ICS 67.140  
 
Reference number
DRS 259: 2020
© RSB 2020
  
 RWANDA 
STANDARD  DRS
259
Second edition
2020 -mm-dd
Prevention and reduction of mycotoxins  
contamination in coffee  — Code of 
practice  
   
DRS 259: 2020  
©RSB 2020  - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2020  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without  
prior written permission from R SB. 
Requests for permission to reprodu ce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 259: 2020  
iii                ©RSB 2020 - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ...................... iv 
1 Scope  ................................ ................................ ................................ ................................ ................ 1 
2 Normative references  ................................ ................................ ................................ ....................... 1 
3 Terms and defi nitions  ................................ ................................ ................................ ...................... 1 
4 Recommended good practices  ................................ ................................ ................................ ........ 4 
4.1 Pre-harvest  ................................ ................................ ................................ ................................ .......4 
4.2 Harvesting ................................ ................................ ................................ ................................ ......... 4 
4.3 Post -harvest  ................................ ................................ ................................ ................................ .....6 
4.4 Drying of sorted and processed coffee beans  ................................ ................................ ................ 7 
4.4.1  Recommended measures to dry the coffee beans  ................................ ................................ ......... 7 
4.5 Storage, transportation and trading  ................................ ................................ ................................ 8 
4.6 Shipping  ................................ ................................ ................................ ................................ ..........  10 
 DRS 259: 2020  
©RSB 2020  - All rights reserved                  iv 
 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by Rwanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratifie d by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 259 was prepared by Technical Committee RSB/TC 035, Coffee and derived products . 
This second  edition cancels and replaces the first edition ( RS 259: 2014 ), which  has been technically revised.  
Committee membership.  
The following organizations were represented on the Technical Committee on Coffee and derived products 
(RSB/TC 035) in the preparation of this standard.  
Rwanda  Standards Board  (RSB) – Secretariat  DRS 259: 2020  
v                ©RSB 2020 - All rights reserved  
 Introduction   
Ochratoxin A (OTA) is a toxic fungal metabolite classified by the International Agency for Research on Cancer 
as a possible human carcinogen (group 2B). JECFA established a PTWI of 100 ng/kg bodyweight for OTA.  
OTA is produced by a few specie s in the genera Aspergillus and Penicillium. In coffee, only Aspergillus 
species, specifically A. ochraceus and related species ( A. westerdijkiae  and A. steynii ), A. niger and related 
species, and A. carbonarius are involved. OTA is produced when condition s of water activity, nutrition and 
temperature required for growth and biosynthesis are present.  
Coffee cherries may be processed under two basic systems: a) the dry processing system which produce s 
what is called natural coffee or dried coffee cherry (the  seed is enclosed in the whole fruit) and b) the wet 
processing system that generates what is called parchment coffee, where the seed is enclosed in the inner 
integument or endocarp.  
In the dry processing of natural coffee, the whole fruit is either direct ly sun dried, on bare soil, bricks, tiles, 
concrete or even asphalt, or dried using a combination of sun and mechanical drying (particularly on  more 
technologically advanced farms).  
In wet processing, the fruit parts are mechanically separated, giving the pulp as by -product and the parchment 
as the main product. The latter is coated with mucilage, which can be degraded by fermentation and t hen 
washed or mechanically removed directly, without fermentation. After removing or not removing the mu cilage, 
the par chment is usually sun dried, in a drying yard, or on suspended tables with many variations and 
technological innovations. Sun and mechanical drying can be combined and used together.  
After processing, the dried coffee can be stored, separated from the frui t tissues by hulling and passed  
through sizing (grading), sorting, polishing, cleaning and bagging, before being sold.  
Coffee roasting can remove a very significant percentage of OTA. Depending on the roasting process, 65 % - 
100 % reduction of OTA can be achieved.  
While this code of practices is focused on the reduction of OTA contamination in wet processing syst em, 
which is the primary food safety issue in the production of green coffee bean, industry food safety 
programmes shall also effectively manage o ther potential hazards associated with the production, processing 
and handling of coffee.  
 
 
 
 
 
 DRS 259: 2020  
1                ©RSB 2020 - All rights reserved  
 Prevention and reduction of mycotoxins contamination  in coffee —Code 
of practice  
1 Scope   
This Draft Rwanda standard provides guidelines for prevention and reduction of mycotoxins in  coffee ( Coffe a 
arabica  and Coffea canephora ) production chain . 
2 Normative references   
The following documents are referred to in the text in such a way that some or all of  their content constitutes 
requirements of this document.  For dated references, only the edition  cited applies. For undated references, 
the latest edition of t he referenced document (including any amendments) applies.  
