(Wheat flour)
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This entry is compiled and applied by the scientific encyclopedia entry of "Popular Science China"? Review.
Flour is a kind of powder ground from wheat. According to the content of protein in flour, it can be divided into high gluten flour, medium gluten flour, low gluten flour and gluten-free flour.
Flour (wheat flour) is the staple food in most parts of northern China. There are many kinds, patterns and flavors of food made from flour? [ 1]。
Chinese name
flour
Foreign name
wheat flour
Another name
wheat flour
primary raw materials
Wheat and barley
Does it contain preservatives?
no
Main nutritional components
Protein, sugar.
Main edible efficacy
Nourish the heart and kidney, clear away heat and quench thirst, strengthen the spleen and thicken the intestines.
Suitable crowd
all
side effect
not have
Storage method
Select dry storage.
density
The density of common household flour is 520 g/L.
catalogue
1? Basic information
Rough classification
Hierarchical application
Price situation
Distinguish flour
2? Classification correlation
Classification basis
Classified application
3? Classification category
Whole wheat flour
bread flour
Cake powder
Stone mill flour
4? Selection skill
white
Gluten strength
Fermentation endurance
High water absorption capacity
5? Formula example
Noodles steamed bun
Method for making fried dough sticks
6? Storage method
7? Nutritional components of food
Basic information
Editor? speech sound
We often say "flour" refers to wheat flour, that is, flour ground from wheat, and names like "high gluten wheat flour" refer to what we usually call flour. Wheat flour can be divided into special flour (such as bread flour, jiaozi flour, biscuit flour, etc. ), common flour (such as standard flour and rich flour) and nutritionally fortified flour (such as calcium-rich flour, iron-rich flour and "7+ 1" nutritionally fortified flour, etc. ) according to its performance and use. According to the precision, it can be divided into special first-class powder, special second-class powder, standard powder and ordinary powder. According to the strength of gluten, it is divided into high gluten flour, medium gluten flour and low gluten flour. ? [2]?
Rough classification
According to the content of protein in flour, flour can be divided into high gluten flour, medium gluten flour and low gluten flour.
type
Protein content (g)
use
strong flour
10.5- 13.5
bread
Medium gluten powder
8.0- 10.5
Noodles and snacks
cake flour
6.5-8.5
Snacks and dishes
Hierarchical application
In terms of grades, we can divide flour into super-grade flour, first-grade flour, second-grade flour and other grades.
grade
Protein (%)
Minerals (%)
type
use
Special powder
7.2
0.32
cake flour
dessert
Primary powder
12.7
0.43
strong flour
Bread use
Primary powder
10.7
0.45
strong flour
French bread
Secondary powder
13.5
0.54
strong flour
Bread use
Price situation
The monitoring data shows that since September 20 12, the national flour price has risen obviously, and the price of 10/65438+ has gradually stabilized, and the price of 65438+has risen again at the end of February. Compared with 20121February 28th, the prices of 20 13 1.0% special powder and standard powder increased by 1.3% and 1.0% respectively. In terms of regions, about 60% of the provinces, autonomous regions and municipalities saw the price increase, with Hebei, Tianjin and Beijing among the top gainers, accounting for 16.4%, 5.0% and 4.8% respectively. About 70% of provinces, autonomous regions and municipalities saw their prices rise, with Tianjin, Shanghai and Sichuan leading the way, accounting for 6.4%, 3.9% and 3.0% respectively. The national price of special powder and standard powder is obviously higher than that of 20 12, and the price of 65438+ 10/0/8 increased by 5.2% and 5.7% respectively.
Distinguish flour
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When choosing flour, the information we want is the classification of different products such as high gluten flour, medium gluten flour and low gluten flour, or the purity grade of flour, as well as the contents of minerals and crude protein. When buying flour, many people mistakenly think that "high gluten flour = high gluten flour". In fact, the meaning of "high-gluten flour" is simply advanced refining, which only means the processing technology of wheat, but not the gluten of flour. Therefore, "advanced refining" may be high-gluten flour, low-gluten flour, special flour or second-class flour. From this perspective, the term "high precision" is actually unscientific, at least not an industry standard term. Therefore, it is suggested that when purchasing flour, we should pay attention to its protein content, that is, gluten, rather than "advanced refining".
High-gluten flour: dark in color, active and smooth, not easy to form balls by hand; It is more suitable for making bread and some cakes, such as Danish cakes. Mostly used in muffins (thousand-layer cakes) and cream hollow cakes (puffs) in western cakes. In terms of cakes, it is only used in high-content fruit cakes.
