Process flow: sweet potato (potato) starch → desanding → decoloring → mixing powder → extrusion gelatinization → solidification → loosening silk → drying and molding → adding seasoning → packaging finished products.
Key operation points:
① Starch treatment: high-quality sweet potato (potato) starch is selected and soaked in water. Use a desander to remove sand and gravel, pass through a 120 mesh sieve, filter out coarse residue, add acid slurry according to 30% of dry starch, fully stir, decolorize for 6-8 hours, and rinse with clear water for 3 times.
(2) Flour mixing: pour the processed sweet potato (potato) and corn starch into a flour mixer according to a certain proportion, add a little vegetable oil and sodium alginate, and stir for 8- 12 minutes to ensure that the dough is dry and thin.
(3) Extrusion gelatinization: directly pour the mixed dough into a single-screw extruder, and shape it through a φ 0.8 mm sieve plate at a water bath temperature of 95℃. The essence of this process is starch gelatinization, also known as gelatinization, and the formed vermicelli is cooled by a blower.
(4) coagulation: the gelatinized vermicelli is coagulated for 4-5 hours at normal temperature, or frozen for 2-3 hours in a cold storage at -4℃, and then dispersed with loose silk.
⑤ Drying and packaging: after the vermicelli is loose, drain the Mingshui, put it into a tray quantitatively, dry it with hot air from a dryer, dry it at 65-75℃ until the water content is about 65,438 02%, then add seasoning, cover it, and shrink-package it automatically to get the finished product.
2, quick-frozen sweet potato products
Key operation points:
① Acceptance of raw materials: choose spindle-shaped, cone-shaped, yellow-orange, disease-free and mechanical-damaged sweet potato raw materials.
② Slicing: Cut the sweet potato into strips with a cross-sectional area of 2.8 cm× 2.8 cm and a length of 8- 10 cm with a multifunctional cutting machine.
(3) steam: evenly spreading that clean French fries on a steaming tray, draining water, and steam until cooked, wherein the steam pressure is 0.2mpa, and the steaming time is 3-5 minutes.
④ Quick freezing: it is advisable to use a fluid continuous quick freezing machine. Feed when the quick-freezing temperature drops to about -40℃, and adjust the running speed within 25-30 minutes, so that the central temperature of the product reaches-18 ~-25℃, and the surface does not crack and the potato body does not connect.
⑤ Frozen storage: Send the sweet potato strips packed in cartons to the cold storage quickly, keep the storage temperature at-18℃ or lower, and control the temperature fluctuation within 2℃ during frozen storage.
3. Canned sweet potato stem tips
Key operation points:
(1) Selection and treatment of raw materials: remove the diseased leaves, dead leaves and damaged leaves on the stem tips of fresh sweet potatoes, cut them evenly, drain the water, soak them in 0.2% Na2SO3 color protection solution 18-24 hours, rinse them with clear water until the leaves are not sticky, then can them and inject them into the pot at 80-90℃. ② venting and sealing: after filling, venting at 80℃ for 10 minute, and then sealing. ③ Sterilization and cooling: 1 15℃ for 3 minutes, and then quickly cool to below 40℃. The sterilization formula is 5-3-5 minutes/1 15℃. ④ Inspection and packaging: After the damaged and expanded cans are taken out, samples are taken for sensory, physical, chemical and microbial indicators inspection.
Sweet potato stems and leaves are rare health food, which can be used for value-added through deep processing. Several deep processing methods of sweet potato stems and leaves are introduced as follows:
First, quick-frozen sweet potato stems and leaves
Fresh sweet potato stems and leaves are cleaned, blanched and quickly beaten. To a great extent, the original color, flavor and vitamins of fresh sweet potato stems and leaves are maintained. Can be stored for a long time and is convenient to eat. It is a rare natural green health food. The key points of process operation are as follows:
1. Select and clean sweet potato stems and leaves with excellent varieties, moderate maturity and tender quality for harvesting. When harvesting, the old leaves, yellow leaves, moth-eaten leaves, cobweb leaves and rotten leaves are removed, and they are scattered in special plastic baskets without soaking or bundling, and transported in time. Wash the dirt, dust and sand attached to sweet potato leaves with clear water before processing, and drain the water.
2. blanching and quick-freezing: quickly put the drained sweet potato stems and leaves into a container filled with boiling water with a plastic basket, blanching for 5 ~ 1s, and mastering a moderate degree to achieve half-cooked to kill enzymes; Immediately after taking it out, it is sent to the pre-cooling room, and its temperature is reduced to about 10℃ with cold water. The precooled sweet potato stems and leaves are quickly frozen with a flat mesh belt type quick freezer. The average temperature of the freezer is -32℃, the average inlet temperature of frozen products is 65438 05℃, and the outlet temperature is-65438 08℃.