RS CAC/RCP 1, Code of practice —General principles for food hygiene  
3 Terms and definitions   
For the purposes of this standard, the follow ing terms and definitions apply . 
3.1 
coffee cherry  
fresh, com plete fruit of the coffee tree  
3.2 
floating (or floats) coffee  
cherry coffee of low density, buoyant in water  
3.3 
mucilage  
common word to describe the slimy layer found between the pulp and adhering to the parchment inside a 
coffee cherry, but not removed by pulping. Not present in unripe and overripe coffee  
3.4 
pulp  
part of the coffee cherry composed of the external exocarp and most of the internal mesocarp (mucila ginous  
tissue)   
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 3.5 
bean in parchment  
coffee bean entirely or partially enclosed in its parchm ent (endocarp, pergamino)  
3.6 
defects  
general term for common undesirable particles, which can include various types of beans, parts of be ans, fruit  
tissue and foreign matter, found in green and roasted coffee beans  
3.7 
green coffee bean  
dried seed of the coffee plant, separated from non -food tissues of the fruit  
3.8 
parchment (or Parch) or endocarp  
coffee fruit endocarp located between the fleshy part (pulp) and the silver skin. It is a thin, crum bly paper -like 
covering left on wet -processed beans after pu lping and fermentation, removed during hulling.  
3.9 
gleaning (or Sweeping)  
coffee fruit found lying on the ground beneath coffee bushes, detached during harvest or abscised du ring 
development  
3.10 
dry process  
treatment of coffee cherries consisting in drying them, either under sunlight or in drying machines, to give husk 
coffee. This is usually followed by mechanical removal of the dried pericarp (husk) to produce “natu ral” green 
coffee  
3.11 
wet process  
treatment of coffee cherries consisting of the mec hanical removal of the exocarp (pulp) in the presence of 
water  DRS 259: 2020  
3                ©RSB 2020 - All rights reserved  
 3.12 
pulping  
technological operation used in the wet process to remove the pulp (exocarp) and as much as possible  of the  
mucilage (mesocarp) by mechanical means  
3.13 
fermentation process  
treatment intended to digest the mucilaginous mesocarp adhering to the parchment of the pulped coffe e, 
allowing its elimination by washing  
3.14 
washing  
technological operation intended to remove by water all traces of the mucilaginous mesocarp from the  surface 
of the parchment  
3.15 
drying of parchment coffee  
technological operation to reduce the moisture content of parchment coffee to a level that allows hu lling under  
satisfactory technical conditions and that will not be detrimental to further storage of t he coffee.  
3.16 
hulling  
removal of the dried endocarp of parchment coffee to produce green coffee  
3.17 
polishing  
technological operation to remove the residual silverskin (perisperm) from green coffee by purely me chanical  
means  
3.18 
sorting  
technological operation intended to remove foreign matter, fragments of coffee and defective beans from  
green coffee   
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 3.19 
roasting  
heat treatment that produces fundamental chemical and physical changes in the structure and composit ion of  
green coffee, bringing about dar kening of the beans and the development of the characteristic flavour of  
roasted coffee  
4 Recommended good practices  
Mycotoxins are sec metabolites produced by toxigenic moulds, which can infect coffee at any stage of  
production chain. The most known myctoxi n that contaminates coffee is ochratoxin A (OTA ) 
4.1 Pre-harvest  
4.1.1   Infection on the plant may involve two different contamination routes: either  through the flowers 
without visible sign, or by insect invasion such as the coffee berry borer (CBB)  (Hypothenemus hampei), that 
can carry spores to the fruit by making holes in the cherries and one or more  tunnels in the beans leaving 
visible signs.  
4.1.2  Recommended practices to reduce the development and spore load from OTA --producing fungi on  
coffee p lants and beans are:  
a) keep coffee plants vigorous, through the regular use of good agricultural practices (GAP) at the pro per 
time, such as weeding, improving soil texture, pruning, fertilization, pest and disease control, and  
irrigation;  
b) do not use overhea d irrigation during the flowering period. This could augment normal spore dispersal  
rates and increase the chance of infection of beans by OTA producers;  
c) , encourage the  use of the integrated pest management (IPM) programme  such as use of traps (such as 
alcohol traps) for Hypothenemus hampei control before harvesting  
d) avoid disposal of uncomposted organic wastes, from coffee or any other source, in or around the  
plantation.  
e) Avoid disposal of c offee seeds and seed -associated material, such as dust, earth, parchment and other 
seed  processing residues  in or around the plantation. that can allow proliferation of OTA producing fungi.  
