Freeze drying is a process that removes water from foods and other products after they are frozen and placed under a vacuum. This allows the ice in the product to change directly from a solid to vapor without passing through the liquid phase. Freeze drying preserves the integrity of the product's biological and chemical structure. The freeze drying process consists of three phases - freezing, primary drying, and secondary drying. During freezing, the product is frozen to separate the water. In primary drying, heat is applied under vacuum to sublime the ice directly into vapor. Secondary drying further removes water until the desired moisture level is reached. Freeze drying has advantages like long shelf life and retaining of color, taste and shape, though it is more expensive and time consuming than other
2. OVERVIEW
INTRODUCTION
HISTORICAL BACKGROUND
WHY WE USE FREEZE DRYING
PHASES OF FREEZE DRYING
COMPONENTS
WORKING PRINCIPLE
ADVANTAGES
DISADVANTAGES
APPLICATIONS
CONCLUSION
3. INTRODUCTION
Freeze drying is the process in which water is removed
from a product after it is frozen and placed under a
vacuum allowing the ice to change directly from solid
to vapour without passing through a liquid phase.
Freeze Drying preserves the integrity of the product’s
biological and chemical structure and activity.
4. HISTORICAL BACKGROUND
Origin –
From INCA EMPIRE
Modern invention –
vacuum technology invention in 1909
Maxwell House –
commercial use for retaining flavour of coffee
and to make delivery process easier in 1963
NASA –
preservation of food for astronauts
Modern use –
from 1980’s companies began to preserve
herbs ,vegetables ,beverages and other food items.
5.
6. WHY WE USE FREEZE DRYING
Removing water keeps food from spoiling for a long
period of time
Freeze drying significantly reduces the weight of the
food
7. PHASES OF FREEZE DRYING
Freeze drying process consist of three phases
freezing
primary drying
secondary drying
8. FREEZING
During the freezing phase the goal is to freeze the
mobile water of the product
The rate of cooling will influence the structure of the
frozen matrix
9. PRIMARY DRYING
In this phase the chamber pressure is reduced and
heat is applied to cause the frozen mobile water to
sublime
It is important to control the drying rate and heating
rate during this phase
10. SECONDARY DRYING
The length of the secondary drying process will be
determined by the product
The water content may be carefully controlled
11. COMPONENTS
Mainly the freeze dryer consists of 3
parts
• Freeze drying chamber
• Refrigeration coils
• Vacuum pump
12.
13. WORKING PRINCIPLE
Place the material to be preserved on the shelf when it
is still unfrozen.
Seal the chamber and process begins.
Compressor lowers the temp and freezes the material
and water is seperated.
Vacuum pump forces air out of chamber and lowers
the atmospheric pressure to 0.06 atm.
14. WORKING (Contd…)
Small heat applied for ice to change phase.
Due to low pressure ice turns directly to water vapour
and it flows out of chamber.
Water vapour condenses in freezing coil to solid ice.
Process continues till material dries out.
15. WORKING (Contd…)
Sublimation process accelerated to avoid overheating.
Once dried sufficiently – sealed in moisture free
packages.
As long as package is secure it can sit without
degrading for years and years.
16. ADVANTAGES
Preserves color, taste, shape.
Easy to transport.
Last long.
Easy packing.
Provide high quality product.
17. DISADVANTAGES
Increased handling and processing time.
Very costlier process.
Fire hazards if the chamber is not in proper vacuum,
while heater is on.
18. In pharmaceutical companies.
Food industries.
In flower industries.
For protecting old books.
APPLICATIONS
21. CONCLUSION
The process is much cheaper for pharmaceuticals.
Cost mainly depends on engineering skills and
techniques.
Quality of the product is very high.
22. REFERENCE
Microencapsulation of Nutraceuticals Using Spray Freeze Drying
Method: A Brief Review Rajeev Kumar *, Abhijit Kar Division of Food
and Post Harvest Technology, IARI, New Delhi, India
Freeze-Drying – Application in Food Processing and Biotechnology –
A Review ,Agnieszka Ciurzyńska*, Andrzej Lenart , Department
of Food Engineering and Process Management, Faculty of Food
Sciences, Warsaw University of Life Sciences (SGGW),
Nowoursynowska 159c, 02–776 Warsaw, Poland.
Effect of Freeze-Drying on the Antioxidant Compounds and
Antioxidant Activity of Selected Tropical Fruits Norshahida Mohamad
Shofian 1, Azizah Abdul Hamid 1,2,*, Azizah Osman 1, Nazamid Saari
1, Farooq Anwar 1,3, Mohd Sabri Pak Dek 1 and Muhammad
Redzuan Hairuddin .