Dehydrated vegetable processing method

Dehydrated drying methods are naturally dried and artificially dehydrated. Artificial dehydration includes hot air drying, microwave drying, expanded drying, infrared and far-infrared drying, and vacuum drying. At present, the application of dehydration and drying of vegetables is more hot air drying dehydration and vacuum vacuum drying dehydration. The frozen vacuum dehydration method is a kind of advanced vegetable dehydration and drying method. The product can retain the original color, smell and taste of fresh vegetables. Shape, but also has an ideal rapid rehydration. The process flow and method for processing hot-dried dehydrated vegetables and frozen vacuum-dried dehydrated vegetables are described below.

First, hot air drying dehydrated vegetable processing process and methods

1. Raw material selection Select a vegetable species rich in meat quality. Before dehydration, strictly select the best ones, and eliminate those with pests, rots, and cognac. To 80% maturity is appropriate, over-cooked or uncooked should also be singled out, in addition to melons to the seedlings, other types of vegetables can be washed with water, and then placed in the shade to dry, but not in the sun exposure.

2, cutting, blanching Wash the raw materials according to product requirements were cut into pieces, silk, strips and other shapes. Precooked, because of different raw materials, easy-to-cook place in boiling water, cooked, not easy to cook put a little boiled in boiling water, the general blanching time is 2-4 minutes. Leaf vegetables are best not treated by blanching.

3, cooling, drainage, pre-cooked vegetables should be immediately cooled (usually cold water shower), so that it quickly dropped to room temperature. After cooling, in order to shorten the drying time, the centrifuge can be used to throw water, and it can also be drained by a simple manual method. After the water is drained, it can be spread out to cool it slightly to prepare for baking.

4, drying should be based on different varieties to determine the different temperature, time, color and moisture content when drying. Drying is generally performed in a drying room. There are roughly three types of drying rooms: the first simple drying room with counter-current blast drying; the second is a drying room with a combination of two-story double tunnel and forward/backward flow; the third type is a box type stainless steel hot air drying machine. The dry temperature range is 65°C-85°C. It is dried at different temperatures and gradually cooled. When the first and second drying rooms are used, the vegetables are evenly distributed in the tray, and then placed on a pre-established drying rack to maintain the room temperature at about 50 DEG C., while constantly turning to accelerate the drying, generally drying The time is about 5 hours. 5. Inspected and packaged dehydrated vegetables are verified to meet the requirements of the Food Sanitation Law, which can be packaged in plastic bags, sealed and packaged, and then listed.

Second, frozen vacuum drying dehydrated vegetable processing process and methods

1. Raw materials Picked Vegetable vegetables should not be processed more than 24 hours from the harvesting process. Manual picking should start yellow and rotten parts; root vegetables should be hand-picked out, rotted, and graded.

2, cleaning to remove dirt and other impurities on the surface of vegetables. In order to remove pesticide residues, it is generally necessary to use a 0.5% - 1% hydrochloric acid solution or 005% - 01% potassium permanganate or 600 mg / kg bleach for several minutes to sterilize, and then rinse with water.

3, peeled root vegetables should be peeled. The detrimental rate of raw materials for chemical caustic is low, but export products generally require manual peeling or mechanical peeling. After peeling, they must be immediately put into clean water or color protection solution to prevent browning.

4. Dividing and forming The vegetables are cut into a certain shape (grain, flakes), and the browning vegetables after slicing should be immersed in the color protection solution.

5, blanching generally use hot water blanching, water temperature varies with the variety of vegetables, generally 80 °C -100 °C; time is a few seconds to several minutes. During blanching, some salts, sugars, organic acids, and other substances can be added to the water to change the color and hardness of the vegetables.

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

7. After draining and cooling, some droplets of water will remain on the surface of the vegetables, which is unfavorable for freezing, and easily causes the frozen vegetables to form clumps, which is not conducive to vacuum drying in the next step. The method generally uses centrifugal spin-drying.

8. The material after freezing and draining is rapidly frozen. The freezing temperature is generally below -30°C to prepare for vacuum drying in the next step.

9, vacuum drying pre-frozen vegetables placed in a vacuum container by the vacuum system to reduce the pressure within the window below the triple point, the heating system to heat the material, so that the material moisture gradually evaporated until the end of moisture until the dry.

10. The products after classification, measurement, and freeze-drying shall be classified and checked immediately. Impurities and other foreign products shall be removed and accurately weighed according to the packaging requirements. The product shall be sealed in bags.

11, packaging with a double plastic bag vacuum packaging. As the product is oxidized and browned, it can be packaged with nitrogen and packaged in an external carton for storage.