Freeze-dried products of biological products, need to have some physical form, uniform color, qualified residual moisture content, good solubility, high survival rates, longer shelf life, so not only on the production process and freeze-dried sealed need to be controlled, the more important is to full control the every parameters of freeze-drying process and then to obtain high-quality products, the freeze-drying curve is the fundamental basis for process control.
The freeze-dried container curves is the relationship between temperature and time, generally the temperature is vertical axis and time as the abscissa, which reflects the slab temperature changes at different time during the freeze-drying process.
Freeze-drying curve is based on the plate surface temperature, due to the product temperature is dominated by the board temperature , when set the freeze-drying curve, user need to consider the following factors.
Product variety, different products has different eutectic point, the same eutectic point product temperature require low pre-freezing temperature, so is the heating plate, user should find a optimal freezing rate according to experiments to achieve high-quality products and shorter freeze time.
And different times require different residual moisture. So the freezing time is corresponding different, in addition, the loading amounts, seal device species, freeze dryer performance and other factors are directly related to the curve of freeze-dried, the user should base on the nature of freeze-dried products, and reference to the past experience to set freeze curve, in order to get high-quality freeze-dried products.