Thursday, September 26, 2013

Transport of cacao

Another interesting find on the internet about cacao. The original source of the article below is from this site: 

Cocoa/Cocoa beans

Table of contents

Product information
 Container transport
 Cargo securing

Risk factors and loss prevention:
VentilationMechanical influences
Biotic activityToxicity / Hazards to health
Self-heating / Spontaneous combustionInsect infestation / Diseases

Product information

Product name

GermanKakaobohnen (Rohkakao)
EnglishCocoa beans (raw cocoa)
FrenchCacao en fèves
SpanishCacao en grano
ScientificTheobroma cacao
CN/HS number *1801 00 00

(* EU Combined Nomenclature/Harmonized System)

Product description

Cocoa beans are the seeds, contained in a cucumber-like fruit, of the cacao tree, a member of the Sterculiaceae family. The flowers/fruit are borne directly on the trunk (cauliflory) and on thick branches (ramiflory). The yellowish, reddish to brownish fruits (botanically speaking, berries), which are of similar appearance to cucumbers, are divided into five longitudinal compartments, each containing up to 10 seeds (cocoa beans). As the fruits approach ripeness, the partitions break down and the seeds are located around the central funicle in a whitish pulp with a sweet/sour flavor.

The cocoa bean consists of the seed coat which encloses the cocoa kernel and almost solely consists of the two folded cotyledons, and the radicle. The cocoa kernel is the principal component for the production of cocoa products.

Two subtypes are distinguished:

High-grade, criollo cocoa: the beans are large, roundish and brown in color. They have a delicately bitter, aromatic flavor and are easily processed.
Forastero or common grade cocoa: the beans are smaller than criollo cocoa beans, flattened on the side, have a dark reddish-brown to violet color and a sharper flavor. Forastero cocoa beans account for around 90% of the world's cocoa harvest.

The main zones of cultivation of the tropical cacao tree fall within a band 10° north and south of the equator. Central Africa produces approx. 75% of the world's forastero cocoa harvest, while criollo cocoa is primarily shipped from Central America (Venezuela, Ecuador) and from Sri Lanka and Indonesia.

Due to its high content of fat (cocoa butter), protein and carbohydrates, cocoa has a high nutritional value. Since cocoa contains only small amounts of substances such as theobromine (1 - 2%) and caffeine (0.2%), consuming it has no harmful side-effects.

In order to moderate the initially bitter flavor of cocoa and to develop the flavor typical of cocoa, the beans must be subjected to a fermentation process during which the highly bitter tannins present in the beans are oxidized, resulting in the formation of aromatic substances and the development of the typical brown to deep red-brown color of cocoa. As a result of the heat associated with fermentation, the cocoa beans lose their ability to germinate.

This process is performed after harvesting by heaping cocoa beans in layers in troughs, concrete pits or fermenting tanks.

Fermentation process

Figure 1

Quality / Duration of storage

The quality of cocoa products (e.g. cocoa powder for beverages) is primarily determined by the quality of the raw cocoa.

Fully ripened and correctly fermented cocoa beans are thus of a brown to dark red color and have a very fragile kernel with a pure, bitter flavor.

Apart from exhibiting the appearance and odor characteristic of their variety, perfect beans must be undamaged and ungerminated, must include no foreign matter or mold and must not be infested with insects or have suffered wetting damage. They must not smell sour, musty or smoky.

Poorly fermented cocoa beans are purple in color when underfermented or very dark in color when overfermented. They also have a slaty to solid kernel and an astringent (mouth-puckering) flavor. The core may have changed to a violet to yellowish white color. The excessive heating which occurs in overfermentation also results in butyric acid fermentation, which impairs quality.

In [1], the quality of cocoa beans is assessed according to the following criteria:

Good qualities:

fully ripe, correctly fermented
firm beans of uniform size with a dry weight of no less than 1 g
loose and undamaged shell
light to dark reddish-brown color
readily crumbled, highly fragile kernel

Bad qualities:

unripe and poorly fermented
moldy cocoa beans
strong violet color as a result of underfermentation; purple color when overfermented
slaty and firm kernel as a result of underfermentation
insect infested cocoa beans
flat, unripe, small and broken cocoa beans
germinated cocoa beans
ham-like odor due to overfermentation
smoky odor due to excessively long drying

The product should be shipped shortly after harvest, as extended storage (> 6 months) may result in losses due to the high relative humidities in the tropics.

