Dry processing and wet processing, Washed processing and Unwashed processing, Advantages and Disadvantages of Dry processing and wet processing, Advantages and Disadvantages of Washed processing and Unwashed processing

1. Dry processing and Wet
processing
Advantages and Disadvantages
Phạm Gia Huy – HCMIU- VNU
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2. |Content
Objective: Dry processing and Wet processing
Type of coffee used
Processing Steps
Summary: Advantage and Disadvantage
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3. |Objectives
Dry processing Wet processing
• Keep whole cherry for drying • Sort the coffee cherries
• Removal of the pulp and mucilage
from the coffee bean
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4. Dry processing Wet processing
Most Arabica in
Brazil
Robusta
Arabica
Coffee types |Robusta |Arabica
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5. |Dry processing and Wet processing
Havesting Seperating
Dry processing
Wet processing
CuringHullingSize grading
Sorting
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6. |Processing stages
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7. |Processing stages
Dry processing Wet processing
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8. Selective Harvesting Stripping
-Often used for wet processing
-Picking ripe cherries only
-Often used for dry processing
-Removing all the cherries present on a
branch irrespective of their degree of ripeness.
Harvesting|Selective Harvesting |Stripping
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9. Why do we have to harvest selectively ?
Harvesting|Selective Harvesting |Stripping
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10. Harvesting|Selective Harvesting |Stripping
| Selective
Harvesting
|Stripping
Advantage Disadvantage
-Substantial gains in drying time,
labor and space (sun drying) fuel
and energy consumption
(mechanical drying)
-Even roasting
-Good quality, good flavor
-Need trained worker
Time consuming ( manual
harvesting )
- Convenient where there is not
enough available labour
- Time saving
-Unpleasant or harsh flavor
-Ununiform cherry batch
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11. |Winnowing
- Leaves, stems and dust are removed
- Using air flow
|Sifting
- Heavy impurities smaller or bigger
than the cherries like sand, stones,
mud balls are removed
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12. |Floating
-Separate stones and cherries with different moisture contents
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13. |Floating
Separate stones and cherries with different moisture contents
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14. |Floating
-Problem: ripe and unripe cherries in the sinkers remains in mixture
Semi-dry processing: Separation of unripe and ripe cherries by letting the ripe
pass through a screen with long slotted holes, whereas the unripe cherries are
hard and cannot go through
Color Sorting: Using electronic device to scan color and remove undesired
cherries
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15. |Pulping
Separate the pulp from the coffee bean.
Arabica cherries are easier to pulp than Robusta cherries
Pectin layer
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16. |Pulping
Separate the pulp from the coffee bean.
Pulp is torn off by squeezing the
cherries in one of the following
ways:
• Between a pulping bar and a
rotating disk (disk pulper)
• Between a breast plate and
a rotating drum (drum
pulper)
• As they pass through the slots
of a screen (unripe cherry
separator and pulper, i.e.
screen pulper)
• Between a rotary drum and a
stationary screen case (Raoeng
pulper)
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17. -High power consumption
-High water consumption
-Physical damage concerns
-Use drum pulper
-Use dry pulper, water re-circulation
-Use screen pulpers
g
Pulping |Problem|Solution
|Problem |Solution
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18. Remove the residual part of the mesocarp (Mucilage)
Mucilage Removal |Objective
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19. Fermentation
-Caused by enzymes (pectinases
and pectase) which are natu-
rally present in coffee cherries.
-Dry and Wet fermentation
-Dry fermentation: Fast , but
require protection by a roof.
-Wet fermentation: Slower,
homogenous, not require
covering stuff
-Time: 6 to 72 h
-Accelerated by adding yeast
(Saccharomyces) or hot water.
-Parchment should be washed after
fermentation
Mucilage Removal |Fermentation |Mucilage remover
Figure 2.39 Outlets of
fermentation tanks.
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20. Mucilage remover
-Mechanical mucilage removers.
-Mucilage is removed by rub-
bing the beans against each
other and against the fixed and
mobile fingers as parchment
moves downwards by gravity.
-Water is injected to facilitate
washing and to help parchment
flow out of the machine.
-Integrated washer
Mucilage Removal |Fermentation |Mucilage remover
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21. Mucilage Removal |Fermentation |Mucilage remover
Fermentation Mucilage remover
-High labor requirements
-The consumption of huge amounts
of water
-Strictly controlled
-Weight loss concerns and the risk
of further quality deterioration
-Less labor requirements
-Less water consumption
-Does not require any special
control
-Avoids weight loss and the less
risk of further quality deterioration
-The same organoleptic features
as those that are naturally
fermented.
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22. Drying for both dry and wet processing
|Natural drying|Artificial drying
Natural drying
-Mostly used for dry processing
-Large areas are required
-Berries must be spread out ( 30-
40mm) to prevent fermentation
Dry processing
--Length of Drying – 3 to 4 weeks
-Final moisture content 12%
Wet processing
-Length of drying – 10 to 15 days
-Wet stage : 30-60% moisture content
-Hygroscopic stage <30%
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23. Drying for both dry and wet processing
|Natural drying|Artificial drying
Artificial drying
-Using hot air to dry the cherries
( dry processing) or parchment
(wet processing )
-Optimum temperature : 55-
60oC
-Fuel: wood, husk from
winnowing and sifting, gas
- Final moisture content :
moisture of 20 to 12%
-
Figure 2.26 Simple static dryer
-Some examples:
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24. Drying for both dry and wet processing
|Natural drying|Artificial drying
|Natural drying
|Artificial drying
Advantage Disadvantage
-Low cost
-Easy to carry out
-Independent to climate
condition
- Parameters can be controlled
-Can not control the temperature,
moisture,……
-Quality is not ensured ( overheat,
cracking,….)
-Weather dependent
-Need large areas
-Time consuming
-Risk of infection by microorganism
-Costly
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25. Summary: Advantage and Disadvantage
|Dry processing|Wet proccesing
|Dry processing
|Wet processing
-Low cost
-Easy to carry out
-Less or no water is required
- Parameters can be controlled
- -Higher quality and lower
defects
-Quality is not ensured ( overheat,
cracking,….) evenly among
parchments.
-Cherries are easy to be oxidized
-Costly
-Require mechanical equipment
-Large amount of water
Advantage Disadvantage
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26. |References
Wintgens, J. N. (2009). Coffee: growing, processing, sustainable
production. A guidebook for growers, processors, traders and
researchers. Wiley-Vch.
Clarke, R. J., & Macrae, R. (Eds.). (1988). Coffee: Technology (Vol.
2). Springer Science & Business Media.
Schwan, R. F., & Fleet, G. H. (Eds.). (2014). Cocoa and coffee
fermentations. CRC Press.
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27. Thank you for
your listening
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