Processing technology of tofu

Tofu is a delicious food invented by China people, and it is made of soybean milk. The process includes the steps of bean selection, soaking, grinding, adding water, filtering, heating and boiling. The production process is as follows: when the temperature of soybean milk is reduced to 7℃ ~ 8℃, appropriate amount of brine or gypsum is added to make soybean protein coagulate and sink, and the water is drained. The finished product is white and delicate, and the fragrance is pleasant. Has the effects of invigorating qi, regulating middle warmer, promoting fluid production, moistening dryness, clearing away heat and toxic materials, relieving cough and resolving phlegm.

How is tofu made? Soak soybeans in water, swell and soften, grind them into soybean milk in a stone mill, then filter off bean dregs and boil them. At this time, the protein particles in soybean are surrounded by water and keep moving, as if dancing in a soybean milk bucket, but they can't get together, forming a "colloid" solution.

To turn colloidal solution into tofu, you must order brine. Bittern or gypsum is used to ignite bittern. Brine mainly contains magnesium chloride, and gypsum is calcium sulfate, which can make dispersed protein particles quickly gather together and become shiny bean curd. Squeeze the water out again, and the tofu brain will become tofu. Tofu and tofu brain are both concentrated bean protein. When we drink soybean milk, we sometimes repeat the process of making tofu. Some people like sweet syrup. Soymilk with a spoonful of sugar has not changed. Some people like to drink salty pulp. Pour some soy sauce or add some salt into the soybean milk, and soon, the glistening tofu brain will appear in the bowl. There is salt in soy sauce, and the properties of salt and brine are similar, which can also destroy the colloidal state of soy milk and solidify protein. Isn't this the same as making tofu?

Soymilk is brine, and tofu brain appears. Tofu brain filters out water and becomes tofu. Press the tofu tightly, and then squeeze out some water to become dried tofu. It turns out that soybean milk, bean curd brain, dried bean curd and dried bean curd are all protein beans, but they contain more or less water. Milk is similar to soybean milk and is also a colloidal solution. In fresh milk, casein, that is, protein, is wrapped in cream, dispersed in water and constantly moving. Therefore, milk is always a uniform milky white liquid. Let the milk ferment to make yogurt, and casein will gather and condense into blocks, like tofu brain.

Method for making colored bean curd

1. technological process: selecting beans → beating → defoaming and filtering → mixing (adding squeezed fruit and vegetable juice) → adding hot pulp → squeezing water to make rot → finished product.

Second, the key points of the process

1. Squeezing of fruit juice and vegetable juice. Choose fresh and colorful fruits and vegetables, clean them, chop them up and mash them, then juice them and filter them to remove juice residue. Then the PH value of the fruit and vegetable juice is adjusted to 6.0-6.5 with edible citric acid aqueous solution or soda ash solution.

2. Choose beans. Soybean with high protein content and no mildew is selected as raw material, and dust and impurities are removed by a sieve.

Step 3 grind. Soak the washed soybeans in warm water at 25℃ for 8 -9 hours until they are not hard by hand, and grind them into fine soybean milk with a beater according to the ratio of 10 kg of soybeans and 30 kg of water.

4. defoaming and filtering. First, add 25 grams of oil into 5 kilograms of warm water at 50℃ and stir well, then pour it into soybean milk. After 5 -6 minutes, all the mud foam can be killed. Then 10 kg of water is added to 10 kg of soybeans, filtered twice, bean dregs (used as feed) are discarded, and filtrates are combined to obtain raw soybean milk.

Mix. Generally, 8 ml-10 ml concentrated juice per 50 ml soybean milk is appropriate. After the fruit and vegetable juice is added, it must be fully stirred and mixed evenly to avoid affecting the color of the finished product.

6. Add hot paste. Move the prepared soybean milk into the pot, heat and boil for 2 -3 minutes, and keep stirring to prevent the pot from being burnt. Immediately move the cooked soybean milk into the tank, cover it and keep warm for 8 minutes to 10 minutes. When the temperature of the slurry is reduced to 80℃-90℃, 4 kg of water is heated with 100 g-150 g gypsum powder to prepare gypsum liquid, and the slurry can be discharged after 10 minutes. Stir well when you order until the cooked pulp shows sesame rotten flowers. Cover and keep warm for 30 -40 minutes. When the pulp temperature drops to 70℃, it can be packaged.

7. Squeeze water to rot. First, wash the bag with warm water at 25℃, then pick it up in soybean milk, wrap it up, put it in a platform basket, put it on a wooden board, press 35 -40 kg of stone, and squeeze it for 2 hours to get a high-yield tofu product with bright colors.

Colored tofu, like traditional tofu, is made of soybeans. The difference is that it is made by adding natural vegetable juice auxiliary materials, forming natural color and rich nutrition, preserving the fiber in vegetables, which is beneficial to human body's absorption and digestion. The basic process of making colored tofu is similar to that of traditional tofu, and the key process is the addition of vegetable juice.

The color of colored tofu mainly depends on the color of vegetable juice. For example, celery, radish tassels and celery tassels, pepper leaves and sweet potato leaves can all be used to make green tofu; To make yellow tofu, you can use carrots; To make red tofu, tomatoes can be used to juice.

1. Squeeze juice. Select fresh vegetables, clean them, chop and mash them, then juice and filter them to remove vegetable residues. When the PH value of vegetable juice is less than 6, the colored tofu is not completely solidified, and the texture of the product is too soft. When the PH value is greater than 6.5, the product is hard and easy to break, and the surface is rough. Therefore, it is best to adjust the PH value of vegetable juice to 6.0-6.5, so that the product is tender, smooth, shiny and elastic with high yield.

2, color tofu processing should pay attention to the mixing ratio of soybean milk and vegetable juice. The amount of vegetable juice is small, so it is not easy to color tofu; Too much vegetable juice will produce grass flavor and make the flavor worse. Generally, the appropriate dosage is 8- 10 ml concentrated vegetable juice per 50 ml soybean milk.

Secondly; After the cooked soybean milk is added with vegetable juice, the cooking time should not be too long; So as not to destroy the nutrients in the vegetable juice. After the vegetable juice is added, it must be fully stirred and mixed evenly to avoid affecting the color of the finished product.

3. Precautions In order to improve the utilization efficiency of vegetable juice and reduce the dosage, the concentration of vegetable juice can be considered. If the vegetable juice is concentrated to 1/2, only 8 ml is needed per 100 ml of soybean milk instead of 16 ml, and the product quality is not much different from that without concentration. Vegetable juice should be added after the soybean milk is basically cooked, and then boiled for 2-3 minutes. If the time is too long, vitamins will denature, and if the time is too short, the effect of disinfection and sterilization will not be achieved. When the mixture of cooked soybean milk and vegetable juice enters the pulping process, its temperature is generally 90~C-95℃ and the concentration of soybean milk is about 8 degrees. According to the ambient temperature, add a proper amount of cold water to reduce the temperature of soybean milk to 70℃-80℃, and order soybean milk when the concentration drops to about 7.5℃.

Because the addition of vegetable juice changes the original PH value of soybean milk, the amount of coagulant should be adjusted according to the different PH values of vegetable juice, such as tomato juice with low PH value, and the amount of coagulant should be reduced appropriately.

On the basis of high nutrition of ordinary tofu, vitamins, dietary fiber and minerals are added to keep the natural color and fragrance of fruits and vegetables. It has the characteristics of rich nutrition, attractive color and novel variety, and is a new type of healthy food with high nutritional value.