Chapter 4

TECHNICAL STUDY

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.

4.2 Coffee Roasting Process description

Schematic of coffee production plantR

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4.3 Decaffeinationthe 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.

Decaffeination ProcessGreen 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.

Decaffeination by supercritical CO2 method

Machineries and Equipments

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.

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.

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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

Cont…

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 RoasterUses natural

gas/LP lower operating

temperature rangemore uniform,

higher quality roast.

Are two types: direct fired and indirect fired

Depending on heat source, roasters are classified into two categories: Electric firedGas Fired

Typical coffee roaster

DestonerCooling Tray

Pneumatic Loader

Roasting Chamber

Control Panel

Roast Cart

Afterburner

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

DestonerWhy 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

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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

coffee grind influences coffee's flavor.

Grinder Types1. 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

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

S.NoMachinery and equipment

Purpose

1Green Bean Separator

To separate green coffee beans based on bean size

2Coffee Mixer (Blender)

To mix coffee from different origins in specific proportions so as to get a

consistent taste and flavor.

3 Coffee Roaster

To roast (‘cook’) green coffee beans in order to produces the characteristic flavor

of coffee by causing the green coffee beans to expand and to change in color,

taste, smell, and density.

4 Coffee GrinderTo breakdown roasted coffee beans so as to improve the extraction efficiency in

the preparation of the beverage.

5Automatic Packaging Machine

To seal and pack roasted or ground coffee. The storage conditions of roasted

coffee must ensure hygiene and prevent contamination of the product by

volatile substances, such as oxygen (which can cause oxidisation) and moisture

(which can increase the growth of mould).

6 Destoner

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.

List of major Machineries and Equipments

7Destoner Weighfill Packaging System

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.

8 Loader

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.

9 Afterburner/Oxidizer

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 bi-products of coffee roasting.

10 Blending Mixer

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