LECTURE 2
COCOA
(Theobroma cacao, Linn.)
 Outlines:
The cocoa plant and its distribution
Cultivated species of cocoa
Botany and Agronomy of cacao
Insect and disease pests of cocoa
Harvesting and post-harvest handling of cocoa.
Cocoa Plant And Its Distribution
Cocoa has currently been reclassified as a member
of Malvaceae instead of Sterculiaceae families.
The crop originated from the foot of the Andes in
the Upper reaches of Amazon river.
Theobroma contains about 22 species, all locally
used for refreshing beverages, cooked dishes and
jellies.
Brief History Of Cocoa Cultivation
 Evidently, the Maya Indians firstly cultivated cocoa in Mesoamerica
over 2000 years ago, the beans being consumed and as currency.
 The Aztec Indians collected high levies / taxes in form of cocoa beans
“cacahoatl” – the name cocoa.
 The tribes attributed divine origin to cacao through a god
“Quetzacoatl” (the plumed serpent).
 Its beverage is referred to as xocolatl – hence the name chocolate.
 The sacredness of the crop made Linnaeus to name cultivated cocoa
as Theobroma cacao – “food of gods”
 Cocoa plantations were first established at Martinique in 1660 and
Brazil in 1754.
Introductions Of Cocoa Plantations
 The Spaniards, Dutch, and Portuguese introduced cocoa to their overseas territories.
 By 1874, cocoa got to Nigeria and Ghana from Fernando Po (now Malabo).
 By 1887, cocoa established in Ibadan - seedlings from Botanical Garden, Ebute-Meta Lagos.
 Cocoa got to West African peasant farmers through:
 Trading companies
 Missionaries
 Soldiers
 Chiefs
 Farmers associations
 Cooperatives
 Departments of Agriculture
 West African Cocoa Research Institute (WACRI) (defunct)
 Cocoa Research Institute of Ghana (CRIG)
 Cocoa Research Institute of Nigeria (CRIN)
Cultivated Species Of Cocoa
The Criollo, The Amazonian forastero and The Trinitario
The Criollo group:










Cultivated in Venezuela, Nicaragua, Mexico, Colombia and Guatemala.
Most anciently cultivated.
Poor cacao vigour.
High susceptibity to diseases.
Slender cacao with green pods.
Watty, thin and soft pericarp.
Lignified mesocarp.
Plump beans, embedded in pulpy mucilage with white cotyledons.
Fermented and dried cotyledons are light brown.
Excellent bean flavour.
The Amazonian Forastero Group
 Cultivated in Brazil, West Africa, Central America, South East Asia and
Caribbean Island.
 Staminodes with purple pigments.
 Green and varying shapes of cocoa pods.
 Thick pericarp and very woody mesocarp.
 More or less flat beans
 Dark purple cotyledons
 Relatively bitter flavour and acid taste.
 West African Amelonado belongs to this group.
The Trinitario Group
 Believed to evolve from a cross between Forastero and Criollo groups.
 Highly heterogeneous group.
 Selected from Trinidad, hence the name Trinitario.
 Cultivated in Mexico, Central America, Trinidad, Colombia, Venezuela and
some African and South East Asian countries.
 Botanical traits are intermediate between Forastero and criollo groups.
 Bean flavour is also intermediate between Forastero and Criollo groups.
Botany And Agronomy of Cocoa
 Cocoa is cauliflorous and semi-desidous.
 Height, leaf area, branches and canopy spread of cacao determined by planting
spacing.
 When grown from seeds cacao attains anthesis between 24 and 36 MAT and fully
matured at about 10 YAT.
 A well managed cocoa continue to be economic for over 50 years.
 Dimorphous root: Orthotropic taproot and Plagiotropic lateral root.
 3 to 4 DAS cocoa seeds start germinating through the emergence of whitish taproot
and lateral roots.
