Chemically, starch is a homogeneous polysaccharide formed by the condensation of hundreds (straight-chain starch) or thousands (branched-chain starch) of glucose molecules, and its molecular shapes are of two kinds: straight-chain (soluble in hot water) and branched-chain (insoluble in hot water); all of the glutinous rice starch is branched-chained, all of the starch of certain beans is straight-chained, and both kinds of the starch in general are present. Starch is widely found in plant grains (rice, wheat, corn), fruits (chestnuts, white fruits), roots (sweet potatoes), tubers (potatoes), bulbs (water chestnuts, taro), and is the main form of energy storage in plants. Starch is insoluble in water, and in hot water it will absorb water and swell into a translucent colloidal solution with viscosity.

(A) wheat products

We eat flour from the seeds of wheat, a member of the grass family, and wheat is the most widely planted grain in the world. Unlike other grains that are directly consumed after hulling, wheat has tough surface bran and fragile endosperm, which makes it difficult to be processed into whole grains, so it can only be ground into flour. The biggest difference between wheat flour and other grains is that the two proteins unique to wheat can combine to form elastic and ductile gluten (that is, it can be stretched very long, but will not break), so only wheat can produce a wide variety of pasta products with different tastes. The amount and quality of gluten (that is, the amount of each of the two proteins) in flour depends on the variety of wheat crop and the growing process, not on the flour milling process, but the protein content may change during processing and storage.

Gluten: is the (pure gluten) protein fraction extracted from flour, which can be used to make Chinese specialties such as cold skin and oil gluten.

Wheat starch: also called clarified flour, clarified noodles, ting flour, ting noodles, is the (gluten-free) starch portion left in the flour after the protein is removed, it is very white in color, it is the main ingredient of crystal pastries, and the raw material of cold skin.

High-gluten flour: also called bread flour, bread flour, protein content of 11.5% or more, the strongest gluten, used to make bread, pizzas, puffs, doughnuts, lasagna and other needs to rely on the strong elasticity and extensibility to wrap the air bubbles, the oil layer in order to form a loose structure of the snacks.

Medium gluten flour: the most common flour, plain flour, with a protein content of 9.5-11.5%, is used to make steamed buns, buns, dumplings, pancakes, noodles, twisted flowers, and most other Chinese snacks.

Low-gluten flour: also known as thin flour, cake flour, protein content of 6.5-9.5%, can be used in accordance with the mass ratio of four gluten flour plus a corn starch (other starches can also be) mixed with, suitable for making cakes, cookies, tarts, and other loose, crunchy, no toughness of the snacks.

Self-raising flour: supermarkets sell self-raising flour is flour mixed with a certain percentage of yeast, baking powder and other chemical additives, with only the need to add water, and can save fermentation time. You should follow the instructions on the package to use self-rising flour, as the method of use may vary with different product recipes.

Whole Wheat Flour: Wheat seed consists of three parts: bran, endosperm, and germ. Bran is hard and difficult to digest, and the germ is rich in oil and easily rancid, so the flour is made from the endosperm. But the bran provides rich dietary fiber, which is very beneficial to the human digestive process. Therefore, whole wheat flour is made from the endosperm of ordinary flour with the addition of ground bran, for different purposes such as bread, cakes, noodles, etc., the proportion of bran added and the size and shape of the bran are also different, so in fact, whole wheat flour is not a whole grain of wheat directly milled crude products, but rather more complex refined products.

While pastry recipes will specify which flour is needed, you can generally substitute medium-gluten flour for high-gluten or low-gluten flour without a noticeable difference. Now the flour sold in the grain section of the domestic supermarkets is mainly medium-gluten flour suitable for Chinese pasta, and the labeling of "fine flour", "special flour", "rich and strong flour" is an indication of the degree of refinement of the flour processing, not the gluten content of the flour. The labels "fine flour," "special flour," and "rich flour" indicate the degree of refinement of the flour, not its gluten content. "Dumpling flour" is medium gluten flour, "bread flour" is high gluten flour. In the imported food section of large supermarkets, you can also buy completely imported flour, categorized in detail, purpose-specific, as well as a variety of ready-mixed flour containing other powdered ingredients that can be used directly, but the price is also very expensive.

(2) Other starches

Grain milled flour is different from the starch extracted from grains, just like the difference between wheat starch and flour. Grain ground into powder is usually sold with rice, flour, and a variety of miscellaneous grains, and used in much the same way as flour, and can be made into all kinds of miscellaneous bread, noodles, steamed cakes and so on. Starch is sold with salt, monosodium glutamate and other seasonings, and is mainly used in Chinese cooking for thickening water, thickening soups and porridges, and as a coating for deep-fried foods. Starch is also used as a raw material for vermicelli, vermicelli, and cold noodles. Vermicelli and tai bai powder are general terms for various kinds of starch, and the specific ingredients should be seen in the package description. There are some starches that have a special role in making dim sum.

Glutinous rice flour: the seeds of glutinous rice, a variant of rice (glutinous rice) are ground into flour, also known as jiangmi flour, which is an ingredient in soup dumplings and lanterns.

Sticky Rice Flour: the seeds of the grass plant rice (rice) ground into powder, also called rice flour, is the raw material for turnip cake.

Mung bean starch: from the seeds of the legume mung bean, used to make mung bean vermicelli and mung bean cold noodles, but different from the mung bean noodles used to make mung bean cakes, which are ground directly from mung beans.

Corn starch: also known as cornstarch, comes from the seeds of the grass plant corn, mixed into the flour can reduce the gluten of the flour, in cream pudding filling, pineapple filling, such as pies, towers, tarts and other pastry fillings to play a viscous role, but also one of the raw materials of ice cream. Cornstarch is the starch component extracted from corn, white in color, as opposed to yellow cornmeal, which is made by grinding corn kernels directly.

Sweet potato starch: comes from the tuberous roots of the sweet potato (sweet potato, sweet potato, yam, sweet potatoes, white potatoes, groundnuts, as they are called in the north) of the spinach family.

Potato starch: from the tubers of potato (potato, egg, taro), family Solanaceae.

Tapioca starch: from the plant Euphorbiaceae tapioca (tapioca) tuber, is the main raw material of pearl milk tea in the pearl.

Water chestnut starch: also called horseshoe powder, from the bulb of water chestnut (also known as horseshoe) of the Salviaceae plant, is the raw material of horseshoe cake, water chestnut is mainly produced in the southern warm regions of China.

Kudzu starch: from the tuberous roots of the leguminous plant kudzu, is the raw material of kudzu cake.

Lotus root starch: it is lotus root powder, from the roots and stems of lotus, a plant in the water lily family, and can be eaten directly with boiling water.

Sago: sago, also known as sago rice, is the phonetic translation of the English sago, native to Indonesia, is a small ball of starch extracted from the trunk of the local palm plant, sago palm, has no structure and can not be rooted and sprouted, not the seeds of a certain plant.