ICS 65.040.20  
 
Reference number  
DRS 227: 2019 
© RSB 2019  
  
 RWANDA 
STANDARD  DRS 
227  
 
First edition  
2019-mm-dd 
(Reaffirmed 2019 -mm-dd) 
Post -harvest handling and storage (PHHS) 
of wheat — Guidelines  
   
DRS 227:2019  
©RSB 2019  - All rights r eserved                  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 2019  
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 227: 201 9 
iii                ©RSB 2019  - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 General guidelines  ................................ ................................ ................................ ................................  3 
5 Specific guidelines  ................................ ................................ ................................ ................................  3 
5.1 Pre-harvesting  ................................ ................................ ................................ ................................ ....... 3 
5.2 Harvesting  ................................ ................................ ................................ ................................ ..............  4 
5.3 Threshing  ................................ ................................ ................................ ................................ ...............  4 
5.4 Drying of grain  ................................ ................................ ................................ ................................ ....... 5 
5.5 Cleaning and sorting  ................................ ................................ ................................ .............................  5 
5.6 Packag ing ................................ ................................ ................................ ................................ ...............  5 
5.7 Transportation  ................................ ................................ ................................ ................................ ....... 6 
5.8 Storage  ................................ ................................ ................................ ................................ ...................  6 
6 Major storage pests and their control measures  ................................ ................................ ...............  6 
Annex  A (informative)  Major stored grain pests of wheat and their control measures  .............................  7 
Annex  B (informative)  —................................ ................................ ................................ ................................ . 13 
 DRS 227:2019  
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 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda 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.  
RS 227 was prepared by Technical Committee RSB/TC 003, Cereals, pulses, legumes and derived products . 
In the preparation of this standard, reference was made to the following standard  (s): 
1) XYZ: Title  
2) XYZ:  Title 
The assistance de rived from the above source is hereby acknowledged with thanks.  
This second/third/... edition cancels and replaces the first/second/... edition (RS  nnn-n: yyyy), [clause(s) / 
subclause (s) / table(s) / figure(s) / annex(es)] of which [has / have] been technically revised.  
(The first/second/third/... edition (RS  nnn-n: yyyy) has been re affirmed  by the Board on dd-mm-yyyy. ) 
RS nnn consists of the following parts, under the general title Introdu ctory element — Main element : 
 Part n: Part title  
 Part [n+1]: Part title  
Part [n+2]: Part title  
Committee membership  
The following organizations were represented on the Technical Committee on  Cereals, pulses, legumes and 
derived products  (RSB/TC 003) in the preparation of this standard.  
Paragraph of p articipants  
Rwanda  Standards Board  (RSB) – Secretariat  DRS 227: 201 9 
v                ©RSB 2019  - All rights reserved  
 Introduction   
Post-harvest losses for wheat can occur at many points after harvest during drying, threshing, shelling, 
winnowing, sorting, aggregati on, transport and storage.. Reducing post -harvest losses can increase the 
volume and value of grains within the market and available for consumption and sale.  
This standard has been developed to take into account:  
a) the needs of the market for the quality wh eat grains;  
b) the need to facilitate fair domestic, regional and international trade and prevent technical barriers to trade 
by establishing a common trading language for crop producers, buyers and sellers;  
c) the needs of the producers in gaining knowledge of market standards, conformity assessment and post - 
harvest handling;  
d) the need to transport the product in a manner that ensures keeping of quality until it reaches the 
consumer;  
e) the quality and safety parameters of the product should meet before they are pu t on the market; and  
