SUPPLEMENTARY PAPERS

Organic Coffee, Protocols, Standards and Registration Procedures
Improve Your Coffee Quality by the Prevention of Mould Growth
Global Perspectives in Coffee Quality Improvement

Organic Coffee, Protocols, Standards and Registration Procedures

by K.R. Chapman, Plant Production Officer (Industrial Crops), FAO Regional Office for Asia and the Pacific, Bangkok, Thailand

The Organic Food and Beverage market, was estimated by the ITC in 1999 to be US$13 billion for 1998 in USA and US$11 billion for the group Denmark, France, Germany, Netherlands, Sweden, Switzerland and the UK in 1999.

Organic coffee is coffee grown completely free of synthetic chemicals. The land must have been free of synthetic pesticides and fertilisers for the past three years as a pre-requisite for registration. (Rice and Ward 1996).

Burnett 1998, states that Organic coffee is the fastest growing segment of the US$2.5 billion Specialty Coffee Market, although it accounts for only about 5% of the market in the United States. He points out that certified organic coffee farmers earn 15-20% more for their beans than non-organic coffee farmers. Also, he points out that Organic Coffee is not necessarily any purer than coffee grown with pesticides as the pesticides are destroyed in the roasting process, with perhaps the exception of DDT residues-although DDT is rarely used on coffee today. However, buying Organic coffee supports a system that is improving the lives and health of poor farmers and the environment and helping to provide more equity for such people. Organic coffee promotes the use of many sustainable agricultural practices, which conserve and protect and often improve the environment.

Organic coffee has been growing at a rate of 25% per year since 1993 (Griswold 2000), and in the United States, sales are far larger than Sustainable Coffee or Fair Trade Coffee.

Organic coffee is not automatically of high cupping quality as many of us, including Burnett, 1998, have noted.

Organic coffee certification is an expensive process and annual inspections may cost thousands of dollars for coffee cooperatives. (Rice and Ward 1996). Organic coffee may or may not be more labour intensive, depending on the farming system used for its production. (Lane 1994). This is an issue we hope to explore more in the Round Table meeting, along with procedures required and the practical experience of organic certification of Organic coffee in East Timor.

There is considerable debate between various players on what is Sustainable coffee and what is Organic coffee. Adam Tietelbaum from Adam’s Coffee, and members of the Organic Coffee Association (ORCA) established in 1998/99 in the United States, maintain that with regard to coffee, "If it is not organic it is not sustainable." This view is not necessarily shared by others such as the Sustainable Coffee Coalition, which describe Sustainable coffees as those coffees grown with low or preferably no synthetic chemical inputs into the system. Tietelbaum 1997 indicated that the above mission statement did not indicate which petro-chemicals qualify as ‘low toxicity’ and can be used on coffee, and that a whole new certification bureaucracy, with all its associated costs, is needed to certify Sustainable coffee.

Standards and protocols

A number of organisations have published standards, both general and specific for the certification of Organic coffee production.

The Joint FAO/WHO Food Standards Programme via the Codex Alimentarius Commission has Guidelines for the Production, Processing, Labelling and Marketing of Organically Produced Foods (CAC 32-1999); available at [email protected] from the Secretariat in Rome. These guidelines are generalised with respect to food and not specific for coffee.

The Regulating Council on Organic Agriculture of the European Union requires that organic product inspection bodies conform to guideline EN 45011 and ISO Guideline 65. Details of regulations and operation of certified organisations are given in a German GTZ booklet Local Certification of Organic Foodstuffs in Developing Countries published in 1999.

Many certified organisations for organic products are members of the International Federation of Organic Agriculture Movements (IFOAM), for example, BFA in Australia.

Certification - an example of how it works

As an example, Biological Farmers of Australia Cooperative Ltd., (BFA) is a member of IFOAM, and BFA is nationally regulated by the Australian Quarantine Inspection Service (AQUIS), of the National Government of Australia. BFA operates a Total Quality Management System, accredited to ISO 9002, while conforming to ISO 65 and IFOAM guidelines. The regulation of organic farming and processing in Australia is based on a partnership approach between AQUIS and the organic industry through various AQUIS approved organic certifiers such as BFA. Under this partnership the approach industry is responsible for setting organic standards (in consultation with AQUIS, to ensure compliance with country import requirements) and delivering services directly to exporters and operators while AQUIS is ultimately responsible for enforcement of industry standards. To do this AQUIS approves the individual organic certifier bodies (such as BFA) as well as regularly auditing the performance of those bodies to ensure they are properly carrying out their certification and inspection functions. The AQUIS-approved organic certifiers inspect organic producers, processors, exporters and products and issue Organic Produce Certificates to allow the export of complying products.

