Coffea arabica

Coffee

Introduction

• Coffea (coffee) is a large genus

(containing more than 90 species)

of flowering plants in the family

Rubiaceae

• They are shrubs or small trees,

native to subtropical Africa and

southern Asia. Seed of several

species are the source of the

beverage coffee

Introduction

• The coffee plant is a woody perennial evergreen dicotyledon and because it grows to a relatively large height, it is more accurately described as a coffee tree.

• It has a main vertical trunk (orthotropic) and primary, secondary, and tertiary horizontal branches (plagiotropic).

• (What are plant parts, e.g. roots that grow into the soil called?)

Introduction

• The seeds are called “beans” in the

trade. Coffee beans are widely

cultivated in tropical countries in

plantations for both local

consumption and export to

temperate countries. Coffee ranks

as one of the world’s major

commodity crops and is the major

export product of some countries.

Introduction

• When grown in the tropics coffee is a vigorous bush or small tree easily grown to a height of 3-3.5m. It is capable of withstanding severe pruning. It cannot be grown where there is a winter frost. Bushes grow best at the high elevations.

• To produce a maximum yield of coffee berries (800-1400 kg/ha), the plants need substantial amounts of water and fertilizer.

Introduction

• Calcium carbonate and other lime minerals are sometimes used to reduce acidity in the soil, which can occur due tot run-off minerals from the soil in mountainous areas.

• The caffeine content in the coffee “beans” is a natural defense, the toxic substance repelling many creatures that would otherwise eat the seeds, as with nicotine in the tobacco leaves.

Introduction

• The coffee tree requires a mean temperature of 19-25℃. Thus, the coffee tree is a tropical plant.

• (it is not a coincidence that coffee and humans thrive in the same temperature. Our original home is the same – Africa . It is quite possible that Eve (Hawa) and her contemporaries (about 2.8 million years ago) munched coffee beans for pleasure)

Introduction

• The coffee plant cannot stand frost

but does not die from an occasional

cold night. It needs lots of water

requiring annual rainfall of

1500mm. Coffee plantations are

normally situated in the altitude

range of 300-2000m around the

Equator.

Introduction

• There are several species of coffee

that may be grown for the beans,

but the Coffea arabica is the

considered to have the best quality.

• The other species (especially

Coffea canephora (var. robusta))

are grown on the land unsuitable

for the Coffea arabica

Introduction

• The tree produces red or purple fruits (drupes), which contain two seeds (the “coffee beans”, although not true beans).

• In about 5-20% of any crop of coffee cherries, the cherry will contain only a single bean (seed), rather than the two usually found. This called a ‘peaberry’, which is smaller and rounder than a normal coffee bean.

• (Check on this during practical class!)

Introduction

• Some claim that peaberries have a

different flavor profile in the cup,

while others dispute this.

• Either way, the ‘peaberry’ is often

removed from the yield and either

sold separately (such as in New

Guinea peaberry), or discarded.

Introduction

• The coffee tree will grow fruits after 3-5 years, for about 50-60 years (although up to 100 years is possible). The blossom of the coffee is similar to jasmine in color and smell. The fruit takes about nine months to ripen.

• Worldwide, an estimate of 15 billion coffee trees are growing 100,000km2 of land.

Shade grown coffee

• In its natural environment, coffee grows under the shade. Most coffee is produced on full-sun plantations, some of which were prepared through deforestation.

• Shade grown coffee naturally mulches its environment, lives twice as long as sun grown varieties, and depletes less of the soil’s resources.

Shade grown coffee

• Shade grown coffee is also believed by some to be of higher quality than sun grown varieties, as the cherries produced by the coffee plants under the shade are not as large as commercial varieties.

• Some believe that this smaller cherry concentrates the flavors of the cherry into the seed (bean) itself

• (Contrast between cherry and bean?)

Shade grown coffee

• Shade grown coffee is associated

with environmentally friendly

ecosystems that provide a wider

variety and number of migratory

birds than those of sun grown

coffee farms

Botanical description

• The first coffee plant of economic importance was Coffea arabica. It grows to the height of 7-8 m but the cultivated plants are cut to the height of 2-4 m to get more width. The leaves of the coffee are 10-15 cm long ellipsoids, lustrous dark green with lighter underside. The flowers emerge from the branches together with he leaves.

Botanical description

• The white coffee flower has five petals and a scent resembling that of jasmine. The flowers last only 2-3 days. The coffee berries are cherry-sized and green at first, turning dark red later on. The ripening takes 8 months.

• The coffee tree starts flowering at 2-4 years old and it can simultaneously have flowers and berries in all stages of development.

Botanical description

• A coffee tree can be harvested

from the 5th year and harvesting

can occur many times throughout

the year. At 25th years the tree

becomes old but may live to be a

wiry centenarian (100 years old)

Difference Between Arabica

& Robusta Coffee Beans

• While there are several different coffee species, 2 main species are cultivated today.

