The so-called soft noodle is the phenomenon of longitudinal crack and crack on the surface or interior of the noodle caused by process, equipment, management, raw materials and climate problems. Crispy face, its appearance is rough and uneven, pale, serious when the surface of the face between a clear longitudinal crack. And the texture is crisp, inelastic, bending strength is extremely poor, easy to break, the sound is low or no when broken, the section is stepped trapezoid or serrated. Cooked and broken into short, grated noodles that cannot be scooped up with chopsticks. The product after crisp noodles, its edible effect and the commodity value reduces greatly, after returning machine causes more crisp noodles. Crispy noodles seriously affect the quality and output of the noodles, increase the production cost, and a large number of crisp noodles are returned to the machine for processing, which will cause a vicious circle and further cause poor quality of the noodles.
The main reason
The reason of noodle crisp bar is quite complex, it is the bad result of the comprehensive effect of physical and biochemical process, and it also relates to the problem of management. To sum up, there are mainly the following aspects.
Influence of dough making process
Dough making is the first process of noodle making, and its technical parameters and operation are reasonable. The poor quality of dough is the hidden trouble of the crisp noodles.
The amount of water added to the dough
The function of dough is to add proper amount of water and additives into wheat flour. Through the action of mechanical forces, the protein and starch in wheat flour can fully absorb water and expand to form the gluten network structure, and the dough moisture distribution is even. If the amount of water added is too little, the protein and starch in wheat not only absorb water inadequately, but also the water distribution of dough is not uniform. In the drying process, due to the non-uniform water distribution of wet noodles, the dehydration rate is not uniform, so the shrinkage and drying stress caused by dehydration are not consistent. The local stress inside the noodles increased and there was a distortion and fracture of the crisp noodles. If the amount of water is too much, the structure of wet noodles will be loose and sparse, not only in the early drying period, a large number of broken ends (strip off), but also because of the large porosity of the internal tissues, its resistance to temperature and humidity inward or outward migration is weakened, and when the environmental conditions of hanging noodles are poor, it will absorb moisture or dehydrate and crisp sticks.
The influence of mixing speed of dough mixer
The mixing speed is too slow, the wheat flour and water are mixed unevenly, and the sandwich powder appears, which is not conducive to the protein and starch in the wheat flour to absorb water evenly and expand to form the gluten. If the mixing speed is too fast, the dough temperature will rise quickly, and the gluten will expand excessively, resulting in the phenomenon of "over-cooked dough".
Effects of drying process
There are two processes of noodle dehydration. One is evaporation of water on the surface of the noodle, and the other is diffusion of water on the surface. Although the two processes store each other, they are often not quantitatively equal. When the water content on the surface of the hanging surface is greater than the internal water diffusion amount, the water content on the surface of the hanging surface will inevitably decrease, which leads to the rapid increase of the water gradient on the hanging surface. The size of moisture gradient on the cross section of the hanging surface has a great influence on the quality of the hanging surface. Therefore, in the drying process of the hanging surface, the evaporation of moisture on the hanging surface should be equal to the diffusion of internal moisture to the surface.The main factors affecting moisture evaporation on the surface of the surface are temperature, relative humidity and air velocity. The main factors influencing the velocity of water diffusion to the surface are the temperature and thickness of the surface. By adjusting the temperature, relative humidity and air velocity of each section of the drying room to match each other, so that in the drying and dehydration process, the moisture gradient on the section of the hanging surface should not be too large, and high quality hanging surface can be produced, otherwise it will cause local or large area of crisp surface.