Intended use

For the production of cocoa powder and further processing into beverages, chocolates and desserts.


(Click on the individual Figures to enlarge them.)

Cacao tree

Figure 2
Cacao tree

Figure 3

Figure 4
Cocoa bean

Figure 5

Countries of origin

This Table shows only a selection of the most important countries of origin and should not be thought of as exhaustive.

AfricaIvory Coast, Ghana, Nigeria, Cameroon, other West African coastal countries
AsiaMalaysia, Papua New Guinea, Sri Lanka, Java, Samoa, Philippines
AmericaBrazil, Ecuador, Venezuela, Mexico

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In bags of jute or sisal usually of a (gross) weight of 60 - 65 kg, rarely of up to 100 kg. New or high quality bags should be used due to the high value of the cargo.

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Symbol, general cargo

General cargo
Symbol, temperature-controlled

Bulk cargo

Means of transport

Ship, truck, railroad

Container transport

Transport of bagged cargo in ventilated containers (coffee containers) is possible subject to compliance with lower limits for the water content of goods, packaging and flooring. The wooden flooring of the containers must be absolutely clean and dry. If it has been washed, it must have dried completely. Water content should be 12%, corresponding to a lumber equilibrium moisture content of 70%, so that the flooring does not constitute an additional source of water vapor to dampen the cocoa cargo and container atmosphere.

The cargo may be covered with paper which readily absorbs any moisture to provide protection from moisture damage.

Given the high value of a fully loaded cocoa container, a two-layer anticondensation film or nonwoven should be used to provide protection against dripping sweat.


Figure 6

Cocoa beans are also transported in standard containers using big bags or liner bags.

Alternatively, cocoa beans may also be transported on flatracks in ventilated holds. This approach is a cost-effective alternative to the costly ventilated containers, which are the ideal way to transport cocoa beans.

Cargo handling

Hooks must not be used in cargo handling as they subject the cargo to point loads, so damaging the bags. Due to their shape, plate or bag hooks apply an area load and are thus more suitable for handling bags.

In damp weather (rain, snow), the cargo must be protected from moisture, since wetting and extremely high relative humidities may lead to mold growth.

Stowage factor

1.92 - 2.26 m3/t (jute bags, 60 - 65 kg) [1]
2.00 - 2.15 m3/t (bags) [11]
2.26 - 2.40 m3/t (bags) [14]

Stowage space requirements

Cool, dry, good ventilation.

The cargo should be stowed below deck away from sources of heat because there is a risk of self-heating and postfermentation. In this case, the container is no longer directly exposed to external weather conditions so that the temperature and humidity of the hold air become the decisive external influences. Temperatures below freezing point and major daily variations in temperature may result in spoilage of the cocoa beans. If the containers are nevertheless stowed on deck, they are best stowed as inner deck cargo. The risk of condensation is reduced by stowing between two other containers. However, stowage in this location should only be considered in the summer season if only small temperature gradients are anticipated during transport. Since frost must be expected at the port of destination during the winter months, stowage as inner deck cargo should be avoided.


Fiber rope, thin fiber nets

Cargo securing

In order to ensure safe transport, the bags must be stowed and secured in the means of transport in such a manner that they cannot slip or shift during transport. If loss of volume and degradation of quality are to be avoided, the packages must not be damaged by other articles or items of cargo.

Attention must also be paid to stowage patterns which may be required as a result of special considerations, such as ventilation measures.

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Risk factors and loss prevention

RF Temperature

Cocoa beans require particular temperature, humidity/moisture and ventilation conditions (SC VII)(storage climate conditions).

DesignationTemperature rangeSource
Travel temperature15°C[1]
< 30°C[2]

Raw cocoa must not be stowed near heat sources. Rancidity and overfermentation readily occur at temperatures of > 25°C. Due to its high fat content, the cargo has a tendency to self-heating, and there may even be a risk of a cargo fire on contact with flammable substances, e.g. copra expeller. Cocoa beans absolutely must not be stowed in a container together with oily products.

External temperatures of > 30°C may readily occur during container packing. Severe cooling at night may result in container sweat if the temperature dips below the dew point.

In the hotter parts of the year, the temperature drop between the port of loading and unloading may be 15 - 20°C. In the cold parts of the year, however, the difference may be 30°C or more. Incoming cold polar air may cause sudden drops in temperature which, especially in container interiors, may result in a considerable increase in relative humidity. In this situation, the water content of the cargo is particularly important. Rapid and major cooling from the outside may readily increase relative humidity to 100%, resulting in condensation and wetting, vapor and mold damage to the cocoa beans.

