Green coffee bean

Further Reading

Coffee f221

Code: k70
Latin name: Coffea spp.
Family: Rubiaceae
Common names: Green Coffee, Coffee bean, raw Coffee, unprocessed Coffee
  • C. arabica - Arabica or Arabian Coffee
  • C. canephora - Robusta or Congo Coffee
  • C. liberica - Liberian Coffee

Occupational Allergen
An occupational allergen, which may result in allergy symptoms in sensitised individuals.

Allergen Exposure

Geographical distribution
Coffee was originally consumed in ancient Abyssinia. Cultivated by the Arabians since 600 A.D., Coffee is now used throughout the world.
Coffee comes from an evergreen, glabrous shrub or small tree, up to 5m tall when unpruned. It is widely grown in the warmer, moister mountainous regions of the world. Dried seeds or "beans" are roasted, ground, and brewed to make 1 of the 2 most important beverages in the Western world. Instant Coffee is the dried extract of roasted, ground Coffee.
Coffea arabica (mild, refined, fragrant) accounts for 60% of the world's production, and Coffea robusta (strong, full-bodied, higher caffeine) for 30%.
Despite its name, C. arabica originated in Ethiopia, where it grows at elevations between 1,375 to 1,830m. Cultivation spread from Arabia throughout the West Indies and Central America and favourable regions of South America. Later, the plant reached India and Sri Lanka. Today, most of the world's Coffee comes from this species, most of the remaining portion coming from the Robusta type, or C. canephora.
Coffee production can be roughly separated into 3 main steps:
  1. cherry processing to Green Coffee beans,
  2. storage and transportation of Green Coffee to the place of consumption, and
  3. Green Coffee processing to roasted and ground Coffee and soluble Coffee.
Unexpected exposure
Coffee pulp and parchment are used as manures and mulches, and are occasionally fed to cattle in India. Coffelite, a type of plastic, is made from Coffee beans. The wood is hard, dense, and durable, takes a good polish, and is suitable for tables, chairs, and turnery. Coffee with iodine is used as a deodorant.
No allergens have yet been characterised. Early studies reported that Green Coffee bean allergens were a very heterogeneous group, ranging from 50 kDa to 50 kDa (1). Coffee processing workers are exposed to Green Coffee dust, which may contain Coffee allergens and Castor bean allergens. Analysis of factory dust has shown it to contain 2 groups of allergens. One allergen derives from Coffee beans and is found mainly in the factory dust, mainly where raw Coffee is handled. This allergen is destroyed in the roasting process. The other allergen was reported to be identical to the allergen from Castor bean and was presumed to enter the plant by contamination, via sacks that had been used earlier for Castor beans (2). Both heat-labile and heat-stable allergens are present in Castor bean, and Coffee workers sensitised to Castor bean have IgE antibodies to both allergens (3). Roasted Coffee appears to contain the same antigens as Green Coffee, but at a lower concentration (4).

Clinical Experience

IgE-mediated reactions
Green Coffee bean may frequently result in sensitisation and symptoms of asthma, allergic rhinitis and allergic conjunctivitis in workers involved in the Coffee processing industry (2, 5-17). Occupational asthma may less commonly occur as a result of exposure to roasted Coffee bean (4). Contact allergy to Green Coffee bean dust has been described (18).
The processing of Green Coffee is very dusty, and the dust contributes greatly to sensitisation and the development of adverse symptoms. There are 4 groups (sometimes overlapping) that may be affected: the healthy individual who does not work in the industry but experiences transient effects on respiratory function; workers who have intermittent symptoms following exposure; workers with chronic symptoms; and workers affected by exposure to both Coffee bean allergen and Castor bean allergen, the latter of which often accompanies Coffee bean processing.
In 10 healthy subjects who were pre-screened for airway hyperresponsiveness to an aerosol of Green Coffee extract and in whom lung function response to inhalation of an extract of Green Coffee was studied, a statistically significant decrement in lung function over time (p<.001) following provocation with Coffee both at rest, and following exercise, was demonstrated. The authors concluded that inhalation of Green Coffee extract causes significant bronchoconstriction in selected healthy volunteers and that this was not prevented by pretreatment with cromoglycate (19).