 10 YAT, taproot well developed, (1.5m) with a mass of root hairs covering 5 – 6 m
around cacao.
Botany and Agronomy of Cocoa Contd.
 Stem growth is orthotropic holding the leaves.
 The orthotropic growth is intermittently interrupted by the degeneration of the
terminal bud, below which branches develop – Jorquette.
 Thus, there can be 1st and 2nd jorquette which form the framework of cacao.
 pruning starts at the level of 2nd jorquette through the removal of excessive
orthotropic shoots – chupons.
 Growth in cacao is discontinuous and in successive growth phases – flushes.
 Each flush results in the production of 5 – 6 alternate leaves with short petioles
and 4 – 5 flushes occur in a year.
 The young pigmented leaves may be pale-green, pink or deep blue depending on
variety, mature leaves are dark-green with 7 – 9cm petiole length.
 Flowering is marked indicator of successful field establishment, and anthesis may
be attained in 2 years in improved varieties and it may take a longer period in
unimproved varieties of cocoa.
Botany and Agronomy of Cocoa Contd.
 Flowering depends on favourable physiological, soil and climatic conditions.
 In mature cocoa, fruiting occurs twice a year in the tropics – dry (November /
December) and rainy (June / July) seasons.
 Cocoa is an out-breeder and an entomophilous plant. Pollinators – midges, ants,
thrips and leaf hoppers.
 Within 36 hours after pollination, fertilization occurs leading to the formation of a
young okra-sized pod – cherelle.
 Cherelle continues to develop by longitudinal elongation and girth increase to
become a fully-grown mature cocoa pod.
 It takes up to 150 – 180 days between fertilization and pod maturation. Ripe pods
are light-yellow in colour and thus ready for harvesting.
 A cocoa pod contains 30 – 40 beans on the average and 50 – 60 pods needed to
plant an hectare of cocoa spaced 3m x 3m.
Figure 1: Developing cocoa pods (A Cherelle and a pod).
Site Selection
 2 major factors must be considered while selecting a site for cocoa plantations
establishment: climatic and soil factors.
 Climatic factors:
 Cocoa is a low altitude crop, performing best within 100 – 300m above sea level (asl). It
can be grown at 700m asl.
 Cocoa is sensitive to water deficiency particularly when in competition with other plants
(shade plants, wind breaks and weeds) and also to excess water in the soil.
 It thrives within wide rainfall ranges of 1000 – 3000mm or more per year.
 The site should enjoy an evenly distributed rainfall of 150mm/month and at least for 9
months.
 With provision of irrigation and limited occurrence of dry winds, cocoa can be cultivated
completely without rain.
 Cocoa responds to temperature variations: the maximum being 30 -320C while the
minimum is 18 – 210C. At a temperature lower than 100C, cacao becomes damaged.
Climatic factors contd.
 Cocoa enjoys high relative humidity of between of between 70 – 80%,
above which disease infection occurs and below which (obtainable in
the dry season) cocoa leaves become limp and droop, thus causing
severe defoliation.
 The deleterious effects of drying and strong winds like harmattan (in
West Africa) is reduced through wind breaks, shade trees or even by
high density planting. This is because cacao rooting is superficial thus
offering little resistance to strong and drying winds.
 At early stage of cocoa plantation establishment, temporary shading is
indispensable. A temporary shading / a nurse plant should meet the
following conditions :
• Easy establishment
•
•
•
•
•
Provision of good overhead shade throughout the dry season
Little competition wit young cocoa transplants for moisture and nutrients
Should not serve as alternative host to cocoa disease and insect pests
Easy removal when no longer needed
Its removal should not pose any threat to the plantation.
Soil Factors
The soil on which cocoa will be planted should satisfy the following
conditions:
 The soil must be at least 1.5 m deep.
 The soil structure must be as homogenous as possible.
 It must have good water-retaining capacity, well-drained and well
aerated.
 Sandy soil is not suitable except it contains high organic matter and not
under prolonged hot and dry season.