Cocoa beans must be protected from frost.

The following figure shows an example of the temperature profile of a batch of raw cocoa in various types of container:

Figure 20

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RF Humidity/Moisture

Cocoa beans require particular temperature, humidity/moisture and ventilation conditions (SC VII)(storage climate conditions)

DesignationHumidity/water contentSource
Relative humidity70%[1]
Water content6 - 8%[1]
< 8%[2]
< 9%[9]
Critical water content8.5%[1]
Maximum equilibrium moisture content65%[1]

It is recommended to demand on unloading a certificate which states the intrinsic moisture content of the cocoa beans.

Cocoa beans are known to be highly hygroscopic (hygroscopicity) and to release large amounts of water vapor during transport. Water content has accordingly been observed to fall by 1 - 3% during extended voyages. Improperly fermented and dried cocoa beans have a greater tendency to release water vapor.

If the water content is < 6%, cocoa beans become brittle, while at a water content of > 8%, there is a risk of vapor and mold damage which cause depreciation which may go as far as total loss due to rot.

A fundamental distinction is drawn between two types of moisture damage: sweat damage and vapor damage

Sweat damage (mold damage): Recognizable by spots on the bag fabric caused by drops of dirty water. Under these spots, there are clusters of cocoa beans covered with white mold and stuck together. In serious cases, the mold penetrates into the kernel of individual beans. As a result, these then smell and taste musty. Such losses are usually limited to only a few bags in a consignment and are caused by the formation of ship sweat below deck, especially at night when the surrounding atmosphere and thus the outer walls of the hold cool down. If the upper layer of bags in the hold is inadequately covered, the dripping cargo sweat cannot be absorbed, penetrates into the bags containing the cocoa beans and causes the damage described above.
Vapor damage: this is caused by excessive relative humidity in the hold or container. While the cocoa beans have only a thin covering of mold, from time to time the damage affects the entire contents of the bags stowed in a hold. Vapor damage is thus generally much more extensive than sweat damage. Marked mold growth is not normally observable, but aroma and flavor are still considerably degraded. For this reason, care must be taken not only to prevent formation of sweat, but also to ensure favorable relative humidity values in the hold/container.

On arrival in the port of discharge, the water content of the cargo should be just above 6%; a higher intrinsic moisture content would expose the cocoa to excessive risk on subsequent storage.

The product should also be shipped shortly after harvest as the consequent extended storage in the tropical countries of origin may readily result in losses due to the prevailing high relative humidities.

Since cocoa beans are strongly hygroscopic, they must not be stowed together with moisture-releasing goods, such as copra, bran or rafted logs.

Loss of moisture from the cargo and the consequent release of water vapor from the cocoa beans into the surroundings result in the formation of condensation on surfaces in the hold or on the cargo which may cause considerable damage.

Apart from containing water, the cocoa beans also contain enzymes which bring about postfermentation in the hold. Incorrect covering of batches of cargo resulting in obstruction of air circulation may in particular cause damage.

Bags damaged by rain, seawater and condensation must be rejected during acceptance of a consignment and, whether moist or redried, must never be stowed together with intact bags as the salt has the effect of greatly promoting the hygroscopicity of the raw cocoa, which may demonstrably lead to severe losses. In cases of doubt, already dried bags must be subjected to a seawater test (silver nitrate method). When accepting a cargo from lighters, difficulties obviously arise when rejecting seawater-damaged bags. The water content of the jute bags should be at most 9% (which is already the critical value). Measurements on jute sacks in containers have on occasion revealed values of up to 30%.

When transporting cocoa beans in containers, care should be taken to ensure that the water content of the cocoa beans on packing is approx. 6 - 8%, which corresponds to an equilibrium moisture content of 75 - 85% (at 20°C) and a temperature/dew point difference of 5 - 3°C. These are values which entail greater problems from the outset than are encountered, for example, with coffee shipments, because even the lower water content limit of 6% corresponds to the mold growth threshold of 75%. Moreover, cocoa beans have an elevated fat content which, in conjunction with moisture, results in hydrolytic/enzymatic fat cleavage and self-heating of the cocoa beans. The slight temperature/dew point difference also shows how rapidly the dew point of the cocoa cargo is reached on cooling. It is thus recommended to insist on a water content of 6% when transporting cocoa beans in containers.