Medium gluten powder: milky white in color, between high and low powder, semi-loose in constitution; Generally, Chinese snacks are used, such as steamed buns, steamed bread and noodles. (Note: Generally available flour can be regarded as medium gluten flour unless otherwise specified. Moreover, this kind of flour is generally marked on the package, which is suitable for making steamed buns, jiaozi, steamed buns and noodles.
Low gluten powder: white in color, easy to form balls by hand; The average protein content of low-gluten flour is about 8.5%, and the protein content is low, so the gluten is weak, so it is more suitable for making cakes, muffins, biscuits, cakes, etc., and the taste is fluffy and crisp.
To put it simply, you grab a handful of flour with your hand, then knead it tightly with your fist, then loosen it, and gently weigh the powder ball with your hand. If the powder ball disperses quickly, it is high gluten powder; If the dough can keep its shape in the process of light weighing, it is low-gluten flour.
A bowl of flour
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Wheat grain is mainly composed of three parts: wheat bran accounts for about18%-25% of the grain weight; Only 1%-2% of wheat germ is used for germination. Endosperm accounts for about 80%. There is aleurone layer adhesion between endosperm and wheat bran. Wheat bran, wheat germ and endosperm were separated from wheat seeds by milling technology, and the endosperm was ground into flour for human consumption. Flour processing is a physical separation process, which does not change the original chemical properties of wheat endosperm and the rheological properties of hydrated dough.
Judging from the factors that affect the edible quality of flour, protein content and quality are the most important factors that determine its edible quality, processing quality and market value. For example, to make bread, in order to make it bigger and taste good, high-gluten wheat flour should be used; To make noodles and jiaozi, use medium-strong gluten wheat flour to make it "gluten-free" and smooth; The cakes made of low-gluten wheat flour are soft and the biscuits are crisp. It can be seen that with the development of food industry, the demand for all kinds of special flour is getting higher and higher, and the decisive factor is the "protein content and quality" of flour.
Classification correlation
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Classification basis
The more flour ground near the center of flour particles, the higher its grade; With the increase of the amount of flour mixed near the vermicelli, its grade decreases.
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The grade of flour is also directly related to the content of minerals (ash) in wheat bran and germ. The higher the mineral content, the lower the grade of flour. On the contrary, the lower the content, the higher the grade of flour. If bread has the unique flavor of flour, low-grade flour is more suitable than high-grade flour. For example, healthy whole wheat bread is made of whole wheat flour ground from wheat with bran. As far as ordinary flour is concerned, its mineral content will not have much influence on the properties of bread. But if there are more minerals in it, the color of flour will be slightly gray, and the color of bread will naturally be darker. A few decades ago, if the color of bread was white, it was a symbol of its delicacy, but then the flour was no longer bleached, and people gradually liked the natural color and taste. Another kind of flour is very common in the domestic market-self-rising flour. The so-called self-raising flour is to mix a certain proportion of salt and baking powder into flour in advance, and then package it for sale. This is for the convenience of family use, eliminating the steps of adding salt and baking powder. But I don't like it and I don't recommend it to everyone. First, mixing salt and baking powder in flour is not troublesome. Second, after the spontaneous flour is stored for a certain period of time, the baking powder inside will fail to varying degrees; Third, many cakes need salt when they are made, and there is already salt in the spontaneous flour. Whether or not to add more salt, how much should be carefully converted. These factors will affect the final quality of the cake, so it is not recommended.
Classified application
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Jiaozi steamed bread flour, a common steamed bread on the market, can definitely be used as bread, but the texture of the bread made will not have the slightest wiredrawing effect, and the taste will not be as delicate as bakery toast. If the quality of finished bread is pursued, it is best to choose high-gluten flour if possible, and it is best to use special flour for bread. If there are no conditions, it is the same to use medium gluten flour. After all, it is made in China. No additives, no professional equipment, and the requirements are not that high.
If medium gluten flour is used to make bread instead of high gluten flour, the amount of water in the original recipe should be reduced appropriately, because different kinds of flour have different water absorption rates. Generally speaking, the higher the gluten of flour, the higher the water absorption; Conversely, the lower the gluten of flour, the lower the water absorption of flour.
In fact, due to the different processing technologies and raw materials used by different manufacturers, even different brands, the same flour will have different water absorption, such as high-gluten flour or bread flour, and the water absorption will be slightly different, so please explore the characteristics of the flour used and add water correctly, so as to make a successful West Point.
In China, ordinary household flour is not used to using "high gluten flour, medium gluten flour and low gluten flour" to distinguish and make trade names, so most supermarkets see "steamed stuffed bun flour, jiaozi flour" or "special flour" or "refined flour". Strictly speaking, this name is not standardized, but fortunately it is easy to understand. Hehe, everyone will know what this flour is for at a glance. The characteristic is "high gluten", because you also need flour to do somersaults when making jiaozi steamed stuffed bun noodles, so the gluten is really higher (but the gluten generally does not exceed 1 1), so this is not high gluten flour.