4.2 Harvesting  
4.2.1  The harvesting method chosen on any farm shall be applied to avoid fungal contamination. It should 
be in conjunc tion with the requirements of the  processing method, required quality, economic considerations 
and labour availability  
4.2.2  Four basic harvesting systems may be adopted:  
a) multi -pass selective picking (finger picking), where only ripe cherries are harvested ; and is the most 
recommended harvesting system in Rwanda  DRS 259: 2020  
5                ©RSB 2020 - All rights reserved  
 b) single -pass stripping, where all branches bearing fruit are harvested at once;  
c) multi -pass stripping, where only branches bearing mainly ripe cherries are harvested;  
d) mechanical harvesting, where diff erent types of machines are used to harvest fruit all at once.  
4.2.3  Besides above  basic main harvest systems, the following additional procedures may be used : 
a) during  ‘collection of prematurely ripe cherries during fly harvest’  
b)  collection (gleaning or sweeping) of cherries that fall on the ground or are left on the plants duri ng 
harvest.  
c) Collected cherries from ground should be handled and processed  separately from the other cherries  
d) berries that fall onto the ground should not be collected, particularly in humid conditions, as fungal growth 
may occur, which can give rise to OTA contaminati on. However, brief contact with the ground is not 
problematic but can become so if the contact period lengthens.  
e) In wet or humid climates, onl y collection from the ground on the same day should be considered 
acceptable. If it is necessary to harvest beans that have fallen onto the ground, these should be st ored 
separately until they are processed, to avoid the risk of contaminating the rest of t he crop.  
f)  Care should be taken to ensure that any fallen berries that are collected are rapidly subjected to t he 
processing and drying stages, as these commodities may have a higher likelihood of fungal growth.  
4.2.4  The harvest should be started as soon as there are sufficient ripe cherries for it to be economically  
viable. When the right time to commence harvest is decided, the following should first be carried ou t: 
a) remove weeds, fallen cherries and brush from the proximity of the trees before harvest;  
b) where possible, place mats, canvas or tarpaulins beneath the trees to prevent contamination by old f allen 
cherries; and  
c) ensure that there are adequate arrangements for the subsequent storage and processing of the crop, s o 
that conditions favour mould growt h or other damage are avoided;  
4.2.5  Coffee cherries should be processed as soon as possible after harvesting. The harvesting rate,  
processing performance and labour availability should follow the pace of the drying rate.  
4.2.6  Coffee ready to be processed  should be uniform and not of mixed categories i.e. wet with dry coffee  
or pulpable with not pulpable. Prior to processing low quality cherries (e.g. unripe or overripe fru it, or fruit that  
has coffee berry disease) should be removed.  
4.2.7 Cherries  sorting and floating shall be  done   
4.2.8  Out sorted  cherries shall be processed separately .  
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 4.3 Post -harvest  
4.3.1  Senescence and changes follow once coffee fruit is detached from the plant. The post -harvest period 
is characterized by initial, transitional and final phases.  
4.3.2 The transportation of cherries from farm to coffee washing station should be done in a manner to 
avoid contamination Once cherries reach the coffee washing station, processing should start immediat ely 
within 8  hours after harvesting as per good processing practices,   
4.3.3 Water used in processing should be clean  
4.3.4 Factors that need to be controlled are as follow:  
a) any equipment should receive regular maintenance, to reduce the possibility of failures which could delay 
processing and compromise coffee quality and safety and the following should be considered:  
1) before the beginning of the crop season: clean, reassemble and lubricate the processing 
equipment;  inspect the installation and check it is operational, so that there is enough ti me for 
repairs if any  problem occurs; and  
2) at the end of the crop season: clean, repair, lubricate, dust all equipment and protect from water.  
Check pulping surfaces for wear.  
b) provide proper orientation/training to the workers and define their responsibilit ies. In addition,  define 
quality and acceptability criteria, the monitoring procedures and frequencies, and the corrective me asures 
for each key element of the process, regarding:  
1) cherries – maximum acceptable proportion of immature and over -mature/tree -dried cherries.  
