Let's first understand what the raw materials used in braised pork are and what their characteristics are.
Let's start with the main ingredient pork belly. Pork belly is red and white pork belly composed of several layers of lean meat and fat meat, usually with pigskin. From a biological point of view, pork belly is composed of epidermis, fat layer and muscle. Epidermis, that is, pigskin, is mainly composed of about 85% collagen, followed by elastin. Pigskin can be used to produce gelatin. The fat layer is almost all fat cells, and it also contains some lecithin and cholesterol that the human body needs. Muscle is composed of muscle tissue, the main component is protein, but it is somewhat different from the protein component of pigskin.
Other raw materials include white sugar or rock sugar, onion, ginger, garlic, star anise, fennel and other seasonings. The main function of these raw materials is to increase the flavor of meat and remove the fishy smell of meat.
With the raw materials, how did the smell of braised pork come from?
Raw meat has no fragrance (of course, this is only for humans. For carnivores, raw meat is very fragrant, and it will only be fragrant if it is heated. This is because during the heating process, a series of complex changes have taken place in various components of meat, resulting in some volatile flavor substances. In the process of heating, lean tissue gives meat flavor, while adipose tissue gives meat a unique flavor. If all kinds of meat are defatted, the taste of meat is similar, and there is no big difference. Therefore, if there is no lean meat when cooking, or if there is too little lean meat, it will not be very fragrant.
At present, there are about 1000 kinds of volatile components in meat, mainly including N-S-O- heterocyclic compounds and other sulfur-containing components, including low molecular weight precursors such as furan, pyrrole, thiophene, imidazole, pyridine and cyclic ethylene sulfide. Pyrazine is the main volatile substance. The precursors of these substances are mainly water-soluble sugars and compounds containing amino acids, as well as lipids such as phospholipids and triglycerides. Sugar, amino acids and lipids produce meat flavor through degradation. At the same time, ribonucleotides, ribose -5'- phosphate and methyl furyl alcohol ketone also produce meat flavor through hydrogen sulfide reaction.
Speaking of these complex changes, I have to mention a very classic chemical reaction-Maillard reaction. The Maillard reaction proposed by French chemist L.C. Maillard in 19 12, also known as "non-enzymatic browning reaction", exists in almost all kinds of food processing. This non-enzymatic browning is a reaction between carbonyl compounds (reducing sugars such as glucose and xylose) and amino compounds (amino acids and protein). Because of the complicated process, the final product is brown or even black macromolecular substance melanoidin or melanoidin, so it is also called carbonyl amine reaction. Common things, such as the golden brown of bread crust, the brown and rich flavor of braised pork and the reddish brown of fried food, are largely the result of Maillard reaction.
When cooking braised pork, lean meat, fat and sugar all meet the conditions of Maillard reaction. After Maillard reaction, braised pork has its unique flavor. But the problem is coming again. Since all the above methods can produce Maillard reaction, which one is more fragrant? It depends on which route causes more and more Maillard reactions.
Factors affecting Maillard reaction include:
1, sugar amino structure. Reducing sugar is the main substance of Maillard reaction. The browning rate of five-carbon sugar is 10 times that of six-carbon sugar. Among reducing monosaccharides, the browning rate of five-carbon sugar is ribose >; Arabinose > xylose and hexose are galactose >; Mannose > glucose. Reduced disaccharide has large molecular weight and slow reaction speed. Among carbonyl compounds, α -vinyl aldehyde browning is the slowest, followed by α -disaccharide compounds and ketones. Amines change brown faster than amino acids. Among amino acids, basic amino acids are slower than protein. Therefore, the quality of meat and the added sugar determine the speed of Maillard reaction.
2. temperature. Under the oxidation condition of 20 ~ 25℃, Maillard reaction can occur. Generally, for every phase difference of 10℃, the reaction speed is 3 ~ 5 times different. The speed is accelerated above 30℃. When the temperature is higher than 80℃, the reaction rate is little influenced by temperature and oxygen. Generally, the temperature of processed food is higher than 80℃, such as the temperature of stew is about 100℃ and the temperature of toast is about 150-250℃. High temperature contributes to Maillard reaction. It can be speculated that frying is more likely to react than boiling.
3. Moisture. When the moisture content is 10% ~ 15%, it is easy to react and it is difficult to produce completely dry food. It can be seen that don't fry too much, and it is not a good thing to fry it.
