Coffee [German version]

Table of contents

General:
Product information
Packaging
Transport
  Container transport
  Cargo securing


Risk factors and loss prevention:
Temperature Odor
Humidity/Moisture Contamination
Ventilation Mechanical influences
Biotic activity Toxicity / Hazards to health
Gases Shrinkage/Shortage
Self-heating / Spontaneous combustion Insect infestation / Diseases




Product information

Product name

German Kaffee (Rohkaffee)
English Coffee (green coffee beans)
French Café
Spanish Café
Scientific Coffea arabica
CN/HS number * 0901 11 ff.


(* EU Combined Nomenclature/Harmonized System)



Product description

Coffee shrubs (Coffea arabica), which belong to the madder (Rubiaceae) family, are shrubs with evergreen, leathery leaves, white flowers and spherical, reddish purple stone fruits, known as coffee cherries. Originally native to East Africa, coffee was cultivated for the first time in Brazil in 1740. The coffee shrub thrives in a tropical climate in shady locations with high rainfall in both mountainous areas (Coffea arabica, see below) and lowlying areas (Coffea liberica, Coffea robusta).

Since the coffee shrub blossoms throughout the year, each shrub carries fruits at all the various stages of development.

Green coffee beans are the seeds of the coffee shrub, which are disengaged completely from the husk and to a considerable extent from the seed coat (silver skin). In general, each coffee cherry contains two coffee beans, which lie with their flat sides together and exhibit longitudinal furrows in the middle of these sides.

Coffee beans contain the alkaloid caffeine (0.8 - 2.5%), which has a stimulating effect on the human nervous system, for which reason coffee is counted as a semiluxury item.

There are three varieties of coffee shrub which are of economic significance:

1. Coffea arabica, the Arabian shrub.

Plantations are generally at altitudes of over 1000 m, which make it a "highland coffee". The average length of coffee beans of this variety is approx. 9 mm and their color is greenish to blue-green.

The coffee beans of this variety are more expensive, the higher the plantations, as the fruits ripen more slowly at greater altitudes, becoming horny and hard and containing only little moisture. They consequently have a strong, full flavor. They have a caffeine content of approx. 1.2%. This variety accounts for 75 - 80% of the world's coffee harvest.

Coffea robusta, the robusta coffee shrub.

This is a "lowland" coffee, as its plantations are as a rule below 1000 m. The beans of this coffee variety are small, roundish and generally brownish to yellowy green. The coffee cherries ripen more quickly and their beans have a higher water content than highland coffee and generally have a less powerful flavor. They have a caffeine content of approx. 2.3%.

Coffea liberica, the Liberian coffee shrub.

A lowland coffee, whose beans, though larger than those of Coffea arabica, are less highly regarded because of their sharp flavor.


In addition to these varieties, a distinction is also drawn between two methods of processing green coffee beans: the dry process (produces unwashed green coffee beans) and the wet process (produces washed green coffee beans):

Unwashed green coffee beans

This processing technique is used in particular in Brazil, which is a coffee-producing country. The majority of the world's coffee production is dry-processed.


Figure 1: Flowchart illustrating the dry process


Washed green coffee beans

The washed varieties are generally those from the higher quality grades. However, their higher hygroscopicity makes them more susceptible to moisture damage.


Figure 2: Flowchart illustrating the wet process



Quality / Duration of storage

Green coffee beans are graded according to certain criteria, such as shape, size, uniformity of the beans, color, horniness, husk, cut, gloss, smoothness of the beans, proportion of defective beans, foreign matter and odor.

For instance, beans should be graded into uniform shapes and sizes. A distinction is drawn between flat beans (2 beans in a cherry), peaberries (only 1 bean in a cherry, not flattened) and Maragogype coffee (particularly large beans).

The color of the beans must exhibit a greenish to deep green and fresh background hue and varies depending on variety and origin (top varieties from Central America: strong green to gray-blue, other varieties: light yellow to light green).

Fading color, starting at the tips of the beans, results from a relatively long storage time and is deemed to indicate poor quality. Fresh-colored coffee beans are recently harvested, while yellowish-green hues are indicative of beans from an older harvest.

Horniness is also an indicator of product freshness: fresh beans should be tough and have to be peeled with a knife in the manner of horn. The cutting test shows that highland coffee is hard and has a horny, tightly serrated and wrinkly cut surface. A straight, broad, open cut indicates lowland coffee.

Coffee beans must be hard and not spongy (especially washed coffee beans), i.e. if a finger nail is pressed into the bean, it should leave no trace.

The gloss and smoothness of the beans indicate clean processing.

