Kansui

Kansui is the alkaline additive without which there are no ramen noodles. Japanese labelling rules define it as an alkaline agent for making Chinese noodles that contains one or more of potassium carbonate, sodium carbonate, sodium hydrogen carbonate, and potassium or sodium salts of phosphoric acid. The collective name kansui may be used on the label.

In the EU these salts are ordinary food additives: E500 is sodium carbonates, E501 potassium carbonates, and phosphates belong to the E338 to E452 group. US Cup Noodles Chicken, for example, lists potassium carbonate, sodium carbonate and sodium tripolyphosphate among its ingredients.

The Japanese labelling code calls wheat flour kneaded with kansui, including the traditional tōaku, Chinese noodles, chūka men. Researchers explain what the alkali does: natural flour flavones turn yellow at alkaline pH, and proteins cross-link more strongly, so the noodles become harder, chewier and more resistant to stretching. Kansui is usually 0.5 to 1.7 % of the flour weight; one recipe uses 1 g of a 9 to 1 sodium and potassium carbonate mix and 1.75 g of salt per 100 g of flour.

Why it matters to you. Yellow, springy noodles are a sign of kansui, not necessarily of egg. Look for the word kansui or E500 and E501 in the ingredients.