Analysis of gluten characteristics of steamed buns with old noodles

Steamed buns have a long history in China. According to records, the origin of steamed bread can be traced back to the Three Kingdoms period more than 1,700 years ago, which is a long history. In its long history of development has also formed a large number of species. The wheat used to make steamed buns in wheat-producing areas accounts for 70 percent of the total flour consumption, according to the report. The food that northerners usually call steamed bread is unfilled, solid, complete in appearance, normal in color and color, and it has no peculiar smell, flour and wheat fragrance, and fermented fragrance. Steamed buns have a huge consumer market in China. Some hotels and hotels even offer steamed buns to customers as snacks on the table.

The change of gluten content during dough fermentation; Wheat is rich in nutrients, including carbohydrates, fats, minerals, cellulose, enzymes and water. It also contains unique proteins that make up gluten. Flour protein is the component of gluten, the gluten, add flour is just the right amount of water knead into a ball, soak in water for a period of time after the starch and soluble compositions will be washed with water, the last remaining soft gelatinous material, also become coarse gluten or wet gluten, wheat gluten is able to make it unique food material basis. Flours with a high gluten content produce foods that are tough and chewy. Gluten forms a network structure in the production of steamed bread, which has a good gas retention and makes the appearance of steamed bread plump and smooth. The content of wet gluten had a great effect on the fermentation speed of dough and the quality of steamed bread. The lower the content of wet gluten, the faster the dough fermentation, but steamed bread weak muscle, easy to collapse, poor chewiness. The higher the content of wet gluten, the more difficult the dough is to ferment, but the dough has good air holding capacity, strong strength and good chewiness.

However, with the prolongation of dough fermentation time, the gluten content of dough decreased gradually. Wheat protein and glutenin is the main component of gluten dough fermentation process to produce alcohol, soluble in 60% ~ 70% and the protein of alcohol, dissolve in the protein, glutenin for gluten, the main products, at the same time, the fermentation time is too long, the oxidation, the action of enzyme, alcohol and acid can lead to the destruction of the gluten network structure, It's going to be relatively low. Long time fermentation will make the gluten has been dissolved and destroyed, and eventually make the dough can not wash out the gluten.

The purpose of the surface mainly includes :(1) fully mix all kinds of raw materials, and make it form a unified quality of the whole; (2) Speed up the speed of flour absorbing water and swelling to form gluten; (3) Expand gluten, promote the formation of gluten network, which is conducive to dough with good elasticity, toughness and gas retention. Whole and mixing process is divided into three stages: the first is the initial stage, the mixed starch granules fast water absorbing and swelling, and mobility of water molecules present obvious downtrend, gradually formed the dough is coarser, holes larger gluten network, free water phase distribution in the dough at this stage, at the same time, moisture and macromolecules in combination with the most obvious; The second stage is the formation and improvement of the gluten network. This stage is the formation and expansion of gluten in the dough. Compared with the previous stage, the water absorption rate of starch particles decreases, the protein becomes elastic, and the distribution of starch particles on the gluten network becomes more and more uniform. Destruction stage, finally the formation of gluten network as the stirring time continue to increase, the part of gluten fracture has been formed, thus destroying the structure of gluten network, when mixing continue for more than 30 min, gluten dramatically speed up the fracture degree, parts of the dough water start at the beginning of the mixer mixing rotor under the mechanical action of seepage, As a result, some moisture in the dough which is not firmly bound to macromolecules is separated from the macromolecules and released, which increases the fluidity of the dough. The sensory score of steamed bread is the highest when the dough mixing time is 14min. Because the dough mixing time is too short, the gluten network structure of the dough has not been formed, and the gas holding capacity of the dough is poor, which leads to the steamed bread is too small in volume, partial collapse, uneven internal holes, and low score. If the dough is mixed for a long time, the surface of the dough will be soaked with free water and the dough will return to its sticky state. At the same time, the gluten network structure that has been formed will be damaged and the gas holding capacity of the dough will become poor, leading to the occurrence of the surface of the final product is not smooth and the volume is small, so as to decrease the sensory score.

With the increase of fermentation time, the specific volume of steamed bread showed a trend of decreasing first and then stabilizing. In the fermentation process, the -SH or -S-S- bonds of sulfur-containing amino acids in gluten are oxidized or reduced to make the proteins combine with each other and form a network structure of macromolecules, which enhances the gas holding capacity of dough and expands dough to achieve the purpose of fermentation, thus making the volume of steamed bread larger. So the size of the volume of steamed bread was mainly formed by the dough gluten network and the ability to influence gas, with the increase of fermentation time, dough fermentation acid formed by the gluten protein has very strong damage, caused the destruction of the gluten network structure was formed, the gas capacity is abate, in the second and the time have nothing to add new flour, Therefore, it is difficult to form a large number of surface and texture structures to increase the air-holding capacity of dough, and eventually cause the volume of steamed bread to decline first.