In the past, wheat starch was extracted from wheat through fermentation, that is, the wheat was soaked in water, ground, and then fermented with acid to dissolve the cells around the starch granules and make the starch easy to separate. However, the loss of gluten and protein in starch is not easy to be exhausted, which affects the quality of starch, and has been replaced by the Martin method.
The dough method uses wheat flour as raw material, adds 50 to 80% water to the mixer, and kneads the flour into dough at a speed of 40 rpm. The mixing time is about 30 minutes, and the setting time is 30 minutes, so that the gluten expands and sticks to each other, making the starch easy to separate. If you add an appropriate amount of salt, you can improve the quality of gluten and promote its combination.
If the flour contains free acids, calcium hydroxide can be added to adjust the pH. After the dough has rested temporarily, add 5 to 8 times of water and knead and wash in 3 to 4 times. The rinsed emulsion is starch milk and needs to be refined and purified. The remaining material is gluten, with a moisture content of 65~70%. After drying, the protein content is about 75~85%, and it can be eaten or used as a raw material for making gluten.
The extraction method of wheat starch is segmented and cannot be operated continuously. Continuous manufacturing methods have been reported abroad. The process is basically the same, but it needs to be combined with continuous equipment for production.
In recent years, there is also an alkali method, which uses wheat as raw material to produce starch. The production principle is the same as corn starch. Soft wheat with a moisture content of 14% and a crude protein content of 10% was divided into soft wheat containing 0.2% sulfur dioxide and soaked at 39°C for 12 hours to increase the water absorption rate to 55%. Other operating methods are the same as corn processing. The crude protein content of finished starch is less than 0.4%, and the recovery rate reaches 83%.