2) pulping – acceptable proportion of un -pulped cherries and nipped beans; cost -benefit to increase 
size uniformity of the cherries and effectiveness of skin removal. The efficiency of the operation 
can be improved based on the various estimates  of the monitoring the quality and safety of the 
product.  
c) where applicable, fermentation should be as short as possible ( between 12 hours and 36 hours), to get 
the mucilage degraded and the beans washable. Monitoring procedures and frequencies should be 
established as well as the type and level of inoculum (in the in -coming cherry) and ambient temperature; 
and 
d) fruit-flies should be  minimized;  as high populations can affect fermentation.  
e) If retuned to the processing line, secondary cherry coffee  (outsorted c herries) should have   a specific 
control program; i.e. good drying practices should be applied, such as maintenance of separate facil ities 
for drying; and  
f) washing protocols should be documented and implemented    DRS 259: 2020  
7                ©RSB 2020 - All rights reserved  
 4.4 Drying of sorted and processed coffee beans  
4.4.1  Recommended measures to dry the coffee beans  
For efficient drying, the following should be considered:  
a) the drying yard should be located away from contaminant sources such as dusty areas and should 
receive maximum sun exposure and air circulation, during most of the day, to speed up the drying of the 
beans. Shady and low areas should be avoided;  Mechanical driers may be used  as complementary after 
sun-drying,  
b) To ensure uniform drying, parchment should continuously turn to avoid possible growth of 
microorg anisms. When harvest coincides with a rainy or high humidity season, measures to optimize 
drying should be adopted . 
c)  During drying, moisture content of parchment should be monitored and kept below 12.5%  
d) the surface for the drying yard should be chosen acco rding to the climate of the region, cost and quality of 
the dried product, as any type of surface has advantages and disadvantages. Bare soil is not appropr iate 
for rainy areas. Plastic canvas gets humid under the coffee layer, promoting fungal growth. In rainy or wet 
regions coffee shall be covered and re -spread, once the surface has dried;  
e) the drying surface should be cleanable, in order to avoid picking up taints;  
f) drying tables should be raised/ risen at 75 cm above the ground to allow uniform air circul ation;  
g) the pace and total time of the harvest should be based on the available area of the drying yard and the 
average time necessary for drying, considering both good and bad weather;  
h) the following practical measures should be incorporated into the drying  process:  
1) dry coffee only in thin layers, 3 cm - 5 cm in depth which is equivalent to 25 - 35 kg/m2 of fresh 
parchment.  
2) turn over the coffee layer constantly during the day time to allow faster drying, to reduce the risk  
of fungi growing and help to produ ce a better quality product ; 
3) allow for the appropriate ventilation of the wet coffee during the night in order to avoid 
condensation. After one day of drying, the coffee can be heaped and covered at night or during 
rainy weather, to avoid re -wetting;  
4) do no t mix different types of coffee nor coffee from different days of harvest. Use a specific 
identification for each one of them to identify each type of coffee and day of harvest;  
5) protect the drying yard area from animals, which can be a source of biological  contamination for 
the drying coffee ;  
©RSB 2020  - All rights reserved                  8 
 6) regularly control coffee berry borer (CBB)and other pest populations, using integrated pest 
management in drying yard;  
7) monitor the drying process regularly (< 12.5 %). Start taking samples from different points of each  
lot, two or three days before it is expected to be fully dry and continue re -evaluating it daily until 
it reaches the desired moisture content.  
8)  Instrumental measurements should be adopted at field level. Moisture content measures should 
be calibrated to ISO 6673 method; and  
i) provide a clear and practical training for drying yard workers, including adequate use of moisture 
measuring equipment;  
j) repair, clean, protect and keep equipment  in a clean storage area until the next season.  
4.5 Storage, transportation and trading  
4.5.1  Properly identified lots  of dried parchment coffee should be stored, at the farm level or in out -of-farm 
warehouses, in bulk or in clean bags under appropriate storage conditions.  
4.5.2 During storage, transportation and trading , the coff ee shall also be protected from re -wetting, 
degradation and cross contamination.   
4.5.3 In long term storage conditions, relative humidity sh all be kept between 60% and 80%  
4.5.4  Moisture in the storage place can originate from damp floors and walls, rain  (wind -driven or  through 
leaks), dead air, and the mixing of dry with wet coffee. Appropriate storage facilities, the use of good  storage 
practice and regular monitoring are recommended to prevent  or reduce problems.  
4.5.5 Coffee beans  with black and sour defects may contain the highest levels of OTA.  and should not  be 
re-blended into clean coffee or sold directly unless representative sampling plan and direct OTA  analysis has 
shown them to be acceptable.  
4.5.8  Authorities, through regulatory and non -regul atory mechanisms can  enforce and influence practices 
in order to guarantee that producers reliably operate in a way as to assure the  product safety.  
4.5.9 Stakeholders should adopt procedures to protect coffee in each part of the chain  by ensuring the 
following:  
a) Establish minimum hygiene requirements and a rapid assessment method (including a sampling method 
with representative sub -sample of the in -coming lot for moisture content determination, defect levels, 
general physical quality as sessment and visual or smell signs of mouldiness).  
b) the warehouse design and structure should be adequate to maintain dryness and uniformity of the stor ed 
coffee.  
