Starch is a nutrient stored in plants and exists in seeds and tubers. The starch content in all kinds of plants is high, including rice 62% ~ 86%, wheat 57% ~ 75%, corn 65% ~ 72% and potato 12% ~ 14%. Starch is an important part of food, so it feels a little sweet to chew rice. This is because amylase in saliva hydrolyzes starch into monosaccharides. After food enters the gastrointestinal tract, it can also be hydrolyzed by amylase secreted by the pancreas, and the formed glucose is absorbed by the small intestine wall and becomes a nutrient for human tissues. Partial hydrolysis of amylopectin can produce a mixture called dextrin. Dextrin is mainly used as food additive, glue, paste, and in the manufacture (finishing) of paper and textiles.
Types of starch
Starch used for thickening, also known as dough powder, is a polysaccharide polymer concentrated by multiple glucose molecules. Cooking starch mainly includes mung bean starch, potato starch, wheat starch, water chestnut starch, lotus root starch, corn starch and so on. Starch is insoluble in water, and when heated to 60℃ with water, it is gelatinized into colloidal solution. Thickening is to use this characteristic of starch.
Mung bean starch
Mung bean starch is the best starch and seldom used. It is made by soaking mung beans in water, grinding and precipitating. Features: enough viscosity, small water absorption, white and shiny color.
potato starch
At present, potato starch is widely used in families. It is made by grinding, washing and precipitating potatoes. The characteristics are: enough viscosity, fine texture, white color, luster better than mung bean starch, but poor water absorption.
wheat starch
Wheat starch is precipitated from wheat bran after washing gluten, or made from flour. The characteristics are: white color, but poor luster, not as good as potato powder, easy to precipitate after thickening.
sweet potato starch
Sweet potato starch is characterized by strong water absorption, but poor viscosity and dark red and black color. It is made of fresh potatoes through grinding, scrubbing and precipitation.
In addition, there are corn starch, water chestnut starch, lotus root starch and water chestnut starch.
Thickening affects dishes.
Whether thickening is appropriate or not has a great influence on the quality of dishes. Therefore, thickening is one of the basic skills of cooking. Thickening is mostly used in cooking techniques such as frying, sliding and frying. The common characteristics of these cooking methods are: quickness. The dishes made in this way basically do not contain soup. However, due to the addition of some sauces and seasonings and the moisture of the raw materials themselves, the dishes look more soupy. By thickening, the consistency of the juice is increased and attached to the surface of raw materials, thus achieving the luster, smoothness, softness and deliciousness of dishes.
Use of thickening
There are generally two methods for thickening. One is starch juice with seasoning, commonly known as "juice-to-juice", which is mostly used for dishes cooked by quick frying and stir-frying. The other is simple starch juice, also called "wet starch", which is mostly used in general cooking. Pouring juice is also a kind of thickening, also known as thin thickening and glaze thickening, which is mostly used for stewing, roasting, roasting and soup dishes. According to the cooking methods and characteristics of dishes, the usage of sauce basically has the following kinds:
Bao Peng is usually used for cooking. The powder juice is the thickest, and the purpose is to cover all raw materials with sauce, such as fish-flavored shredded pork and fried kidney flower, which are all covered with sauce. After eating, there is basically no marinade at the bottom of the dish.
Paste cross is generally used for cooking dishes such as stir-frying, sliding, stewing and stewing. Powder juice is thinner than bread, and its purpose is to turn the soup of dishes into paste, so as to achieve the fusion of soup and vegetables and smooth and tender taste, such as sweet and sour pork ribs and sweet and sour carp.
Thin juice is generally used in large or whole dishes to increase the taste and luster of dishes. Generally, after the dish is served, the marinade in the pot is heated and thickened, and then poured on the dish, some of which are stained with colored glass, and some juice can be left on the plate after eating.
Milk soup is the thinnest sauce, also called thin sauce. Generally used for stews, such as spicy tofu, shrimp and crispy rice. The purpose is to thicken the soup of dishes to meet the requirements of fresh color, fragrance and taste.
Thickening is the process of pouring the mixed starch juice on the dishes or soup when the dishes are close to maturity, so that the soup of the dishes becomes thicker and adheres or partially adheres to the dishes. Yuan Mu said in the "Instructions for the Use of Single Fiber for Eating in the Garden": "Bean flour is commonly known as fiber, that is, spunlace fiber. As the name implies. Because the meat therapist wants to make a group but can't get together, and wants to make soup but can't get tired together, he pulls it with the powder. When frying, I was worried that the meat would stick to the pot and paste, so I used powder to hold it. This kind of fiber is also meaningful. " It is called "thickening" because it comes from optical fiber to sound.
Due to the different flavor requirements of dishes, thickening mainly has the following functions:
1? Increase the viscosity of soup. When the dishes are heated, the juice in the raw materials will flow out and merge with the added soup and liquid seasoning to form marinade. Generally, the marinade in cooking is relatively thin, which is not easy to adhere to the surface of raw materials, and it will feel "tasteless" after cooking. After thickening, the gelatinization of thickening juice increases the viscosity of marinade, which makes marinade more attached to dishes and improves people's taste.
2? When the sauce is hooked into the dish, it will tightly wrap the raw materials, thus preventing the water inside the raw materials from overflowing, which not only keeps the flavor characteristics of the dish fresh, fragrant, smooth and tender, but also makes the dish full and not easy to break.
3? After thickening, due to the gelatinization of starch, it has a transparent colloidal luster, which can more vividly reflect the colors of dishes and seasonings, making the colors of dishes more vivid and beautiful.
4? After the dishes are thickened, the soup can be thickened, which can slow down the heat dissipation inside the raw materials, make the dishes have heat preservation, prolong the cooling time of the dishes and facilitate diners to eat hot dishes.