Detailed Explanation of Key Points of Potato Storage and Primary Processing Technology

I. Storage Technology

1. Pit storage. Choose a site with high, dry terrain, and dig a trench 0.8-1.5 m wide and 0.9 m deep. Put potatoes pre-stored in a cool place into the trench for storage when freezing is about to occur, spreading the tubers loosely to a thickness of 40-50 cm, placing a bundle of corn stalks every 1 m to make a ventilation tube, with the ventilation tube extending 0.5 m above the ground, covering with a straw curtain, and covering with soil when the temperature drops, with a thickness not less than the frozen soil layer; the top of the trench should be raised.

2. Stack storage method in a ventilated storage warehouse. The potato pile is 1.3-1.7 m high. 2 m wide, and every 2-3 m place 1 ventilation tube vertically in the potato pile. Check 1-2 times during the entire storage period. Some storage warehouses also use basket-loaded potato stacks 4-5 layers high as a surrounding wall, with loose potatoes in the middle, or use wooden rails as an enclosure with loose potatoes in the middle.

3. Chemical treatment. To prevent tubers from sprouting during storage, methyl naphthaleneacetate or ethyl naphthaleneacetate, maleic hydrazide, or gamma rays can be used for treatment. The method of using methyl naphthaleneacetate is: for storing 5000 kg of tubers, use 150-250 g of methyl naphthaleneacetate liquid, dissolve the chemical in 2 times its amount of acetone, then mix into 10-12.5 kg of fine soil, and evenly sprinkle it in the potato pile.

It is also possible to spray the leaves with a 0.25% maleic hydrazide solution at the late stage of stem and leaf development, when the leaves are still green, and the sprout inhibition effect is also very good. In addition, after harvesting, potatoes treated with gamma rays for wound healing and then irradiated have an obvious sprout inhibition effect.

II. Primary Processing Technology

1. Quick-pickled potatoes. Process flow: ingredients -> salting -> soaking in kelp broth -> finished product.

Ingredients: potatoes 100 kg, salt 2.5 kg, vinegar 5 kg, sugar 12.5 kg, dried (green) peppers 100-200, a small amount of kelp.

Processing method: Wash the potatoes, cut into round slices, spread flat on a board, sprinkle with salt, and put into a container to salt. Wash the kelp, cut into small pieces, boil in clear water, then remove. Put white sugar, vinegar, and shredded chili into the kelp broth and stir thoroughly and evenly. When the kelp broth cools to 50-60 degrees C, pour it into the container holding the salted potato slices, and it is ready in about 30 minutes.

2. Quick-frozen potato pieces

Process flow: raw material selection and handling -> blanching -> freezing and packaging.

Raw material selection and handling: Select potatoes that have not sprouted, are free from pests and diseases, and are uniform in size as raw materials. Clean and peel, cut whole potatoes into 1/4-1/6 pieces in triangular shapes, and immediately put them into 0.5% salt water for color protection.

Blanching: The blanching temperature is 95-100 degrees C, and the time is 1-2 minutes. Remove and drain. Freezing and packaging: Put into -35 degrees C low temperature for quick freezing. After freezing, immediately package in polyethylene plastic bags and store in a cold storage at -18 degrees C or below.

3. Mashed potatoes. Process flow: raw material selection and handling -> steaming and boiling -> blending (drying -> shaping and packaging).

Raw material selection and handling: Select tubers with high specific gravity, high starch content, uniform individual size, thin skin, and shallow bud eyes; remove diseased, insect-damaged, rotten, and deteriorated tubers; clean and peel. Cut the peeled tubers into uniform thin slices 10 mm thick with a slicer, and wash with clear water to remove starch and other substances on the surface of the slices to prevent burning during steaming and boiling. After washing, use a 1-2% sodium bisulfite solution for color protection treatment.

Steaming and boiling: First pre-cook in 55-80 degrees C water for 10-20 minutes, then cool with cold water. Then cook in 98-100 degrees C water for 15-25 minutes, remove, and crush into a paste with a screw crusher.

Blending: Add glycerol monoester or glycerol diester, phosphate, sulfur dioxide, edible pigment, onion juice, and other flavor enhancers. The usual amounts are: glycerol monoester 0.6%, sulfate 0.4%, sulfur dioxide 0.01%. Mix glycerol monoester, edible pigment, and onion juice evenly with water that has undergone precipitation treatment, then add to the mashed potatoes; sulfate and sulfur dioxide are added separately.

4. Fried potato chips

Process flow: washing potatoes -> peeling -> trimming -> slicing -> hot blanching -> frying -> centrifuging -> seasoning -> packaging -> finished product.

Raw material selection and cleaning: Select fresh potatoes that are not rotten, not deteriorated, have no bud eyes, and are regular in shape; soak in water, scrub with a brush, and rinse clean with clear water.

Peeling and trimming: Peel manually or with a peeler, wash clean with clear water, and trim irregular potatoes into regular shapes.

Slicing and cleaning: Cut the potatoes into thin slices 1-2 mm thick with a slicer, rinse the slices with clear water, put them into 90 degrees C hot water for 2-3 minutes, remove, and drain off the water.

Vacuum frying: Put the dehydrated potato slices into a vacuum frying tank and fry for 1-2 minutes until fully cooked and golden yellow.

Centrifuging and seasoning: While hot, de-oil the fried potato slices with a centrifuge, then air-dry until the moisture content is about 3%, and it is ready. Various seasonings can also be added to make seasoned potato chips.

Packaging: The product is packaged in composite film or composite paper tubes, either vacuum-packed or gas-flushed packaging.

5. New-type potato starch

Process flow: A: peas -> soaking -> draining -> crushing -> sieving -> fermentation -> pea sour liquid.

B: potatoes -> washing -> peeling -> shredding -> crushing -> sieving -> potato slurry -> mixing evenly -> standing -> centrifuging -> sand removal -> protein removal -> drying -> quality inspection -> packaging -> finished product.

Preparation of potato slurry: Select fresh potatoes that are not rotten, not deteriorated, have no bud eyes, and have high starch content; soak in clear water for a period of time, scrub clean with a bristle brush, wash clean with clear water, peel, cut into fine shreds, add water at a ratio of 1:2, crush into a paste with a crusher, pass through a 200-mesh sieve, and the filtrate is ready for use.

Preparation of pea sour liquid: Soak peas in 5 times their amount of water for 48 hours, then drain. Add 10 times their amount of water and crush, pass through a 200-mesh sieve, put the powder water into a conical flask, seal it, let it stand at room temperature 18-26 degrees C, and naturally ferment for 48-72 hours. When the powder water turns from white to yellow, bubbles appear on the surface, and the taste becomes sour, with a pH value of 4-5, it is mature sour liquid (total bacterial count 1.6 x 107 per mL). Filter and set aside for use.

Starch extraction: Take the filtered prepared potato slurry, add 20% pea sour liquid, mix evenly, let stand for about 30 minutes, centrifuge, remove the liquid, first remove fine sand and impurities from the precipitate with a sand remover, remove protein with a precipitation separator, dry at 50 degrees C until the moisture content drops to about 14%, and then it can be packaged.