Food processing and preservation

1. DEHYDRATION

2. DEHYDRATION
 Dehydration in food processing is a method used to preserve various food by the application of
heat under controlled conditions to remove moist of the water that is normally present in food
by the action of evaporation
THEORY OF DEHYDRATION
 Dehydration involves the simultaneous application of heat and removal of moisture from foods.
The primary principle behind dehydration is that microorganism such as molds, yeast and
bacteria require water to grow.
 By reducing the moisture content in food through dehydration the microorganism are un able to
strive. These dehydration methods include air drying, sun drying and spray dring and these
methods remove water by evaporation or sublimation that results in reduction of weight and
volume.
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3. EQUIPMENTS OF DEHYDRATION
DEHYDRATORS
These are electric appliances designed to remove moisture from food products through
controlled heating and equal air circulation.
SOLAR DRYERS
makes use of solar energy to dehydrate food. It is commonly used in regions
with ample sunlight
Freeze dryers
food is frozen at low temperature and the subjected to vacuum conditions to remove moisture
through the process of sublimation, preserving food quality and nutrients
Air dryers
natural air circulation is used to dry food products

4. POSITIVE EFFECTS OF DEHYDRATION
 Extended shelf life:
 Retained nutritional value:
 Convenience and portability:
 Intensified flavor:
 Versatile usage

5. NEGATIVE EFFECTS OF DEHYDRATION
 LOSS OF NUTRITIONAL VALUE: it can lead to the loss of certain nutrients in foods for example heat
sensitive vitamins like vitamin c and some B vitamins, reducing the overall nutritional quality of the
product.
 CHANGES IN TASTE AND TEXTURE: dehydration alters the test and texture of foods, sometimes
resulting in a less appearing final product for example fruits and vegetables may become overly chewy or
tough after dehydration.
 INCREASE PROCESSING TIME AND ENERGY CONSUMPTION. It often requires prolonged processing
times and energy intensive methods like heating or freeze drying that increase production costs and
environmental impact.
 LIMITED SHELF LIFE: it can lead to reduced stability over time if not properly stored, resulting in
spoilage of nutrient concentration.