1. How Ramen Noodles Differ from Udon: Kansui in the Dough
One of the major features that separates ramen from udon is the water used. Chinese-style noodles, which include ramen, are made by adding kansui to wheat flour. Kansui is an alkaline salt water. When it is added, the color, taste, and texture become different from other noodles like udon [1]. Using kansui is a key characteristic of ramen noodles. However, it is important to note that some Chinese-style noodles do not use kansui, and others use different alkaline liquids [8].
2. Why Kansui Turns Pigments in Wheat Flour Yellow
Wheat flour naturally contains pigments called flavonoids. According to explanations from noodle manufacturers, when these pigments meet the alkaline nature of kansui, they turn a pale yellow [3]. Another manufacturer’s explanation also states that the alkaline components of kansui cause this coloring [4]. Therefore, the yellow color of standard Chinese-style noodles is mainly due to pigments already in the flour becoming visible through kansui. Some products do use eggs or food coloring. Additionally, some sources suggest that part of the yellow color comes from lutein, a pigment found in wheat, so it is best not to attribute the color solely to flavonoids.
3. What Kansui Is Made Of and Where It Comes From
The basic components of kansui are a mix of sodium carbonate and potassium carbonate. Sometimes, phosphates are also added [2][5]. Officially, kansui is defined as containing at least one type of substance such as potassium carbonate, sodium carbonate, or phosphates [2]. There is no fixed ratio for these ingredients because the mix changes depending on the intended use.
As for its origin, there is a story that noodles were made in Inner Mongolia, China, using alkaline salt water from salt lakes. The noodles had a different texture and flavor compared to those made with ordinary water. This technique is said to have spread to Japan along with the spread of noodles [5]. In the past, people also reportedly used alkaline water from lakes and swamps, or the lye from burned plants. Since the dates are not clear, this should be understood as a legend or tradition rather than a verified historical fact.
4. How Kansui Changes the Chewiness and Aroma of Noodles
When kansui is added to wheat flour, it acts on the protein gluten. This increases elasticity and stretchiness, resulting in the firm "koshi" (chewiness) and smoothness felt when eating [3]. It is said that the more alkaline the solution, the stronger this tightening effect becomes [2].
The unique aroma of Chinese-style noodles also comes from kansui. Sodium carbonate produces more aroma components, leading to a stronger flavor, while potassium carbonate is considered milder [2]. This flavor is said to be divisive, with preferences varying among people.
When kansui is used, the noodles and the boiling water become weakly alkaline, with a pH of 9 to 10. At this level, the amount of noodle that dissolves into the water is relatively low, according to one manufacturer’s explanation [4]. However, these numbers come from a single source, so it is not guaranteed that all noodles will fall exactly within this range.
5. The Difference Between Straight Noodles and Curly Noodles
Noodle shapes are broadly divided into straight noodles, which are cut as they come out of the machine, and curly noodles, which have a wavy shape. Curly noodles are made by kneading by hand, applying pressure with machines, or cutting through blades that create a gentle wave pattern [8][6].
The shape affects not just appearance but also texture. Explanations of noodle making state that the curve changes how force is applied and how elasticity is felt. Therefore, even with the same ingredients, the texture can differ greatly depending on the shape [6].
6. Do Curly Noodles Really Hold More Soup?
It is often said that curly noodles hold soup well because their uneven surface traps the liquid. You will hear this explanation frequently in ramen shops [6].
However, some noodle makers offer a different view. Nakazawa Men, a noodle manufacturer, writes that straight noodles actually lift more soup. They attribute this to surface tension. They also explain that curly noodles feel lighter in the mouth, making it harder to taste the noodle itself, so the soup flavor comes through more clearly even with the same amount of soup [7]. Thus, opinions among noodle makers are divided. The shape of the noodle is chosen considering not just the amount of soup, but also the lightness in the mouth and how the soup flavor is perceived.
7. How to Check for Kansui on Noodle Ingredient Labels at Home
You can investigate this at home by checking the ingredient labels on packaged ramen or fresh noodles at the supermarket. Look for the word "kansui" (alkaline water). Compare this with the label on udon from the same shelf to see the difference in ingredients.
When boiling noodles, always handle fire and hot water with an adult. You can also compare the color of the boiled ramen noodles side-by-side with boiled udon noodles.
If you want to learn more, try eating packaged straight noodles and curly noodles with the same soup. Discuss with your family which one lets you taste the soup more clearly. If you feel the curly noodles are "lighter" or the straight noodles have a "stronger noodle taste," you can see which of the two explanations in Section 6 matches your experience.