Processing technology of dehydrated vegetables


Dehydrated Vegetable Processing Technology

The main varieties of dehydrated vegetables are carrots, edible mushrooms, kale, kale, and ginger.

Dehydration drying methods include natural drying and artificial dehydration. Artificial dehydration includes hot air drying, microwave drying, puffing drying, infrared and far-infrared drying, and vacuum drying. At present, the most common applications of vegetable dehydration and drying are hot air drying and dehydration and freeze-vacuum drying and dehydration. The freeze vacuum dehydration method is an advanced vegetable dehydration drying method. shape and ideal for quick rehydration. The technological process and method of hot air drying dehydrated vegetables and freeze-vacuum drying dehydrated vegetables are now introduced as follows.

1. Process flow and method of hot air drying dehydrated vegetables

1. Selection of ingredients Choose vegetable varieties with the rich meat. Before dehydration, it is necessary to strictly select good and bad, and remove diseased, rotten, and deflated parts. 80% of the maturity is appropriate, over-ripe or immature should also be eliminated. Except for melons, other vegetables can be washed with water and dried in a cool place, but not exposed to the sun.

2. Cutting and blanching According to the product requirements, the washed raw materials are cut into slices, wires, strips, and other shapes. When pre-cooking, it varies according to the ingredients. If it is easy to cook, put it in boiling water, if it is not easy to cook, put it in boiling water and cook for a while. The general blanching time is 2-4 minutes. It is best not to blanch green leafy vegetables. 3. Cooling and Draining Vegetables that have been precooked should be cooled immediately (usually with cold water) to quickly return to room temperature. After cooling, to shorten the drying time, the water can be shaken off with a centrifuge, or it can be squeezed with a simple manual method.

4. Drying The drying temperature, time, color and moisture content should be determined according to different varieties. Drying is generally carried out in a drying chamber. The drying room is roughly divided into three types: one is a simple drying room, which adopts countercurrent blast drying; the second is a drying room with two layers and double tunnels combined with forward and reverse current; the third is a box-type stainless steel hot air dryer, the drying temperature range is 65℃-85℃, dry at different temperatures, and gradually cool down. When using the second type of drying room, evenly spread the vegetables on the tray to dehydrate the vegetables, and then put them on the pre-set drying rack, keep the room temperature at about 50 °C, and keep rotating to speed up the drying speed. The general drying time is about 5 hours. 5. Sorting and packaging Dehydrated vegetables can be put into plastic bags after being inspected to meet the requirements of the Food Sanitation Law and put on the market after being sealed and boxed.

2. The technological process and method of freezing and vacuum drying dehydrated vegetables

1. Selection of ingredients: Leafy vegetables are selected manually for no more than 24 hours from harvesting to processing, and the yellowing and rotten parts are manually selected; root vegetables are manually selected, and other external products, rotten parts, are graded.

2. Cleaning Remove soil and other impurities from the surface of vegetables. To remove pesticide residues, it is generally necessary to soak in 1.55%-1% hydrochloric acid solution or 0.05%-0.1% potassium permanganate or 600 mg/kg bleaching powder for a few minutes. Disinfect and rinse with clean water.

3, peeled root vegetables should be peeled. Chemical lye peeling raw material loss rate is low, but export products generally need manual peeling or mechanical peeling. After peeling, it must be placed in water or color protectant immediately to prevent browning.

4. Slicing and shaping Cut the vegetables into a certain shape (granular, flake), and the vegetables that are easy to brown after cutting should be soaked in the color protection solution.

5, blanching generally uses hot water blanching. The water temperature varies depending on the vegetable variety, generally 80°C-100°C; the time varies from a few seconds to a few minutes. When blanching, you can add some salt, sugar, organic acid, and other substances to the water to change the color of vegetables and increase their hardness of vegetables.

6. After cooling and blanching, it should be cooled (water or ice water) immediately. The shorter the cooldown the better.

7. Drainage After cooling, some water droplets will remain on the surface of the vegetables, which is not conducive to freezing, and it is easy to make frozen vegetable agglomerate, which is not conducive to the next vacuum drying. This method generally adopts centrifugal drying.

8. Freezing Quickly freeze the discharged materials, and the freezing temperaCut peppers into rectangular slices about 3 cm long and 2 cm wide.

5. Color protection and hardening: soak in 0.5% calcium hydroxide solution for 2 hours. Green pepper is soaked in lye so that its chlorophyll is saponified into chlorophyll under the condition of lye, to fix chlorophyll and keep it green. The pectin in the green pepper reacts with ca2+ to produce calcium pectate, which hardens the green pepper.

6. Rinse: rinse with clean water. drain.

7. Blanch: Blanch green pepper flakes in boiling sugar for 2 minutes. 8. Sugar production: The honey method is used, and the total sugar used is equal to the number of chili flakes.

9. Drying: Take the chili flakes out of the sugar solution, drain the sugar solution on the surface, put them on a baking tray, and send them to the oven for drying. , the water content is about 20 ℃.

10. Packaging: Sort by belly size, fullness, color, and trim.

2. Chili Pickles

(1) Process

Preparation of kimchi tank, selection and processing of raw materials, preparation of kimchi brine → brewing in tank → fermentation and acidification → finished product

(2) Technical points

1. Prepare the kimchi jar: Rinse it, pour it into boiling water, sterilize it for 10 minutes, and dry it for later use. 2. Material selection: Use peppers with thick meat, small placenta, good hardness, no moth-eaten, and no scars as raw materials.

3. Material treatment: Rinse the selected peppers with water 3-4 times to remove sediment and impurities and control the moisture on the surface. 4. Preparation of brine: use well water and mineral water with a hardness of 16°h or more to prepare the solution. According to the weight of the water, add 6%-8% salt, 2.5% white wine, 2.5% rice wine, 3% sugar, 1% dried ginger slices, and 1% garlic cloves. Other seasonings such as 0.1% star anise, 0.1% prickly ash, 0.1% licorice, grass fruit, dried tangerine peel, etc. are wrapped in gauze for later use.

5. Brewing in a tank: Put the processed raw materials into the tank and pack them tightly. When filling half a jar, put the prepared spice packet into the jar, and then continue to serve the jar at a distance of 6 cm-8 cm from the mouth of the jar. Stick the bamboo pieces, and the brine should fully submerge the raw materials. Then put the lid on the jar and fill the mouth of the jar with salt water to form a water seal.