f) the need to promote good agricultural practices that will enhance wider market access, involvement of 
small -scale traders and hence making farming a viable means of generating income.  DRS 227:201 9 
1                ©RSB 2019  - All rights reserved  
 Post -harvest handling and storage (PHHS) of wheat  — Guidelines  
1 Scope   
This Draft  Rwanda Standard specifies the guidelines for Post -Harvest Handling and Storage (PHHS) of 
common wheat (Triticum aestivum L.), club wheat (T. compactum Host.), and durum wheat (T. Durum Desf.).  
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 the referenced document (including any amendments) ap plies.  
RS EAS 51, Wheat grain — Specification  
RS 231, Guidelines for storage of grains and pulses with practical recommendations  
RS 2 64, Warehouse and warehousing for storage  of bagged grains — Requirements  
3 Terms and definitions  
For the purposes of this st andard, the follow ing terms and definitions apply  
3.1 
wheat grain  
grain obtained from the varieties of species of common wheat ( Triticum aestivum L.), club wheat ( T. 
compactum Host.), and durum wheat ( T. Durum Desf.)3.2  
harvesting  
operation  of gathering  mature earheads  
3.3 
drying of earheads  
operation during which the harvested plant with earheads are dried to the desired moisture content so as to 
undergo the next operation of threshing  
3.4 
threshing  
operation  of separating the grains from the crop with mature earheads   
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 3.5 
winnowing  
operation of blowing air through grains in order to remove the chaff  
3.6 
drying of wheat grains  
operation during which wheat  grains are dried to the safe storage moisture content  
3.7 
moisture content  
amount of water in the grain expressed as percentage of the total weight of the sample on wet basis  
3.8 
transportation  
process of moving of earheads/grains of wheat from one location to other location during different unit 
operations of  post-harvest handling  
3.9 
post -harvest losses  
measurable quantitative and qualitative loss of wheat grains occurred during the various post -harvest 
operations like harvesting, threshing, drying, cleaning, transporting and storage  
3.10 
quantitative loss  
reduction in weight and volume  
3.11  
qualitative loss  
loss which occurs as a result of degradation of physical, chemical and biological properties, under the effect of 
environmental conditions  
 DRS 227:201 9 
3                ©RSB 2019  - All rights reserved  
 4 General guidelines  
Throughout the whole process of PHHS the following shall be considered:  
a) the products being handled shall comply with RS EAS 51;  
b) hygiene conditions shall be maintained throughout the whole process of PHHS;  
c) materials and equipment used shall comply with the requirements of relevant standards;  
d) chemi cals and their use shall comply with relevant  standards and regulations; and  
e) measures shall be taken to prevent attacks by pests, moulds and rodents throughout the PHHS process  
(for the control of pest refer  to Annex A).  
5 Specific guidelines  
5.1 Pre-harvesting  
. Pre -harvesting should consider the following:  
a) prior to the harvest, it is important that farmers are already prepared for their postharvest activities and 
they should ensure that:  
1) the equipment needed for their harvest and postharvest activities is avai lable and in good  working 
condition;  
2) the place of important activities like drying and threshing has been identified;  
3) there should be sufficient storage space for the crop;  
4) the grain stores and food grade packaging materials have been thoroughly cleaned  
5) the residues of the old harvest (last season’s crop) has been removed from all cracks and  crevices and 
disposed in a hygienic manner;  
b) farmers should ensure the timely harvest of the wheat crop to avoid losses and the following should be 
considered:  
1) the time of harvesting can be identified by the change of colour of the plant from green to  yellow 
showing the maturity of grains;  
2) not to wait for stalks and leaves to dry because they remain green in most of the hybrid and  
composite varieties;   
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 3) wheat cultivate d for obtaining kernels (grains) should be harvested when the kernels are  
physiologically matured with 17-20% moisture; and  
4) farmers can collect a wheat grain from its panicle in the field itself and test the hardness, size,  
shape and maturity of the grain and decide the time of harvesting.  
c) avoid pest infestation prior to harvesting; and  
d) protecting the grains in the field from birds should be controlled, when wheat is in the stage of ready to 
harvest . 
5.2 Harvesting  
Harvesting activity shall be done as follows:  
a) the wheat crop should be cut at the stalk 5 cm - 7 cm above the ground level;  