BFA’s Standard for Organic and Bio-dynamic Produce Version 3 October 2000, covers:

• Introduction
• Scope
• Definitions
• Production standard
• Livestock standard
• Processing and preparation
• Miscellaneous production systems
• Manufactured products
• Marketing and handling
• Inputs treatments and cleaning aids
• Annexes on crop production inputs and livestock treatments and inputs.

Sugar, spices, tea, coffee and herbs are specifically mentioned, along with special projects, plantations and estates.

"Villages, special projects and plantations such as tea, coffee, bananas etc., are allowed as a grouping to be certified, where there is an umbrella company or management group, which undertakes to maintain BFA certification by entering into a license agreement with the BFA Certification Office."

"Such operations may be traditional agriculture/production systems, forest or wild harvesting systems or similar traditional low-input systems, and be verified to have been compliant with this Standard for a minimum period of three (3) years prior to certification as Organic."

In addition, specific Basic Production Standards, management and extension guidelines, specific production requirements and socio-economic benefits must apply as set down in the Standard.

BFA standards are already applied to Organic Coffee produced in Papaua New Guinea for export.

Others use Biogrow-the NZ organic certification agency of which Chris May is the founding Chairman. He is a very experienced person in the field of Organic Coffee certification. Biogrow is also a member of IFOAM. Guidelines are similar. Methodology is elaborated in Mr. Anthony Marsh’s paper using a US agency.

Costs of organic certification, by certification offices or agencies, may be of major concern to potential coffee producers.

GTZ 1998 in Peru, Colombia and Bolivia estimated the cost to be around US 8 cents per lb. However, to minimise costs to small farmers, certification agencies are willing to inspect cooperatives on condition that a detailed, carefully documented internal supervision system is in place, so random inspections of a sample of farmers can be used to cover the whole group. (ICO, 2000).

In some countries such as India, costs of certification are being minimised by setting up a similar arrangement to that of AQUIS in Australia, and approving and monitoring/auditing organic certified organisations/agencies.

There are many organisations/agencies involved in the certification of organic produce and the above are just mentioned as examples; recommendation of any particular agency is not implied.

A number of these points relating to costs and practical certification issues will be raised by other speakers at this coffee round-table meeting. In particular Mr. Anthony Marsh will be detailing the East Timor experience.

References

Biological Farmers of Australia Cooperative Ltd. (BFA). 2000. Standard for Organic and Bio-dynamic Produce. Version 3 October 2000.

Burnett. 1998. Mexican Coffee Cooperative Seeks Better Prices, Working Conditions. Sustainable Development Reporting Project-Mexican Coffee Cooperatives.
www.lanic.utexas.edu/project/sdrp/coffee.html

CODEX Alimentarius Commission. 1999. Guidelines for the Production, Processing, Labelling and Marketing of Organically Produced Foods (CAC 32-1999). [email protected] OR FAO/WHO Secretariat, FAO, Rome.

Griswold, D. 2000. The Future of Sustainable Coffee. In, Fall Coffee and Tea Handbook. Nov. 2000. The Gourmet Retailer. www.gourmetretailer.com

GTZ. 1999. Local Certification of Organic Foodstuffs in Developing Countries. Jochen Neuendorff and Ulich Sabel-Kochella. A GTZ publication.

ICO. 2000. Organic Coffee-Summary of a Round Table Discussion on Coffee Produced by Organic Farming Methods and the Position in the Year 2000. ICO publication.

Rice, R.A., and Ward, J.R.1996. Coffee, Conservation and Commerce in the Western Hemisphere. In, How Individuals and Institutions Can Promote Ecologically Sound Farming and Forest Management in Northern Latin America. Natural Resources Council and Smithsonian Migratory Bird Centre, White Paper. Washington D.C.

Tietelbaum, A. 1997. Sustainable Coffee. Adam’s Organic Oracle No.2 Spring 1997. www.adamsorganiccoffees.com/oracle2.htm

* The opinions expressed in this paper are those of the author’s alone and do not imply any opinion whatsoever on the part of the FAO/UN.