Classification category
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Whole wheat flour
Whole wheat flour is only ground whole wheat, and there is no procedure to remove bran. It is whole wheat containing all bran and germ. Wheat bran contains cellulose and has high nutritional value.
bread flour
Some people may ask, I thought it was said that bread was made of high-gluten flour. In fact, bread flour is not equal to high-gluten flour. The so-called special flour for bread is to add malt, vitamins and gluten to flour to improve its bread-making performance, increase the content of protein and make bread easier to make. Therefore, flour with protein content as high as 14- 15% appeared, so that bread with larger volume can be made.
In addition, there is an instant mixed powder, which can be simply made into bread embryo by mixing two or three materials with water.
Cake powder
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Cake powder, also called cake powder. In fact, low-gluten flour is not equal to cake flour, because in some areas with fine flour classification abroad, low-gluten flour is also divided into two grades. One is cake flour, which means that the acid value of the original low-gluten flour is reduced after chlorine treatment, which is beneficial to the organization and structure of the cake; One is pastry flour. The gluten of pie flour is slightly higher than that of cake flour, but it also belongs to low gluten flour.
Of course, in China, the classification of household flour in the market is not detailed. You can use low-gluten flour to make cake powder, and you can make cakes, muffins and biscuits. If you can't buy low-gluten flour, you can also use medium-gluten flour and 20% corn starch instead, that is, the ratio of medium-gluten flour to corn starch is 4: 1, and corn starch can reduce the gluten of flour.
Stone mill flour
Stone mill is flour processed by traditional stone mill (the rotation speed of stone mill is 20 rpm), and no additives are added. Low-speed grinding and low-temperature processing will not destroy the nutrients in wheat. Therefore, stone mill flour retains many nutrients such as protein, gluten, carotene, carbohydrate, calcium, phosphorus, iron, vitamin B 1, etc. B2 in wheat is the largest, especially carotene and vitamin E in stone mill flour are 18 times higher than other flours. Its low-speed grinding keeps the molecular structure of flour without adding any additives. When cooking noodles, the noodle soup with stone flour is light yellow, while other noodle soup with additives is white. Therefore, the stone mill flour retains the original flavor of wheat, and all kinds of pasta made of stone mill flour have flexible taste, rich wheat flavor and higher nutritional value, which is a real natural green health food.
However, the traditional stone mill is made of two round stones, which are chiseled by hammer. Both of them are hand-carved into flat cylinders with large stones of a certain thickness, and twill is chiseled on two disks, which is called gear grinding. Grinding teeth with a stone mill is a highly specialized and complex technology. Its reasonable, natural and scientific design features must be modulated by hand, and its angle, size and gap are irreplaceable by some modern tools.
The primary color flour with slightly yellow color has higher nutritional value. Primary color flour turns yellow because it retains a lot of B vitamins, which is of great benefit to human nervous system and skin tissue.
Characteristics of stone mill flour
① Low-speed and low-temperature grinding with a stone mill will not destroy the nutrients in wheat, but will retain many nutrients in wheat, such as protein, carotene, carbohydrate, calcium, phosphorus, iron and vitamins, especially carotene and vitamin bile, which is 0/8 times higher than other flour.
(2) Its low-speed grinding keeps the molecular structure of flour without adding any additives.
(3) When cooking noodles, the flour noodle soup with ground flour is light yellow, and other flour noodle soup with additives is white.
Selection skill
Editor? speech sound
white
The color of flour will directly affect the color of bread. The closer the wheat grains are, the whiter the flour is and the better the quality of the flour is. So the quality of flour can be seen from its color. You can't bleach with bleach, but bleaching too much color will lead to death, but the color of flour is not important for making hard bread.
Gluten strength
Gluten in flour constitutes the network structure of bread. If the network structure is too weak, no good bread can be made. So flour should have enough gluten to make bread:
(1) protein has sufficient quality and protein has good quality.
(2) Enough sugar and amylase to supply sugar for yeast fermentation.
(3) Adequate α -amylase can regulate the gelatinization of starch.
Fermentation endurance
Bread exceeds the predetermined fermentation time, but it must be able to make good bread, which is called fermentation endurance. Therefore, flour should have sufficient fermentation endurance.
High water absorption capacity
When flour and water are mixed, a lot of water can be added, but good bread can be made. The more water is absorbed, the lower the cost, the longer the storage time and the greater the economic value.
