This document discusses different types of extraction processes including liquid-liquid, solid-liquid, and gas-liquid extraction. Liquid-liquid extraction involves using a liquid solvent to remove a liquid component from a liquid mixture. Solid-liquid extraction allows soluble components to be removed from solids using a solvent. Gas-liquid extraction uses a densified gas solvent to extract compounds from liquids. Coffee extraction is provided as an example of solid-liquid extraction, where water is used as the solvent to extract soluble flavors from coffee grains. Key factors that affect the extraction rate and yield are also summarized such as temperature, time, surface area, and solvent viscosity.

1. EXTRACTION
presented by:
CECILLE ABOAGYE DINAH ADOMAKO EMMANUEL BERKO

2. INTRODUCTION
• Method of removal of a soluble fraction in the form of
a solution from an insoluble medium with the help of
a suitable solvent.
• Process by which a solute is transferred from one
phase to a new phase.
• Removal of soluble constituents from a phase with the
means of suitable solvent.
• Separation can be due to gravitational force or

3. TYPES OF EXTRACTION
• Liquid-Liquid (Solvent extraction)
• Solid-Liquid (Leaching)
• Gas-Liquid (Absorption)

4. LIQUID-LIQUID
• Involves using a liquid solvent to remove a liquid
component from a liquid mixture.
• The component dissolves preferably in the solvent.
(Lewis, 2007)

5. APPLICATION OF LIQUID-LIQUID
EXTRACTION
• Removal of vitamins from aqueous solutions
• Aromatic compounds from crude oil fractions

6. SOLID-LIQUID
• Allows soluble components to be removed from solids
using a solvent.
• Soluble material is dissolved into the solvent and
solvent is evaporated to recover the solute(s) in
powder or crystalline form.
(Lewis, 2007)

7. APPLICATION OF SOLID-LIQUID
EXTRACTION
• Drinkable coffee (solvent with dissolved flavors).
• Obtaining oil from oil seeds
• Leaching of metal salts from ore

8. GAS-LIQUID
• This involves the use of a densified gas (solvent) to
extract a medium from a liquid mixture.
• Heavy volatile compounds often require this process.
• Principle behind extraction is Change in Pressure
and/or Temperature.

9. APPLICATION OF GAS-LIQUID
EXTRACTION
• Solvent used mostly is Carbon dioxide (CO2) and
Extracts are usually Esters, Alcohols etc.
extra
ct

10. CONSIDERING SELECTION OF A
SOLVENT
• Solvent must form a separate phase from the feed
solution.
• Able to extract the solute from the feed solution.
• Chemical reactivity and stability
• Flammability and Toxicity
• Cost analysis of process.

11. FACTORS THAT AFFECT RATE OF
EXTRACTION
Holding time – (depending on the solvent and solute of
interest)
• The longer the holding time, the more solutes are
extracted.
• Takes a shorter time if the solute is easily soluble in
the solvent.
Temperature
• the higher the temperature the faster the rate of

12. FACTORS contd.
Surface area of the solids exposed to the solvent
• the larger the surface area, the faster the rate of
extraction.
• implies reduction of size for solids.
Viscosity of the solvent
• the thicker the solvent, the slower and more difficult
the rate of extraction.
• the solvent would not be able to penetrate into the

13. EQUIPMENT USED
(EXTRACTOR)

14. SINGLE STEP MIXER – (SEPARATOR)
•It is the simplest form of extraction
•Uses the principle of gravitational force.
•Has a High efficiency rate of extraction per
step.
•Requires large amounts of solvent.
• Hence expensive.

15. Solvent

16. MIXER-SETTLER-CASCADE
• This involves a multiple stage separation of liquid
mixtures.
There are two designs:
• Box type – mixing and settling zones are separated by
plates
• Tower type – the single steps are one above the other
so that less ground area is used.

18. CENTRIFUGAL EXTRACTORS
• Heavier phase is transported to the periphery and the
lighter phase to the center.
• Centrifugal force is responsible for the counter current
flow of the phases.
• There’s high throughput, low amounts of solvent
needed.
• High cost of operations.

20. APPLICATION TO COFFEE
EXTRACTION
PRINCIPLES

21. CONCEPT
• Coffee extraction is a solid-liquid type of extraction.
• Solvent used is water.
• Extract of interest are soluble flavors.
• Generally involves the transfer of solutes from a solid
(coffee grains) to a fluid (water).

22. FACTORS CONSIDERED
• Quantity of coffee grains/water used (mass/weight).
• Grind precision (size particles).
• Correct degree of extraction (efficiency).
• Controlled by correct Temperature and Time.

23. SCHEMATIC DIAGRAM OF THE COFFEE
GRAIN
• Øh – volume fraction of
intergranular pore
• (1– Øh) – volume fraction of
grains
• Øc – soluble volume fraction
• Øs,i – insoluble volume
fraction

24. SETUP FOR THE EXTRACTION

25. INTERACTION OF WATER & COFFEE
GRAINS

26. Terms Used
Total Dissolved Solids (TDS)
• TDS is expressed in parts per million (ppm).
Strength
• Also known as "solubles concentration", measured by
Total Dissolved Solids – how concentrated or watery
the coffee is.
Brew ratio
• The ratio of coffee grounds (mass) to water (volume)
• how much coffee is used for a given quantity of water.

27. EQUATION INVOLVED
Extraction yield (%)
• The percentage by mass of coffee grounds that ends
up dissolved in the brewed coffee.
Extraction yield % =
Brewed Coffee[g] x TDS[%]
Coffee Grounds[g]
NB: TDS (mg/L) = 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑟𝑒𝑠𝑖𝑑𝑢𝑒(𝑚𝑔) ×1000
𝑚𝑙 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒

28. EXAMPLE
• 18 grams of coffee was placed in an espresso and this
brewed 36 grams of coffee from it. It is observed that 10%
of solids are dissolved from the grounds. Calculate the
extraction yield of this coffee grounds.
Assumption: 1 milliliter (ml) of water = 1 gram of water
• 𝐸𝑥𝑡𝑟𝑎𝑐𝑡𝑖𝑜𝑛 𝑦𝑖𝑒𝑙𝑑 = 36𝑔 𝑏𝑟𝑒𝑤𝑒𝑑 𝑐𝑜𝑓𝑓𝑒𝑒 × 10% 𝑇𝐷𝑆
18𝑔 (𝑐𝑜𝑓𝑓𝑒𝑒 𝑔𝑟𝑜𝑢𝑛𝑑𝑠)
= 20%

29. CONCLUSION
• Substance distribution between two liquids determines
its potential to be extracted.
• Extraction generally involves separation of elements.
• Solutes can be obtained by concentrating impurities.
• Solutes can form part of the solvent as a desired
solution.

30. REFERENCES
• Lewis, R. J. (2007). Liquid-Liquid Extraction. PreLab,
73–92.
https://doi.org/10.1002/9780470114735.hawley098
99
• Gamse, T. (n.d). Extraction. Department of chemical
engineering and environmental technology, Graz
university of technology.
• http://www.cst.ur.ac.rw/library/Food%20Science%20b
ooks/batch1/Food%20Processing%20Technology%20Pr

31. Thank
you