Freeze vacuum drying varieties processing process

Freeze vacuum drying varieties processing process

1, raw material selection of leafy vegetables from harvesting to processing should not exceed 24 hours, manual selection of yellow, rotten parts; Root vegetables are manually picked out, rotten parts, and graded.

2. Clean and remove soil and other impurities on the surface of vegetables. In order to remove pesticide residues, it is generally necessary to soak 1.55%-1% hydrochloric acid solution or 0.05%-0.1% potassium permanganate or 600 mg/kg bleach powder for a few minutes for sterilization, and then rinse with clean water.

3, peel root vegetables should be peeled. The raw material loss rate of chemical lye peeling is low, but the export products generally require manual peeling or mechanical peeling, and must be immediately put into clear water or color protection solution after peeling to prevent Browning.

4, cutting molding will cut vegetables into a certain shape (grain, sheet), easy to brown vegetables after cutting should be immersed in the color protection solution.

5, blanching generally use hot water blanching, water temperature changes with vegetable varieties, generally more than 100℃; The time varies from a few seconds to a few minutes. When blanching, some salt, sugar, organic acids and other substances can be added to the water to change the color and increase the hardness of the vegetables.

6, after the end of the cooling ironing should be cooled immediately (water cooling or ice water cooling), the shorter the cooling time the better.

7, after draining and cooling, the surface of the vegetables will retain some water droplets, which is unfavorable to freezing, easy to make frozen vegetables clumped, not conducive to the next step of vacuum drying. Methods Centrifugal drying is generally used.

8. The frozen and drained material is quickly frozen, and the freezing temperature is generally below -30 ° C to prepare for the next step of vacuum drying.

9. The vegetables after vacuum drying and pre-freezing are put into the vacuum container by means of the vacuum system, the pressure in the window is reduced to below the triple point, and the material is heated by the heating system, so that the water of the material gradually evaporates until it is dried to the end of the water.

10, the product after freeze-drying should be immediately separated, remove impurities and other foreign products, and accurately weigh according to the packaging requirements, into the bag to be sealed.

11, packaging with double plastic bags vacuum packaging. Due to oxidative Browning of the product, it can be packed with nitrogen, and then put into the outer carton for storage.