3. État de l’art
3.2 Recherches bibliographiques
3.2.2.2 Création, réorganisation et promotion de centres de documentation 33
Pacífico, C.1 / Silva, I.2 / Novais, M. I.2 / Gonçalves, M.2 / Viegas, S.1,3 /Viegas, C.1, 3
Resumo
Os fungos são contaminantes naturais do café e, em certas condições ambientais, têm o potencial de produzir toxinas. Aspergillus sp., Penicillium sp. e Fusarium sp., têm sido reportados em vários estudos como os principais géneros fúngicos presentes em amostras de café. Trabalhadores da indústria do café podem estar expostos a estes microrganismos e aos seus metabolitos (micotoxinas) e a partículas principalmente pela via inalatória, o que origina preocupações no que concerne à exposição e efeitos para a saúde dos trabalhadores envolvidos no processamento do café. Esta problemática foi revista e o resultado conduziu á identificação de um problema complexo com várias variáveis que devem ser consideradas com o objectivo de desenvolver medidas preventivas adequadas.
Palavras-chave: Processamento de café, Carga fúngica, Micotoxinas, Exposição ocupacional. Abstract
Fungi are natural coffee contaminants and under certain environmental conditions have the potential to produce toxins. Aspergillus sp., Penicillium sp. and Fusarium spp. have been reported as the main genera present in coffee samples. Coffee production workers can be directly exposed to microorganisms and their metabolites (mycotoxins) and other dust particles via the inhalative route, which raises some health concerns regarding the occupational exposure and safety during coffee processing. This issue has been addressed and the result lead to the identification of a complex problem with several variables that should be taken into account for the development of preventive measures.
Keywords: Coffee industry; Fungal burden; Mycotoxins; Occupational exposure.
1. Introduction
According to the International Coffee Organization, there is an increase in the global coffee production (+1.4% in 2015/2016 when compared with 2014/2015), motivated by an increase in the total demand (2.1% per annum in the last four years), resulting in higher exportation rates (growth rate of 3.1% since 2010). The first work concerning occupational exposure of workers in coffee processing factories was performed around 1950 (Figley & Rawling, 1950). It was the first time that cases of asthma were described in sensitized workers on this occupational setting. In primary coffee processing units, exposed workers have an increased risk of developing airway symptoms. Previous works in secondary coffee processing units (coffee silos, coffee haulage companies, and coffee manufacturing companies) showed that workers in this settings had reduced lung function and higher incidence of chronic cough and bronchitis when compared with controls (Brera et al., 2002).
Green coffee, spices and cocoa beans are usually imported from countries thus being common the development of fungi that produce mycotoxins. These accumulate in the dust, and the handling of these raw materials can lead to their spreading in aerosols and workers exposure by inhalation. Ochratoxin A (OTA), a very well-known mycotoxin, was already shown to be present in this settings in concentrations higher than in other food processing industries. It is classified as a group 2B potential human carcinogen by the International Agency for Research on Cancer (IARC 1993).
The central goal of this review was to evaluate the current knowledge about the potential exposure to fungi, mycotoxins and dust in the coffee industry, in a perspective that emphasizes the hazards for the workers and possible prevention strategies.
1 Environment and Health Research Group (GIAS) Escola Superior de Tecnologia da Saúde de Lisboa, ESTeSL,
Instituto Politécnico de Lisboa, Av. D. João II, Lote 4.69.01, 1990-096 Lisboa, Portugal.
2Environmental Health Students, Lisbon School of Health Technology-Polytechnic Institute of Lisbon, Lisbon, Portugal 3 Centro de Investigação em Saúde Pública, Escola Nacional de Saúde Pública, New University of Lisbon, Lisbon,
2. Materials and Methods
An extensive literature search was made about coffee and coffee contamination covering papers available in scientific and technical databases. The following key words were used: coffee contamination, occupational exposure, coffee industry, fungi in coffee. As a result, we have found 35 scientific papers. Either English or Portuguese written articles presenting findings regarding coffee contamination with fungi and mycotoxins were selected for further analyses.
