Tofu is a food made from soybean raw materials, and the process is still simple and limited to the household scale. Suryanto (in Hartaty, 1994) states that what is meant by tofu is solid food which is molded from soy essence (Glycine spp) by the process of protein deposition at its isoelectric point, without or with the addition of other permitted substances.
Preparation in principle is made by extracting the protein, then collecting it, thus forming a protein solid. The way of soybean milk is commonly done by adding acid clot. Commonly used agglomerates are vinegar (CH3COOH), tofu (CaSO4nH 2O) and tofu seedlings (the one-ton-well-squeezed orange juice).
In general the stage of the process of making the tofu is as follows:
- Selected soybeans cleaned and sorted. Cleaning is done by winnowing or using a cleaning tool.
- Soaking in clean water so that the soybean can expand and soft enough to be ground. Immersion duration ranges from 4 to 10 hours.
- Washing with clean water. The amount of water used depends on the amount or amount of soybean used.
- Milling soybeans into soybeans with milled machines. To smooth the milling it is necessary to add water with an amount equal to the amount of soybeans.
- Cooking of soybeans is done on the stove and boiled for 5 minutes. During cooking it is maintained so as not to foam, by adding water and stirring.
- Soy porridge filtering is done by filter cloth. The obtained bundles are squeezed and rinsed with warm water. The amount of wetted waste is about 70% to 90% of the dry weight of soybeans.
- After that the clumping using acid water, at a temperature of 50oC, then silenced to form large clumps. Furthermore the water on the precipitate is removed and partly used for the clotting process.
- The final step is the pressing and printing that is coated with a filter cloth until solid. After the water is low, the mold is opened and aerated.