 It must be of acceptable chemical properties.
 It must have pH of between 5 and 8 – optimum being 6.5.
 High organic matter content in the topsoil is essential for good growth
and high productivity.
Raising cocoa seedlings in the nursery.
 Cocoa beans readily germinate when sown and lose viability easily on
extraction from pods within 5 – t days unless specially treated with moist
fine sand or sawdust. They retain viability for 4 weeks inside pod after
harvesting.
 Nursery establishment is done between December and February, in order
to allow the seedlings a period of 4 months under intensive care.
 Seedlings bags of 20/25cm x 12cm are used for raising the seedlings. The
are filled with sifted top soil, heavily watered the previous day and arranged
under a shade in the nursery.
 The beans are sown at seeding rate of 2 per bag and later thinned to 1 per
bag after germination. Daily light watering till germination at 7 -10 days.
Adequate watering follows.
 Regularly examine for the incidence of disease and insect pests. Seedlings
that show symptoms of bacterial or viral infections must be burnt outside
the plot. Fungal and insect attacks are chemically controlled.
Transplanting Of Cocoa Seedlings Into The Field.
 In preparing the land for cocoa transplanting, some trees are left
unfelled to act as windbreaks (upper storey).
 The field should have been planted to a temporary shade of
plantain suckers the previous year or simultaneously with cocoa
seedlings (middle storey) at same planting density with cocoa
(100% shade density).
 Both upper and middle storey are to provide conducive
environments for cocoa transplants when eventually transplanted.
 Prior to transplanting, the seedlings should undergo hardening –
gradual exposure of the seedlings to environmental conditions
obtainable on the field, especially, light.
 Transplanting of cocoa seedlings is carried out when the rains are
steady.
Transplanting contd.
Vigorous seedlings are transplanted with ball-of-earth at
the age of 4 – 5 months. Bare-rooted seedlings are treated
with clay slurry or artificial polymer before transplanting.
Transplanting of overgrown seedlings, seedlings in flush or
seedlings with broken taproot results in high seedlings
mortality / low survival percentage after transplanting.
Alternatively, cocoa can be transplanted into a selectively
thinned forest or along traces cut through regrown forests.
The crop is transplanted at a spacing of 3 m x 3 m giving a
plating density of 1,111 plants/ha. High density planting in
cocoa is practicable.
Vegetative / Clonal Propagation in Cocoa
 Conventionally, cocoa is clonally propagated through budding, grafting, cutting,
marcutting (air layering) and soil layering. Cutting being the most popular method.
 In rooting stem cuttings, the following precautions should be adhered to:
 Fan branches should be taken for rooting
 Cuttings should be taken in the early hours of the day and setting done same
day.
 The stem base of the cutting should not be thicker than the stem of a lead
pencil.
 Set cuttings in an humidified chamber made of transparent polythene sheet.
 A fine jet sprayer should be used for watering to saturate the air inside the
chamber.
 After successful rooting (ramets) cuttings should be hardened off and
subsequently kept in the nursery till transplanting.
 The shade provided should be uniform
 If sawdust should be used, it should have been partially weathered – 3 months
in the dumping site.
 The hardened off ramets are transplanted into the field under a combined
temporary and permanent shading.
Cocoa Disease Pest
 Black pod / Phytophtora pod rot:
 Most serious disease of cocoa in West Africa, especially, Nigeria and Cameroon.
 Caused by Phytophtora megakarya, during the rainy season when the relative humidity
is higher than 80%.
 The causative organism had hitherto been P. palmivora, but the strains had been
brought to a low level.
 Damage characteristics include:
 rotting of pods which begins with small brown spot with irregular water soaked
margins.
 Tiny whitish downy mould, at the centre of the brown spot
 Enlargement of brown spot and downy mould until the entire pod is covered
 The beans contained become rotted. This may take up to 18 days in matured and
normal-sized pods.
