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Dry processing and wet processing of Coffee - Washed processing and Unwashed processing of Coffee
- 1. Dry processing and Wet processing Advantages and Disadvantages Phạm Gia Huy – HCMIU- VNU 1
- 2. |Content Objective: Dry processing and Wet processing Type of coffee used Processing Steps Summary: Advantage and Disadvantage 2
- 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 3
- 4. Dry processing Wet processing Most Arabica in Brazil Robusta Arabica Coffee types |Robusta |Arabica 4
- 5. |Dry processing and Wet processing Havesting Seperating Dry processing Wet processing CuringHullingSize grading Sorting 5
- 7. |Processing stages Dry processing Wet processing 7
- 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 8
- 9. Why do we have to harvest selectively ? Harvesting|Selective Harvesting |Stripping 9
- 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 10
- 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 11
- 12. |Floating -Separate stones and cherries with different moisture contents 12
- 13. |Floating Separate stones and cherries with different moisture contents 13
- 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 14
- 15. |Pulping Separate the pulp from the coffee bean. Arabica cherries are easier to pulp than Robusta cherries Pectin layer 15
- 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) 16
- 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 17
- 18. Remove the residual part of the mesocarp (Mucilage) Mucilage Removal |Objective 18
- 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. 19
- 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 20
- 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. 21
- 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% 22
- 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: 23
- 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 24
- 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 25
- 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. 26
- 27. Thank you for your listening 27