When the noodles are running in the hot and sweaty area, if the discharge volume is too high, the moisture on the surface of the noodles will evaporate greatly. Because of the rapid evaporation of water on the surface of the hanging surface and the low internal temperature of the hanging surface, the diffusion rate of water on the hanging surface is slow, which leads to excessive water loss on the surface of the hanging surface and rapid conjunctival, hindering the diffusion of water on the inner surface. Therefore, the water diffused outwards accumulates under the conjunctival layer and exerts a wedge pressure on the outer layer. Due to its dewatering and shrinkage characteristics, the inner and outer water of the surface of the hanging surface decreases in different degrees and its contraction degree is also different. At this time, the surface of the hanging surface is subject to the effect of tensile stress. At the same time, the hanging surface has higher moisture and is still in the stage of plastic body.When these forces exceed the tensile strength of the conjunctiva, cracks appear on the surface of the surface, most of which are transverse (the lateral tensile stress is greater). This kind of crack, although very shallow before the beginning, but with further drying, because of the stress concentration of the hanging surface and in the drying process the hanging surface unceasingly swings, the crack gradually deepened and lengthened. Because this kind breaks defect, hang the face to want to produce crispy face phenomenon mostly, when serious, hang the face after the oven can be crisp broken.When the surface of the hanging surface enters the area of rising temperature and falling tide, the evaporation of water on the surface of the hanging surface and the diffusion of water in the inner surface of the hanging surface increase rapidly due to the rise of temperature and the decrease of relative humidity. However, as mentioned above, the water distribution on the surface section is generally not uniform. According to the principle of gas evaporation, the four corners of the surface have two evaporation surfaces, so the moisture is lower, and the internal moisture of the surface is not easy to run out, so the moisture is higher. If the water lines are drawn on the cross section of the hanging surface, they will be approximate ellipses that are interlaced one by one. Because the inner and outer water of the hanging surface are different, its dehydration and contraction are different. Therefore, the outer layer of the hanging surface is subject to tensile stress, while the inner layer is subject to compressive stress. If the water gradient on the cross section of the hanging surface is not large, that is, the evaporation of water on the surface of the hanging surface is roughly equal to the diffusion of water in the interior, and the stress is not large. If water gradient is too large, this kind of stress is very big, when the stress exceeds the intensity of the weakest part of the hanging surface, it will be pulled and broken from here. From the cracks formed, it can be seen that the four angles of the hanging surface have higher strength due to lower water content, and the weakest part is just in the middle of the hanging surface section. When the veneer is thin, it just breaks from up and down. When the surface is thicker, it even breaks from left to right. This creates a longitudinal crack in the face. The final formation of this kind of crack is usually in the cooling and heat dissipation zone or the buffer zone, but its formation process is in the heating and tidal zone.
In addition, the liner by temperature drop tidal mode to the cooling heat dissipation area, due to the lower temperature, especially the cooling speed, often in an accelerating role in the formation of longitudinal cracks, because the liner encounter cold contraction, and four angles to cool down, and the center part cold not come down for a while, due to shrinkage encounter cold, must increase the role of the tensile stress.The damage of the vertical crack of the hanging surface is not as serious as that of the transverse crack, but such a hanging surface is obviously not resistant to storage. This is because the noodle when I first got out of the dryer, dry noodles, although have crack due to uneven liner inside and outside water, water is low, its outer is hard, so the strength of the liner is good, 'when placed after a period of time, water gradually converge, liner, hard shell will be increased due to moisture and soft gradually, and the internal stress of liner has not completely disappeared, reduce the strength of liner shell, in turn, lead to crack expand, thus the liner or storage in the late dry easily during produce crisp surface phenomenon.
The effects of drying
Hanging surface is a kind of poor heat conduction material. As the moisture of hanging surface decreases gradually during drying process, its thermal conductivity becomes worse and worse. Although the external temperature decreases after leaving the oven, the heat and humidity transfer within the hanging surface cannot be stopped abruptly, and the temperature and humidity inside and outside the hanging surface and the relative balance between them and the external air temperature and humidity are maintained all the time. Therefore, if the temperature and humidity of the hanging surface treatment site and the air at the end of the drying road differ greatly, due to its hygroscopic expansion or dehydration shrinkage and easy to crisp. The processing site includes packaging room, product warehouse and sales warehouse.The drying interval at the end of the production line is not easy to be too short (the appropriate interval length is 25%-30% of the total length of the baking channel), otherwise the temperature and humidity difference between the air between the end of the baking channel and the package is too large, and the baking surface is easily caused by sudden heat and cold or moisture absorption. Another problem is that the finished product warehouse has no insulation and moisturizing measures. In wet and cold weather (such as winter and rainy seasons), the difference between the temperature and humidity of the hanging surface and the air temperature and humidity is too large, resulting in crisp.In addition, the quality of wheat flour (such as low gluten or sprouted wheat milled wheat flour), as well as the effect of the rolled sheet (such as too few rolling track, excessive rolling, etc.), have a certain impact on the crisp noodle. The level of operation and management has a great or even important impact on the formation of crisp noodle. Must strengthen the staff's business quality and the sense of responsibility of education, implement the entire process quality control, maximum limit reduces the phenomenon such as the crisp bar, enhances the hanging quality.
According to the mechanism of causing crisp noodles, the size of noodles (the size and shape of the cross section) is also the main factor affecting the crisp noodles. Under the same conditions, the larger the size, the slower the internal moisture in the drying process moves towards the surface, the easier the crisp noodles will appear.The addition of some additives can reduce the appearance of crisp noodles. For example, when adding salt to the dough, it can reduce the evaporation rate of surface moisture during drying and increase the speed of internal moisture migration to the surface, which can prevent the occurrence of crisp noodles during drying.In conclusion, if the wheat flour meets the standard requirements, the reason for the noodle crisp is the dough, drying and the post-drying treatment environment. And flour is the primary key to prevent shortcake, drying is the key to prevent shortcake, drying is the main link to prevent shortcake.
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