ICS 65.040.20  
 
Reference number  
DRS 22 8: 2019 
© RSB 2019  
  
 RWANDA 
STANDARD  DRS 
228  
 
First edition  
2019-mm-dd 
(Reaffirmed 2019 -mm-dd) 
Post -harvest handling and storage (PHHS) 
of sorghum  — Guidelines  
   
DRS 228: 201 9 
©RSB 2019  - 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 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 228: 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  ................................ ................................ ................................ ................................  2 
5 Specific guidelines  ................................ ................................ ................................ ................................  3 
5.1 Pre-harvesting  ................................ ................................ ................................ ................................ ....... 3 
5.2 Harvesting  ................................ ................................ ................................ ................................ ..............  4 
5.3 Drying of earhea ds ................................ ................................ ................................ ................................  4 
5.4 Threshing  ................................ ................................ ................................ ................................ ...............  5 
5.5 Drying of grain  ................................ ................................ ................................ ................................ ....... 5 
5.6 Cleaning a nd sorting  ................................ ................................ ................................ .............................  6 
5.7 Packaging  ................................ ................................ ................................ ................................ ...............  6 
5.8 Transportation  ................................ ................................ ................................ ................................ ....... 6 
5.9 Storage  ................................ ................................ ................................ ................................ ...................  7 
6 Major storage pests and their control measures  ................................ ................................ ...............  7 
Annex  A (informative)  Major stored grain pests of sorghum and their control measures  ........................  8 
Annex  B (informative)  —................................ ................................ ................................ ................................ . 12 
 DRS 228: 201 9 
©RSB 2019  - All rights reserved                  iv 
 Foreword   
Rwanda Standard s are prepa red 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 ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
RS 228 was prepared by Technic al 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 228: 201 9 
v                ©RSB 2019  - All rights reserved  
 Introduction   
Sorgh um is one of the most important cereal crops in the world and is one of the four major food grains in 
Rwanda. Besides being a major source of staple food for human beings, it also serves as an important source 
of fodder, animal feed and industrial raw mate rial. 
It was found that there is reduction in weight of ready to consume grain during harvesting operations, farm 
storage, transport and market storage. For sorghum, the mean post -harvest loss is 2.20 %. This led to the 
development of standards which provi des guidelines on post -harvest handling and storage of sorghum grains.  
This standard has been developed to take into account:  
a) the needs of the market for the quality sorghum 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 transpo rt 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 put 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 228:201 9 
1                ©RSB 2019  - All rights reserved  
 Post -harvest handling and storage (PHHS) of sorghum grains  — 
Guidelines  
1 Scope   
This Draft Rwanda Standard specifies the guidelines for Post -Harvest Handling and Storage (PHHS) of 
sorghum grains ( Sorghum bicolor L. Moench).  
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 ed ition of the referenced document (including any amendments) applies.  
RS EAS 757 , Sorghum 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 standard, the follow ing terms and definitions apply  
3.1 
sorghum grain s 
grain s  obtained from the species Sorghum  bicolor L. Moench  
3.2 
harvesting  
operation of gathering  mature earheads  
3.3 
drying of earheads  
operation during which the harvested earheads are dried to the desired moisture content so as to undergo the  
next operation of threshing   
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 3.4 
threshing  
operation of separating the grains from the dried earheads  
3.5 
winnowing  
operation  of blowing air through grains in order to remove the chaff  
3.6 
drying of sorghum g rains  
operation during which sorghum grains are dried to the safe storage moisture content  
3.7 
foreign matter  
all organic and inorganic material other than sorghum grains, broken kernels, other grains and filth  
3.8 
moisture content  
amount of moisture in the grain expressed as percentage of the total weight of the sample, wet basis  
3.9 
transportation  
process of moving  of sorghum from one location to other location during different unit operations of post -
harvest handling  
3.10 
post -harvest losses  
measurable quantitative and qualitative loss of sorghum grains occurred during the various post -harvest 
operations like harve sting, threshing, drying, cleaning, transporting and storage.  
4 General guidelines  
Throughout  the whole process of PHHS the following shall be considered : 
a) the products being handled shall comply with RS EAS 757  DRS 228:201 9 
3                ©RSB 2019  - All rights reserved  
 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) chemicals and their use shall comply with relevant  standards and regulations; and  
