Analysis and study on the quality of wheat flour with different particle sizes of the same material -2 Powered by: www.immy.cn www.immyhitech.com

Analysis and study on the quality of wheat flour 

                                                     with different particle sizes of the same material -2

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As can be seen from Figure 3, the gluten index and drop value decreased significantly as the grain size of wheat flour decreased. The gluten index can make the rheological properties of various wheat flours different, affect the balance and stability between dough elasticity and ductility, and then affect the processing technology and production operability of wheat flour. Due to the grinding operation, the damage degree of endosperm particles increased, and the continuous integrity of wet gluten was damaged to a certain extent, and the gluten index was reduced after centrifugal weighing, which affected the gluten network structure of wheat dough. At the same time, the sensitivity of damaged starch in wheat flour to amylase was higher than that of natural starch, and it was easier to be affected by amylase to form reducing sugars and dextrin, so the degradation rate was accelerated, indicating that the falling value decreased with the decrease of particle size.

2.3 Analysis of flour characteristics of wheat flour with different grain sizes

The flour characteristics of wheat flour are important indicators reflecting the rheological properties of dough, which are closely related to the quality of flour products, and the flour characteristics of wheat flour with different particle sizes are shown in Fig. 4 and Fig. 5. Among them, the water absorption was related to the protein content and the damaged starch content in wheat flour, which had a significant impact on the quality of flour products, and the particle size and water absorption showed an inverse change, which indicated that the total surface area of wheat flour increased with the decrease of grain size, and the water absorption increased. The degree of weakening is affected by the speed of stirring and is related to the gluten strength of the dough, and it can be seen from Figure 4 that the degree of weakening of wheat flour with different grain sizes increases slightly with the decrease of grain size, but the difference is not significant.

The formation time and stabilization time represent the elasticity of the dough and the gluten strength, the kneading resistance of the dough and the strength of the gluten [7], respectively, with the decrease of the grain size of wheat flour, the formation time is gradually extended, and the stabilization time does not change significantly, the analysis is that the grain size of wheat flour becomes smaller, the water absorption process of the particles is prolonged, and the flour clumps become slower, which will lead to the reduction of the industrial production efficiency of food.

2.4 Analysis of tensile characteristics of wheat flour with different grain sizes

The tensile properties of wheat flour can directly reflect the quality of the dough and provide guidance for the processing of wheat flour and the preparation of flour products. Among them, the energy can reflect the gluten strength of the dough, the extensibility reflects the transverse ductility of the dough, the tensile resistance represents the elasticity of the dough, the R/E tensile ratio represents the balance between the strength and extensibility of the dough, and the smaller the ratio, the stronger the dough has strong viscosity, ductility and higher adhesion [8]. It can be seen from Table 6 that the energy, extensibility and maximum tensile resistance have increased and decreased, and there is no obvious regularity in the trend of change over time.

The R/E ratio showed a consistent upward trend, as shown in Figure 6, which indicated that with the decrease of wheat flour grain size, the increase of maximum tensile resistance was greater than that of ductility, and the ratio of elasticity to extensibility of dough was increasing.

2.5 Analysis of gelatinization characteristics of wheat flour with different grain sizes

The essence of starch gelatinization is to break hydrogen bonds, that is, to break the intermolecular bonds of starch in crystalline and amorphous forms in starch, and complete the gelatinization of starch under the synergistic action of heating and endogenous amylase. Among them, the gelatinization temperature reflects the difficulty of gelatinization of wheat flour, the peak viscosity reflects the amylase activity of wheat flour, and the lowest viscosity reflects the content of amylose in wheat flour [9]. As shown in Figure 7, with the decrease of wheat flour particle size, the peak viscosity and minimum viscosity of wheat flour decreased, which may be due to the fact that wheat flour with small particle size has higher damage starch content, strong binding ability with water molecules, and relatively easy to break intermolecular hydrogen bonds, which adversely affects the peak viscosity of wheat flour, thereby reducing the peak viscosity. The gelatinization temperature is the opposite, which may be due to the fact that as the particle size decreases, the natural starch in wheat flour is converted into small molecule damaged starch and protein fragments through high-intensity commination, which increases the water absorption and promotes gelatinization, resulting in a small increase in temperature [10].

2.6 Correlation analysis between particle size and physicochemical characteristics, rheology and gelatinization characteristics of wheat flour

The correlation between the grain size of wheat flour and physicochemical indexes, rheology and gelatinization properties was analyzed by using the volume average grain size of three kinds of wheat flour with different particle sizes as the particle size characteristic values, as shown in Table 7. The results showed that the average particle size of wheat flour was negatively correlated with damaged starch and R/E value (r=-1.000, r=-1.000, P<0.01). There was a significant negative correlation with whiteness, formation time and gelatinization temperature (r=-0.994, r=-0.990, r=-0.990, P<0.05). It was significantly positively correlated with gluten index, falling value and peak viscosity (r=0.998, r=0.997, r=0.999, P<0.05).