Making starch from sweet potato is an easy-to-learn and easy-to-promote application technology. It has many advantages such as convenient material extraction, on-site processing, wide application, and obvious benefits. Its application and promotion will effectively promote the adjustment of the agricultural structure of the city's hilly drylands, accelerate the industrialization of sweet potato, and increase farmers' income. First, the principle of preparation. The chemical composition of sweet potato mainly includes water, starch, protein, fat, fiber, ash, etc. The preparation of sweet potato starch is a physical separation process using starch that is insoluble in cold water, whose specific gravity is greater than that of water, and the specific gravity of other components. Second, the operating point 1, the choice of raw materials and cleaning. Select potato chips that are free from pests and diseases, remove fibrous roots, and wash impurities such as sediments on the surfaces of the chips with clean water. 2, crush. The potato pieces are first broken into small pieces of 2 cm in size, and then further ground. The finer the better, the formation of porridge-like potato paste. 3, filter. Slowly pour the mash into a 60-mesh sieve, filter it while pouring it, add water, sifter, sieve through a 120-mesh screen, and use it for secondary filtration (if the quality of the starch is high, use a finer sieve) . After 2 times of filtration, the starch milk under the sieve enters the sedimentation tank, and the coarse and fine potato residues left on the sieve can be used as feed. 4, precipitation. Starch milk naturally precipitates when it enters the sedimentation tank. It usually takes 8 to 10 hours at a temperature of 15 to 20°C. If the temperature is high, the settling time is shortened accordingly. After the precipitation is complete, the brown aqueous solution in the upper layer is decanted (partially retained) and the starch surface is washed 2-3 times. 5, fermentation. The starch was crushed, and the brown aqueous solution was added. The amount of water added was 25-30 kg of an aqueous solution per 50 kg of fresh potatoes, and the starch milk was fully mixed and fermented at a temperature of 15 to 20°C for about 24 hours. Specifically, it is considered that the fermentation is completed when the sour taste can be smelled, the brown aqueous solution on the surface becomes cyan, and a small amount of foam is generated. 6, from the powder. After the fermentation is completed, the upper aqueous solution (also called acid slurry, which can be used as the next fermentation to replace the brown aqueous solution, can shorten the fermentation time and improve the fermentation quality) is removed, and then a small amount of brown powder on the surface of the starch is removed, and starch is finally released. When dusting, pay attention to the small amount of sediment sedimentation to clean. 7, finishing. After the starch is taken out, the excess water is filtered off with a sling, and then dried to a moisture content of 14%. After sieving and smashing until all powder forms, it is finished starch.
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