面筋由面团里的不溶于水的各种蛋白质——麸质组成，通常由小麦、大麦等谷物中所提取，如果把面团放于水里冲洗，当把所有可被水冲走的物质冲走后，剩下的就是面筋（如果把被冲洗到水中的部份沉淀滤干，就是淀面）。早在宋朝，沈括的《梦溪笔谈》中已有“濯尽柔面，面筋乃见”的记载。

在东亚食品和素食品中，面筋常被用作肉类的替代物。但有些人也会对其麸质产生过敏反应（如乳糜泻患者），所以在美国等地也有出售针对该等人士、不含面筋的代用食品（例如意大利粉），通常以马铃薯、稻米等制成。

Wheat gluten, also called seitan (Japanese: セイタン), wheat meat, gluten meat, or simply gluten, is a food made from gluten, the main protein of wheat. It is made by washing wheat flour dough with water until all the starch granules have been removed, leaving the sticky insoluble gluten as an elastic mass which is then cooked before being eaten.