Starch noodles

Starch noodles, also called glass or cellophane noodles, are thin clear strands made from purified starch rather than from flour. The starch comes from mung beans, peas, potato or sweet potato. Made from pure starch they contain no gluten, and the best-known kind, Longkou Fen Si from China, is a name protected in the EU. ¹²³⁸

Starch, not flour. The Codex standard for instant noodles already allows starches instead of flour as the main ingredient. The Longkou Fen Si specification shows the classic method: the beans or peas are soaked and pulped, the skins removed, the starch settled out of the liquid by a lactic acid fermentation, then the starch paste is beaten, filtered into threads and dried in the sun or with hot air. ¹⁶

Longkou Fen Si. Since 2010 the name has been a protected geographical indication in the EU. It is made in the north of the Shandong Peninsula, in Longkou, Zhaoyuan, Penglai, Laiyang and Laizhou in the Yantai area, where spring water with a pH of 6.9–7.4 suits the fermenting bacteria. The best noodles come in spring and autumn: winter is too cold for the fermentation and summer too hot to keep other bacteria out. ¹²

From Zhaoyuan to the world. According to the specification, people in Zhaoyuan made starch as early as the Northern Wei period and vermicelli from the Song dynasty on. In 1860 the Hongtai shop in Hong Kong bought Zhaoyuan vermicelli shipped through the port of Longkou with «Longkou Fen Si» on the packs, which gave the product its name; Longkou opened to foreign trade in January 1914. ¹

The quality limits. Longkou Fen Si must contain more than 75 % starch, less than 15 % water and less than 0.5 % ash, with strands thinner than 0.7 mm that stay whole, with under 10 % broken after 45 minutes of boiling. The beans and peas must be plump, with at most 1 % impurities and under 13.5 % moisture, stored no longer than a year and grown without fertilisers or chemicals. ¹

Many starches. Korean dangmyeon, the noodle of japchae, is studied in versions from mung bean and potato starch, and researchers in India made gluten-free noodles from sweet potato starch blended with banana, cassava or mung bean starch. The starch changes the texture: in the Korean study, mung bean noodles rehydrated best whatever the drying method. ³⁸

What is in them. Per 100 g, dry mung bean glass noodles have 351 kcal, 86 g of carbohydrate, only 0.16 g of protein and 0.06 g of fat, with 2.2 mg of iron and 10 mg of sodium. Researchers describe sweet potato starch noodles as gluten-free but poor in protein, minerals and vitamins, and fortified them with 20 % whey protein for the best protein retention after cooking. ³⁵

Resistant starch and sugar. A 2025 study found that holding cooked mung bean starch at −10 °C raised its resistant starch to 15.85 %, and that freezing glass noodles for 19–25 hours gave the best result. Sweet potato noodles blended with banana or annealed cassava starch had a medium glycemic index of 66.3 and 67.2. A 2012 Tokyo study found aluminium from additives at 0.04–0.14 mg per g in three of four vermicelli samples and warned that some foods might push children over the tolerable weekly intake. ³⁴⁹

Why it matters to you. Several different starches hide behind the name «glass noodles», so read the ingredients, and if you avoid gluten look for «gluten-free», which in the EU means no more than 20 mg of gluten per kg. Glass noodles bring energy but almost no protein, so pair them with beans, egg, fish or meat. More on Mung bean glass noodles, Dangmyeon, Longkou Fen Si, Japchae and Rice noodles. ³⁵⁷