1) the desirable characteristics are: cement floor with a damp proof course; not subject to flood ing; 
water pipelines properly located to avoid wetting coffee in case of plumbing problems; water 
proof windows and roof and a high ceiling to allow good air circulation.  DRS 259: 2020  
9                ©RSB 2020 - All rights reserved  
 2) do not expose stored coffee to direct sunlight nor store it near heating sources, to avoid the 
possibility of temperature differentials and water  migration  
c) the operation of a storage facility shall be optimised to prevent cross contamination, the reintrodu ction of 
moisture and to allow the best execution of receiving, sale and value -added operations that will preserve 
the coffee quality until it is sold to the next stakeholder in the production chain. The main 
recommendations are:  
1) record initial condition and age of the received stocks;  
2) arrange the coffee bags on pallets and away from walls , to allow good air circulation;  
3) implement cleaning and maintenance programmes in order to ensure that storage facilities are 
periodically inspected, cleaned and renewed;  
4) check coffee weevil in the warehouse, using integrated pest management;  
5) farms and other operations should separate coffee types. This requires planning of the storage 
area and adoption of a labelling system.  
6) Non-food materials should not be stored with coffee to prevent contamination or taints in the 
product.  
7) regular monitori ng of the moisture content of coffee and relative humidity of warehouse  
d) coffee cleaning and sorting should not physically damage the product as this will make it more 
susceptible to contamination/deterioration or introduce new contamination and should assu re reduction of 
undesirable materials to acceptable pre -determined levels.  
1) when storage is combined with cleaning and sorting, attention is required to avoid contamination 
of post -sorted coffee  with the sorting  by-products of dust and foreign matter, (e.g.  through the 
use of partition walls or extractor fans); and  
2) remove defects from main -crop production, discarding or screening them before their inclusion 
into the food chain.  
e) transport of coffee also requires the adoption of practices to avoid re -wetting,  to maintain temperature as 
uniform as possible and to prevent contamination by other materials. The main requirements here are:  
1) cover coffee loading and unloading areas to protect against rain;  
2) before receiving a new cargo, the vehicles shall be cleaned f rom residues of the previous cargo;  
3) the vehicles shall have floor, side walls and the ceiling (in closed vehicles) checked for the 
presence of points where exhaust fumes or water from rain can be channelled into the coffee 
cargo.   
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 4) Tarpaulins and plastic canvas used to cover the cargo should also be regularly checked to ensure 
they are clean and without holes.  
5) The vehicles should also receive regular maintenance to be kept in good condition; and  
6) reliable transport service -providers that adopt the recommended good transportation practices 
should be selected by operators  
4.6 Ship ping  
4.6.1  Coffee is transported from producing to consuming countries in bags or in bulk, usually in 18 – 22 
tonnes capacity containers. Temperature fluctuations , during the transportation time, can cause condensation 
of the remaining water (present even in well -dried beans) and local re -wetting. The redistribution of water can 
lead to fungal growth, with the possibility of OTA production. The recommended practice s during 
transportation in the port are:  
a) cover coffee loading and unloading areas to protect against rain;  
b) check coffee lots to ensure that they are uniformly dried and below 12.5 % moisture content, free of  
foreign matter and respecting the established de fect levels;  
c) check containers, before loading, to ensure they are clean, dry and without structural damage that c ould 
allow water entrance into the container ; 
d) bags should be well stacked and crossed over for mutual support in order to avoid the formation o f empty 
vertical columns (chimneys).  
e)  The top layer and sides of bags should be covered with materials that can absorb condensed water, 
such as silica gel or cardboard for protection against the growth of fungi that could result in OTA 
production.  
f) For cof fee in bulk , a sealable plastic liner (e.g. big bag which allows aeration) is desirable and this should 
be kept away from the roof of the container;  
g) choose an appropriate place, not directly exposed to external weather  conditions,  aboard the ship to 
reduce the possibility of undesirable situations mentioned that can lead to OTA contamination ; 
h) keep the ventilation holes in the containers  uncovered ; 
i) avoid unprotected stowage on the deck (top layer) and stow away from boilers and heat ed tanks or 
bulkheads;  
j) the moisture content level should not exceed 12.5 % anywhere, from the point where the coffee leaves  
the loading area to the point at which the coffee is unloaded, stored and/or subjected to other proc essing 
procedures such as roasti ng. 
 DRS 259: 2020  
11                ©RSB 2020 - All rights reserved  
 Bibliography  
[1] RS 259: 2014,  Prevention and reduction of Ochratoxin A contamination in coffee — Code of practice, 
First Edition  DRS 259: 2020  
 
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