3. Coffee production
Worldwide, two methods of coffee processing are employed: in Colombia, Central America and Hawaii, the “wet” method is more frequently used (Figure 1), while in Brazil and Ethiopia the “dry” method (Figure 2) is the most popular (Silva et al.,2000).
Figure 1- Wet method.
Figure 2 - Dry method.
Fungi presence and OTA production during coffee production should be assessed in all stages from wet and dry production methods. Urbano et al. (2001a) analyzed 18 samples of coffee inoculated with a strain of A. ochraceus complex at different temperatures for 10 to 15 minutes as shown in Table 1. The level of OTA destruction varied from 0% to 100% depending on the time and temperature combination. Such variability could be related to the different analytical conditions or roasting process or heterogeneity in toxin distribution. The same variability should be considered when analyzing other mycotoxins already reported in coffee, such as Fumonisin B2 and Aflatoxin B1 (Nakajima et al., 1997; Noonim et al., 2009). Dark roasting was proven to be the most efficient way to reduce the amount of OTA, even if for smaller periods of time. Some explanations for the OTA reduction during roasting were suggested: physical removal of OTA with husk, thermal degradation with possible involvement of moisture or isomerization into other diastereomers (Cramer, Königs & Humpf, 2008).
Table 1- Effect of roasting on OTA reduction by toxins from different origin on coffee beans (either inoculated with toxigenic spores of Aspergillus ochraceus complex or naturally contaminated). Samples
n. Toxin origin Roasting condition reduction % References 4 Innoculation 200ºC/10-20 min 0-12 Tsubouchi et al. (1988) 2 Natural 5-6 min/dark roasting 90-100 Micco et al. (1989)
6 Natural 223ºC/14 min 84 Blanc et al. (1998)
3 Innoculation 200ºC/15 min (medium roasting) 65.6 Urbano et al. (2001a)
3 Innoculation 200ºC/15 min (dark) 93.6 Urbano et al. (2001a)
2 Innoculation 252ºC/100-190 seg 2-8 Studer-Rohr et al. (1995) 4. Occupational exposure to fungi, mycotoxins and dust
Ochratoxin A in coffee are probably due to the presence of Aspergillus sp. section Circumdati (Ciegler, 1972) and Nigri (Joosten et al., 2001) or Penicillium verrucosum (Pitt, 1987). This mycotoxin is known to be nephrotoxic for animals and humans. The biggest percentage of A. ochraceus complex contamination was found in fruit during drying and storage, showing that the major contaminations sources are likely to be the soil, equipment and drying yard surfaces. Depending on the substrates, growth conditions, and properties of the fungal
Harvested coffee cherries Drying (dried cherries) Dehullying (removing pulp and parchment) Size grading, air cleaner and sorting (green coffee beans) Storage and transport Roasting (roasted coffee) Roasting (roasted coffee) Harvested coffee cherries Pulp
removal removed by Mucilage is fermenta- tion and washing Drying (dry parchment coffee) Dehullying (removing parchment layer) Size grading, air cleaner and sorting (green coffee beans) Storage and transport
species, the spectrum of airborne molds in the indoor working environment is very broad and can lead to allergies, headache, nausea, fatigue, arthritis and other unspecific symptoms (Horner et al., 1995).
Regarding exposure of workers in farms, the toxins produced by Fusarium sp. (which are produced pre-harvest in the field) Aspergillus sp., Penicillium sp., and Stachybotrys sp. (primarily produced during unsuitable, wet storage conditions) have been shown to occur in the form of inhalable dust (Fischer et al., 1999; Mayer et al., 2007; Lanier et al., 2012). It is unclear whether the toxicity of mycotoxins inhaled in aerosolized form or bound to spores or dusts differs in comparison when the intake is via food or feed. Kelman et al. (2004) concluded that workers with airway exposure to dust contaminated with Aspergillus flavus complex had a higher risk of hepatocellular carcinoma compared with those that were not exposed (Lai et al., 2014).