In addition, the proportion of defective beans and foreign matter constitutes an important criterion in the quality grading of coffee. Thus, the highest quality green coffee is sorted (previously hand-sorted, now sorted by machine) and contains only a few defective beans. Foreign matter, such as sticks, stones and leaf residues, has been almost completely removed, while medium quality green coffee still contains a considerable proportion of defective beans and foreign matter.

Overview of typical green coffee defects:

Designation Cause Appearance Odor/Flavor
Sour or waxy beans starting to rot due to overfermentation, the most dangerous coffee defect yellowish to brown, often with mottled surface, glassy repellent, rotten, rancid
Frosted beans, also known as stinkers frost at sunrise, also night frosts speckled or black, somewhat spongy acrid and stinking
Quakers unripe fruits underdeveloped, shimmery green to grass-green, firmly attached silver skin sharp, sour or grassy/pea-like
Broken beans damage during processing or transport fragments same as whole beans
Insect-damaged beans insect bites and chewing holes or chewed edges same as undamaged beans
Ear-shaped and deformed beans beans damaged during hulling ear-shaped, hollow beans weak aroma
"Triplets" three-seed beans flat sides beveled as normal beans
Elephant beans several beans fused together    
Foreign matter contamination due to stones, sticks, small lumps of earth etc.    


The following terms allow conclusions to be drawn as to the quality of the coffee:

ship fillings: coffee spilled on the floor of the hold; before delivery, the ship should clean and bag this coffee (or pay to have the above operations performed).
ship sweepings: highly contaminated coffee lying on the floor of the hold (not generally fit for recovery).
ship samples: coffee samples taken shortly before loading onto the ship or during loading operations (deposited at the port of loading).
ship spills: coffee gathered up using clean shovels, without having come into contact with the floor.
shipper's slacks: bags recorded by the ship as being too weak when loaded.
skimmings: damp coffee from partly wetted bags; the coffee beans may be divided into good skimmings, medium skimmings or poor skimmings.


Quality specifications for coffee vary very widely in Europe. Basically, the darker the coffee is roasted, the lower is the required starting quality. If German quality requirements are taken as a baseline of 100%, the coffee qualities required in Scandinavia are between 110 and 120%, while Southern Europe demands qualities of between 60 and 70%, i.e. a loss causing depreciation of 20% in Germany does not constitute a loss at all in southern Europe.

Washed coffee may be stored for several years if the recommended storage conditions are complied with.


Intended use

As a semiluxury item: green coffee beans are roasted, ground and brewed. They are further processed to yield products such as (freeze-dried) instant coffee.


Figures

(Click on the individual Figures to enlarge them.)

Coffee plant

Figure 3
Coffee bean

Figure 4
Coffee plant
Figure 4a
Coffee beans

Figure 4b
Coffee plant
Figure 5
Coffee plant

Figure 5a
coffee cherries
Figure 5b
Coffee beans

Figure 6
Coffee beans

Figure 7
Coffee beans

Figure 8
Coffee beans

Figure 9
Coffee beans

Figure 9a



Countries of origin

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

Europe  
Africa Ethiopia, Ivory Coast, Cameroon, Kenya, Madagascar, Uganda
Asia Indonesia, India, Philippines, Vietnam
America Brazil, Colombia, Mexico, Costa Rica, El Salvador, Guatemala, Honduras, Ecuador, Peru, Venezuela
Australia Papua New Guinea


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Packaging

Coffee beans are usually packaged in new bags of woven natural materials (e.g. jute or sisal), which allow free air circulation. Their net weight is generally 60 kg, but may be 69 kg in Central America/Colombia.

Coffee from Mexico is sometimes shipped in a sisal outer bag containing a plastic inner bag. This plastic inner bag is perforated. Woven plastic bags, as are occasionally used for transport from West Africa, have no effect on the quality of the coffee, provided that they are air-permeable.

Coffee bags

Figure 10



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Transport

Symbols

Symbol, general cargo

General cargo
Symbol, temperature-controlled

Bulk cargo



Means of transport

Ship, truck, railroad
Storage

Figure 11



Container transport

The protective and ventilation measures conventionally taken in a general cargo ship do not generally apply to containers.

Containers have increased handling speeds decisively. The constant increase in container ship tonnage has increasingly reduced the supply of space in conventional ships. Approx. 95% of European coffee imports are already transported in containers - the change-over to containerized coffee transport is largely complete.

Two types of container are used to transport coffee:

1.) Standard containers

Standard containers differ in the materials used for wall and ceiling construction. Corrugated steel sheet, fiber glass-reinforced plastics and, occasionally, plywood, are used. The floor always consists of wood or perforated pressure plate.

