Should onions, ginger and garlic be used to stir-fry/boil the pot before cooking?

Everyone does this.

Why use onions, ginger and garlic?

It smells good.

Do I have to use onions, ginger and garlic?

Just put whatever you have at home.

How long does it take to explode?

People always say on TV that they should be stir-fried until fragrant before adding vegetables.

China’s culinary culture is extensive and profound. Many cooking techniques are passed down orally, and even experienced chefs find it difficult to explain them clearly. When I cooked my dumplings for the first time, I didn’t know when they were ready. I saw many people’s advice on the Internet saying that just adding cold water 3 times is enough. People who are confused will want to know how big a bowl should be used to add water? How big a pot should I use to cook dumplings? How many dumplings to cook? Why add 3 times instead of 4 times. When I was a child, I watched daily food programs. The chefs always used the appropriate amount and small amount to measure the amount of seasoning. I always wanted to ask what these two words meant. Many people don't care about these cooking experiences, as long as they taste good.

Recently, I suddenly thought about the need to stir-fry the pot when cooking (some readers may call this step the stir-fry pot), and I checked online with great interest as to why it is necessary to stir-fry the pot. There is really no one. To make this matter very clear, today I will just talk about my opinions in random terms.

In fact, the cooking technique of "stir-frying" does not exist in many countries. In ancient times, people did not have mature oil-pressing technology, nor did they have the economic conditions to stir-fry every day. The initial stir-fry can be traced back to the Northern and Southern Dynasties. . People first used air as a medium to cook food, such as barbecues. Later, water and steam replaced air, and then oil. Oil can increase cooking temperature and efficiency, and add flavor and color to food. On the one hand, the boiling point of oil is high, and hot oil can reach more than 200 degrees, which can stimulate some chemical reactions that cannot occur in boiling water, including the oil itself. On the other hand, oil and water have different solubility properties, and oil can dissolve many flavor substances with poor water solubility. Finally, the viscosity and surface tension of the two are different. The oil has a higher adhesion ability to the material and can transfer the flavor to the food. For example, when you stir-fry green vegetables with dried chili peppers, the final effect is that the green vegetables are covered with red oil, which is very delicious. But if you don't add oil, the pan will be mushy at the end of the frying, and there will be no flavor exchange between the ingredients, making it difficult to swallow.

I don’t know when one day, people put some spices into the hot oil, which gave off an attractive fragrance, and since then, they have had the habit of popping the pot. The principle is very simple. There are special substances in onions, ginger, garlic and other spices that are stable at low temperatures. Various chemical reactions occur at high temperatures, such as decomposition, oxidation, rearrangement, etc. These small molecules produced partially volatilize, producing aerosols, which is why stir-fry dishes are fragrant. There are also some molecules that dissolve in the oil and then adhere to the surface of the food or penetrate into the food. This is why it tastes delicious.

Oil and spices meet not only in the cooking method of stir-frying. If you think about butter hot pot, it reflects the characteristics of oil very well. The oil and chili peppers need to be boiled together in a large pot for several hours. If water is used, it will be difficult to extract the flavor substances of the chili peppers. The temperature is not high enough and the reaction is insufficient. , the solubility is not good enough. When stewing, sometimes the pot must be exploded first to allow the substances in the spices to fully react and then be released into the water.

The main aromatic substance in raw garlic is allicin. At high temperatures, garlic can release 40-60 volatile substances, while boiled garlic only releases 16 of them. These substances are mainly allicin-derived sulfur-containing compounds, such as diallyl disulfide, which is the most abundant. After frying in soybean oil for 1 minute, only 16% of the sulfur-containing substances are left in the oil, and the rest have evaporated. Therefore, the frying time should not be too long, as the aroma will be gone and the food will no longer taste good. Similar to garlic, green onions and shallots also contain sulfur-containing organic matter. This substance can further react with the fatty acids in the oil to produce a richer variety of molecules. So to sum up, the flavor produced by hot pot comes from three parts: 1. The spice molecules themselves pyrolyze. 2. Fat pyrolysis. 3. The reaction product of fragrance molecules and oil.

According to statistics, ginger is used in about 30 Chinese dishes. The main flavor in ginger is gingerol. As the saying goes, "Ginger is still spicier when it's old" because this type of substance is more abundant in old ginger. Such molecules can undergo dehydration reactions and decomposition reactions at high temperatures. They are not very volatile and the taste is more integrated into the ingredients. Therefore, if you want the dish to be more fragrant, give priority to onions and garlic, and ginger can play a supporting role.

Cooking is a learned thing, we will talk about it next time.

References:

Fereidoon Shahidi, Chi-Tang Ho. Flavor Chemistry of Ethnic Food. (1999)