• Coffea arabica, known as the Arabica coffee, accounts for 75-80% of the world’s production

• Coffea canephora, known as Robusta coffee, accounts about 20% and differs from the Arabica coffees in terms of taste.

Difference Between Arabica

& Robusta Coffee Beans

• While Robusta coffee are ore robust than the Arabica plants, but its beans produces an inferior tasting beverage with a higher caffeine content.

• Both the Robusta & Arabica coffee plant can grow to heights of 10 m if not pruned, but the coffee plant is normally maintain at a height reasonable for easy harvesting

Coffee Plant Growth and

Development

• 3-4 years after the coffee is

planted, sweetly smelling flowers

grown in clusters in the axils of the

coffee leaves. Fruit is produced

only in the new tissue.

• The Coffea arabica plant is self-

pollinating, whereas the Robusta

coffee plant depends on cross

pollination.

Coffee Plant Growth and

Development

• About 6-8 weeks after each coffee flower is fertilized, cell division occurs and the coffee fruit remains as a pin head for a period that is dependent upon the climate. The ovaries will then develop into drupes in a rapid growth period hat takes about 15 weeks after flowering.

• During this time the integument takes on the shape of the final coffee bean. After the rapid growth period the integument and parchment are fully grown and will not increase in size.

Coffee Plant Growth and

Development

• The endosperm remains small until about 12 weeks after flowering. At this time it will suppress, consume, and replace the integument. The remnants of the integument are what make up the silver skin. The endosperm will have completely filled the cavity made by the integument 19 weeks after flowering. The endosperm is now white and moist, but will gain dry matter during the next several months.

Coffee Plant Root System

• The roots of the coffee tree can extend 20-25km in total length and the absorbing surface of a tree ranges from 400-500m2. There are main vertical roots, tap roots, and lateral roots which grow parallel to the ground. The tap roots extend no further than 30-45cm below the soil surface.

• 4-8 axial roots may be encountered which often originate horizontally but point downward. The lateral roots can extend 2 m from the trunk.

Coffee Leaves

• The elliptical leaves of the coffee tree are shiny, dark green and waxy. The coffee bean leaf area index is between 7-8 for a high-yielding coffee. The coffee plant has become a major source of oxygen in much of the world. Each hectare of coffee produces 86 lbs of oxygen per day, which is about half the production of the same area in a rain forest

Coffee Plant Propagation

• For the propagation of Arabica coffee, ripe red cherries are collected, pulped, and the mucilage is removed by fermentation. The freshly picked coffee seeds (typically referred to as beans) can either be planted immediately or dried for later use

• Coffee drying takes place on wire mesh rays in the shade. Correctly storing coffee beans is essential for a longer seed life. Dried coffee seeds can be used up to a year or more if properly stored.

Coffee Bean Germination

Process

• There are 2 basic methods for the

germination of seeds:

• In one method, coffee seeds are

pre-germinated by spreading on a

sand bed and covering with moist

burlap bag sacks (karung guni) or

straw. The seeds are watched

closely and removed as soon as

radicals emerge.

Coffee Bean Germination

Process

• An alternative method of

germinating coffee beans is to mix

the seeds with moist vermiculite or

expanded polystyrene and keep in

the polystyrene bag

• Coffee seedlings are grown in

nursery beds or polybags and are

planted in the coffee fields when

they reach 20-40 cm

Growing Coffee Seeds in

Nursery Beds

• Once pre-geminated, the coffee seedlings are planted in nursery beds containing soil consisting of well rotted cattle manure (10-20 l/m) and phosphate fertilizer (100 g/m)

• Nursery beds should built to be 1 m wide and 50 cm deep and seedlings are spaced between 12-15cm apart (for 20 cm tall plants) or 20 cm apart (for 30-40 cm tall plants)

• The nursery beds are shaded 50% for the first couple months. Shading is reduced slowly and completely removed the last 2 months before planting coffee seedlings

Growing Coffee Seeds in

Polybags

• Polybags, are commonly used and

filled with a mixture of top soil, well

rotted cattle manure, course sand,

gravel, coffee pulp, and coffee husks

• A ratio of 3 parts top soil to 1 part

course sand and 1 part cattle manure

is often used. A top dressing of

nitrogen is applied by applying 20 g

urea in 5 liter of water per meter of

bed

Harvesting Coffee Beans

• Coffee Harvesting Times

• Each year coffee is harvested

during the dry season when the

coffee cherries are bright red,

glossy, and firm

• About 12-20 kg of export ready

coffee will be produced from every

100 kg of coffee cherries

harvested.

How to Harvest Coffee

Beans

• Ripe cherries are either harvested by hand, stripped from the tree with both unripe and overripe beans, or all the coffee beans are collected using a harvesting machine

• These processes are called selective picking, stripping and mechanical harvesting respectively. To maximize the amount of ripe coffee harvested, it is necessary to selectively pick the ripe coffee beans from the tree by hand and leave behind unripe, green beans to be harvested at a later time