Sorption isotherm

Figure 7

The Figures show typical types of damage which may occur during cocoa transport:

Sweat damage

Figure 8
Sweat damage

Figure 9
Sweat damage

Figure 10
Sweat damage

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15
Sweat damage

Figure 16

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RF Ventilation

Cocoa beans require particular temperature, humidity/moisture and ventilation conditions (SC VII)(storage climate conditions)

Recommended ventilation: air exchange rate 10 - 20 changes/hour (airing)

Important: Good ventilation is required, so a suitable ventilation program must be drawn up depending upon external temperature, relative humidity, cargo temperature and moisture content of the cocoa beans.

Since the beans constantly release water vapor during the voyage, this vapor must be removed to the outside by suitable ventilation in order to reduce the risk of condensation in the event of unfavorable ambient conditions (e.g. sudden drops in temperature of the external air) and the risk of mold growth due to high relative humidity in the hold.

In the hold, it is particularly important for the covers which provide protection from dripping sweat (wooden dunnage, mats or jute coverings) to be arranged in such a way that air can still circulate freely. Ventilation channels and wells should be arranged in the stow.


Figure 17

When containers are shipped below deck, vigorous ventilation is necessary. A minimum air exchange rate of 20 changes/hour in the hold is recommended if continuous airing is to be achieved in the ventilated container. Ventilation of the hold must be arranged such that the air is blown in from beneath and rises upwards through the containers, so continuously removing warm, moist air. It is important to unpack the containers quickly on arrival at the port of destination, especially at cold times of year: when the containers emerge from the relatively well protected surroundings of the ship's hold and are exposed to the sometimes much colder outside air, the relative humidity in the containers may rise rapidly, resulting in the formation of condensation.

Using plastic materials to cover the container contents results in severe cargo sweating and consequent damage. Containers holding cocoa beans should, on principle, be stripped on arrival and have good ventilation (ventilated container).

In order to ensure more effective airing of the cocoa bags stowed in the container, a particular stowage pattern, similar to that for coffee or pepper, should be used:

Two layers of bags are first laid crosswise in two stacks, with some space being left at the side walls (important, so that the ventilation openings in the floor are not blocked up). Free space, which should usually be of a size of 20 - 30 cm, is also left in the middle in order to provide a ventilation channel.
A layer is then stowed lengthwise on the second layer.
The next layer is again stowed crosswise, bridging the gap between the two stacks with one bag.
Stowing is continued in this manner until the container is full. Approx. 50 - 75 cm of free space must remain between the uppermost layer and the container roof in order to ensure free circulation of fresh air supplied from outside.
Free space (approx. 10 - 15 cm) must also remain between the container door and the stowed bags so that the necessary air circulation can be maintained here as well. The bags in the door area must be secured with lashings so that they do not slip into this free space in transit, which would block air circulation.

When the cargo is conventionally loaded on general cargo ships, the hatch covers should be slightly lifted or opened in dry weather (relative humidity < 80%) and in safe sea conditions in order to dissipate any water vapor and to permit temperature equalization between the outside air and cargo.

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RF Biotic activity

Cocoa beans display 3rd order biotic activity.

They belongs to the class of products in which respiration processes are suspended, but in which biochemical, microbial and other decomposition processes still proceed, which, as a result of possible postfermentation, are in particular associated with oxygen consumption and CO2 evolution. Although they lose their ability to germinate as a result of fermentation, poorly fermented cocoa beans may germinate.

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RF Gases

Evolution of CO2 by postfermentation may endanger life. Thus, before anybody enters the hold, a gas measurement must be carried out. The threshold limit value (TLVD) is 0.49 vol.% CO2.

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RF Self-heating / Spontaneous combustion

Oil content: 39 - 60% [1]

Under suitable ambient conditions (temperature > 25°C, high relative humidity, lack of oxygen supply) and due to their high oil content, cocoa beans have a tendency to self-heating and postfermentation. Some species of fungus, such as Aspergillus fumigatus, participate in the self-heating.

