Downstream Downstream

ProcessingProcessing

2

Downstream processing, what and why

Downstream processing is any treatment

of culture broth after fermentation to

concentrate and purify products.

Cell disruptionRemoval of insolubleProduct recovery

Purify the productFinishedproduct

Downstream Processing

Market

Crude product

Cell disruptionCell disruption

• Some product are intracellular including Some product are intracellular including many enzymes and proteins required to many enzymes and proteins required to disrupt the cell and release these products disrupt the cell and release these products e.g. Yeast e.g. Yeast

• Cell disruption can be achieved by both Cell disruption can be achieved by both mechanical and non-mechanical methods.mechanical and non-mechanical methods.

• Mechanical- sonication and liquid shear Mechanical- sonication and liquid shear homogenization etchomogenization etc

• Non mechanical- autolysis, osmosis shock Non mechanical- autolysis, osmosis shock etc.etc.

Removal of insoluble's

Separation of cells, cell debris or other

particulate matter from fermentation broth

culture.

Separation of particles from liquid by applying a pressure to the solution to force the solution through a filter. Filters are materials with pores.

Particles larger than the pore size of thefilter are retained by the filter.

Particles smaller than the pore size of the filter pass through the filter along with the liquid.

FiltrationFiltration

Membrane Fraction Technologies

Ultrafiltration(2000 - 50,000 MW)

Nanofiltration(200 - 700 MW)

Micro filtration(100,000 MW)

Reverse Osmosis(<200 MW)

Wate

r

Salts

Lactos

e

Protei

n

Micr

obes

+ fat

CentrifugationCentrifugationCentrifugation used to separate particles Centrifugation used to separate particles

as small as 0.1as small as 0.1μμm diameter and is also m diameter and is also

suitable for some liquid-liquid suitable for some liquid-liquid

separations.separations.

Higher speed centrifuge are required for Higher speed centrifuge are required for

the separation of the smaller particles the separation of the smaller particles

Use of the centrifugal force for the Use of the centrifugal force for the

separation of mixturesseparation of mixtures

Disc stack centrifugeDisc stack centrifuge

Coagulation  and  Flocculation

Coagulation:

Forming semisolid lumps in a liquid.

Flocculation:

Forming woolly cloudlike aggregations.

Product purificationProduct purification

• Removing components with properties Removing components with properties similar to those of the productssimilar to those of the products

ChromatographyChromatography• Separates molecules by their chemical

and physical differences E.g. – E.g. – adsorption chromatography adsorption chromatography • affinity chromatographyaffinity chromatography• ion exchange chromatography ion exchange chromatography

etc.etc.

Gel Filtration Chromatography

dialysisdialysis

• These membrane separation These membrane separation techniques are primarily used for the techniques are primarily used for the removal of low molecular weight removal of low molecular weight solutes and inorganic ions from a solutes and inorganic ions from a solutionsolution

Distillation• Separating components with different

volatilities. Such as organic solvents , beer, wine and sprits.

Product Polishing

Final processing steps which end with

packaging of the product in a form that is

stable and easily transportable

Crystallization, concentration and drying

are typical unit operations

Crystallization Process

Liquid Mixture

Generation of Supersaturation :Driving force

Nucleation: Birth of Solid Phase

Crystal GrowthFinal Product

Crystallization - by cooling saturated solution

Drying

Drying involves the transfer of heat to the

wet material and removal of the moisture as

water vapor. Drying Methods（ 1 ） Atmospheric drying（ 2 ） Vacuum drying (Decompression )（ 3 ） Freeze-drying (lyophilization)（ 4 ） Spray drying

lyophilization

Freezing the material

Reducing the surrounding pressure and

adding enough heat to allow the frozen

water in the material to sublime directly

from the solid phase to gas.

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