dehydration process which is use topreserve a material or make the materialmore convenient to transport

•A slow batch process

•Main 2 techniques

freeze

evaporation

•Use a vacuum system

•Main 4 stages

1. Pretreatment

2. Freezing

3. Primary drying

4. Secondary drying

Any method of treating the product before freezing

•Concentrating the product.•Addition of components to,

- improve stability- improve processing

• Freeze concentration

• Solution phase concentration

• Formulation to preserve product

appearance

• Formulation to stabilize reactive products

• Formulation to increase surface area

• Decreasing high vapor pressure solvents

Can be done in 2 ways;

1. Small scale(in a lab),

-place the material in a freeze drying flask

- rotate the flask in a bath (shell freezer)

Cooled by mechanical refrigeration

use,

- dry ice

- methanol

- liquid nitrogen

2.Large scale

-use freeze drying machine

* It is important to cool the material below triple point in both ways

•Pressure is lowered•Enough heat is supplied to the material

(water to sublime)•95% of water in the material is sublimated•Process is slow

(much heat could alter the materials structure)•Pressure is controlled through a application of partial vacuum.

(speeds up the sublimation)

Aim;

-to remove unfrozen water molecules

•Temperature is increased greater than in

primary drying stage

•Vacuum is break with an inert gas (Nitrogen)

before material is sealed

Less damages to their physical structures

No need to refrigerate

No need to use chemicals for preservation

Easy to transport

Can reconstitute quickly and easily

Can increase the shelf life

No risk of contamination

Expensive

Long process time

Can cause structural deformation

Storage problems

Effective for selected items

Industry Applications

1.Ceramics To create formable powder

2.Food processing For instant meals and soups.For breakfast cereals, juices.For flavorings.

3.Dairy industry High value proteins

4.Nutraceuticals Aloe vera, mussels, shark cartilage.

5.phamaceuticals Protiens,enzymes, hormones, vaccines and other biological products.

6.Research Stabilization and storage of biological materials.

7.Document recovery Water logged artifacts.Water damaged books and documents.

Industry Applications

8.Starters and cultures For use in cheeses, yoghurts, meats and probiotics

9.Floral Preserved petals and whole flowers.Preserving wedding bouquets and memorial flowers.

10.Taxidermy Animal preservation.

11.Technological industry Chemical synthesized products.Late stage purification procedure.

To make ceramic powder

To produce porous ceramics

To make ceramic plates

To create superconductors

A water based

ceramic slurry

Freeze while the

growth direction

of ice is

controlled

Sublimation of

ice

Green bodyPorous ceramic

From a sprayed slurry mist.

Creates softer particles with a more homogeneous chemical composition.

More expensive

S/08/924-A.M.P.L. Adikari

S/08/927- I.N.K. Darandakumbura

Thank you!