Solid Liquid extraction unit operation in food leaching methods applications

1. Presented by Atta-ur-Rehman (12)
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2. SOLID-LIQUID
EXTRACTION
(Also ----LEACHING PROCESS)
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3. SOLID LIQUID EXTRACTION
• Solid-liquid extraction allows soluble
components to be removed from
solids using a solvent
• Solid liquid extraction means the
removal of a constituent from a
mixture of solids by bringing the solid
material into contact with a liquid
solvent that dissolves this particular
constituent
• Also called leaching
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4. Example
• An ideal example is the preparation
of coffee.
• Here water (solvent) is used to
remove the coffee flavors (transition
component) from the coffee
powder(extraction material).
• Ideally, it results in drinkable coffee,
with the completely depleted coffee
grounds remaining in the filter
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5. Process of solid liquid extraction
• Solid- liquid extraction is also
called- leaching and involves simple
physical solution or dissolution
made by chemical reaction
• Extraction is enhanced by increased
surface area and decreased radial
distance by decreased partial size
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6. Mechanism
Extraction involves two steps which are:-
1- Contacting step:- of solvent and the material to be
Treated, so as to transfer soluble constituent to the
Solvent.
2- Separation step:- of the solution formed from the
relatively exhausted solids.
The above two steps may be conducted in separate
Equipment or in one and the same equipment.
Solution resulting from separation step is termed
Overflow, Solids left over are termed Underflow.
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7. 1-Contacting Step:-
Basically, it’s a mass transfer step , it aims at transferring
The soluble constituent from the solid phase into the
liquid phase by diffusion and dissolution.
The solute is first dissolved from the surface of the
solid, then passes into the main body of the solution by
diffusion.
This process may result in the formation of pores in the
solid material which exposes fresh(new) surfaces to
subsequent solvent penetration to such surfaces.
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8. 2-Separation step:-
• This is a momentum transfer step in which separation is done.
• It can be carried out by (settling or filtration).
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9. Methods of Extraction process
• A. Simple single contact.
• Fresh solvent is in contact with CD,one time extraction only
• Common Equipments are:
• Mixers
• Vertical extractors
• B. Simple multiple contact.
• Fresh solvent is in contact with CD, after first extraction, repeated extracts are dilute, recovery of
solute is improved.
• Common Equipments are:
• Diffusion battery
• Rotocel extractor
• Basket extractor
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• C. Continuous Counter current contact
• In counter-current extraction (CCE), wet raw material is pulverized using toothed disc disintegrators to
produce a fine slurry. In this process, the material to be extracted is moved in one direction within a
cylindrical extractor where it comes in contact with extraction solvent
• Screw extractor
• Pulsation column extractor

11. APPLICATIONS
• Solid–liquid extraction is a unit operation with diverse applications in the
food industry
• Production of vegetable oils with organic solvents
such as hexane , acetone and ether by extraction the oil
• Peanuts , soybeans, sunflower seeds, cotton seeds and
halibut livers.
• Leaching of soybean oil from flaked soybeans with hexane.
• Leaching of sugar from sugar beets with hot water.
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12. APPLICATIONS
• Soluble tea is produced by water leaching of tea
Leaves.
• Gold is leached from its ore using an aqueous
sodium cyanide solution.
• Extraction of copper oxide from low grade ores with
dilute H2SO4 acid
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13. EXTRACTION OF SUGAR FROM BEETS
• Sugar can be obtained from sugar beet using water as the extraction liquid.
• The extractors
• >diffusion battery >Hildebrandt >Bonotto extractors
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14. METHOD
• In order to facilitate the extraction operation
1- beets are cut in long V-shaped slices.
2-slices immersed in water.
3-introducing water under pressure.
4-Diffusion occurs.
5-The extract is purified by sedimentation and
filtration
6-concentrated in evaporators
7-The crystals are separated by centrifugation.
8-obtaining sugar.
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15. EXTRACTION OF PALM OIL FROM
PALM FRUIT
• Bunch reception
Reception of palm fruit bunches.
• Sterilization
To deactivate enzymes.
Soften the fruit bunches.
• Threshing
Removing of palm fruit from bunch.
• Digestion
Crushing of palm fruit.
• Pressing
Squeeze the palm fruit into
1.oil and water 2.press cake
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16. EXTRACTION OF PALM OIL
• Clarification
Separation of oil from water and
impurities.
• Purification
This process improves oil purity.
• Drying
Removal of water to 0.1%.
• Fiber separation
Separation of fiber and nuts from
press cake.
• Separation
Separation of kernels and shells from
nuts.
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17. Advantages
• Common method.
• Easiest method to use.
• Selectivity of direct extraction.
• Reduction of production loss.
• Suitability over a wide range.
• Use of minimum amount of solvents
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18. Disadvantages
• Chances of impurities.
• Application of analytical errors.
• Time consuming
• Expensive method.
• Precision can be difficult.
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19. References:
• https://slideplayer.com/slide/3953611/
• https://youtu.be/rw0rBD4Fca0
• https://www.sciencedirect.com/topics/biochemistry-genetics-and-
molecular-biology/countercurrent-extraction
• Albert Ibarz & Gustavo V. Barbosa-Canovas.UNIT OPERATIONS IN FOOD
ENGINEERING, Chapter 21
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