 Phytophtora pod-rot is different from cherelle wilt, which is a physiological disorder.
 Under severe attacks, especially when there is long periods of rains cool weather,
chupons, seedlings and leaves are attacked and killed.
 The spread is through and infected pod by rain drops.
Figure 2: A cocoa pod infected by P. megakarya.
Control of Phytophtora pod rot
The incidence of the disease is preferably prevented
in the cocoa plantation through:
Frequent removal of weeds / other plants that can
increase the relative humidity of the plantation.
Removal and burning of the infected cocoa pods.
Application of the copper-based fungicides to control
the incidence.
The use of resistant / tolerant varieties.
Swollen shoot
 A viral disease which may not appear till 6 months after cacao is infected.
 Symptom appears at the shoots produced after infection.
 Characteristics of infection:
 A network of red vein banding
 Vein clearing
 Chlorosis
 Swellings of the stems, fan branches, chupons and seedlings
 Infected pods become rounded and small with some mottling.
 Infected cocoa seedlings have reduced plant height, stem diameter, number of
leaves, number of roots and root length.
The disease does not affect stem / root ratio.
Control measures:
 Removal and burning of the infected cacao
 Breeding programme has put the disease under check through the introduction
of the resistant / varieties.
Cherelle wilt
 This is a physiological problem affecting only cherelles – 10cm long or less.
 The cherelles suddenly wilt and die. Dead cherelles are seen hanging on
cacao.
 It results in 40 – 50% loss of the total pod set.
 It is measure by which cacao regulates the number of pods it is able to carry
to maturity – physiological cherelle wilt.
Charcoal Rot:
 This is a fungal disease caused by Botryodiplodia theobromae.
 It is a weak pathogen. It only infects wounded, overripe or weakened cocoa
pods.
Major insect pests of cocoa
Cocoa Mirids (Capsids or Jori-jori):
 Most serious insect pest of cocoa in West Africa.
 The insects attack both young and mature cacao.
 Cocoa mirids are of 3 types:

(1) Sahlbergella singularis (Brown mirids): Feed on pods, chupons, soft
and hard wood branches and tips.

(2) Distantiella theobromae (Brown mirids): Feed on pods, chupons
and fresh green shoots especially, on young plants. Mainly found in IfeOndo-Akure area of Nigeria.

(3) Helopeltis bergrothi (Cacao mosquito): Feed on pods.
 Mirids feed at night and rest during the day at the axils of leaves and
behind the pods.
 Mirids are vectors of weak fungal pathogens especially die-back
infections.
Mealy bugs
 Mealy bugs are vectors of viral disease especially swollen shoot.
 Control methods:
 Chemical control method is effective, but the hard cuticle of the insect
prevents penetration of the insecticide.
 Use of systemic insecticide through cacao results in toxicity of cocoa.
 Chemically killing the ants that provide shelter for mealy bugs is found
effective.
 Exposure of mealy bugs following killing of the ants results in the reduction in
numbers of the mealy bugs.
 Biological control method through the use of mealy bug predators has not
been effective.
 Spraying of a fungus (Cephalosporium sp.) cultured in rice and crushed in water
is very effective against these mealy bugs.
Harvesting and post-harvest handling of cocoa
 It takes 150 – 180 days between pollination and ripening in cocoa, depending on
varieties.
 Only mature and ripe pods are harvested, diseased and damaged pods must not be
processed for markets.
 Harvesting should be regular and frequent in order to avoid damage due to overripening, disease and animals.
 In a case of irregular / delayed harvesting, the beans start germinating in-situ, such
cocoa is unsuitable for marketing.
 Harvesting of unripe cocoa pods results in poor-quality beans with low aromatic
compounds after fermentation.
 During harvesting flower cushion must not be damaged, if damaged, subsequent years’
harvests will be reduced.
 Cocoa pods must not be pulled off in order to avoid any damage to flower cushions.
Harvesting contd.
