Bioscience Methods 2025, Vol.16, No.2, 70-82 http://bioscipublisher.com/index.php/bm 73 stability and resistance to enzymatic degradation (Peng et al., 2022). In addition, the physicochemical properties of starch, such as amylose content and granule morphology, also play an indispensable role in influencing the rheological properties of dough. These factors determine the processing performance of wheat products (Cao et al., 2019). 3 Traditional Separation Techniques for Wheat Starch and Gluten 3.1 Wet separation The dough washing method (dough washing method, DWM) is one of the traditional techniques for separating wheat starch and gluten. The specific process involves mixing wheat flour with water to form a dough, which is then allowed to rest. After sufficient fermentation, the dough is washed with water. Since gluten is insoluble in water, during the washing process, starch particles are carried away by the water, thus achieving the separation of starch and gluten. Additionally, factors such as water temperature and the flour-to-water ratio affect the effectiveness of the washing method. They directly relate to the yield and purity of both starch and gluten during the separation process (Yöndem-Makascioğlu et al., 2002). Process A and process B are two common procedures in wet separation. Process A typically uses a hydrocyclone separation system. The specific process is as follows: wheat flour is mixed with water, and a hydrocyclone is used to separate the slurry. At this point, starch is washed out with clean water, while gluten, being insoluble in water, spontaneously aggregates into blocks, allowing it to be separated by screening. This process can save water and is more efficient for processing large amounts of flour. However, it requires more complex equipment and precise control of process parameters. Process B, represented by the traditional Martin method, is more manual and relies mainly on hand washing or simple mechanical assistance to separate the dough. Process B requires less investment in equipment, making it more suitable for small-scale production. However, it involves higher labor intensity, and the separation yield and purity are not as high as those of processes using modern equipment for wet separation (Witt and Goldau, 2000). In wet separation, more advanced technologies include liquid flow classification and centrifugal separation. These methods rely on differences in the density and particle size of gluten and starch. Liquid flow classification uses the impact and dispersion of water flow to separate starch and gluten based on their settling velocities. Centrifugal separation uses centrifugal force to effectively separate gluten, which has a lower density and larger particles, from starch, which has a higher density and smaller particles (Sayaslan, 2004). These technologies are favored in industrial production for their high efficiency and ability to produce high-purity starch and gluten. However, they require high investment in equipment and expertise in operation (Sayaslan, 2004; Van Der Borght et al., 2005). 3.2 Dry separation Traditional dry separation techniques for wheat starch and gluten include dry milling and sieving. The principle is to grind wheat into powder and use sieving technology to separate based on particle size. However, Remadnia et al. (2014) argue that due to the limitations in effectively separating fine particles, this method is not very efficient in separating high-nutrient components. Air classification is also a common dry separation technology, which uses differences in particle size and density between starch and gluten to separate them by high-speed airflow. Although air classification can effectively increase the protein content, it cannot achieve high-purity separation due to issues such as powder contamination, equipment fouling, and low overall separation efficiency (Assatory et al., 2019; Silventoinen et al., 2020). Electrostatic separation utilizes the charge difference between particles and is a more innovative dry separation technique. This method generates different charges on the particles through friction, and then separates them in an electric field based on the charge differences. However, the separation efficiency of this method is affected by particle aggregation effects, which can be minimized by optimizing airflow and field strength (Remadnia et al., 2014; Wang et al., 2015). Although electrostatic separation has potential, the presence of a protein layer on the surface of starch particles often interferes with the separation. Therefore, directly separating starch and gluten from the original flour remains a challenge.
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