Starch pretreatment and microwave puffing drying process
    Starch material mixing process can be a certain amount of water added , and then heated at a temperature above 90 ℃ , and then kneading was adequately mechanical means . Its purpose is to destroy after α of starch molecules aggregate structure, so as to form a complex network structure conjugates. Dry operation of the process so that the ratio α of the starch molecules , although it will again a regular arrangement of molecules , but this re- arrangement of the molecules binding structure of the molecule , is much weaker than the original . So you can reduce the temperature required to understand molecules , only about 130-220 ℃ enough .
    For most of the starch material processing temperature should be at about 150 ℃ , therefore . Puffing drying process to take the temperature of the heat transfer medium with a certain food ingredients with top quality mix , which uses 130-180 ℃ heat transfer medium body ( such as rock , etc. ) and have been fully kneaded α of pre-drying and puffing ingredients together and mixing , a conveyor belt into the microwave heating apparatus of the relevant extruded, dried products
    Using the pre- heated to 180 degrees of heat storage thermal heat transfer medium larger premixed with food materials , food materials can rapidly increase surface temperature , microwave energy only when used in processed foods, the internal temperature increased rapidly expanding . Two heating methods used here with rapid heating of the amount of food material extruded around the purpose of drying . Because the degree of food raw materials not only the foaming expansion α of the starch material and the degree of α , the amount and type of additives , water content size and other factors , but also on the heating temperature ( in particular, the initial heating temperature ) with the heating time . Generally speaking , for the α of kneading and after a full semi-finished products after pre cadres at 130-180 ℃ heat transfer medium quality combined with microwave heating case, only 10 to 30 seconds, and you can become dizzy of the original volume more than six times . The typical curve shown in Figure 5-7 puffing . Experimental results show that , before the material for rendering water content of about 18-22 % most appropriate. If the string is less than 15% water , the hair becomes small bubble level expansion , and the paste may be scorched . If the string of more than 30% moisture content , then prolonged heating foaming and foam appears uneven and Gansu places back after puffing phenomenon .
    Heat transfer medium according to the type of workpiece , the choice of salt particles , sand , glass or ceramic beads , silica particles , etc. For example , the heating of food , preferably salt particles , heating the face of non-food , the choice of glass beads and so on.