Food leavening agent, Chinese and Western pastry are indispensable delicious magic

　　When I was a child, I always felt that the kitchen had magic, and after some vegetables and some meat were bought back into the kitchen, they would become all kinds of delicious food. For the author at that time, the most amazing thing was steamed buns. Why does loose powdery flour become white and fluffy after kneading and steaming? Ask the adults, they will say that the yeast is released. But what is "motherhood"? Why does it get bigger after releasing this "mother"? Is there a "call for justice"? Adults can't answer, so they can only say, "Go and play, and the children's families will make trouble." So, this kitchen magic remained in the author's mind until...

　　I studied chemistry. Oh my God the mystery of the century is solved! Chemistry is magical! Since then, he has embarked on the road of no return for the chemistry major...

　　Ok nonsense, today let's talk about the delicious magic of pasta - leavening agent.

　　Leavening agent

　　Leavening agents, which play an important role in food processing, especially pasta processing, can make pasta – whether It is a Chinese steamed bun or a Western-style bread cake – loose and porous, resulting in a soft and fluffy taste. Therefore, the definition of leavening agent is: added to the main raw material for the production of baked goods wheat flour, and in the process of processing, the dough blank is raised, forming a dense porous tissue, so that the product has a bulking, soft or crispy class of substances.

　　In general, leavening agents can be divided into two main categories: biological leavening agents and chemical leavening agents. Biological leavening agents generally refer to yeasts; chemical leavening agents can also be divided into acidic leavening agents and alkaline leavening agents.

　　Bio-bulking agent

　　Yeast generally refers to a variety of single-celled fungi that can decompose fermented sugars, which can be used for brewing and production, and is one of the earliest microorganisms used in the history of human civilization.

　　The market is generally sold in vacuum-packed dry yeast, when the yeast is in a "sleeping state", when it encounters water and flour after being activated, the fermentation process begins. Yeast fermentation has two processes, "oxygen-consuming fermentation" and "anaerobic fermentation", and the main reason for the bulky and larger pasta is "anaerobic fermentation". In this process, the sugars in flour are transformed into carbon dioxide, alcohol and heat through complex biochemical reactions under the action of yeast. The dough contains a lot of carbon dioxide gas, which naturally becomes larger and larger, and later in the steaming process, the gas is heated and will further enlarge the dough. The alcohol produced during fermentation, as well as the esters formed after the reaction of alcohol and acid, are the sources of the unique flavor of the pastry.

　　So sometimes the dough is "overdone" and you will smell a strong wine, which is why there is too much alcohol in fermentation.

　　Chemical leavening agent

　　Chemical leavening agents generally include sodium bicarbonate NaHCO? (baking soda), ammonium bicarbonate, ammonium carbonate, carbonate and complex leavening agents. Compound leavening agent is mostly composed of carbonate, acidic substances and starch, such as the commonly used baking powder is baking powder with acidic materials and corn flour.

　　In addition, organic leavening agents such as gluconic acid-δ-lactone are now available on the market.

　　The chemical reaction of commonly used leavening agents is as follows:

　　2NaHCO3→CO2↑+H2O+Na2CO3

　　NH4HCO3→CO2↑+NH3↑+H2O

　　Comparison of advantages and disadvantages of different leavening agents

　　Yeast has a long history of use, is non-toxic, and is inexpensive and easy to obtain. However, improper storage is susceptible to inactivation.

　　Alkaline leavening agents such as ammonium bicarbonate have higher safety and better foaming ability. However, after decomposition by heat, there will be a certain residue, affecting the taste, and improper use will make the pastry yellow.

　　Compound leavening agents can effectively neutralize the alkaline salts formed during the production of carbon dioxide due to the addition of acidic substances, and can also adjust the rate of carbon dioxide production, so that the pasta bubbles are evenly distributed. However, compound leavening agents are relatively more complex in composition and have too many additives.

　　Safety standards for leavening agents

　　Although leavening agents will make the pastry taste better, excessive additions can have health effects, such as baking powder is very prone to aluminum exceeding the standard. Therefore, China has also formulated relevant standard policies for the use of leavening agents.

　　The "Sanitary Standard for the Use of Food Additives" (GB2760-2007) stipulates that alkaline leavening agents can be applied to various types of foods due to their high safety, and are added in an appropriate amount according to production needs; aluminum-containing composite leavening agents should be applied in limited quantities in fried foods, aquatic products and products, bean products, baked foods, wheat flour and their products, puffed foods and shrimp flavored tablets, and their aluminum residues (dry samples, al-counted) ≦ 100mg/kg.