To simplify opening and closing of the containers, standard containers have a few small "ventilation holes", which have no ventilation effect but merely equalize pressure differentials on opening and closing of the containers.

A standard container stuffed with coffee should be stowed below deck. The extreme temperature differences on deck (up to 60°C between day and night) could result in container sweat during maritime transport.

In addition, a sharp drop in temperature in the container caused by the effects of the wind and weather of a northern winter may result in considerable container or cargo sweat. Below deck, these effects are considerably reduced.

The bottom, sides and top areas of the cargo block in the container should be lined with packing paper. Incipient container sweat (initial drips) may be soaked up and distributed by the paper.

Packing paper

Figure 12
Nonwoven fabric

Figure 13
Inlet

Figure 14
Inlet

Figure 15
Nonwoven fabric

Figure 16
 


2.) Ventilated containers ("coffee containers")

Ventilated containers have ventilation openings over the entire length of their side walls in the floor and roof areas. This ventilation is passive, i.e. the ventilated containers have to be actively ventilated from outside. Active ventilation can only take place when the hatch is closed. Upwardly directed air flow may be produced by extracting the hold air at the top and supplying fresh air in the area of the hold floor. This air then also flows through the ventilated container. This is the only way to ensure ventilation in the ventilated container.

Container ventilation

Figure 17
Container ventilation

Figure 18
Container ventilation

Figure 19
Container ventilation

Figure 20


Because the ventilated containers are ventilated in this manner, they must be loaded below deck. On deck, the airflow through such containers might not be sufficient and the containers would also be exposed to considerable temperature fluctuations. Furthermore, on deck the additional ventilation openings in the container create the risk of seawater spray deposition.

The container floor should be lined with paper. There must be no dunnage at the sides and in the top area, since the ventilation action would otherwise be impaired or completely prevented.

The wooden flooring of the containers must be absolutely clean. If washed, it must be completely dried; the water content of the flooring 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 coffee cargo and container atmosphere.

Unpacking/stripping of the containers: green coffee beans are stuffed at intrinsic temperatures of 30 - 35°C. Since they are loaded below deck, coffee containers have a core temperature of approx. 18 - 20°C even during the Northern European cold season, due to the short duration of the voyage. If such containers are unloaded at -10°C, speed is of the essence. The more quickly are the containers stripped, the lower is the risk of moisture damage. Long truck or rail journeys should be avoided, since the extremely rapid cooling of the container would inevitably lead to container sweat. A container should where possible be unpacked within 24 to 48 hours of unloading from the container ship. Top and side dunnage cannot prevent wetting damage, but they can delay it. This period of delay may have a crucial effect on whether the cargo suffers damage or survives transport without damage.

"Bulk containers": Approx. 1/3 of containerized coffee is transported as bulk cargo in 20' standard containers. Liner bags of plastic fabric are suspended in the containers. The container and liner bag are filled in a tilted position and both are then closed. The dunnage recommendations for "bulk containers" are the same as those for standard containers.

Alternatively, coffee bags may also be transported on flatracks in ventilated holds. However, handling of the flatracks is problematic, as the cargo is exposed to the ambient atmosphere without any protection.


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 moisture ingress may cause damage.

Unpacking

Figure 21
Packing

Figure 22
Unpacking

Figure 23



Stowage factor

1.90 m3/t (flat bags of jute fabric, 60 kg, Santos, Brazil) [1]
1.98 m3/t (jute bag, 61 kg, Mombasa, Kenya) [1]
1.72 - 1.81 m3/t (bags from Brazil) [11]
1.81 - 2.09 m3/t (bags) [11]
1.70 - 1.90 m3/t (bags) [14]


Stowage space requirements

Cool, dry, good ventilation.

The containers should be stowed below deck away from heat sources. External meteorological conditions do not then have a direct effect on the containers. They are shielded from the external conditions by the surrounding containers and the ship's walls, so meaning that the hold air, with its temperature and moisture/humidity values, constitutes the decisive external influence. The risk of frost on the one hand and major daily variations in temperature may result in spoilage of the coffee, so stow below deck where possible.


Segregation

Fiber rope, thin fiber nets. Used nets must be washed and dried before use, to prevent tainting by odors or seawater.


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

Coffee beans require particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

Designation Temperature range Source
Travel temperature 0 - 20°C [1]
< 20°C [2]


The goods must be protected from frost (< 0°C).

In general, temperatures should be between 10 and 20°C during transport of green coffee beans.