 In West Africa, there 2 cocoa seasons:
 Main crop season – September to March
 Light crop season – April to August
 Harvesting tools include:
 Sharp cutlass, for removing pods within easy reach.
 A sharp knife with short handle, for removing pods well above ground level.
 A sharp knife attached to a long pole (go-to-hell) for plucking pods at the topmost part of cacao.
 A basket or other container for packing pods.
Breaking / opening of cocoa pods:
 Never use a cutlass. Use a blunt object such as a stone or a thick piece of
wood for the breaking. This is to avoid damage to cocoa beans.
 Extracted beans with mucilaginous pulp are collected in a clean container
for fermentation.
Preparation of Commercial Cocoa
• In order to be sold as cocoa beans, the fresh cocoa removed from
pods have to undergo two very important processes – Fermentation
and Drying: The main aim of which include:
• To remove the mucilaginous pulp which surrounds the beans.
• To cause the death of the embryo and consequently prevents it from
germinating.
• To bring about complicated biochemical changes inside the
cotyledons, leading to a reduction in the bitterness and astringency
thus enabling the precursors of the chocolate flavour to develop.
• Finally, to reduce the water content of the fermented beans from
approximately 60% to 6 – 7%, in order to block the enzymatic
reactions and to enable the commercial product to be stored safely,
free from pests and diseases.
Fermentation
 Fermentation in cocoa is a process by which mucilaginous pulp surrounding the
beans is removed under the gradual influence of heat and pressure for the purpose
of removing the beans’ bitter taste and the development of acceptable bean
flavour and colour.
 It is necessary to ferment cocoa beans in order to fulfill the following conditions:
 To get the proper taste, colour and flavour associated with cocoa products.
 To kill the embryo and stop germination.
 To remove pulp/mucilage so that the beans may dry properly.
 To loosen the skin from the cotyledon thereby allowing easy and proper deshelling during processing.
 Cocoa is fermented by different methods of fermentation which include:
 Heap fermentation
 Basket fermentation
 Sweat box fermentation
 Tray fermentation.
Heap Fermentation
 Wooden base with perforated banana/plantain leaves.
 Fresh cocoa beans are piled on the platform until a heap of 60
– 90 cm high is made.
 The heap is covered with the leaves again and weigh down
with logs of wood in order to retain the heat.
 The heap is thoroughly turned on the 3rd and 5th days with a
wooden spade or hand.
 The mixing should be fast in order to avoid heat losses.
 The cocoa beans are fully fermented and ready for drying on
the 7th day.
Basket Fermentation
 Woven baskets lined with perforated banana / plantain leaves
to facilitate drainage of the sweating.
 The baskets are placed on a wooden raised platform to aid
further drainage.
 After being filled with cocoa beans, the baskets are tightly
covered with banana / plantain leaves again and pressed with
stones / wooden logs.
 Turning into another basket is done on the 3rd and 5th days.
 On the 7th day, fermentation completes.
Sweat Box Fermentation
 An improved method employed in large cocoa plantations.
 Three wooden boxes (90 x 90 x 90 cm each / 120 x 120 x 120 cm) each, perforated
at the bottom are used.
 One side of the box should be removable and no lid is necessary.
 The boxes are placed on raised platforms for aeration and drainage.
 This method requires a ventilated and roofed building with adequate drainage
system against rains.
 The boxes are arranged in steps on top of one another.
 The fresh beans are placed on the top-most box, covered with sufficient
banana/plantain leaves and sacks and pressed with stones / wood.
 The beans from the top-most box are turned into the middle and last boxes on the
3rd and 5th days respectively and covered as before.
 On the 7th day the beans are properly fermented and ready for drying.
Tray Fermentation
 An efficient and standard method of fermentation in a number of cocoa countries.
 The bottom of the tray is covered with slatted mat made from palm frond midribs.
 The 4 sides of the tray (75 x 75 x 10 cm) are made of strong wood.