3. Packaging, cold storage and quick freezing. At the same time, quantitatively package with food plastic bags (generally divided into 0.5 kg and 1 kg), then put them into 20 kg waterproof packaging cartons, and store them in the cold storage below-18℃ after bundling.
Second, dry sweet potato stems and leaves
Picking fresh and tender sweet potato stems and leaves with excellent varieties and moderate maturity, washing, scalding with boiling water until half-cooked, then drying in the sun, quantitatively sealing with plastic bags, and refined packaging.
Third, sweet potato stem and leaf health drink
Squeezing fresh sweet potato stems and leaves, scientifically blending, can be made into a fragrant and refreshing drink that integrates dietotherapy and food supplement. Its key points of operation:
1. Material selection and cleaning methods are the same as above.
2. Cooking juice blending: put the drained sweet potato stems and leaves into a jacketed pot, soak them in water, boil them for 65438±00min, keep the temperature at 65 ~ 70℃ for about 65,438 0 h, filter out the juice, add water to the filter residue, heat them at a slightly boiling state or 95℃ for 30 min, filter out the juice, and stir for the second time to obtain a yellowish green clear solution. When blending, add 30% sweet potato stem and leaf juice, 6% sucrose, 0.03% molasses and citric acid according to 100 kg water, and adjust the ph value to 3.8-5.2, 0.2% honey, sodium isovitamin C, ethyl malt powder and 0. 1% sodium hydroxymethyl vitamin.
3. Filling and sterilization. Stir evenly when the temperature of feed liquid is 85℃, and fashion can. After sterilization, it is quickly cooled, packaged and put into storage in time.
4. Canned sweet potato stems and leaves
Raw materials: fresh sweet potato leaves, tender buds, refined salt and citric acid.
Key operation points:
1. Choose clean, fresh, pest-free and rot-free sweet potato leaves and their tender buds.
2. Remove impurities. Wash the silt on leaves and stems with clear water, remove yellow leaves, rotten leaves, diseased leaves, missing leaves and stems and leaves with older texture, and then pour off the water.
3. Compared with the tender buds, the nutritional components of the potato leaves after cutting and grading are slightly higher than those of the tender buds, but the taste of the processed dishes is somewhat different. Therefore, they can be divided into three processing methods for consumers to choose from. That is, canned potato leaves, canned potato buds (including some tender stems), undivided canned potato leaves and buds.
4. Before canning, boil potato leaves and buds in boiling water for 2 ~ 5 min, then canning, and inject a small amount of salt solution containing citric acid. Vent the air in the exhaust box and disinfect it.
5. Sterilization and cooling were carried out by pasteurization at 90℃ for 65438±00min. It should be noted that high temperature is easy to discolor potato leaves for a long time. In order to prevent discoloration and vitamin decomposition loss, three methods can be considered: vibration treatment in magnetic field, ultraviolet irradiation and freezing treatment. Sterilization and cooling.
Five glasses of sweet potato beer
Fresh sweet potato was used as raw material, supplemented by jujube juice, mixed with beer yeast and grape ball yeast for fermentation, and after blending and sterilization, a fresh sweet potato fermented beverage with sweet and sour taste, pure flavor and rich foam was made.
Key operation points:
① Liquefaction: add 0.1%α -amylase and liquefy at 70℃ and pH = 5.6 for 60 minutes.
② Saccharification: add 0. 1 glucoamylase and react for 30 minutes at 55℃ and pH = 4.5.
③ Adjusting the mash: adjusting the concentration of soluble solids in the slurry by 4%-5%. The ph is 4.8-5.2, and the dried hops are 65438 0%.
④ Inoculation and fermentation: 2%-3% beer yeast liquid culture medium and 2%-3%(w/w) immobilized wine yeast seeds were added, and the fermentation temperature was 10- 12℃ for 3-4 days, and the content of soluble solids at the end of mash fermentation was 2%-2.5%.
⑤ Fermentation after blending: add jujube juice with soluble solid content of 5.5%-6%, adjust the ph to 4.2-4.3, and ferment at 10- 12℃ for 2-3 days, and the soluble solid content will be 2%-2.5% at the end of fermentation.
⑥ Clarification: Reduce the temperature of the tank to about 0℃, keep it at 12 hours, and suck out the supernatant. The liquid transmittance is required to be greater than 95%.
⑦ Sterilization: The final ph of feed liquid is 4.0-4.2, which belongs to acidic food, and the pasteurization formula is10-20-15min /70℃.
The above contents are for reference only.