There are few ingredients required in making tofu such as soy milk, water and coagulating agents. The modern approach of manufacturing tofu is relatively faster and automated version of the traditional one.
The first step to make tofu is to soak the soybeans and extracting the milk. To curd the milk, coagulant is added into it. Modern manufacturers make use of calcium sulfate or magnesium chloride for this step. The curds are processed into the desired form of tofu. Variety of textures is being produced and this depends on the water content. Then the tofu will come in firm, soft and silken.
When the beans are soaked in water, they soften for they absorb the water and they double in size. Then the beans are mashed using stone grinders or pureeing machines and water into slurry. This will be boiled for the purpose of enzyme neutralization since the enzyme is indigestible. The soy milk is extracted using roller presses that separate the pulp consisting fiber and hull. This will most likely take two hours to complete. After extracting, the juice of the soy bean is pumped to curding vats and it is mixed with a coagulating agent such as magnesium chloride or calcium sulfate. This would curd the milk similar to that of making cottage cheese.
The traditional way of pressing the curds are using hand screw presses. Then the tofu can be pressed in cheesecloth-lined boxes. But nowadays, modern systems are using hydraulic presses that drain the whey off and leave soft blocks of curds.
Slicing the cake tofu is done using automated cutters and the blocks are being washed in vats of water making them firm. They will be stored until they become ready to be processed further.
Then the tofu is packaged in shrink wrapped blocks. Water can be added into the packages before they are sealed, weighed and dated. There are some companies processing the soy milk directly in the package.
The packaged tofu will undergo the pasteurization process at 82 degrees Celsius and this is done to extend the shelf life of tofu for 30 days. It will be chilled then in water once it is ready to be placed in boxes before they are shipped to distributors.