4.pH value. That is, ph, when the pH value is above 3, the reaction is accelerated with the increase of pH value. When the pH is greater than 7, the reaction speed is fast, it is difficult to control and the flavor is poor. The pH value is related to the water used and the seasonings added, which may explain why the food made from water in some places tastes better than that in other places.
From the above analysis, we can draw a conclusion that the method of frying is better than the method of water copying, but the process of frying should be short and not too dry.
Salt first or later?
To answer this question, we need to know what the role of salt is. Salt (NaCl) is an essential seasoning for cooking, but it is not only a seasoning, but also can maintain the balance of osmotic pressure and other physiological needs of human body. What is osmotic pressure? The phenomenon that water moves from a high water potential system to a low water potential system through a semi-permeable membrane is called osmosis. Osmotic pressure is the difference of water potential in which osmosis occurs. The greater the osmotic pressure, the faster the infiltration. When cooking braised pork, one of the functions of salt is to adjust osmotic pressure.
When the braised pork is cooked, the water potential of the soup and the water potential in the meat cells form a water potential difference, and infiltration will occur. Either the water in the soup enters the cells or the water in the cells comes out into the soup (water potential balance is also possible). If salt is not put at first, the osmotic pressure of meat cells is high, and water molecules will automatically enter the meat cells. When there is too much water, the cell membrane will burst when it can't stand it. When cells rupture, the contents are released, and the taste of meat is stronger. Therefore, it is generally not to put salt first, and then put salt last, so that the original flavor of the meat comes out and the soup is fresher. If you put salt in the beginning, the osmotic pressure in the soup will be higher, and the meat cells will produce water, but only water, and other ingredients will remain in the meat. This will easily lead to burning meat and firewood, and the taste and taste are not good.
It seems better to add salt at last. In fact, it is not necessarily true. Braised pork is no better than soup. The key to making soup is the freshness of soup. Braised pork eats meat. Therefore, meat must be seasoned, which means that NaCl must enter the meat to be fragrant. It seems that salt should be put first, but salt cells are easy to come out first. What should I do? In some places, water is used before cooking, which skillfully solves this problem. Blanching water with water actually destroys meat cells, and the cells are destroyed, which makes it easier to taste when cooked again. In addition, if you put salt at the beginning, you can inhibit the rupture of residual meat cells and maintain the taste of meat-although water molecules will escape.
Generally speaking, it is best to add salt in the middle to make braised pork, that is, to treat the meat first and then add salt. There are two ways to treat meat: frying and blanching. Both methods can make delicious braised pork. Water blanching can break the external cells and help to improve the taste; Frying helps to start Maillard reaction, form a protective layer on the outside, prevent internal water loss, and make the meat more tender. Therefore, the key to delicious food is actually temperature. The frying time should not be too long and the blanching time should not be too short. In addition, the amount of salt is also critical. Reaching an appropriate osmotic pressure can not only taste, but also protect the original flavor of meat cells. The delicious braised pork is also related to the water quality and seasoning. In a word, it is not easy to make a delicious braised pork, which requires experience and skill.
I hope this article can provide a scientific reference for friends who like food. If you are interested, try it yourself and compare which method is better.
Attach recipes to friends drooling here.
Classic braised pork practice:
1, wash pork belly (lean meat and fat meat are layered, preferably with skin) and cut into squares, 2 cm square.
2, put oil in the pot (more), add a spoonful of sugar (white sugar, rock sugar can be) (more) after heating, stir-fry until it is paste (commonly known as caramel. There should be smoke in the pot at this time. Don't be afraid. Or put it in boiling water for 5 minutes and take it out to remove the smell and foam! (secret recipe: it is best to add some white wine! )。
3. Pour in chopped meat and seasonings (thick ginger slices, garlic cloves (don't break them), cinnamon, dried peppers, star anise and dried tangerine peel (not dried tangerine peel), stir-fry for three minutes, and then the meat turns dark red.
4. Add a proper amount of salt, a spoonful of soy sauce, 1/5 tablespoons of vinegar, half a spoonful of sugar, two tablespoons of cooking wine, half a spoonful of chicken essence, and clear soup (cold water is also acceptable) until the meat is submerged for 3 mm, and the fire boils (it begins to smell).
5. Pour into a saucepan and simmer for 1.5 hours. At this point, the soup should be small and sticky (if there is too much soup, you can collect the soup on high fire, but you should stand by and watch), add green pepper (not very fat lantern pepper), add some coriander, then taste the salty taste and simmer for 3 minutes.
To sum up, braised pork is my favorite. If it is delicious, it can really be called braised pork. General restaurants taste good, and friends who like meat can try it!