"The Making of Tofu" Organic Compounds PPT

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"The Making of Tofu" Organic Compounds PPT

Part One: [Material Reading]

Ingredients 1: The traditional making process of tofu

1. Raw material processing. Peel and sieve the soybeans, wash them and soak them in a water tank for 4 to 5 hours in winter and 2.5 to 3 hours in summer.

2. Grind the beans and filter the residue. After the soybeans are soaked, take them out and grind them into pulp at a ratio of 6 kilograms of water per kilogram of soybeans. Use a bag (made of sewn tofu cloth) to pack the ground slurry. Pinch the mouth of the bag tightly and squeeze out the soy milk.

3. Boil the pulp and add it. Pour the squeezed raw pulp into the pot and bring to a boil. Do not cover the pot and skim off the foam on the surface while cooking. The fire should be strong, but not too fierce to prevent the soy milk from overflowing after boiling. The soy milk can be cooked until the temperature reaches 90~110℃. Insufficient temperature or too long time will affect the quality of soy milk. Pour the salt brine into the soy milk just scooped out of the pot, stir gently with a spoon, and after a few minutes, the soy milk will condense into tofu curds.

4. Make water tofu. Within about 15 minutes of the tofu curd condensing, use a spoon to gently scoop it into a wooden tray (or other container) that has been covered with cloth. When it is full, wrap the tofu pudding with a cloth, cover it with a plate, and press it for 10~ In 20 minutes, water tofu is ready.

5. Make dried tofu. Scoop the tofu flowers into a wooden tray, wrap it with cloth, cover it with a wooden board, pile it on stones, and press out the water to make dried tofu. Generally, 10 kilograms of soybeans can be used to make 25 kilograms of dried tofu.

Material 2: Chemical principles of making tofu

The protein particles in the soybeans are surrounded by water and are constantly moving. They cannot come together and form a "colloid". To turn the colloid into tofu, it must be stewed. Use salt brine or gypsum to make brine. Salt brine mainly contains magnesium chloride, and gypsum is calcium sulfate. They can make the dispersed protein pellets gather together quickly to become white tofu brain. Then squeeze out the water and the tofu brain becomes tofu. Tofu and tofu are condensed soy protein. Adding salt to marinate tofu is a process of coagulation, which is due to the neutralization of positive and negative charges leading to a decrease in the stability of the particles in the turbid liquid. Strictly speaking, it is not a chemical reaction. The solute molecules in the protein solution are too large (between 1 and 100 nm), forming a colloidal solution (liquid sol). When substances such as electrolytes (and solutions) are added, agglomeration occurs due to the mutual attraction between the charged particles and the electrolyte ions. When the agglomerated particles are large enough, the colloidal particles will agglomerate out of the solution. Tofu is the coagulation product of soy milk (protein colloid solution).

Tofu making PPT, the second part of the content: [Thinking about improvement]

1. Soy milk is a colloid. How to conduct a simple experiment to verify it?

Tip: Use a laser pointer to illuminate soy milk and you can see the Tyndall effect, indicating that soy milk is a colloid.

2. Salting out generally refers to the process of adding inorganic salts to a solution to reduce the solubility of a certain substance and cause it to precipitate. Such as the process of adding concentrated (NH4)2SO4 solution to cause protein agglomeration. During the process of making tofu, salt brine is added to precipitate the protein in the soy milk. Is it salting out of the protein or denaturation of the protein?

Tip: Adding salt brine (mainly containing magnesium chloride) during the process of making tofu causes the protein in the soy milk to precipitate out, which is the salting out of the protein. When proteins are denatured, heavy metal salts are added, such as copper salts, barium salts, etc.

Tofu production PPT, the third part: [Migration application]

1. Huainan tofu making technology is well-known at home and abroad. The chemical changes that occur in the following steps of hand-made tofu are ()

A. Refining B. Filtering residue C. Boiling D. Forming

[Analysis] Choose C. No new substances are generated in the pulp refining, which is a physical change. Item A is wrong. No new substances are generated in the filter residue, which is a physical change. Item B is wrong. When boiling the pulp, the protein is denatured, which is a chemical change. Item C is correct. No new substances are generated in molding. It is a physical change, item D is wrong.

2. Spinach is rich in nutrients and is known as the "King of Vegetables". Folklore: Eating spinach and tofu together is easy to get stones. A chemistry interest group explored issues such as "Can spinach and tofu be eaten together?"

[Check the information] ① Spinach is rich in iron, oxalate, carbonate, etc., and tofu is rich in protein and calcium salt.

②The main component of human stones: calcium oxalate (CaC2O4).

③ Acetic acid does not react with calcium oxalate, but can react with calcium carbonate to form soluble salts, etc.

[Making a guess] The reason why "spinach and tofu cannot be eaten together" may be ____________________.

[Experimental Research] Analysis of some components in spinach

(1) The purpose of adding sufficient CaCl2 solution in step ③ is to _____.

(2) It is known that gas C can make clear lime water turbid. The chemical formula of acetic acid is represented by HAc. Write the chemical reaction equation of step ④_____________. The mass relationship between precipitates A and B is m(A)______m(B) (fill in ">", "<" or "=").

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For more information about the "Preparation of Tofu with Organic Compounds" PPT courseware, please click the "Preparation of Tofu with Organic Compounds ppt" ppt tag.

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Update Time: 2024-11-17

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