How to Add Value to Sweet Potato and Rice Through Processing

Sweet Potato Starch Production Technology

Wash the sweet potatoes, drain the water, crush them into pieces about 2 cm in size with a crusher, feed them into a stone mill or electric pulp grinder, add 3 to 3.5 times their volume of water, and grind into a starch slurry. Pour the starch slurry into a sieve with a mesh size of 60 and sieve out the potato residue to obtain starch milk. Place the starch milk in a settling tank and let it stand overnight so that the starch settles to the bottom of the tank. Drain off the supernatant, take out the crude starch, repeatedly rinse and settle it with clean water to obtain pure starch, then sun-dry, crush and sieve the starch to obtain dried starch. This method is the traditional method of producing starch in rural areas, requires no mechanical equipment at all, and the starch obtained through processing can be used as a raw material for processing other starch foods.

If you need to produce refined sweet potato flour, you can invest 1.3 million yuan to purchase equipment, with an annual output of about 5,000 tons.

Sweet Potato Sheet Jelly Production Method

Take wet starch with a moisture content of 45% to 50%, slowly add 2.5 times its amount of cool water while stirring gently with a wooden stick, and at the same time add 0.3% alum. Use a starch ladle to take a small amount of the starch paste and place it in a rotating tray, float the rotating tray on top of boiling water in a pot, and use your hand to move and rotate it so that the starch paste spreads out. When there are no white spots in the middle, take it out together with the tray, place it in clean water to cool for a moment, then peel off the formed sheet and put it into clean water to cool. Soak the sheet jelly in the supernatant liquid from settling the starch for 3 to 5 minutes, then take out the sheet jelly and dry it in the sun on a bamboo screen, turning it over once so that both sides dry evenly. When it is dried to a moisture content of 16% to 17%, it becomes the finished product.

This method is a traditional production method, requires no large equipment investment, and the total investment is within 20,000 yuan.

Sweet Potato Vermicelli Processing

Weigh out a certain amount of dried sweet potato starch. Take 4% to 10% of the dried starch and place it in a porcelain basin, add an equal amount of clean water, and stir evenly. Place the porcelain basin in a wooden basin containing boiling water, add 4 times the starch amount of boiling water into the porcelain basin, and while pouring, stir rapidly with a wooden stick so that the starch gelatinizes into a thin paste. Place the dough-mixing basin in a wooden basin containing hot water at 60°C, then pour the remaining 90% to 96% of the sweet potato starch into the dough-mixing basin, then pour the prepared thin paste into the dough-mixing basin and stir continuously until there are no raw starch granules. Knead thoroughly to make it into a semi-liquid state, then immediately place it in a vermicelli leaking gourd. Under the vibrating force of the vibrating machine, the semi-liquid starch paste flows out in threads from the small holes of the leaking gourd, falls into a pot of boiling water, is immediately cooked through, and quickly floats to the surface. Take out the vermicelli with a bamboo pole, soak it in cold water for a moment, then put it into the clear supernatant liquid poured off when settling the starch for rinsing. Then take out the vermicelli and sun-dry it.

This method is an indigenous production method and requires a pot, basins, a leaking gourd, etc., with a total equipment investment within 10,000 yuan. If mechanized production is to be carried out, a boiler, shaping machinery, electromagnetic vibrating machine, rinsing tank, etc. are needed, with a minimum investment of 100,000 to 150,000 yuan.

Sweet Potato Preserved Fruit Processing

First wash the fresh sweet potatoes and remove the skin with a peeling machine or by hand. Use a stainless steel knife to cut the sweet potatoes into strips 2 cm x 2 cm x 5 cm. According to the weight of the strips, add 1.5 times their amount of water, 30% to 40% white sugar, 2% to 3% honey, and 0.2% sulfurous acid, place them in a stainless steel pot and boil, taking care to cook them through without cooking them to pieces. Take out the strips together with the sugar liquid, place them in a large vat and soak for 24 hours, scoop out the strips with a slotted ladle, place them on a bamboo sieve, and dry them in a drying room at 50 to 60°C. After the strips cool, pack them into polyethylene plastic bags and seal them.

The production equipment for this product is simple and only requires a stainless steel pot (within 10,000 yuan), a drying room (within 10,000 yuan), and other auxiliary facilities (within 10,000 yuan). If production volume needs to be expanded, it is only necessary to add production lines.

Instant Rice Noodle Production Technology

Wash the rice clean, then soak the rice in clean water until its moisture content reaches about 40%. In winter, soak generally for 7 to 8 hours, and in summer, soak generally for 4 to 5 hours. Grind the rice into a slurry with a stone mill or electric mill, control the slurry concentration at 25 to 30 Baume degrees (Baume meters are available on the market), and the fineness should be such that all passes through an 80-mesh sieve. Use sheet jelly production equipment to make the slurry into sheets. Then steam the sheets with a steaming machine at a temperature of 105°C for 55 seconds. Quickly send the steamed sheets into a cooling room for cooling, then send them into a pre-drying room for pre-drying, with a maximum drying temperature of 70 to 80°C and a time of 15 to 20 minutes. Then cut them by hand or machine into noodles 1 mm wide. Send the noodles into a drying room for drying, with a maximum drying temperature of 50 to 60°C and a time of 20 to 40 minutes, so that the moisture content is reduced to below 13%.

The production of this product requires a flour mill, boiler, noodle-making machine, cooling room, steaming machine, drying room, shredding machine, etc., with a minimum investment of 200,000 yuan.

It must be noted that when producing rice noodles, bleaching agents and preservatives must never be added at will. For producing dry rice noodles, no preservative needs to be added; if producing wet rice noodles, preservative treatment is needed, and calcium propionate may be added at 0.25% of the weight of the rice noodles. The addition of any other non-food substance must comply with the provisions of the national standard GB2760-1996.