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

1. FREEZE DRYING
PRESENTED BY,
ALVIN SAJAN

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.

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

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

19. Examples of FREEZE DRYING
Freeze dried
banana
Freeze dried
coffee

20. Freeze dried garlic
Freeze dried
strawberry

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 .

23. THANK YOU