Food Dehydration

1
CHAPTER 10

• Food Dehydration
• Concentration

2
Water is Removed

• Under natural field conditions
• grains, raisins, seeds
• Cooking/baking
• Controlled dehydration processes

3
Dehydration vs. Concentration

• Dehydration - almost complete removal of water
• dried milk, coffee, corn flakes
• Concentration
• condensed milk, syrups, flavorings

4
Dehydration Principle

• Apply Heat / Remove Water
• Enhanced by
• Increased surface area
• Increased temperature
• Increased air velocity
• Reduced humidity
• Reduced pressure (vacuum)

5
Drying Methods Equipment

• Air convection driers
• Drum or Roller drying
• Vacuum drying

6
Air Convection Driers
7
Cabinet or Tray Drier
8
Tunnel Drier
9
Fluidized Bed Drier
10
Spray Drier
11
Drum or Roller Driers
12
Vacuum Belt Drier
13
FOOD CONCENTRATION
14
Concentration Benefits(similar to dehydration
benefits)

• Form of preservation (maybe)
• Reduces weight
• Reduces volume

15
Methods of Concentration

• Solar
• Open Kettles
• Flash Evaporators
• Thin Film Evaporators
• Vacuum Evaporators
• Freeze Concentration
• Reverse Osmosis

16
Flash Evaporator
17
Thin Film Evaporator
18
Ultra-filtration Reverse Osmosis
19
Changes During Concentration

• Cooked flavor
• Darkening of product
• Nutritional changes
• Some microbial destruction possible