Introduction

Starch is a homopolymer of glucose, which is hydrolyzed to the disaccharide stage as maltose, and completely hydrolyzed to give glucose. There are two types of starch: straight chain starch and branched chain starch. Straight chain starch contains several hundred glucose units and branched chain starch contains several thousand glucose units. In natural starch straight chain accounts for about 22% to 26%, it is soluble, the rest is branched chain starch. When tested with iodine solution, the straight-chain starch solution appears blue, while the branched-chain starch becomes reddish brown when in contact with iodine.

Starch is a nutrient stored in the plant body, exists in the seeds and tubers, all types of plants in the starch content is high, rice contains starch 62% to 86%, wheat contains starch 57% to 75%, corn contains starch 65% to 72%, potatoes contain starch 12% to 14%. Starch is an important part of food, chewing rice, etc. feel some sweetness, this is because the saliva of the amylase enzyme will be hydrolyzed into a monosaccharide starch. After the food enters the stomach and intestines, it can also be hydrolyzed by the amylase secreted by the pancreas, and the glucose formed is absorbed by the wall of the small intestine and becomes a nutrient for human tissues. Partial hydrolysis of branched-chain starch produces a mixture called dextrin. Dextrins are mainly used as food additives, glues, pastes, and in the manufacture (finishing) of paper and textiles.

Classification of starch

Starch granules can be divided into mono-granular starch, complex granular starch and semi-complex granular starch.

Types of starch

The starch used for thickening, also called clumping starch, is a polysaccharide polymer formed by the condensation of several glucose molecules. Cooking starch, mainly mung bean starch, potato starch, wheat starch, diamondback starch, lotus root starch, corn starch and so on. Starch is insoluble in water, in and water heated to 60 ℃, it is pasted into a colloidal solution. Thickening is the use of this characteristic of starch.

Mung bean starch

Mung bean starch is the best starch, generally rarely used. It is made from mung beans by soaking them in water and grinding them, then precipitating them. It is characterized by sufficient viscosity, small water absorption, and white and glossy color.

Potato starch

Potato starch is a commonly used starch in households, which is made by grinding potatoes, kneading and precipitating. It is characterized by sufficient viscosity, fine texture, white color and better luster than mung bean starch, but poor water absorption.

Wheat starch

Wheat starch is wheat bran after washing gluten, precipitation or made from flour. Characteristics are: white color, but the luster is poor, the quality is not as good as potato flour, thickening easily precipitated.

Sweet potato starch

Sweet potato starch is characterized by strong water-absorbing capacity, but the viscosity is poor, no luster, dark red with black color, from fresh potato grinding, kneading and washing, precipitation.

In addition, there are corn starch, rhododendron starch, lotus root starch, water chestnut starch and so on.

Thickening influence dishes

Thickening is appropriate, the quality of the dish has a great impact, therefore, thickening is one of the basic skills of cooking. Thickening is mostly used for simmering, sliding, frying and other cooking techniques. These cooking methods **** with the same characteristics are: the fire quickly into. With this method of cooking dishes, basically no soup. However, due to the cooking of certain sauces and seasonings and raw materials itself out of the water, so that the dishes look soup increased by thickening, so that the consistency of the juice increased, and attached to the surface of the raw materials, so as to achieve the dishes glossy, smooth, tender and delicious flavor.

The use of thickening

Thickening is generally used in two ways. One is the starch juice and seasonings, commonly known as "on the juice", mostly used in the fire power, the speed of simmering, bursting and other methods of cooking dishes. The other is simply starch juice, also known as "wet starch", mostly used for general fried dishes. Pouring juice is also a kind of thickening, also known as thin gravy, glazed gravy, mostly used for simmering, burning, steak and soup dishes. According to the cooking method and the characteristics of the dishes, there are generally the following types of gravy usage:

Packet gravy is generally used for stir-fry method of cooking dishes. Powder sauce is the thickest, the purpose is to make the gravy all wrapped up to the raw materials, such as shredded pork with fish, fried cashews, etc., are used to wrap the gravy, after eating the dishes, the bottom of the plate basically does not leave the marinade.

Paste cross generally used for simmered, slippery, stewed, braised method of cooking dishes. Powder juice is thinner than the package of gravy, the use of the soup of the dishes into a paste, to achieve the soup and vegetables fusion, taste smooth and soft, such as: sweet and sour pork, sweet and sour carp, and so on.

Streaming gravy is thinner, generally used for large or whole dishes, its role is to increase the flavor and luster of the dishes. Generally in the dishes on the plate, and then the pot of marinade heating thickening, and then poured on the dishes, part of the dip in the dishes, part of the glazed state, after eating the plate can be part of the remaining juice.

Milk soup gravy is the thinnest gravy, also known as thin gravy. Generally used for braised dishes, such as: spicy tofu, shrimp potpourri. The purpose is to make the dish soup a little thicker to achieve the color and fresh requirements.

Thickening, that is, when the dishes are close to maturity, the starch juice will be adjusted to pour on the dishes or in the soup, so that the dish soup thick, and adhere or partially adhere to the process of dishes. Yuan Mu in the "with the garden food single - with fiber instructions" said: "commonly known as soybean meal for fiber, that is, pulling the boat with fiber. The name must be taken into account. Because the treatment of meat to be a group and can not be combined, to be made into a soup and can not be greasy, so the powder to pull together. Frying time, consider the meat stick to the pot, will be scorched old, so use the powder to hold it. This fiber meaning." The gravy is from the fiber transcription, so now commonly referred to as "thickening".

Because of the different flavor requirements of the dishes, thickening the main role of the following:

1?Increase the consistency of the soup. Dishes in the heating process, the juice in the raw materials will flow outward, with the addition of soup and liquid seasonings will be fused to form a marinade. General stir-fried vegetables in the marinade is thin, not easy to adhere to the surface of the raw materials, into the dish will produce a "not into the flavor" feeling. After thickening, the thickening effect of the paste to increase the consistency of the marinade, so that the marinade can be more attached to the dishes on top, improving the people's feelings about the flavor of the dishes.

2?Thickening hooked into the dishes, the gravy will be tightly wrapped raw materials, thus preventing the spillage of water within the raw materials, which maintains the flavor characteristics of the dishes fresh and tender, but also make the dishes full of form and not easy to break up.

3?After thickening, due to the paste of starch, with a transparent colloidal luster, the dishes and seasoning color more distinctly reflected, so that the color of the dishes more bright and beautiful.

4?After thickening the dishes can make the soup thicker, can slow down the internal heat emission of raw materials, so that the dishes have heat preservation, prolonging the cooling time of the dishes, is conducive to diners eating hot dishes.