In a study of 38 Coffee workers who were exposed to Coffee dust intermittently, acute symptoms of the eyes, nostrils and respiratory tract were reported: cough in 84.2%, sputum production in 76.3%, sneezing in 73.7%, difficulty in breathing in 63.2% and a runny nose in 55.3%; 10.5% experienced wheezing. These symptoms lasted only during the hours that workers were exposed to the dust, and subsided on their return home after the day's work (20).
Occupational allergy to Coffee dust and Green Coffee bean was found to be the major allergy occasioned by Coffee manufacturing plants (3). In 9 Coffee workers who complained of job-related respiratory symptoms, bronchoprovocation testing with Green Coffee allergen provoked immediate asthmatic reactions, with acute reductions of ventilatory capacity in 4 workers. Eight workers out of 9 had increased total IgE serum levels, and 6 showed a positive response to skin-specific IgE testing with Green Coffee allergen (21).
It is apparent from studies that Coffee allergens vary according to whether the Coffee bean is green or roasted. Direct or indirect contact with Coffee dust will influence the risk. To illustrate these differences, a study in a Coffee processing plant reported that sensitisation to Green Coffee bean was found in 25.8% of Green Coffee workers (31 cases), in 2.7% of roasted Coffee workers (37 cases) and in 4.5% of the clerks (44 cases) (22).
Occupational allergic respiratory symptoms in Coffee workers have been frequently reported, but the ultimate cause of sensitisation is still debated. Castor bean dust is considered a common contaminant of the sacks used to transport Coffee beans. Studies have therefore examined the influence of Castor bean as well as Green Coffee beans on occupational allergy in Coffee processing workers.

In a study examining both the presence of Castor bean antigens in the settled dust of the Green Coffee bean warehouse and the possible cross-reactivity between the two beans, 211 workers were examined. Oculorhinitis alone was reported in 10%, and 16% complained of asthma (often associated with oculorhinitis). Skin-specific IgE tests were positive in 15% for Green Coffee beans and 22% for Castor bean. Dust analysis confirmed the presence of Castor bean antigens. The study concluded that Castor bean is the major cause of occupational sensitisation among Coffee workers (23).
Similarly, in 45 Coffee workers, skin-specific IgE tests with Coffee allergens demonstrated the highest percentage of positive reactions to dust collected during emptying bags (40.0%), followed by dust of Green (12%) and then roasted (8.9%) Coffee. In a control group of 34 skin-specific IgE tested workers, 14.7% had positive skin reactions to dust collected during emptying bags, but none had positive skin reactions to Green or roasted Coffee. The prevalence of all chronic respiratory symptoms was significantly higher in Coffee workers than in control subjects (24). 
The content of Castor bean dust-contaminated sacks appears to be related to the country of origin of the Green Coffee beans. In a study using a RAST inhibition test, a significant concentration of Green Coffee bean and Castor bean was demonstrated, with the highest values were found on sacks from Brazil (25).
Coffee bean sensitisation may occur even in individuals not directly in contact with the manufacturing process. In a study of 112 workers in a modern Coffee manufacturing plant in Trieste, Italy, where the process is completely automatic and the environmental conditions good, and where exposure to Castor bean can be considered absent because only new sacks had been used for Coffee transportation for over 3 decades, sensitisation to Green Coffee Bean was found in 25.8% of 31 Green Coffee workers, in 2.7% of 37 roasted Coffee workers and in 4.5% of 44 clerks. Specific IgE for Castor bean was positive in 3 of 10 subjects sensitised to Green Coffee bean. Six Green Coffee bean workers complained of work-related respiratory symptoms (asthma and/or rhinitis), compared with only 1 subject in the roasted Coffee group and 1 in the control group. Asthma was reported by 2/31 of the Green Coffee workers and by 1/44 of roasted Coffee workers (26).
Similarly, rhinitis and environmental asthma caused by unroasted Coffee was reported in an adolescent living in a building in which Coffee roasting occurs. Serum-specific IgE, a positive skin-specific IgE using unroasted Coffee extract and broncho-provocation testing confirmed sensitisation to Coffee bean (27).
It is therefore not surprising that dock workers may also develop sensitisation to Castor bean and Green Coffee bean. In 218 dock workers exposed to Green Coffee beans, 31 (14.3%) complained of allergic symptoms of the eye, nose and bronchial system at the workplace. Skin-specific IgE was detected in 21 workers (9.6%). A positive skin-specific IgE determination for Castor beans was found in nearly all of these cases. Ten workers were also sensitised to Green Coffee bean allergens, and in 14 cases skin-specific IgE tests were positive to extracts of sacks. The authors conclude that there is a significant risk of sensitisation to Castor bean and Green Coffee bean allergens in dock workers handling Green Coffee bean, despite the fact that the exposure is not continuous (28).
Other reactions
A 50-year-old female developed rhinitis and conjunctivitis following exposure to a Coffee plant used for indoor decoration. A skin-specific IgE test, serum-specific IgE and rhinoconjunctival provocation test to Coffee leaf allergen extract were all positive. The commercially available serum-specific IgE test for Green Coffee beans was said to be appropriate for diagnosing allergy to the potted Coffee plant (29).
Compiled by Dr Harris Steinman,


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As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.