e) measures shall be taken to prevent attacks by pe sts, 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 available and in good  working 
condition;  
2) the place of important activities like drying and threshing  has been identified;  
3) there shall be sufficient storage space for the crop;  
4) 5)3) 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 hygie nic manner;  
b) farmers should ensure the timely harvest of the sorghum 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 completely dry because they remain green in most of the 
hybrid and composite varieties; and  
3) sorghum cultivated for obtaining kernels (grains) shall be harvested when the kernels are  
physiologically matured with 15-20% of moisture content;  
c) farmers can collect a grain from the earhead in the field itself and test the hardness, size, shape and  
maturity of the grain inside the earhead and decide the time of harvesting;  
d) pest infestation shall be avoided prior to harve sting; and   
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 e) protecting the grains in the field from birds should be controlled, when sorghum is in the stage of ready to 
harvest.  
5.2 Harvesting  
Harvesting activity shall be done as follows:  
f) the sorghum ear heads shall be cut at the stalk;  
g) 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;  
h) delay in harvesting results in grain loss and cracking o f sorghum kernels and expose the crop to insects, 
rodents, birds and pests attack;  
a) harvesting during wet weather conditions shall be avoid ed; 
b) harvesting should be done by adopting proper method and avoid missing of earheads;  
c) the harvested crop shall be carried in a sack to the drying yard without much transportation loss;  
d) the harvested material shall be protected from rain and excessive dew by covering;  
e) the harvested sorghum should be kept separately for each variety, to get true to type variety (grains) ; 
f) harvesting at too much dried sorghum crop leads to more field and transportation losses and shall be 
avoided  
g) the contact of the earhead with soil should be avoided as it can be source of contamination or attack by 
insects; and  
h) Harvested sorghum crop shou ld be transported immediately to the drying yard.  
5.3 Drying of earheads  
Drying of earheads shall be done as follows:  
a) drying of the earheads should  be done immediately after harvesting;  
b) if there is a delay in drying, earheads should be kept under shade with p lenty of aeration to avoid heating  
of the earheads;  
c) for rapid and safe drying the following should be considered:  
1) a single layer of thin bed drying of earheads should be used; and  DRS 228:201 9 
5                ©RSB 2019  - All rights reserved  
 2) the earheads should be regularly turned for uniformity of drying;  
d) for better  sanitation, clean concrete floor or brick floor or  tarpaulin  shall be used to dry the 
earheads/sorghum  grain;  
e) care shall be taken to protect the earheads from soil contamination, cyclonic wind and rain or dew;  
f) where heated air is used to dry the earheads , temperature 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; 
g) The air heated drying machine shall comply with relevant standards;  
h) any source of  contamination and pest infestation shall be avoided during drying; and  
i) hygienic practices shall be followed during drying . 
5.4 Threshing  
Threshing shall be done as follows:  
j) the machine used for threshing shall comply with relevant standards  
k) threshing may be done by manual methods or by power operated multi crop thresher for large quantities;  
l) techniques that cause damage to the grains such as severe beating with sticks shall be avoided to  
prevent the damage of grains;  
m) when power operated threshers are used, th e clearance between the concave and cylinder should be  
adjusted so that the percentage of broken grains shall be avoided;  
n) power operated thresher should have operator safety arrangements like the belt and pulley guard as per  
the relevant standards;  
o) threshi ng machine shall not be a source of contamination  such as  rust, paint, grease  
5.5 Drying of sorghum grain s 
The following shall be considered in drying of grains:  
a) the drying of the grains sh ould  be done immediately after threshing;  
b) the sorghum grains shall be dried to 13.5 % of 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   
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 d) where heated air is used to dry the grains, temperature and drying ti me 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  
5.6 Cleaning  
Cleaning may be done manually  or by using machine:  
a) when power operated cleaning machine is used, car e 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 dam aged, etc) grains shall be minimized  
d) grading shall be in accordance with RS EAS 757.  
5.7 Packaging  
Sorghum grains shall be packaged according the following:  
a) sorghum grains shall be packaged in clean and;  
b) sorghum grains shall be packed in food grade packaging materials which will safeguard the hygienic, 
nutritional, and  organoleptic qualities of the products;  
c) each package shall contain sorghum grains of the same type and of the same grade designation;  
d) each container shall be securely closed  
5.8 Transportation  
Transportation of sorghum 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 infe station;  
b) sorghum 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 vehicle is not fully enclosed, i t should 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 moisture condensation; and  
e) transpo rtation of sorghum grains with chemicals and products in liquid form shall be avoided.  DRS 228:201 9 
7                ©RSB 2019  - All rights reserved  
 5.9 Storage  
Storage facility and management should be in such ways that preserve the safety and quality of sorghum  
grains and shall comply with RS 231 and RS 264  
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 give n in Annex A.  
 
