Browning Other chemical reactions may also take place during drying. Browning occurs in many foods which results in color changes. Protein denaturation can occur during drying, which causes increasd viscosity, Thermal degradation of vitamins and proteins may also influence the nutritional status of dried products
Browning Other chemical reactions may also take place during drying. Browning occurs in many foods which results in color changes. Protein denaturation can occur during drying, which causes increasd viscosity, Thermal degradation of vitamins and proteins may also influence the nutritional status of dried products
The extent of these changes depends on the nature of the drying process. Some types of dryers produce products having superior properties on reconstitution. The instant coffee spray-dried and freeze-dried is different. Since freeze-drying does not involve a vapor-liquid interface, the volatile flavor and aroma compounds are not lost during drying, and freeze-dried products have higher quality
The extent of these changes depends on the nature of the drying process. Some types of dryers produce products having superior properties on reconstitution. The instant coffee spray-dried and freeze-dried is different. Since freeze-drying does not involve a vapor-liquid interface, the volatile flavor and aroma compounds are not lost during drying, and freeze-dried products have higher quality
MOISTURE SORPTION AND DESORPTION During drying, both moisture content and water activity change. At any given relative humidity of air used for drying, there is an equilibrium water content with the product, At this point the activity of water in the air is the same as that in the product. This relationship specifies the water content in a food product that can be reached for any condition of drying air
MOISTURE SORPTION AND DESORPTION During drying, both moisture content and water activity change. At any given relative humidity of air used for drying, there is an equilibrium water content with the product, At this point the activity of water in the air is the same as that in the product. This relationship specifies the water content in a food product that can be reached for any condition of drying air
Isotherms By holding a food product in air at different relative humidities and measuring the equilibrium water content, the curve of water content and water activity can be obtained. It’s nature depends on whether the food product is being dried or allowed to pick up moisture from the air. The direction of the experimental measurement affects the relationship between water content and water activity. Isotherms
Isotherms By holding a food product in air at different relative humidities and measuring the equilibrium water content, the curve of water content and water activity can be obtained. It’s nature depends on whether the food product is being dried or allowed to pick up moisture from the air. The direction of the experimental measurement affects the relationship between water content and water activity. Isotherms
MOISTURE SORPTION AND DESORPTION Moisture sorption (picking up water) curves typically are slightly lower in water contents than moisture desorption (drying) curves. Several mechanisms have been proposed for this hysteresis behavior. capillary forces volume expansion
MOISTURE SORPTION AND DESORPTION Moisture sorption (picking up water) curves typically are slightly lower in water contents than moisture desorption (drying) curves. Several mechanisms have been proposed for this hysteresis behavior. capillary forces volume expansion