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The swelling capacity and swelling degree of the starch granules largely determine the viscosity of the starch paste. The high-expansion starch granules occupy a relatively large volume and are squeezed tightly. When gelatinized, the starch granules are tightly contacted with each other, and high internal friction is transmitted, so that the peak viscosity of the flour is higher. Moreover, there is a significant or extremely significant positive correlation between peak viscosity and noodle score, which is an important indicator for measuring the applicable quality of wheat. Some studies have pointed out that the differences between the two varieties of strong gluten, weak gluten, and waxy wheat are mainly followed by the highest viscosity, while the differences between the two cultivars of medium-gluten wheat are mainly reflected in the peak viscosity.
The minimum viscosity depends mainly on the content of amylose in wheat flour or the ratio of amylose to amylopectin content. In addition, there is a test confirming that the damaged starch content is positively correlated with the lowest viscosity, which is due to the fact that the amylase is more likely to act on damaged starch, and the dough with high damaged starch content is low in water holding capacity. The release of water can reduce the consistency of the dough and increase the viscosity of the wheat flour. . The smaller the wheat flour particle size, the higher the damaged starch content.
Through the use of a circular powder sieve to determine the thickness of the test sample wheat flour, the relevant determination of gelatinization was carried out. It was found that the gelatinization temperature of wheat flour RVA basically decreased with the decrease of particle size, and the gelatinization temperature of different system powders was not too large. difference. With the decrease of the particle size of wheat flour, its viscosity (lowest, peak, final viscosity) showed an overall upward trend. The RVA final viscosity of wheat flour also gradually increased with decreasing particle size. The difference between the wheat flours in different systems was larger, which may be due to the difference in particle and quality between different system flours, which resulted in different adsorption and binding of starch granules and water molecules in wheat flour, which eventually led to the change of uniform gelatinization state of starch.
Wheat flour is affected by the gelatinization of wheat flour during processing and flouring, and this characteristic reflects the chemical thermal denaturation of wheat flour. However, because the starch granules in the flour absorb water and swell and disintegrate, the starch gelatinizes and gelates when heated, and the viscosity of the system also changes significantly. Because of the inherent quality differences, there are large differences in the viscosity changes of pasting. In food science research, gelatinization characteristics and viscosity analysis are often used as an important basis for judging the quality of starch or starch-containing foods. The viscosity characteristics of RVA reflect the gelatinization characteristics of wheat flour starch, and can also reflect the α-amylase activity of the sample to some extent. It is the main indicator to measure wheat flour quality and food processing quality. The viscosity of starch has a great influence on the performance of its activity. The decrease of viscosity can greatly increase its bioavailability. In the process of measuring its viscosity, it is necessary to use a circular powder sieve to measure the sample, to ensure the consistency of the degree of thickness to obtain more accurate results.