A catty of soybean milk is generally put with 1.3g of lactone. The dosage ratio of lactone is 0 kg soybean milk 1.3 g, and the dosage of lactone directly affects the quality of finished tofu. Please note that lactone should be melted in cold water. Melting lactone with cold water can better exert its coagulation effect, so that soybean milk can be solidified into tofu brain. At the same time, melting lactone with cold water can also prevent lactone from losing its activity at high temperature, and ensure the quality and taste of tofu brain. Lactone is a kind of food additive, which is mainly used for preservation, antisepsis and taste correction. It can keep food fresh and prevent premature decay. Moderate intake of lactone is harmless to human body, but if excessive intake, it may lead to lactone accumulation, which in turn will stimulate gastric mucosa and intestine, which is prone to dry mouth, thirst, slow intestinal peristalsis and other symptoms, and may even lead to constipation in severe cases, which is not conducive to human health.