Drying

• The methods of drying are spray-drying, air-drying, freeze-drying, and vacuum-drying.
• Drying is the process of removing water from food to prevent spoilage (yeast, bacteria), reduce weight, improve texture, and facilitate storage.
• Vacuum-drying uses reduced pressure to remove water from foods with low temperature
• Freeze-drying involves freezing the product at low temperatures (-40°C) followed by sublimation under high vacuum (10^-2 mbar).
• Vacuum-drying uses reduced atmospheric pressure to remove water vapor from foods without damaging them.
• Air-drying involves exposing foods to hot or cold air until they reach their desired moisture content.
• Moisture removal during drying can be achieved through evaporation, sublimation, or desorption.
• Air-drying can be done using natural or forced convection.
• Hot air is used to heat and evaporate the surface moisture of the material to achieve the purpose of drying.
• During drying, there are three stages: constant rate period, falling rate period, and equilibrium stage.
• The forced ventilation function can improve the drying efficiency of the hot air drying oven and ensure that samples are processed evenly and quickly