There is a close connection between fluctuations in the ambient temperature and the formation of condensation water (sweat) in the hold or container. Thus, during a voyage from a hot climate (port of loading, e.g. South America in December, i.e. summer in southern hemisphere) to a cold climate (port of discharge, e.g. Northern Europe in December, i.e. winter in the northern hemisphere) intensive cooling of the cargo is essential. Temperatures gradients of as much as 50°C between "summer in the southern hemisphere" and "winter in the northern hemisphere" are entirely possible. A sudden fall in temperature also leads to a higher probability of condensation water formation below the ship's deck or in the container. The resultant dripping sweat then causes considerable cargo losses. Overintensive cooling of the cargo surfaces may also lead to condensation water formation directly on the cargo (cargo sweat).

Condensation water

Figure 24


For this reason and owing to the close relationship between temperature and humidity in the hold together with the external weather conditions, it is necessary to take daily temperature and humidity measurements (external temperature, hold temperature, relatively humidity), so that an appropriate ventilation program can be drawn up.


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RF Humidity/Moisture

Coffee beans require particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

Designation Humidity/water content Source
Relative humidity 50 - 65% [1]
50 - 65% [2]
Water content 8.5 - 10% [1]
9 - 12% [2]
10 - 12% [4]
Maximum equilibrium moisture content 65% [1]


Preventing the formation of condensation water in the hold is absolutely essential and constitutes the number one priority.

The cargo in the hold (or in the container) should be protected from dripping sweat by placing mats, jute coverings, gunny cloth or similar coverings at a distance of approx. 0.5 m above the cargo surface (where possible). The spacing from the cargo is necessary to ensure adequate ventilation. For this reason, use of tarpaulins or plastic films should be avoided, since the coffee beans may otherwise start to postferment.

Condensation water

Figure 25
Condensation water

Figure 26


According to the sorption isotherm for green coffee beans, beans with an 8.5 - 10% water content are at equilibrium with a relative humidity of 50 - 65%.

SI

Figure 27


If coffee beans have an excessively high moisture content, there is a risk of mustiness, mold growth and post- or overfermentation. Washed coffee frequently has a higher moisture content than unwashed coffee, due to the processing technique used, so meaning that it also releases more water vapor and is therefore more at risk from sweat.

Moisture damage (vapor damage, fresh and salt water damage) does not generally become apparent until several days after the beans have come into contact with water and is then manifested by a musty odor and visible changes to the beans.

Exposure to wetness (excessive humidity, rain, sweat) turns the beans white, and sometimes subsequently black, moldy and swollen. A relatively long period of exposure to wetness results in a musty/rotten odor.

Damp cargo

Figure 28


Salt water damage may have been caused by seawater ingress during lighterage (=> seawater test using the silver nitrate method). Bags damaged by sea- or rain water should be rejected. In addition, the salt content of the seawater increases water vapor absorption by coffee beans.

Damp bags

Figure 29


The various types of damage, such as discoloration, swelling, moldiness, post- or overfermentation, always have an effect on aroma and flavor.

Green coffee beans should never be transported in the same compartment in conventional ships as rafted logs (high water vapor release).

It is advisable to monitor the water content of the cargo by sampling.

Container transport of coffee beans:

    Normal loading humidity of between 11 and 13%. Values of up to 13.5% are still acceptable. Where values are between 13.5 and 14%, i.e. the mold growth threshold of 75% relative humidity has already been reached, it is essential to use ventilated containers, and to ensure very rapid stripping after unloading the container from the ocean-going ship.

    Very few exporters dry coffee to a level of 10%. Since the weight of coffee is the basis for trade, tax and duty, in this case special agreements and preparations are required on the part of the exporter. If the water content of coffee is reduced to values below 10%, the structure, flavor and odor of the coffee change (depreciation due to loss of aroma).

    The Far East exports coffee at particularly high moisture levels (approx. 14%). Ventilated containers must be used for the purpose of loss prevention. Stripping must be performed very quickly, especially in winter in the northern hemisphere.


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RF Ventilation

Coffee beans require particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

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

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

The beans constantly release water vapor during the voyage, and the water content may fall by 0.5 - 1%. This released water 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). Intensive cooling must be provided, especially during voyages into cold climates. A sudden drop in temperature causes sweat to form below deck. Considerable damage may be caused by dripping sweat. Overintensive cooling of the cargo surfaces after a sharp drop in temperature may also lead to sweat formation directly on the cargo.

The elevated relative humidity in the hold may also lead to mold damage.

