What is 'kansui' and what does it do to ramen noodles?

Kansui is an alkaline solution that is a key ingredient in ramen noodles. It's what gives them their characteristic springy texture, yellow color, and unique flavor. The alkaline salts in kansui interact with the gluten in the wheat flour, making the noodles firmer and more elastic. This allows them to stand up to the hot broth without becoming mushy. The ratio of potassium carbonate to sodium carbonate in the kansui can be adjusted to create noodles of different textures, from the firm and straight noodles of Hakata ramen to the soft and wavy noodles of Sapporo ramen.