 The trays are filled with the wet beans to a desired level.
 The first tray is placed on a raised wooden platform to facilitate aeration and
drainage.
 The number of the trays used depends on the volume of the cocoa beans, but 10 or
more trays could be stacked upon one another to a convenient height for handling.
 The wet beans, when loaded into the trays are covered with banana / plantain
leaves and sacks to retain the heat.
 The beans are properly fermented on the 4th day of fermentation and are ready for
drying.
 The advantages of this method are as follows:




It requires far less labour compared to other methods.
The average cost of a tray is not much and a try can be used for more than 2 years.
It is fast, only 4 days required to complete fermentation.
No mixing of beans required and good and well-fermented cocoa are obtained.
Factors Affecting Fermentation of Commercial Cocoa.













The degree of ripeness of cocoa pods.
Healthiness of cocoa pods.
Types of cocoa: Criollos ferment at a shorter periods compared to Forasteros and Trinitarios.
Climatic and seasonal variations:
Low temperature of high altitude (800 m asl) slows the rate of fermentation.
The weight of pulp and sugars per bean depend on growing conditions.
Bean has limited amount of pulp during the dry season.
Quantity of cocoa:
A minimum quantity of about 70 – 90 kg of fresh bean is needed per fermentation unit in
order to have a satisfactory fermentation.
Duration of fermentation:
A complete fermentation gives the bean a uniform brown colouration.
Inadequately fermented cocoa bean has purple colour and this gives a bitter and astringent
product.
An excessively long fermented cocoa bean runs the serious risk of having a very bad taste
due to the commencement of putrid fermentation.
Drying.
 The aim of drying is:
 to reduce the water content of fermented cocoa beans from about 60 % to 8 %.
 to ensure that cocoa is kept under good conditions for storage and transportation.
 If drying is slow, mould may develop.
 If drying is too rapid, oxidation may be prevented, acetic acid may be retained in the
cotyledon resulting in excessive acidity of the cocoa beans.
 Flat beans, germinated beans and broken beans as well as foreign bodies must be
removed.
 Methods of drying.






Sun-drying
Drying autobus
Movable roof dryer.
Simple dryers
Mechanical dryers
Automated workshops.
 Test for dryness.
 A well-dried cocoa bean will crack when squeezed between the fingers.
 Cut through the sample beans with a knife, if properly dried, the cotyledon will separate
easily.
• Grading of cocoa.
– Grade 1 cocoa: less than 3 % slaty, mouldy and defective beans each.
– Grade 2 cocoa: less than 5 %, 4 % and 5 % slaty, mouldy and defective beans
respectively.
– The international standards state that the net weight of a cocoa bag must be
62.5 kg, (16 bags makes a ton).
• Cleaning and bagging of cocoa.
– Sorting and elimination of flat, broken, germinated beans and other impurities.
– The beans are packed in jute bags.
– Polythene bags must not be used for bagging cocoa.
• Storage of commercial cocoa.
– The international standards stipulate the following conditions.
– The ambient humidity must not exceed 70 %.
– The bags must be stored at least 7 cm above the ground in order to allow air
circulation.
– There must be at least a passage of 60 cm between the walls and the bags and
between bags of different types of cocoa.
– Disinfect by fumigation. Protection against rodents and other pests must be
carried out as and when due.
– Steps must be taken to avoid contamination by odour, off-flavours or dust.
– Periodic checking of the moisture content of each lots must be carried out.
Economic Importance Of Cocoa.


















Beverages (not tea)
Foreign exchange earnings.
Black soaps
Herbs
Chocolates
Ice cream
Cocoa juice
Wine production
Jin production
Hair cream
Body cream
Toilet soaps
Fire wood
Organic nutrient sources
Wrapping of pap
Employment generation
Recreational / ornamental uses
Income generation.