24
2023
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04
What is the reason for the high moisture content of the products produced by the freeze-drying machine?
The low-temperature drying of a freeze-drying machine involves pre freezing a material containing a large amount of water to reduce the temperature and freeze it into a solid state.
The low-temperature drying of a freeze-drying machine involves pre freezing a material containing a large amount of water to reduce the temperature and freeze it into a solid state. Then, the water vapor is immediately sublimated under the standard of a vacuum pump, and during the freezing and cleaning process, the material itself remains on the ice shelf.
After freeze-drying, its volume does not change, and the loose porous structure requires digestion and absorption of heat during the sublimation process. The temperature of the product itself will decrease, and the sublimation rate will decrease, thereby increasing the sublimation rate and reducing the drying time. All drying will be carried out at lower temperatures.
The moisture content of the product, the performance of the freeze-drying machine, the control time of drying analysis, and the temperature of drying analysis are the main factors affecting moisture content. For freeze-dried products, the moisture content is required to be ≤ 3%. The high moisture content of freeze-drying products will lead to product decomposition and shrinkage.
The main reasons for the high water content of the product are:
1. Excessive liquid medication. The thickness of the medicine solution is usually 10-15mm and should not exceed 15mm. If the filling amount is large, it can be considered to replace a larger sized container to reduce the thickness of the solution. Excessive thickness of the medicinal liquid can worsen the heat transfer effect during the drying process, which is not conducive to removing moisture from the product, resulting in excessive moisture content in vacuum freeze-drying machine products.
2. Dry products absorb moisture again. For varieties that are easy to absorb moisture, if the vacuum freeze dryer is not properly treated after drying, the product will absorb moisture again, which will increase the moisture content of the product. If the gas enters the freeze-drying oven during exhaust, it is necessary to sterilize, filter, and dry the gas that enters the product causing high moisture content.
The temperature of the product that is ready to use out of the box can also affect the moisture content of the product. Therefore, the temperature of the product when opened should be higher than the temperature in the clean room to prevent moisture from condensation in the air on the product. In addition, the temperature is 2-3 ° C, and the relative humidity of the dust-free room should be strictly controlled below 50%.
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