Sweet potato starch is in high demand in the market, and timely processing yields high returns.

Sweet potato starch occupies an increasingly important position in people's daily diet. Potato-based chemical products have now become the main raw materials for chemical products such as lactic acid, citric acid, disposable tableware and degradable agricultural mulch film. It is understood that the current price of refined white potato starch has risen by nearly 10% compared with last year, and the reason for this price trend is undoubtedly the supply-demand gap for sweet potato starch. Relevant data show that at present, the demand for sweet potato starch in the domestic market alone is more than 1 million tons, while the production volume is far less than this number. Due to the wide use of the product, the low price of raw materials, and the large value-added space for processing and development, the sweet potato starch processing industry has good prospects.

How can the starch yield of fresh potatoes be increased? According to our company's processing experience, there are mainly the following steps:

1. Harvest potatoes at the right time. If sweet potatoes are harvested too early, they are not mature enough and the starch yield is low; if harvested too late, they are prone to frost damage, which also affects the starch yield. For early-maturing varieties, harvest the potatoes before the local frost, around September 10 to 20; for late-maturing varieties, harvest from the local Frost's Descent to 10 days after Frost's Descent, which gives a high starch yield. This is because the temperature is suitable at this time, and after the sweet potatoes are crushed, the starch slurry ferments quickly and yields more starch. If the potatoes are harvested too late and the temperature drops, the starch in the tubers gradually converts into sugar, and the starch yield decreases. In particular, if fresh potatoes are processed into dried potato slices, the starch yield will drop greatly.

2. Shorten the storage period as much as possible. In rural areas, there is a habit of storing first and processing later, which greatly affects the starch yield of sweet potatoes. After sweet potatoes are harvested, as the storage time lengthens, the starch gradually saccharifies, and the starch yield decreases. If they are crushed immediately after harvest, the starch yield can reach about 35%; if stored for 20 days after harvest, the starch yield will decrease by about 20%. Therefore, completing the processing of sweet potatoes within 20 days after harvest can increase the starch yield by 10% to 12%. If there is a large quantity of sweet potatoes, they can also be stored first and processed later, but the storage period should be shortened as much as possible, and attention should be paid to controlling the temperature and humidity in the cellar to prevent the sweet potatoes from developing dry cores.

3. Select potatoes. There are many varieties of sweet potatoes. Choosing white-fleshed varieties such as "Yiwohong" and "Shengli Baihao" can yield about 10% more starch than red-fleshed varieties such as "138", and the starch blocks are white with good starch quality.

4. Clean. Remove moldy and spoiled sweet potatoes, wash away sand, mud and other debris stuck to the potatoes, rinse them thoroughly with clean water several times, and set aside for later use.

5. Grinding the slurry. First soak the sweet potatoes in dilute alkaline water or soda solution to separate the fiber and starch. Then pour the soaked sweet potatoes into the grinding vat. When grinding the slurry, hold the vat with one hand and keep rotating with the other hand so that the slurry residue slowly settles.

6. Sedimentation. After grinding the slurry, do not rush to wash the slurry with clean water. The slurry milk should be left to settle for 24 hours, then according to the ratio of 50 grams of baijiu for every 50 kg of sweet potatoes, dilute the baijiu with an appropriate amount of clean water, pour it in and mix evenly, and then wash the slurry.

7. Washing the slurry. Use gauze for filtering soybean milk (about 1 m long and 1 m wide) and tie it to a tripod at chest height. Place a larger slurry collection bucket under the frame (preferably with a drainage hole in the bucket wall 0.67 m from the bottom), then put the already ground potato slurry into the tied filter cloth, 4 to 5 kg each time. During filtering, while shaking and rubbing, slowly add 2 to 2.5 times the amount of clean water so that all the starch is filtered into the bucket (the standard should be that the filtered water turns clear). Generally, it can settle in 10 to 12 hours, then drain the water to remove floating residue and clear liquid. If the water is still as turbid as when it was first filtered, pour it into the bucket according to the ratio of 150 grams of alum for every 500 kg of water (first crush the alum and dilute it with a little water), stir evenly, and drain the water after 4 hours.

8. Drying. After the water is drained, spread the filter cloth flat on the starch. After the starch dries, cut it into pieces with a knife, take them out and dry them in the sun, and then they can be stored for processing or @#@136@#@.