Drying and drying of walnut

   1. Natural air-dried walnut nuts should not be exposed to the sun after cleaning, so as not to break the nut and deteriorate the nucleolus. Washed nuts should be dried in the shade for half a day on bamboo foil or sorghum straw foil, and then spread out on Reed mat or bamboo foil to dry after most of the moisture evaporates. Spread the thickness should not exceed two layers of fruit, too thick is easy to heat, so that nucleolus deterioration, it is not easy to dry. Turn frequently when drying, lest the backlit surface of the core and shell turn yellow, and pay attention to avoid rain and dampness at night. Generally, it can be dried after 5 to 7 days. The criteria for judging whether it is dry are as follows: the sound of nuts is crisp, the diaphragm is easy to crush with your hands, and the skin color of the nucleolus changes from milky white to light yellowish brown. If drying too much, the nucleolus will produce oil and reduce the quality of nuts.

   2. Compared with natural drying, manual drying has good heating equipment, heat preservation equipment, ventilation equipment and better sanitary conditions. Although the cost of manual drying is high and the operation technology is more complex, whether it is the condition of drying or the quality of dried nuts, it is better than natural drying, which represents the direction of food drying.

   at present, according to the heat action mode of drying, the artificial drying equipment in China is generally divided into three types: convection drying equipment, heat radiation drying equipment and inductive drying equipment. In addition, there are intermittent drying chamber and continuous channel drying chamber, low temperature drying chamber and high temperature drying chamber. The heat carriers used are hot water, steam, electric energy, flue gas and so on. The intermittent drying chamber generally uses plain gas and electric energy heating, while the continuous channel drying chamber mostly uses infrared heating. Electromagnetic induction drying has not been widely used at present. Drying stoves and drying rooms are widely used in production, which heat the stove and complete the heat conduction by air convection.

   (1) oven drying is the simplest artificial drying equipment, which has a variety of forms, some laying stoves on the ground and some digging holes underground. When drying, make a fire in the stove or at the bottom of the pit, put wood on the top and spread the mat foil, and the raw materials are spread out on the foil to dry, and the required temperature is controlled by the size of the firepower. This kind of drying equipment has the advantages of simple structure, low production cost, low production capacity, slow drying speed and high labor intensity, so it is suitable for individual farmers to use.

   (2) at present, the drying rooms used by production units are mostly hot air convection drying equipment heated by flue gas, which is generally a relatively simple building with rectangular civil structure. There are many forms of buildings, according to the different heating mode, it can be divided into one furnace and one side linear heating type drying room, one furnace and one chimney tempering type drying room, one furnace and two chimneys tempering type drying room, one furnace and two sides tempering type drying room, two furnaces and two chimneys linear heating type drying room, two furnaces and two chimneys tempering type drying room, two furnaces and one chimney linear heating type drying room, two furnaces and one chimney tempering type drying room, high temperature drying room and so on. In addition, the drying room can also be divided into roof ridge type, flat roof type, cave type and so on. According to the different setting mode of the drying rack in the drying room, it is divided into the fixed drying rack type drying room and the movable drying rack drying room. The tempering drying chamber with two furnaces and one chimney is a form commonly used in production at present. it is a rectangular civil structure, with a length of 6 to 10 meters, a width of 3 to 3.4 meters and a height of 2 to 2.2 meters The main equipment includes heating equipment (including fire pit, ash door, furnace, main fire channel, wall fire channel, chimney, etc.), ventilation and dehumidification equipment (intake window and exhaust tube), loading equipment (drying rack and drying tray), door, aisle, lighting equipment, temperature and humidity measurement equipment and so on.