable (I guess mainly pH, but also in many ways).
    – xuq01
    May 12, 2021 at 19:17
  • @xuq There's your buffer right there. Likely pH 7 to 8.
    – Wayfaring Stranger
    May 12, 2021 at 20:02

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