1. Processing technology and practice of ordinary brine tofu: (1) Raw material formula The main raw material for making tofu is soybean, especially the new bean with neat particles, no impurities, no insect eyes and no mildew and deterioration. Secondly, some coagulants and defoamers are needed. Generally, the coagulant used to make tofu is bittern magnesium chloride, and the dosage is about 3% of the raw material. When in use, it is diluted to 1: 2 with a Baume of 16 ~ 18. Filter and use. Before gypsum is used, water is added in the proportion of 1: 1.5 for grinding, and then water is added to make 5 times suspension, and the bottom is cut for later use. Defoamer for tofu can mix oil residue or vegetable oil with calcium hydroxide according to the ratio of 10: 1, and ferment to a thin paste, with the dosage of 1%. Emulsion silicone and liquid foam can also be used. (2) Manufacturing technology and method 1. Blister. After strict acceptance and inspection, the first working procedure of soybeans is to put them into the material pool and soak them in water. The soaking time should be treated differently according to the quality, water content, season, room temperature and grinding of soybeans, and everything should not be cut. In northern China, you can soak 12 ~ 14 hours in spring and autumn, 6 ~ 8 hours in summer and 14 ~ 16 hours in winter. Soak in cold water for 3-4 hours for the first time. When the water surface is about 65,438+0.50 mm, and the soybean absorbs water, and the water level drops to 60-70 mm below the water surface, water is continuously added 1-2 times, so that soybean grains continue to absorb enough water and the weight of soaked soybean is doubled. In summer, it can be soaked to 90% open, slightly concave in the middle and slightly dark in the middle. In winter, it can be soaked to 100%, and the douban is milky white, with a light yellow center and a pH value of about 6. If the grinding wheel is used to grind the pulp, the soaking time should be shortened by 1 ~ 2 hours. 2. Abrasiveness. Pulping is the second process of making tofu. Soaked soybeans should be washed with clear water or water before grinding. When grinding with grinding wheel, it is necessary to clean it in advance, adjust the spacing between grinding discs, and then drip water to feed. It is best to try grinding first, and then grind at normal speed after the test grinding is normal. The dripping and blanking of abrasive should be coordinated, and water or material should not be cut off in the middle. The grinding paste should be smooth, appropriate in thickness and even before and after. When using the stone mill, the grinding body should be cleaned, the grinding cover and funnel should be pressed, and the top thread should be adjusted. When the mill is started, the material and water will not stop. Abrasive should be ground as required to ensure the fresh quality of abrasive. In case of temporary power failure, water cut-off or mechanical failure, the beans should be taken out immediately and spread on the concrete floor. Pump out plenty of water and pay attention to ventilation. Rinse 1 ~ 2 times with cold water before use, so as not to affect the quality of finished tofu. The third step is filtering. Filtration is the premise to ensure the quality of tofu products. At present, centrifuges are widely used in bean products factories all over the country. The use of centrifuges not only greatly reduces the heavy physical labor, but also has high efficiency and good quality. Filter by centrifuge, coarse first and then fine, in stages. The nylon filter screen is first used with 80 ~ 100 mesh, and then used with 80 mesh for two or three times. The trumpet-shaped filter screen has better filtering effect. When filtering, the filter residue is washed for three times and filtered clean, so as to make full use of the filter residue in washing water. The content of protein in the residue shall not exceed 2.5%, and the water consumption for washing the residue shall be subject to the concentration of "grinding paste". Generally, the total water consumption of 0.5 kg of soybean refers to about 4-5 kg of soybean milk. Centrifuge is an important mechanical equipment in bean products factory. During the operation, strictly implement the electromechanical safety operation procedures and do a good job in environmental sanitation. 4. Boil the pulp. Cooking is also very important for the quality of tofu products. Usually, there are two cooking methods for tofu, one is to use an open cauldron, and the other is a sealed cooking pot with modern equipment. Boil the pulp in a boiling pot, and the boiling time should be short, and the time should not exceed 15 minutes. Immediately after the pot is boiled, put it out for use. Soymilk should be used in cooking and boiling to eliminate floating foam. Closed valves are usually used for fire fighting. Three ups and downs "to eliminate floating foam. Fire fighting generally adopts closing the valve, three falls and three passes. The foam floated in the pot for the first time. After the foam closes the valve and sinks, open the valve again. Cracks can be seen in the middle of secondary foam floating, resulting in transparent bubbles. At this time, defoamer can be added to defoam, and then the valve is opened. When the boiling temperature reaches 97 ~ 100℃, close the valve and leave a small amount of residual gas to discharge the slurry. It is worth noting that raw pulp or raw water should not be injected when boiling, defoamer should be used according to the specified dosage, the sizing in the pot should not be too full, and the