Improve Your Coffee Quality by the Prevention of Mould Growth

by European Coffee Co-operation, (AFCASOLE, CECA, EUCA, ECF, EDA, ASIC, ISIC, PEC)

Good quality coffee receives bigger payments. In order to protect your revenue from coffee, it is essential that you provide only the best quality commodity available.

Use good agricultural practices to achieve results

• Cherries that have dried on the tree and those that have fallen to the ground are known to be susceptible to mould growth and therefore these should not be picked.
• Process cherries as quickly as possible. Avoid storage of cherries, especially ripe and over-ripe ones, as any period of storage increases the likelihood of mould growth.
• Do not dry on bare soil. Mould spores from previous lots are known to remain on the ground and this could result in clean cherries being contaminated during drying.
• Protect cherries during drying from rain and night dew.
• Avoid re-wetting of drying cherries.
• Protect dried cherries from the moisture and rain.
• Clean coffee from all husk material-more than 90% of mould comes from husks in sun dried cherries.
• Remove as many defects (husks, un-hulled cherries or mouldy beans) as possible.
• Keep cleaned dried beans separate from discarded material.

During processing

• Site processing plant in good conditions.
• Provide good drying facility-turn regularly.
• Prevent recontamination by avoiding contact with dust, husks, and dirty bags.
• Do not store cleaned, dry, graded coffee near rejects and husks as cross-contamination may occur.
• Keep moisture content as uniform and as low as possible-below 13%.

During transport and storage

• Cover bags during transport and storage to prevent re-wetting.
• Load and unload trucks or containers only in dry weather or under cover.
• Do not use damaged containers and prevent water leaks.
• Make sure that pallets or wooden floors of trucks and containers are dry.
• Store coffee in well-ventilated and leak-proof warehouses. Store away from the walls.
• Cover bags/beans in container with waterproof or water-absorbent cover to prevent re-wetting from condensation.
• Provide good quality control tests and ensure that they are adhered to, especially to check for moisture and defects.

September 2000

Global Perspectives in Coffee Quality Improvement

by ¹R. Viani, FAO Consultant, Corseaux, Switzerland

Abstract

Coffee is drunk for pleasure, its flavor is, therefore, the most important quality criterion; it is the sum of different parameters all coming into play during primary production of green coffee:

• plant genetics, with the choice of variety based on resistance to pests, productivity, morphology, and, not to be neglected, liquoring characteristics;
• orchard practices, particularly at harvest, when only ripe fruits should be selected;
• primary processing, where the choice between dry and wet processing must depend, not only on local climate, but also on end-use of the product (filter, espresso or soluble coffee).

All the downstream operations (storing, roasting, brewing, etc.) can only preserve cup quality. Besides its flavor characteristics, other factors such as environmental impact, purity and safety are becoming important for the global evaluation of coffee quality. The presentation shall review all these factors (taste testing, measures of physical parameters, chemical and microbiological purity, etc.), and discuss their impact on consumers and regulators in consumer countries.

Introduction

Each year 6 million tons of coffee are produced, more than 80% to be consumed as roasted and ground (R&G) brews, while a little less than 20% goes into the production of soluble coffee.

Within the roasted and ground coffee are different types of brews, ranging from the crystal clear filter coffee to thick and foamy espresso, 3-4% of total consumption, but fast-growing worldwide. Within the soluble coffees we find liquid coffees, becoming important particularly in the Far East, and powder coffees, picking up a ‘share of the throat’ especially in the tea-drinking countries of the world.

The required quality depends on the use, which does not mean that any coffee should finally find a buyer. Unfortunately this is sometimes the case and poor quality coffee finds its way onto the market.

Quality

Quality at production

Quality of green coffee depends on:

Climate, soil, species and breeding characteristics. In breeding programs, beside resistance to diseases, productivity, and morphological traits, cup quality must always be considered.

Harvest. The most important parameters are ripeness of cherry and time to processing.The best coffee may give an astringent or impure cup, if harvested immature or if kept too long before processing.

Processing to green beans, simplified here as:

• dry-processing with development of rich body and aroma;
• wet-processing, for fine aroma and acidity.