One example is the spontaneous combustion of broken raw cocoa beans in a bulk load in the form of smoldering cavities or channels. There are four distinct phases in the development of the fire:

1st phase: General biological phase in which mesophilic microorganisms multiply in a wet spot, raising the temperature to approx. 37°C.
2nd phase: Phase involving the highest level of activity from thermophilic microorganisms at temperatures of up to approx. 70°C. Samples from the seat of the fire exhibit a particularly high content of thermophilic microorganisms.
3rd phase: The thermophilic decomposition phase which is characterized by exothermic chemical breakdown reactions, in particular by oxidation reactions between unsaturated fatty acids and atmospheric oxygen (the cocoa beans having a fat content of > 50%). A strong, pungent stench of fermentation becomes perceptible.
4th phase: The pyrophoric gas phase, in which pyrophoric carbon and gases (e.g. phosphine) are formed. The resultant abrupt increase in temperature gives rise to smoldering cavities and channels within the bulk load.


Figure 18

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RF Odor

Active behaviorCocoa beans have a characteristic, strong odor. This odor may taint, for example, raw coffee, which should thus not be stowed together with cocoa beans in a hold/container. Excessively long fermentation may impart a typical, ham-like odor to the beans; a smoky odor is due to incorrect drying.
Passive behaviorCocoa beans are very odor-sensitive (particularly towards copra bran, pepper and palm kernels). Due to the elevated odor-sensitivity, holds or containers must not smell of previous loads (e.g. citrus odor, odor of leather, pepper, chemicals etc.). Before containers are loaded, they must be inspected to establish whether they are free of foreign odors.

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RF Contamination

Active behaviorCocoa beans do not cause contamination.
Passive behaviorCocoa beans are sensitive to contamination by dust, dirt, fats and oils. Raw cocoa is particularly sensitive to cement and coal dust: cement dust passes through the bags onto the beans, causing major losses.

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RF Mechanical influences

Point loads applied for example by hooks may result in damage (tears) to the bags and thus to losses of volume. Plate or bag hooks, which, due to their shape, distribute the load and reduce the risk of damage, should thus be used. Exposure to moisture in particular increases the susceptibility of jute bags to rotting, which reduces their mechanical strength.

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RF Toxicity / Hazards to health

Evolution of CO2 due to respiration and postfermentation. Take care when entering the hold. Possible oxygen shortage! Use gas detector.

For example, 121 metric tons of raw cocoa were loaded onto an ocean-going vessel at the Port Kelang (Malaysia), occupying 300 m³ out of a total available hold volume of 800 m³. Shortly after entering the hold, the 1st officer felt dizzy and so dashed back out again. On returning to hold with a breathing apparatus, a CO2 content of 6 vol.% was measured. By way of comparison, breathing air containing of 8 - 10 vol.% of CO2 is fatal within just 5 - 10 minutes. Despite constant ventilation of the hold, a content of 2 vol.% CO2 was still recorded some time later. The threshold limit value (TLVD) is 0.49 vol.% CO2.

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RF Shrinkage/Shortage

Shrinkage of 1% (normal), rising in exceptional cases to 3%, should be anticipated due to drying during the voyage.

"Slack bags" should be rejected on acceptance of a consignment as the slackness indicates short quantities.


Figure 19

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RF Insect infestation / Diseases

Before the means of transport is loaded, the cargo should be fumigated (obtain a fumigation certificate).

Typical pests are the cocoa and meal moth, together with ants and cockroaches, which may cause severe losses by eating and contaminating the cargo. Infested cargo is usually fumigated to eliminate the living insects. On board pest control using fumigation tablets may result in dust deposits on the bags. This dust still contains residues of the poison, which can also be highly hazardous to humans.

Insect infestation usually originates in the country of production when the raw cocoa has been stored for an extended period; but insect infestation may also occur on long voyages.

Mold infestation: mold growth may considerably reduce the quality of cocoa beans. Scientific investigations [52] have revealed eight mold species which produce foul-smelling substances and also cause the tissue of the beans to decompose. Some species participate in self-heating of the cargo, while others may form strong toxins.

If the molds find favorable living conditions, i.e. when the critical water content of 8.5% is exceeded at an equilibrium moisture content of approx. 88%, the molds rapidly develop within 3 - 4 days, at the end of which period thousands of spores have formed on the surface of the cocoa beans.

The number of mold spores may also be used to assess the quality of the cargo:

CategoryNumber of spores/gramMacroscopic examination of samplesSuitability for useQuality
1100 - 1.000No traces of mold growthYesHigh
21000 - 10,000Slight development of molds on individual beansYesLow
325,000 - 100,000Slight to considerable mold growth on all beansUncertainLow
4> 100,000Severe mold growth over entire sampleZeroPoor

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© Gesamtverband der Deutschen Versicherungswirtschaft e.V. (GDV), Berlin 2002-2013

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