boiling pressure should be sufficient, and the minimum pressure should not be less than 3 kg/cm2. In addition, boil the pulp as needed, cook as much as possible, and don't leave it in the pot for too long. The sealed stepped overflow cooking pot is a scientific cooking equipment, which can automatically control the temperature in each cooking stage with high accuracy and good cooking effect. When this tank is used for cooking, soybean milk can be pumped into the bottom of the first cooking tank by the milk pump of the sanitary pump, and the convection generated by steam heating can make the slurry water at the bottom of the tank rise, overflow to the bottom of the second cooking tank through the interlayer slurry channel of the second cooking tank, and contact with steam again for secondary heating. When the temperature reaches 100℃ after repeated heating for five times, it is immediately fed into the buffer tank from the upper end of the fifth cooking tank through the pulp discharge pipeline, and then put into the buffer tank. According to experience, the slurry temperature in 1 tank is 55℃, 75℃ in 2 tanks, 85℃ in 3 tanks, 95℃ in 4 tanks and 0/00℃ in 5 tanks/kloc. When the slurry temperature exceeds 100℃, protein denaturation will seriously affect the subsequent process treatment. 5. refining. The boiled slurry should be filtered with 80 ~ 100 mesh copper mesh screen or finely filtered with vibrating screen to remove trace impurities, chaff and scum in the slurry. Don't be too hasty when adding fine slurry. The slurry flow rate should be consistent with the filtrate flow rate, that is, the fast filtration flow rate is larger and the slow filtration flow rate is smaller. For large quantities, consider setting two fine screens. 6. Solidification. Solidification is the key to determine the quality and yield of bean products. First of all, we should master the concentration and pH value of soybean milk, use coagulants correctly, and master harrowing skills skillfully. According to the different requirements of bean products, the temperature and concentration of soybean milk are different when it is solidified. For example, the temperature of Beidoufu is controlled at about 80℃, and the concentration is determined at 20℃ of1~12 milk juice. The temperature of semi-dehydrated bean products is controlled between 85℃ and 90℃, and the concentration is between 9 ~ 10; The temperature of oily tofu is about 70 ~ 75℃ and the concentration is 7 ~ 8. The optimum pH value of coagulated soybean milk is 6.0 ~ 6.5. In the specific operation, harrow first and then salt water, and the salt water flow rate is first large and then small. Rake the material first and then slowly, and pour the brine while raking, and 50% brain flowers appear in the groove. The salt raking speed will slow down and the brine flow will decrease accordingly. When 80% of brain flowers appear, stop saltwater. When the brain flower slowly swims and sinks, the density of the brain flower is uniform and the raking stops. Iron removal and harrow stopping should be smooth to prevent the drum from rotating. After stopping harrowing, the brain flower gradually sinks, is soaked by salt water, has no spots, and the brain is tender and thin. If your brain is tender, you should rake it in time. To prevent squeezing and sticking to the bag, after stopping raking, pour some brine on the surface of the brain. If there are spots, it is a spot. Let the brain rest for 20 ~ 25 minutes and squat down. 7. molding. After squatting down, open the cylinder, put the sizing and press it. When opening the cylinder, put the brain slice in the cylinder at the front end of the cylinder with an upper pressure spoon and pump out the yellow slurry. Normal yellow serosity should be clear and light yellow, indicating that the brain is moderate, not old or tender. The yellow serous fluid is dark yellow of brain aging, dark red of excessive aging, and the yellow serous fluid of brain tenderness is milky white turbidity. In this case, measures should be taken in time, or add brine or open the pot pulp. Straighten the bottom plate and die before pressing, wash the cooked cloth, wring it out and smooth it, press the edges and corners, draw out the yellow slurry, and press it in different ways according to the brain age. Generally, it is hierarchical, light, fast and fast, lying on an old spoon, pulling a young spoon, or digging a hole. Paving with high-quality brain first, then using ordinary brain, not only ensures the smooth surface of the product, but also prevents the bag from sticking. The four corners should be fully leveled, the number should be accurate, the movement should be steady and fast, and the package should be tightly wrapped to avoid the brains from scattering, so that the brains in the cylinder are stable and unbreakable. The pressing time is1.5 ~ 20min, and the weight is about 60 kg according to two plates. Squeeze the tofu immediately after pressing, quickly turn the board with the scrubbed board cover, gently put the board, stably uncover the package, accurately remove the cover, move it strictly and stack it slowly. Spread the bottom of the stack first, and then press it separately. Each stack shall not exceed 65,438+00 boards, and it shall not exceed 8 boards in summer. In the whole process of making tofu, strictly abide by the "30%" operation method, that is, point your brain in, squat your brain in, squeeze in, and don't be greedy. Under normal circumstances, each person operates 6 plates to press the membrane and prepares 4 brain grooves. The capacity of each tank is 4 plates with the same thickness.