When climatic conditions allow it (dry weather at harvest), dry processing of Arabica coffee adds to the body of the liquor, a characteristic appreciated by the fast growing espresso segment. All downstream operations can at best only maintain the liquoring qualities attained by green coffee, never improve or correct them.

Quality for the roaster

Quality evaluation for the roaster requires:

• reliability of supply;
• uniform low moisture and agreed defect count;
• regular roasting characteristics;
• cup quality.

Quality for the consumer

Although consumers generally do not possess a refined vocabulary to explain if their likes or dislikes for a particular cup of coffee, which is often either ‘bitter’ or ‘good’, their consumption patterns are strongly influenced by taste and smell-top quality coffees always find consumers who can afford them.

In the recent years, environmental (green issues), such as Organic, Fair Trade or Sustainable coffees have also become criteria of choice for the consumers. These new quality criteria can bring benefits for the planters who receive a guaranteed minimum price, or a bonus for above-standard quality and advice on quality control and market needs. Roasters also benefit by ensuring that the farmers produce coffee according to the required standards, and may sell their product under a special label.

Quality for the regulator

In the interest of consumer protection, the regulator acts from purity and from safety considerations.

Quality parameters for the food technologist

Many hundreds of the compounds formed at roasting by the chemical interaction between the carbohydrates, chlorogenic acids, amino acids and other reactive compounds present in the green bean have been identified. Differences are minor, mainly quantitative, and the complete chemical profile, cannot be used to explain why one coffee gives a better cup than another. (Viani, 2000).

Aroma

The most important parameter in the appreciation of quality is the organoleptic quality of the cup, mainly due to the volatile substances present, accounting for no more than 0.1% of the total, while non-volatile components can only explain acidity and bitterness. (Vitzthum, 1998).

Among the many hundreds of components discovered in the aroma complex (most of which are unimportant for flavor), the active smelling compounds have now been identified by sniffing all the components coming out of the column outlet of a gas-chromatograph (Figure 1). The most intense smelling components-the majority already present in green beans, may then be identified by successive dilutions of the aroma until only a few can still be detected (Table 1).

Figure 1: Sniffing profile of a R&G coffee (The vertical axis gives the abundance - Thresholds are indicated on the peaks)

Figure 2: Star-diagram profile of a coffee infusion

Table 1. Main odorants in a coffee brew (µg/l)

Aroma	Arabica	Robusta	Threshold in water
(E)-ß-Damascenone*	1.3	1.5	0.00075
3-Mercapto-3-methylbutylformate	5.5	1.5	0.0035
2-Furfurylthiol	19.1	39.0	0.01
Methanethiol	210	600	0.2
3-Methylbutanal	550	925	0.35
Methylpropanal	800	1350	0.7

* It may contribute to the process flavor of soluble coffee.

Table 2. Main off-flavors of coffee

Off-flavor	Responsible chemical(s)	Threshold in water (µg/l)
Medicinal, ‘rioy’	2,4-6-Trichloroanisole	0.001
Earthy, Robusta	(-)2-Methylisoborneol*	0.0025
Musty	Geosmin	0.005
Fruity, rotten, stinker	Ethylesters of 2- and 3-methylbutanoic, and cyclohexanoic acids	5,000-10,000

* (-)2-Methylisoborneol represents some 60-70% of the characteristic Robusta flavor (Vitzthum, Weisemann, Becker & Köhler, 1990), and a patent to reduce its content to below its threshold level has been taken (Becker, Weisemann & Schlabs, 1989).

A technique which proves very useful in the evaluation of new processes, particularly in soluble coffee manufacture, indicates the flavor evaluation by a trained test panel in the form of a star diagram, where notes like burnt, cooked, fruity are profiled semi-quantitatively. The sample analyzed in Figure 2, has been characterized by the panel, as possessing an intense overall aroma and flavor, a roasted/burnt/smoked note, and a stale/oxidized off-flavor.

Quality parameters for the roaster

The European Contract for Coffee states that, "all goods contracted for shall be of sound merchantable quality..." A new version of the contract, including a reference to excessive moisture as not being in conformity with the quality requirements, is under study by the European Coffee Trade Federation (Anon. 1997).