In a study conducted by our research group, we aimed to evaluate the fungal distribution and prevalence of Aspergillus sections Fumigati, Flavi, Nigri and Circumdati from Coffea arabica (Arabica coffee) and Coffea canephora (Robusta coffee) green samples from a wide range of proveniences (data not published). The results obtained suggested a 64.3% contamination of the samples (n=27), and 22.2% of those presented colony counts higher than 3000 per gram of coffee. Aspergillus sections Nigri (30.1%), Circumdati (20.4%) and Nigri and Circumdati concomitantly (17.9%) were the most commonly found in the analyzed samples, through molecular methodologies (Viegas et al. 2016 submitted). Applying conventional methodologies (macro- and microscopic analysis), besides the species-complexes mentioned above, also Aspergillus sections Fumigati, Versicolores, Aspergilli and Penicillium genus were isolated and all have toxigenic potential and were previously reported as coffee beans contaminants.
This setting has been already studied in the past (Table 2). However, only recently these studies acquired a broader spectra of research, concerning not only the dust as a potential agent, but also the fungal and mycotoxin contamination present in the different units of a coffee producing unit.
Table 2 – Studies related with coffee industry and workers health effects (1979 – 2011).
Location Number
samples (n)
Tests Setting Reference
Not
described.
103 Questionaires, respiratory
function and dust samples.
Processors of roasted coffee and processors of green coffee.
(Zuskin, Valić, & Skurić, 1979)
USA 372 Dust, coffee samples,
industrial hygiene survey, lung function. Distribution, storage, roasting, grinding, packing, shipping. (Jones et al., 1982) Papua New
Guinea 69 Forced spirograms, gravimetric expiratory
assays of dust particles.
Not described. (Smith, Brott, &
Koki, 1985)
England 197 Spirometry, questionaires,
dust and microbiological air samples Warehouse, roasting, extraction and maintenance. (Thomas et al., 1991)
Italy 112 Questionaires, sensitization
to green coffee beans, serum, spirograms. Workers exposed to roasted coffee. (Larese et al., 1998) Italy Serum, 6;
Dust, 4 Aflatoxins, OTA Loading, storage and unloading. (Brera et al., 2002)
Germany 60 Questionaires, lung
function, airborne dust samples.
Coffee haulage company, silo and decaffeinating company.
(Oldenburg, Bittner, & Baur, 2009)
Tanzania 45 Cross-sectional study Parchment coffee
storage, warehouses and primary coffee factories.
(Sakwari, Bråtveit,
Mamuya, & Moen, 2011)
5. Conclusion
Studies indicate that the main toxigenic fungal genera (Aspergillus, Penicillium and Fusarium) are natural coffee contaminants, and are present from the field to the warehouse (Nakajima et al., 1997; Silva et al., 2000). It has been shown that, while the initial contamination may occur at farm level, OTA formation may happen throughout the entire chain, at every stage of production (Taniwaki et al., 2002).
According to the information gathered by the previous studies, the impact of these contaminants in the health of coffee workers should be assessed by considering the synergistic effect of particles, fungal organisms, and also mycotoxins, since they can be a part of these airborne aerosols. The Center for Disease Control and Prevention (CDC) (2016) suggests that air sampling during specific tasks, such as roasting, grinding, packaging, opening storage bins or containers with roasted coffee beans, and pouring and adding flavorings, is an important way to identify where exposures may occur and for targeting workplace interventions (e.g., engineering controls, ventilation changes) to reduce the air concentrations of the several contaminants.
Additional safety guidelines should be implemented in order to reduce exposure, such as respiratory protection equipment, and by the application of specific coatings in the floor in order to avoid particles resuspension.
6. References
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