b) wheat should  be harvested when the grains are hard and matured with optimum moisture content of  17-20 
%to avoid field loss of grains by shattering  
c) harvesting before maturity means a low milling recovery and also a higher proportion of immature seeds, 
high percentage of broken kernels, poor grain quality and more chances of disease attack during storage 
of grain  
d) delay in harvesting results in grain shattering and cracking of wh eat kernels and expose the crop to 
insects, rodents, birds and pests attack, as well as lodging  
e) harvesting during wet weather conditions should be avoided;  
f) harvesting should be done by adopting proper method and avoid missing of the secondary tiller panicl es; 
g) the harvested crop should be tied into a bundle and carry it to threshing yard without much transportation 
loss; 
h) the harvested material shall be protected from rain and excessive dew by covering;  
i) harvested wheat should be kept separately for each varie ty, to get true to type variety (grains);  
j) contact of the earheads with soil shall be avoided, as it can be source of contamination or attack by 
insects; and  
k) harvested wheat crop shall be transported immediately to the threshing yard.  
5.3 Threshing  
Threshing shall be done as follows:  DRS 227:201 9 
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 a) the machine used for threshing shall comply with relevant standards  
b) threshing may be done by manual methods or by power operated multi crop thresher for large quantities;  
c) when power operated threshers are used, the clearance betwe en the concave and cylinder should be adjusted 
so that the percentage of broken grains shall be minimized ; 
d) power operated thresher shall have operator safety arrangements like the belt and pulley guard as per  the 
relevant standard; and  
e) threshing  machine shall not be a source of contamination  such as  rust, paint, grease.  
5.4 Drying of wheat grain s 
The following shall be considered in drying of wheat grains:  
a) drying of the wheat grains should  be done immediately after threshing  
b)  wheat grains shall be dried to 14 % moisture content prior to packaging and storing;  
c) the drying area (concrete floor,  tarpaulin ) shall be clean and not be a source of contamination to the 
grains; and  
d) where heated air is used to dry the grains, temperatur e and drying time shall be synchronized so that they 
do not result in adverse effect on the nutritional composition and quality of the grains in its intended use  
5.5 Cleaning and sorting  
Cleaning may be done manually or by using machine:  in order for the grain s to comply with the requirements 
specified in :RS  EAS 51  
a) when power operated cleaning machine is used, care should be taken by adjusting the fan speed to 
reduce the loss of grain in the chaffy outlet;  
b) the grains shall be aspirated to remove all the straws , chaff and leafy vegetative matter;  
c) defective (mouldy, discoloured, shrivelled, rotten, broken, insect damaged, etc) grains sh ould  be 
removed;  
d)  grading shall be in accordance with RS EAS 51.  
5.6 Packaging  
Wheat grains shall be packaged according to the following:   
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 e) wheat shall be packed in food grade packaging materials which shall safeguard the hygienic, nutritional, 
and organoleptic  qualities of the products;  
f) each package shall contain grains of the same type and of the same grade designation  
g) each container shall be securely closed  
5.7 Transportation  
Transportation of wheat grains shall consider the following:  
a) the grains may be transported in vehicle itself (bulk) or in transportable container then the vehicle and 
container shall be clean, dry and free from undesirable odours and infestation;  
b) wheat grain should be handled and transported in such a way so that they remain well protected from  sun, 
rain or other sources of excessive heat, objectionable odour and from any type of cross infestation  
c) if the veh icle is not fully enclosed, it shall have a covering such as tarpaulin to keep out of the rain or any  
form of water;  
d) transported grains should be well ventilated with dry air to remove moisture resulting from respiration of  
the grains and to prevent moistu re condensation; and  
e) transportation of wheat grains with chemicals and products in liquid form shall be avoided  
5.8 Storage  
Storage facility and management shall be in such ways that preserve the safety and quality of wheat grains and 
shall comply with RS 231 and RS 2 64. 
6 Major storage pests and their control measures  
Measures should be taken to control insect infestation using either physical, chemical, mechanical or  
biological means or combinations of these methods. The prevalent storage pest and their control  measures  
are given in Annex A.  
 
