Tofu is rich in nutritional value, and soybean is also an important calcium supplement food in ancient China. In the past, the fields planted with beans were used for fertilization, while maintaining the balance of calcium and potassium, which was more beneficial to the nutrition and health of China people. It can be said that tofu is no less important to the Chinese nation than the four great inventions.

Tofu is a common food on everyone's table, and its invention history can be traced back to the Han Dynasty. His inventor is Liu An, the author of the famous Huai Nan Zi. Liu An was originally the uncle of Emperor Wu of the Han Dynasty, and was named King of Huainan. All day long, he fantasized about immortality and wondered how to refine it into a fairy medicine.

In Liu An's alchemy, bean milk was made from beans and water mill, and gypsum was added, thus tofu was invented. Although tofu was invented long ago, it was not until the Song Dynasty that tofu became an important food. Su Shi, a writer in the Northern Song Dynasty, likes eating tofu very much, and he likes making Dongpo tofu himself. It is said that when Kangxi went to the south of the Yangtze River, he was tired of delicacies. When he saw tofu, he immediately became a fan of tofu.

Although the inventor of tofu is Liu An, it is also a widely accepted fact that Huainan holds a tofu culture festival every year. But Liu An had a bad reputation in ancient times, because he wanted to rebel and was forced to commit suicide after his crime was exposed. Rebellion was a heinous crime in ancient China. Of course, it is impossible for tofu circles to respect a heinous person as a granddaddy. In this context, Le Yi and Guan Yu are regarded as the grandfathers of tofu industry.

Guan Yu has no historical reference for making tofu, but he is still regarded as the granddaddy by tofu industry practitioners, just as Guan Yu has never cut his hair, but he is described as the granddaddy of barber industry by Yi Zhongtian.