1. Chapter 4
TECHNICAL STUDY

2. 4.1 Introduction

This chapter highlights processing steps as
well as important machineries and equipments
used along production line in coffee roasting .

coffee roasting process consists essentially of
cleaning, roasting, cooling, grinding, and
packaging operations.

main machineries and equipments along the
production line are vibrating screen, blender,
roaster, destoners, grinder, and the packing
machine.

3. ROAST BEAN
4.2 Coffee Roasting Process
description
Schematic of coffee production plant

5. 4.3 Decaffeination
the process of extracting caffeine from green
coffee beans prior to roasting.
 general decaffeination process includes
soaking green coffee beans in hot water
(700C -1000C) and then some sort of solvent
or activated carbon is used to extract/dissolve
the caffeine.
 Several methods of decaffeination are used
including supercritical carbon dioxide (CO 2)
extraction, water extraction, and solvent
extraction using oil (extracted from roasted
coffee), methylene chloride, or ethyl acetate
as a solvent.


6. Decaffeination Process
Green coffee beans (before roasting) are first soaked in water to
make them swell and allow the scCO2 to penetrate more
easily. It is also thought water may be needed to help free the
caffeine from chemical complexes in the bean.
ScCO2 is circulated for up to 10 hours through pre-soaked
beans in a high-pressure extraction chamber. In the second
vessel, water and the caffeine-rich carbon dioxide are passed
in opposite directions and the caffeine dissolves in the water.
The carbon dioxide is re-pressurised and re-used.
Caffeine is recovered from the water as a concentrated solution
using one of a range of processes, including reverse
osmosis. In reverse osmosis pressure is used to make
solvent pass through a semi-permeable membrane from high
to low concentration of solute, rather than the other way
round. This concentrates the caffeine further.

7. Decaffeination by supercritical
CO2 method

8. Machineries and Equipments

9. Green Bean Separator
Foreign matters in green
coffee:
sticks, rocks, dirt, lint,
strings, leafs, fibers, metallic
scraps, seed grains etc
 Why cleaning needed?
 To ensure a quality product,
 to eliminate hazards like bits
of combustible material that
may cause serious fires in
roasters.
 Some foreign materials may
also clog up conveyors and
piping that lead to reduction
in production efficiency.


Industrials coffee cleaning
process involves different
machines that sort the coffee
by density of bean and by
bean size.

10. Coffee Mixer/Blender
Why blending needed?

to have a consistency in quality, aroma, flavor etc,
Blender is hollow cylinder,
mounted horizontally.
Helical flanges inside blender
mix different grades of coffee
in few minutes.
dust or chaff loosened by
mixing is removed by an
exhaust system.
The blended coffee then goes
to holding bins, to feed
hoppers over roasters.

11. Roaster

Roasting determines
coffee’s final taste and
aroma

Roasters are horizontal
rotating drums that tumble
green coffee beans in
current of hot combustion
gases.
Operating Temp: 370°C 540°C
Roasting time: few minutes
to about 30 minutes
The more the coffee beans
are roasted the darker they
become and more bitter will
be the final taste



11

12. Cont…
Depending on heat source, roasters are classified into two
categories:
Electric fired
Gas Fired
Electric Fired
Roaster
 use halogen lamps
 faster starts to the
coffee roast cycle
 more control over
roast profile
 Safe from dangers
of fire
 No CO poisoning
Gas Fired Roaster
 Uses natural
gas/LP
 lower operating
temperature range
 more uniform,
higher quality
roast.
 Are two types:
direct fired and

13. Typical coffee roaster
Afterburner
Roasting
Chamber
ontrol Panel
Roast
Pneumatic
Loader
Cooling
Tray
Destoner

14. Cooling
Why needed?
 to avoid beans
from cooking
further at higher
temperatures
 Some machines
accomplish
cooling through
built in cooling fan
 Other use water to
quench beans

Cooling tray equipped with rotating arm
and blower

15. Destoner
Why needed?
To remove stones,
metal fragments, and
other waste not
removed during
initial screening
Working principle:
airflow is regulated to
lift
roasted beans and
leave the bits of rock
and metal behind


16. Grinder
Why neded?
to improve extraction efficiency
& aroma retention in
preparation of beverage






Grinding texture depends on
the coffee-making method:
fine- for the espresso coffee
machine
medium- for the moka pot
coarse- for the filter coffee
machine
more coarse- for the coffee
pot
16

17. coffee grind influences
coffee's flavor.
Grinder Types
1. Blade Grinder

 economical

Grind controlled by time blade
runs
But difficult to get
consistent granule size
2. Burr Grinder
 modern upgrade to the
millstone grinding
method
 consistent grind
 Crushes rather than
cutting


18. Packaging
To retain aroma
Roasted coffee is
packed either as
whole beans or as
ground coffee.
 Common forms of
packs :
 at atmospheric
pressure,
 vacuum packs and
 gas-filled vacuum
packs


19. List of major Machineries and Equipments
S.No
1
2
Machinery and
equipment
Green Bean
Separator
Coffee Mixer
(Blender)
Purpose
To separate green coffee beans based on bean size
To mix coffee from different origins in specific proportions so as to get a
consistent taste and flavor.
To roast (‘cook’) green coffee beans in order to produces the characteristic
3
Coffee Roaster
flavor of coffee by causing the green coffee beans to expand and to change in
color, taste, smell, and density.
4
Coffee Grinder
To breakdown roasted coffee beans so as to improve the extraction efficiency in
the preparation of the beverage.
To seal and pack roasted or ground coffee. The storage conditions of roasted
5
6
Automatic Packaging coffee must ensure hygiene and prevent contamination of the product by
Machine
volatile substances, such as oxygen (which can cause oxidisation) and moisture
Destoner
(which can increase the growth of mould).
This is used to remove the foreign debris (i.e. stones, buttons, sticks, etc.) from
coffee after it is roasted. The destoner is attached to the cooling bin chute,
separates the coffee from the foreign debris and via an "elephant trunk"
transports the roasted coffee to a holding silo.

20. 7
8
9
10
Destoner Weighfill
Packaging System
Loader
Afterburner/Oxidizer
Blending Mixer
This combines the destoner and a semi-automatic packaging unit. The
packaging unit allows you to take either whole bean or ground coffee, weigh
and dispense the proper amount into your coffee bags. Bag filling however is
a manual operation via a foot pedal to release the pre-weighed amount
programmed into the scale.
The Loader transports the green coffee from a loading station that is about
knee/thigh height to the roaster's funnel. It also saves time between
batches. Highly recommended with roasters starting at 12 kilos and virtually
required on anything larger than a 45 kilo roaster. There are three different
types of loaders namely, pneumatic loaders, Mechanical (bucket) feeder /
loader, and screw-type (worm) loader.
This is pollution abatement equipment used to treat the effluents from the
coffee roaster. Its purpose is to eliminate smoke, odor, and to reduce the
total amount of emissions released into the atmosphere to an acceptable
level. Smoke, odor, and various chemical compounds that are natural biproducts of coffee roasting.
A drum style piece of equipment that allows you to blend varietals
throughout with minimal bean breakage. Typically, this is sized based upon
the following:
Full kilo batch size of roaster X maximum number of varietals in
the blend