Frozen vacuum drying of Dehydrated vegetables processing process and methods
writer :Jiade Food ; Date:2016-10-18 15:41
(1) selection of raw materials. For leafy vegetables, from harvesting to processing should not exceed 24 hours of artificial selection yellow and decay; for root vegetables, artificial selected goods, decomposed, and grading.
(2) cleaning. Removal of dirt and other impurities on the surface of vegetables. In order to remove pesticide residues, the general need to use 0.5%~1% hydrochloric acid solution or 0.05%~0.1% Potassium Permanganate or 600mg/kg bleaching powder soak for several minutes, and then rinse with water.
(3) peel. For root vegetables, should be peeled. Chemical lye peeled, the raw material loss rate is low, but does not meet the requirements of export. Export products are generally required to be artificial peeled or mechanical peeling, skin must be immediately put into water or color protection liquid, in order to prevent browning.
(4) segmentation. Cut vegetables into a certain shape (grain, flake), after the cut, easy browning of vegetables should be dipped into the color protection liquid.
(5) ironing and bleaching. Generally use hot water, hot water, water temperature changes with the variety of vegetables, generally 80~100 degrees Celsius; time is a few seconds to a few minutes. When hot and bleach, can add some salt, sugar, organic acid and other substances in the water, to change the color of the vegetables and increase the hardness.
(6) cooling. After the end of the hot bleach should be immediately cooled (water or ice cold), the shorter the time the better.
(7) drain. After cooling, the surface of the vegetables will remain some water droplets, which is detrimental to the freezing, easy to freeze the vegetables to form a block, is not conducive to the next step vacuum drying. Centrifugal drying is generally used.
(8) freezing. The material fast frozen drain, freezing temperature is generally -30 degrees Celsius, ready for the next step of vacuum drying.
(9) vacuum drying. The pre frozen vegetables into a vacuum container, by means of the vacuum system will be reduced to the point of the pressure inside the window by the heating system to the material, so that the material moisture gradually evaporated until the end of the drying to moisture.
(10) division measurement. Freeze drying products should immediately remove impurities and reject sorting according to the packing requirements accurately weighed into the bag to be sealed.
(11) packaging. Vacuum package with double layer plastic bag. Due to the oxidation of products browning, can be filled with nitrogen packaging, wrapped in the outer carton storage.