Analysis and study on the quality of wheat flour with different particle sizes of the same material -1 EDITED BY: www.immy.cn www.immyhitech.com

Analysis and study on the quality of wheat flour 

                                                     with different particle sizes of the same material -1

EDITED BY: www.immy.cn   www.immyhitech.com 

According to the fixed mechanical parameters, the front core mill system on the production line is pulverized to make three kinds of wheat flour with different particle sizes, so as to ensure that the grain size of the wheat flour sold on the market is within the particle size range of the experimental powder.

The physicochemical indexes, rheological properties, gelatinization properties and texture properties (dough softness) were studied, the relationship between grain size and the physical and chemical indexes of wheat flour was analyzed, and the differences in the texture characteristics of wheat flour dough with different grain sizes were explored over time, and the influence of grain size on the cooking quality of wheat flour was explored. The experimental results show that some physical and chemical indexes of wheat flour with different grain sizes show obvious changes and significant differences.

The average particle size of wheat flour was significantly negatively correlated with damaged starch and R/E value, negatively correlated with whiteness, formation time and gelatinization temperature, and positively correlated with gluten index, falling value and peak viscosity. The texture characteristics of wheat flour dough (the degree of return to softness) increased with the decrease of particle size. The cooking quality also decreases with the decrease in particle size.

Wheat flour particle size is an important parameter to measure the quality index of wheat flour, and the particle size of wheat flour is closely related to grinding strength, powder path, screen configuration, grinding roller speed and moisture conditioning in the process of grinding and sieving

• , reflecting the degree of damage of endosperm particles in the process of milling, which is an important indicator affecting the quality of wheat flour products, so with the change of wheat flour particle size, the physical and chemical indexes, rheological properties, gelatinization properties and texture characteristics of wheat flour will change. Fresh noodles, steamed buns, and noodles (as well as pulled noodles, ramen, braised noodles, etc.) are very popular noodles among residents in northern China, and the daily demand is extremely high

[2]. There are many factors affecting the processing and production quality and sensory quality of steamed bread and noodles, and particle size is one of the most influential factors[3], by studying the influence of particle size on the physical and chemical indexes of wheat flour, as well as on the production and cooking quality of flour products, it can provide a theoretical and practical basis for flour processing enterprises to choose the appropriate grinding strength and milling process.

1, Materials and methods

1.3 Experimental Methods

1.3.1 Preparation of wheat flour with different grain sizes

10 kg of CM1 experimental flour was taken and crushed into two kinds of wheat flour with different particle sizes according to the fixed mechanical parameters by ultrafine pulverizer, which were named CM2 and CM3 respectively, and the finished product (Xirui Star Royal Kitchen Superfine Wheat Flour) was taken from the market, a total of 4 kinds of flour were used for later use.

1.3.2 Determination of grain size of wheat flour

According to GB/T 19077 particle size distribution laser diffraction method, the average particle size distribution of wheat flour with different particle sizes was determined by laser particle size distribution instrument.

1.3.3 Determination of physical and chemical indicators

According to national standards and industry standards, the ash, moisture, protein, wet gluten content and gluten index, whiteness and damaged starch of wheat flour with different particle sizes were detected.

1.3.4 Determination of flour characteristics of wheat flour dough

According to GB/T 14614 Determination of water absorption and rheological properties of wheat flour dough, the water absorption, dough formation time, stability (stability time) and weakening degree of wheat flour were measured by flour meter.

1.3.5 Determination of tensile properties of wheat flour dough

According to the tensile instrument method for determining the physical properties of wheat flour dough, water absorption and rheological properties of wheat flour dough, the energy, maximum tensile resistance, extensibility and R/E ratio of dough were measured by stretching instrument.

1.3.6 Determination of gelatinizing properties of wheat flour dough

According to the GB/T 14490 viscometer method for determining the gelatinization characteristics of grains and starch, the gelatinization temperature and peak viscosity of dough were measured.

1.3.7 Operation and sensory evaluation of wheat flour steamed foods

(1) Noodles. Refer to the method of LS/T 3202 Appendix A to make noodles. The ingredients are based on the quality of the flour and 36% water is added. The scoring criteria are shown in Table 1.

Production process: weighing→ dough (5 min), tableting → pressing (12 times of dough pressing→, 6 sheets), cutting strips (1 mm thick, 2 mm wide) → boiling water for 3 min.

(2) Steamed buns. Refer to the method of LS/T 3204 Appendix A to make steamed bread. The ingredients are based on the quality of flour, with 1% yeast and 48% water.

Production process: weighing→ dough (5 min), forming →→ proofing (32°C, humidity 75%, about 40 min), steaming →with boiling water (25 min), → natural cooling.

• Pull the strips. The ingredients are based on the quality of flour, with 1% salt and 52% water.

Production process: weighing→ dough and dough (5 min), → into a dough (repeatedly kneading and relaxing 4 times), → resting dough (covering with plastic wrap for 45 min), → dividing and rubbing strips (75 g/piece), → relaxing (covering with plastic wrap for 15 min), → drawing (repeatedly stretching and beating, folding in half 3 times), → boiling water and boiling noodles for 3 min.

1.3.8 Data Processing and Analysis

SPSS 26 and Origin 2019 were used to analyze the variance and plot the data, and the significance analysis was performed at the detection level of P<0.05, and all the data were the results of three parallel experiments.

2, Results & Discussion

2.1 Particle size distribution of wheat flour with different grain sizes

It can be seen from Fig. 1 and Table 4 that with the increase of crushing strength, the particle size distribution of wheat flour gradually shifted to the left, and the average particle size and median size became smaller. Among them, the particle size of Xirui Star Royal Kitchen Super Refined Wheat Flour was distributed in the middle of the experimental flour particle size.

2.2 Analysis of physicochemical indexes of wheat flour with different grain sizes.

The statistical analysis of other physical and chemical detection indexes of wheat flour samples with different particle sizes is shown in Fig. 2 and Fig. 3. As shown in the figure, some of the physical and chemical characteristics of the samples are different to varying degrees. Whiteness is one of the most intuitive ways for users and consumers to judge the purchase of flour products.

It can be seen from Figure 2 that particle size has a significant effect on damaged starch, generally speaking, wheat flour contains a small amount or an appropriate amount of damaged starch, and the processed flour products have good chewiness and toughness, and high eating quality. The damaged starch granules have higher water absorption than the natural starch granules and are more easily hydrolyzed by amylase, while the excess damaged starch will adversely affect the rheological properties and texture properties of the dough, and reduce the edible quality of the dough products.

As shown in Figure 2, the whiteness and damaged starch content of wheat flour increased with the decrease of particle size, which was due to the fact that with the increase of grinding strength, the particle size decreased, the large endosperm particles were further destroyed, and the reflective effect of wheat flour particles became stronger, so the whiteness value and damaged starch content increased, which was consistent with the results of Sun Lingling et al. [6].