FREEZE DRYING

PRESENTED BY,

ALVIN SAJAN

OVERVIEW INTRODUCTION

HISTORICAL BACKGROUND

WHY WE USE FREEZE DRYING

PHASES OF FREEZE DRYING

COMPONENTS

WORKING PRINCIPLE

ADVANTAGES

DISADVANTAGES

APPLICATIONS

CONCLUSION

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.

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.

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

PHASES OF FREEZE DRYING

Freeze drying process consist of three phases

freezing

primary drying

secondary drying

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

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

SECONDARY DRYING

The length of the secondary drying process will be determined by the product

The water content may be carefully controlled

COMPONENTS

Mainly the freeze dryer consists of 3 parts

• Freeze drying chamber

• Refrigeration coils

• Vacuum pump

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.

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.

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.

ADVANTAGES

Preserves color, taste, shape.

Easy to transport.

Last long.

Easy packing.

Provide high quality product.

DISADVANTAGES

Increased handling and processing time.

Very costlier process.

Fire hazards if the chamber is not in proper vacuum, while heater is on.

In pharmaceutical companies.

Food industries.

In flower industries.

For protecting old books.

APPLICATIONS

Examples of FREEZE DRYING

Freeze dried banana Freeze dried coffee

Freeze dried garlic Freeze dried strawberry

CONCLUSION

The process is much cheaper for pharmaceuticals.

Cost mainly depends on engineering skills and techniques.

Quality of the product is very high.

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 .

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