It can still be used after 2 months in Kaifeng, self-raising flour, provided it is preserved. The preserved flour can be used to expire.

Self-raising flour is a kind of flour made of wheat flour and leavening agent. 1845 was invented and patented by British baker Henry Jones. Adding a proper amount of water to flour can easily make various flour products. However, due to its own characteristics (that is, it is suitable for making fermented products), self-raising flour can't make jiaozi and noodles, because the gas has been generated during the production, which will damage the gluten and lead to the skin and cross section of jiaozi.