Both analytical (moisture, defect count) and organoleptic (taste testing) criteria are available and are used by the roasters for the choice of the green coffee qualities they use in their blends:

• Specialty coffee roasters, espresso in particular, need special qualities (e.g., body from top dry-processed Arabicas, absence of immature beans, which make the cup astringent and metallic);
• Major roasters need large quantities of reliable constant good quality coffees, particularly Robustas.

Moisture

Several different ISO standards are available for the measurement of moisture. They do not all give the same results, thus contradicting the idea of standardization. In the last meeting of ISO TC34 (Agriculture) SC 15 (Coffee), (Anon. 1999) it has been agreed:

• to select among the methods already available the most suitable to be used as reference;
• to standardize a rapid method, based on devices, such as Sinar, Dickey-Jones or Dole, which have become common in the trade.

Defect Count

Many different grading systems are used in the trade of coffee and at the last meeting of ISO TC34 (Agriculture) SC 15 (Coffee) a revision of ISO 10470, simplifying it, was proposed (Anon. 1999):

• by considering together both dry and wet processed Arabicas and Robustas;
• by classifying defects according to their incidence (1) or (0) on the organoleptic profile of the cup, and on the economic aspects;
• by indicating if the defect is serious (s), so that it could be applied generally in the trade.

The weight of each defect is also being reassessed in the light of new information available, and the following defects are now considered as serious:

• Organoleptically-beans that are black, partly black; dark brown, amber, with foxy silverskin, sour, stinker, spotted bean; pergamino, bean in pergamino; pod, husk fragment; mouldy bean.
• Commercially-bean fragments, bean in parchment; large, medium, small sticks; large, medium, small stones; soil agglomerates; foreign matter.

That new criteria must be considered in the evaluation of defects has also been agreed by the London International Financial Futures and Optional Exchange (LIFFE) classification of Robustas (Anon., 1999), stating that "... coffee is not tenerable if:

• it has more than 450 defects per 500 g;
• it is unsound;
• it contains more than 10% passing through a round screen 12;
• in respect to a lot graded (effective from 1 February 2000), it has more than 5 fully mouldy or 10 partially mouldy beans in combination thereof, such that the total exceeds the equivalent of 5 fully mouldy beans per 500g."

Liquoring

The techniques of organoleptic evaluation, useful in the development of new processes, would be too cumbersome for the roaster wishing to ensure routinely the wholesomeness of the raw material used. A simple and clear vocabulary is in general sufficient to a trained expert panel in the day-to-day liquoring routine:

For Arabica, flavor can be defined as the sum of aroma plus acidity plus body, where

• flavor is the taste of a sound, clean Arabica coffee, not the level of roastiness;
• aroma is the smell of a sound, clean, freshly brewed Arabica coffee;
• acidity is a sharp and pleasing taste as opposed to a sour taste, which may indicate signs of fermentation. Acidity is best appreciated in a low roasted filter coffee;
• body is the viscosity, fullness and weight in the mouth, ranging from thin and watery to thick and heavy. It is an important characteristic particularly in espresso coffee, where it is associated with a good body, as shown by the comparison of a correctly prepared cup with a poorly prepared one when using the same blend.

The panel must also recognize a few undesirable flavors and all off-flavors, such as:

• undesirable flavors of Arabica-green/grassy, cereal/woody/papery, baggy;
• off-flavors of Arabica-chemical/medicinal, hard/metallic, earthy, fermented, mouldy/musty.

The flavor of a Robusta must be neutral/bitter, and devoid of woody and rubbery notes.

Undesirable/off-flavors of Robusta are: green/grassy, chemical/medicinal, and earthy, fermented or mouldy/musty.

The organoleptic profile is usually obtained by one of two techniques:

• by oral agreement within an expert tasting panel after open discussion; this technique is the most effective if the aim of the panel is to identify the top quality coffees;
• by the average of independent results (either blind or by comparison with a reference), of members from the tasting panel. This technique is useful for maintaining a good constant average quality in industrial production.

Quality parameters for the regulator

Purity

Lack of physical criteria, such as defect counting, has hindered the objective evaluation of soluble coffee, particularly when imported from producer countries, where no control of stocks could be easily achieved, and only taste testing could give some indication of the quality of the product.

Findings, showing that there was a precise carbohydrate fingerprint for pure soluble coffee (Blanc, Davis, Parchet & Viani, 1989), led to the establishment of an ISO analytical standard (Anon., 1997), and to national Codes of practice in the United Kingdom (BSCPIA/BSCMA, 1995) and France (Syndicat Français des Fabricants de Café Soluble, 1999), which, by indicating maximum acceptable levels of certain carbohydrates, have helped in reducing the import of adulterated products into the European Union (Table 3).