Brief introduction of flour quality terms
1. crude protein: the value of protein content determined by whole wheat flour, expressed in percentage points. This is a very important parameter representing nutritional quality. The protein of flour is closely related to the protein content of grain, which is generally one percentage point less than the former. The greater the value, the better the quality.
Quality standards of various special wheat flour in China
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2. Wet gluten: expressed in percentage points. Gluten in flour is the basis of baking bread and other fermented foods. The quantity and quality of gluten are the main factors that determine the processing quality of flour. Wet gluten is gluten that contains a certain amount of water and has not been dried. The greater its value, the better its quality.
3. Settlement value: also called settlement value. It is a comprehensive index to measure gluten content and quality, expressed in milliliters. The greater the value, the better the quality. In some countries, flour is divided into three grades according to sedimentation value: strong, medium and weak. The sedimentation value of strong powder is greater than 45ml, the sedimentation value of medium powder is 30-45ml, and the sedimentation value of weak powder is less than 30ml.
4. Dough formation time: Short dough formation time means less gluten and poor quality, and vice versa.
5. Stability time of dough: The short stability time of dough reflects that gluten is not resistant to kneading and is easy to decompose after dough is formed.
6. Evaluation value: comprehensive price index, the greater the value, the better the quality.
7. Baking quality: Wheat with good baking quality requires strong water absorption of flour, moderate toughness, ductility and elastic fermentation strength of dough, and no additional equipment is required for kneading and baking. Baked bread is large in size, well developed, beautiful in appearance, bright in color, crack-free in epidermis, small and uniform in internal pores, soft and elastic in texture and delicious in taste.
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8. Bread volume: the volume of bread baked with 100g flour, expressed in milliliters. The bigger the volume, the better the quality.
9. Specific volume: the ratio of volume to bread weight (gram) is one of the indexes to evaluate the processing value of bread. The greater the specific volume, the greater the volume of bread.
10. Water absorption: the amount of water needed to make the dough reach the standard consistency in the process of kneading with water. Flour with high water absorption can bake more bread.
1 1. Decline value: Its size reflects the strength of α -amylase activity in flour. Hard wheat with large falling value and low α -amylase activity is suitable for bread. Soft wheat with moderate falling value and moderate α -amylase activity is suitable for making cookies and cakes.
Formula example
Editor? speech sound
Noodles steamed bun
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Steamed bread is a kind of food made by mixing flour with water and sugar, adding stuffing such as meat, vegetables and bean paste, fermenting and steaming in a steamer. The finished product has a hemispherical shape. In Jiangnan area, steamed bread is generally called steamed buns.
Dosage: flour 1000g, baking powder, meat stuffing 750g, vegetables 50g, vegetable oil 50g, a little sesame oil and chicken essence.
Method for making fried dough sticks
① Stir the flour, sugar and yeast powder evenly with warm water.
② Pour yeast water into flour and knead it into dough, then add cooking oil to continue kneading.
(3) After fermentation for one hour, the dough is twice as big.
④ Add salt and baking soda, melt it with 15ml warm water, and knead it into dough again with baking soda water. It is best to rub water into the noodles. )
⑤ Cover with plastic wrap to continue fermentation, and send it to twice the size, and use it the next morning. It doesn't have to be sent one day in advance, but it can be sent on the same day, as long as there is enough time. )
⑥ Grease the chopping board and hands, and press the dough into a rectangle on the chopping board.
⑦ Grease the knife and cut the dough into small strips.
⑧ Fold the two noodles together, flatten them, and press the middle ditch with chopsticks.
Pet-name ruby oil to 70% heat, fry fritters, while frying and turning.
Storage method
Editor? speech sound
1, well-ventilated flour can breathe, so let the air circulate so that flour can be used.
2. Humidity Dry flour will change its water content according to the temperature and humidity of the environment. The higher the humidity, the higher the water content of flour, which is easy to agglomerate. The lower the humidity, the lower the water content of flour. The ideal humidity is about 60%-70%.
3. Suitable storage temperature will affect the ripening time of flour. The higher the temperature, the faster the maturity. But the temperature will also shorten the shelf life of flour. The recommended ideal temperature for flour storage is 18℃-24℃.
4. clean environment a clean environment can reduce the breeding of pests and microorganisms, thus reducing the chance of flour pollution.
5. odorless flour is a substance that can absorb and store the odor in the air, so the surrounding environment where flour is stored should be odorless.
6. Must leave the wall and the ground, in order to have good ventilation, reduce moisture, reduce pest pollution and legal provisions. Plastic products should be used for stacking plates. If you use wood products, you should pay attention to avoid wood thorns and make them polluted.
7. FIFO ensures the stability of flour and reduces the artificial expiration of flour.
8, regular cleaning to reduce the breeding of insects and rats, thereby reducing flour pollution.