Container transport of coffee beans:

In the event of a sharp drop in external air temperature, any consequent rapid impact upon the holds and thus upon the containers may be alleviated by reducing or completely ceasing ventilation. In the event of a sharp decline in the temperature of the hold air, the ceilings and free wall surfaces of the containers are particularly prone to cooling. If the air above the cargo has a relatively high water vapor content (which occurs with goods with a high water content), it must be expected that condensation will form to a particular degree on these surfaces.

In winter, the containers are sometimes exposed to extreme temperature differences during unpacking, as they move from the relatively protected environment of the hold into the sometimes substantially cooler external air ashore. The consequence is a rapid rise in the relative humidity in the container, which may very quickly lead to the formation of condensation. For this reason, the containers should be unpacked or placed in appropriately protected storage immediately on arrival at the port of discharge.


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RF Biotic activity

Coffee beans display 3rd order biotic activity.

Respiration processes are essentially suspended, but biochemical and microbial processes continue. Despite the fermentation process, the embryo is preserved: the loss of the ability to germinate has an unfavorable effect on the contents and thus on the quality of the green coffee beans.

Inadequate ventilation may result in fermentation and rotting of the coffee beans as a result of increased CO2 levels and inadequate supply of atmospheric oxygen.


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RF Gases

If ventilation has been inadequate (frost) or has failed owing to a defect, life-threatening CO2 concentrations or O2 shortages may arise. Therefore, before anybody enters the hold, it must be ventilated and a gas measurement carried out.


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RF Self-heating / Spontaneous combustion

No risk.


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RF Odor

Active behavior Extremely slight unpleasant odor. Green coffee beans release a peculiar odor. "Fruity" smelling coffee beans have been loaded when very fresh (not to be confused with beans tainted with a citrus odor).

To test the odor of coffee, rub it between the hands. Good new crop coffee smells fresh and leguminous. Poorly processed green coffee beans or those which have been stored in damp conditions smell musty.
Passive behavior Green coffee beans are extremely sensitive to foreign odors. The specific intrinsic odor of an individual coffee variety may even taint other varieties. Thus, for example, "Minas" coffee (origin: Brazil) has a sharp, carbolic odor, and "Rio" coffee has an iodoform-like odor. These "hard" coffee varieties may odor-taint "softer" varieties (e.g. "Santos" coffee).

The causes of foreign odor may be:

foreign odor from other goods, such as fish meal, raw sugar, pepper, citrus fruits, hides, furs, chemicals (citrus odor not to be confused with the fruity smell of very fresh coffee beans)
inadequate deodorization of storage spaces and ships' holds and of containers


In container transport there are two causes of odor taint:

the container was contaminated at the time of loading (e.g. by previous damaged chemical cargo) and
odor may be transferred from the hold to the coffee, at least in the case of a ventilated container.


Since the responsibility for the cleanliness of a container to be loaded is delegated to very low level, there is a greater risk associated with using a container.



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RF Contamination

Active behavior Coffee does not cause contamination. Some dust may fall out of the porous jute bags.
Passive behavior Green coffee beans are extremely sensitive to contamination and must be kept absolutely clean. They must be protected from cement and coal dust, as this penetrates through the jute bags used and cannot thereafter be removed from the beans by machine.

Stones

Figure 30



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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

Where a cargo has become excessively damp, postfermentation leads to CO2 development; thus, before anybody enters the hold, it must be ventilated and the gas content of the air must be checked. There is a possibility of an oxygen shortage.

Black spots resulting from the formation of condensation water may be caused a mold containing the toxin ochratoxin A, which is suspected of being carcinogenic. This mold is extremely heat-resistant and is not destroyed even by roasting (160°C). It may occur in grain, pasta, spices, wine and beer. Coffee roasters must ensure that the green product is fit for use (max. permitted level 3 micrograms / 1 kg foodstuff).


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RF Shrinkage/Shortage

Weight loss caused by the release of water vapor during the voyage may amount to up to 0.5%. Loss of volume may also be caused by tears in bags.

In addition, weight differences arise through:

inaccurate weighing in the exporting country
underfilling of bags
sampling after filling
storage after filling and before shipment (release of water vapor caused thereby leads to weight loss)
tare differences


If very dry coffee is shipped, storage under conducive conditions may even result in a weight increase.


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RF Insect infestation / Diseases

Containers and holds must be absolutely free from insects.

The coffee beetle (Araeocerus fasciculatus) is a typical storage pest, which easily spreads during relatively long periods of storage ashore. Coffee may additionally be infested with cockroaches, rats and mice.

Fumigation is generally carried out in the countries of origin (fumigation certificate), which does not as a rule cause any depreciation. Occasionally, fumigation agents are incorrectly applied to the product and residues with a carbide-like odor are left on the sacking, which may taint the coffee.


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