 
 
 
 
 
  
©RSB 2019  - All rights reserved                  8 
 Annex  A 
(informative)  
 
Major stored grain pests of sorghum and their control measures  
Name of pest and figure of pest  Damage  Control measures  
1. Rice weevil   
Sitophilus oryzae  (Linn.)  Adults and larvae both bore into 
grains and feed on the grain.  
 
 Two types of treatments are 
followed to control infestation.  
A. Prophylactic treatment:  
Use following insecticide to 
prevent  infestation in godown and 
stock of  sorghum  
1. Malathion (50 % EC):  
Mix 1 litre in 100 litre of water. 
Use 3 litre prepared solution per 
100 square meter area. Spray 
every 15 days interval . 
2. DDVP (76 % EC):  
Mix 1 litre in 150 litre of water. 
Use 3 litre prepared solution per 
100 square meter area. Do not 
spray on stock.  Spray on walls 
and floors of the go down as and  
when required or once in a 2. Lesser grain  borer 
Rhizopertha  dominica (fabr.)  Beetles and larvae both penetrate 
the grain and feed. Sometimes, 
larvae feed on the waste flour 
produced by the adults. Heavy 
infestation makes the grain warm 
and moist, which leads to mould 
formation.  
DRS 228:201 9 
9                ©RSB 2019  - All rights reserved  
  month.  
3. Deltamethrin (2.5/WP):  
Mix 1 kg. in 25 litre of water. Use 
3 litre prepared solution per 100 
square meter area. Spray on 
gunny bags after 3 months’ 
interval.  
B) Curative treatment:  
Use following fumigation 
insecticide to control infested 
stock/go down of sorghum in 
airtight condition.  
1. Aluminium Phosphine : 
For stack fumigation use 3 tablets 
/ tonne and put polythene cover 
on infected stock. For godown 
fumigation, use 120 - 140 tablets 
per 100 cubic meter area and 
keep  godown structure airtight 
and closed for 7 days.  3. Khapra beetle  
Trogoderma granarium  Larvae is a very serious stored 
pest but the beetle itself does not 
damage. First the larvae feed 
germ portion and later other parts 
of the grains.  
 
4. Saw -toothed  grain beetle  
Oryzaephilus surinamensis 
(Linn.)  Both beetle and larvae feed 
broken grains and damaged 
grains of other insects. They are 
usually found as a secondary pest 
together with other grain pests.  
 
 
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 5. Red rust flour  beetle  
Tribolium castaneum  Beetle and larvae both do not 
cause damage to whole grain but 
feed on broken and damaged 
grains produced by milling and 
handling or infested /damaged 
grains of other insects.  
 
6. Rice moth  
Corcyra cephalonica  Larvae feed broken and 
processed sorghum. Larvae 
produce dense webbings. Whole 
grain kernels are bound into 
lumps.  
 
7. Rodents  Rodents eat whole grains, broken 
grains, flour etc. They spill more 
grains than they consume. 
Rodents also contaminate 
sorghum by hair, urine and feces, 
which cause dis eases like 
cholera, food poisoning, 
ringworm, rabies etc. They also 
damage the storage structures 
and other accessories of storage 
like wire and cable etc.  
 Rat cage:  
Different types of rat cages are  
available in the market. Caught 
rats can be killed by d ipping into 
water.  
Poison baits:  
Anti-coagulant pesticide like Zinc 
Phosphide is mixed with bread or 
any other food stuff used as bait. 
Keep baits for a week.  
Rat burrow fumigation:  
Put tablets of Aluminum 
Phosphide in each hole and 
DRS 228:201 9 
11                ©RSB 2019  - All rights reserved  
 burrow and block that hole by 
mud mixture to make it airtight  
 
 
 
 
   
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 Annex  B 
(informative)  
 
— DRS 228:201 9 
13                ©RSB 2019  - All rights reserved  
 Bibliography  
[1]  
 DRS 228: 2019  
 
Price based on  11 pages  
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