 
 
 
 
 DRS 227:201 9 
7                ©RSB 2019  - All rights reserved  
 Annex  A 
(informative)  
 
Major stored grain pests of wheat and their control measures  
Name of pest and figure of pest  Damage  Control measures  
1.Grain Weevil  
Sitophilus granarius (L.)  
(Calandra granaria (L.)  Larvae and beetles  feed on 
grains.  
Adults feed on flour, mass 
infestation  
makes grain moist and warm 
leading to mould infection.  
 Malathion, DDVP, Deltamethrin, 
Fumigation with Phostoxin or 
Magtoxin  
2.Lesser rice Weevil  / 
Sitophilus oryzea ( L)/ 
Greater Rice Weevil  
S.Zeamais (Motsch)  Adults and larvae feed on grains 
and flour. Larvae bore into grains 
and feed on the grain.  
 
 
 
 
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3.Lesser grain borer  
Rhizopertha dominica (Fabr.)  Beetles and larvae bore the 
grains and feed. The larvaefeed  
on flour. Heavy infestation makes 
the grain warm and moist, which 
leads to mould formation  
 
 
4.Khapra beetle  
Trogoderma granarium Ev  The larva is a very serious stored 
product pest; the beetle does no 
damage. The grains are often 
hallowed out until onl y the husk 
remains.  
 
5.Rust -red and confused  
flour beetle  
Cryptolestes ferrugineus  
(Steph.) / Tribolium Confusum  
J.Du V.  Beetles and larvae feed on 
undamaged and broken kernel, 
common mill pest, flour develops 
sharp odour if badly infested.  
DRS 227:201 9 
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6.Drugstore beetle  
Stegobium paniceum (L.)  The larva is omnivorous, feeds on 
a wide range of plant materials 
and grain. The badly infested 
grains are full of small round 
holes.  
 Malathion, DDVP, Deltamethrin, 
Fumigation with Phostoxin or 
Magtoxin  
7.Saw Toothed grain beetle  
Oryzaephilus surinamensis  
(L.) Both beetle and larvae feed on 
broken grains and attack grains, 
already infested by other insects. 
It is a secondary pest together 
with other grain pests.  
 
 
 
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 8.Cadelle  
Tenebroides mauritanicus (L.)  It damages grains.  
 
 
9.Angoumois grain moth  
Sitotroga cerealella (Oliv.)  It attacks in field also, but mostly 
in storage, causing loss of weight 
upto 50 per cent. Badly infested 
grain has a sickening smell and 
taste that makes it unpalatable.  
 
10.Mediterranean Flour  
Moth Ephestia (Anagasta)  
kuehniella Zell.  The caterpillar feeds on flour, 
bran, whole grains.  
 
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11.Warehouse Moth  
Ephestia elutella (Hubn.)  The caterpillars attacks grain.  
 Malathion, DDVP, Deltamethrin, 
Fumigation with Phostoxin or 
Magtoxin  
12.Indian Meal Moth  
Plodia interpunctella  
(Hubn.)  Attacks grain and grain products, 
whereby only the grain germs are 
eaten.  
 
13.Rodents  
Rattus norvegiens (Brown  
rat), R.Rattus Rattus (Black  
rat) , Bandicota bengalensis  
(Indian mole rat), Mus  
musculus (House mouse)  Rodents feed on whole and 
broken grains, flour etc. They 
spoil more wheat than they eat by 
contaminating it with hair, urine 
and fasces  
 Rat cage :  
Different types of rat cages are 
available in the market. Rates 
caught in cage can be killed by 
dipping in water.  
Poison baits :  
Anti-coagulant pesticide like zinc 
phosphate is mixed with bread or 
any other food stuff used as bait. 
Baits are kept for a week.  
Rat burrow fumigation:  
Tablets of Aluminum phosphate 
 
©RSB 2019  - All rights r eserved                  12 
  are put in each hole and burrow 
and holes are blocked by mud 
mixture to make airtight.  
 
 
 
 
 
  
DRS 227:201 9 
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 Annex  B 
(informative)  
 
—  
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 Bibliography  
[1] ISO/IEC Directives, Part  2, Rules for the structure and drafting of International Standards , 2016  
[2] ISO/IEC  TR 10000 -1, Information technology  — Framework and taxonomy of International  
). 
 DRS 227: 2019  
 
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