Table 3. Tolerable control limits for carbohydrates in soluble coffee

Indicator Carbohydrate	Maximum Content in Pure Coffee (%)	Control Limit (%)
Total glucose	2.1	2.6
Total Xylose	0.4	0.6
Free Fructose	0.6	1.0

The question of soluble coffee purity has become particularly important in Eastern Europe after the opening of the markets in the 1990s, and must still be solved, particularly after a link between relatively high contents of Ochratoxin A (see following section), and adulteration has been found. (Pittet, Tornare, Huggett & Viani, 1996).

Safety

The possible presence of contaminants, such as pesticides (McCarthy et al., 1991), polycyclic hydrocarbons formed at roasting (Maier, 1991), or paraffins from the coffee bags (Grob, 1991), have at various time alerted authorities until analytical data were made available indicating that the safety problem had been solved.

Mycotoxins, Ochratoxin A in particular, (a nephrotoxic and carcinogenic substance), may be formed during cherry processing, storage or transport of the beans, if moisture is uncontrolled, and will still be present in the cup (van der Stegen et al., 1997), even if it is partially destroyed during roasting (Blanc, Pittet, Muñoz-Box & Viani, 1998). A multicenter project is active to solve this new challenge (Anon., 1999).

Conclusions

Both fine organoleptic and analytical criteria are now available and are used in the following ways by roasters in the selection of the coffee types used in their blends:

• Specialty coffee roasters, espresso producers in particular, need special qualities, such as a rich body from the best dry-processed Arabicas, and the absence of immature beans, which make the cup astringent and metallic.
• Major roasters need large quantities of reliable supplies of constant, good quality coffee, particularly Robustas.

Regulators need to be assured that the product entering the market is neither adulterated nor contaminated.

Finally, consumers wish to drink a good, not bitter cup, which they can recognize even if they may have difficulties in describing it!

References

Anon. 1997. ISO 11292, Instant coffee-Determination of free and total carbohydrate content.

Anon. 1997. Standard contracts, European Coffee Federation, Brussels.

Anon. 1999. Enhancement of coffee quality through prevention of mould formation, Common Fund for Commodities, Amsterdam.

Anon. 1999. Exchange contract No. 406, Robusta coffee futures contract, ECF, Brussels.

Anon. 1999. ISO/TC 34/SC 15 Coffee-Draft proposal for the revision of ISO 1047, Green coffee-Defect reference chart.

Anon. 1999. ISO/TC 34/SC 15 Coffee-Draft Report of the 13th Meeting, Paris.

Becker, R., Weisemann, C. and Schlabs, B. 1989. KJS EPA No. 0 425 824.

Blanc, M., Pittet, A., Muñoz-Box, R. and Viani, R. 1998. J. Agric. Food Chem. 46, 673.

Blanc, M.B., Davis, G.E., Parchet, J.M. and Viani, R. 1989. J. Agric. Food Chem. 37, 926.

Bobillot, S., Brévard, H., Feria-Morales, A., Krebs, Y., Memound, A.F. 1997. 17th ASIC, Nairobi, 214.

BSCPIA/BSCMA. 1995. Code of practice for the soluble coffee industry in the UK.

Grob, K. 1991. Z. Lebensm. Unters. Forsch. 193, 213.

Maier, H.G. 1991. Café Cacao Thé 35, 133.

McCarthy, J.P. et al. 1991. 14th ASIC, S. Francisco, 175.

Pittet, A., Tornare, D., Huggett, A. and Viani, R. 1996. J. Agric. Food Chem. 44, 3564.

Syndicat Français des Fabricants de Café Soluble. 1999. Code de bonne pratiques concernant l'authenticité du café soluble.

Van der Stegen, G. et al. 1997. Food Add. Contam., 14, 211.

Viani, R. 2000. Coffee, In Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim.

Vitzthum, O.G. 1998: Thirty years of coffee chemistry research, Annual Meeting of the ACS, Boston, MA.

Vitzthum, O.G., Weisemann, C., Becker, R. and Köhler, H.S. 1990. Café Cacao Thé 34, 27.