KENYA STANDARD     DKS 2783:2018  
                                                          ICS  
  
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Warehousing and storage of roots and 
tubers —Requirements  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
    © KEBS 2018  First Edition  
 
 
 
   DKS 2783:2018  
ii  KEBS 2018  — All rights reserved   
TECHNICAL COMMITTEE REPRESENTATION  
 
The following organizations were represented on the Technical Committee:  
 
University of Nairobi  
Agriculture and Food Authority - Food Cop directorate  
Kenya Agricultural & Livestock Research Organization  
International Potato Center  
National Potato Council of Kenya  
Kenya Industrial Research & Development Institute  
Propack Ltd.  
Norda Lt d 
Mhogo foods Ltd  
Tropical Heat Ltd  
Consumer Information Network  
Kenya Bureau of Standards — Secretariat  
 
 
 
 
 
 
 
REVISION OF KENYA STANDARDS  
 
In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed.  Suggestions 
for imp rovements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, 
are welcome.  
 
 
 
 
 
 
 
© Kenya Bureau of Standards, 2018  
 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 130 of 2001 of  the Laws of Kenya, copyright 
subsists in all Kenya Standards and except as provided under Section 25 of this Act, no Kenya Standard produced by Kenya Bure au of 
Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means w ithout prior permission in writing 
from the Managing Director . 
 
 
 
 
 
 
 
 
 
 
  KENYA STANDARD                                     DKS 2783:2018  
                                                                                                                              ICS  
KEBS 2018  — All rights reserved    iii DKS 2783:2018  
iv  KEBS 2018  — All rights reserved   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Warehousing and storage of roots and 
tubers —Requirements  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA BUREAU OF STANDARDS (KEBS)  
 
Head Office: P.O. Box 54974, Nairobi -00200, Tel.: (+ 254 020) 605490, 602350, Fax: (+254 020 ) 604031  
E-Mail: info@kebs.org, Web:http://www.kebs.org  
 
Coast Region     Lake Region    Rift Valley Region  
P.O. Box 99376, Mombasa -80100   P.O. Box 2949, Kisumu -40100        P.O. Box 2138, Nakuru -20100  
Tel.: (+254  041) 229563, 230939/40  Tel.: (+254 057) 23549, 22396        Tel.: (+254 051) 210553, 210555  
Fax: (+254  041) 229448    Fax: (+254 057) 21814  
 
 
 
 KENYA STANDARD                                     DKS 2783:2018  
                                                                                                                              ICS  
KEBS 2018  — All rights reserved    v Foreword  
 
This Kenya Standard was prepared by the Tubers  and Tuber  Products Technical Committee under the 
guidance of the Standards Projects Committee, and it is in accordance with the procedures of the Kenya 
Bureau of Standards.  
 
Warehouses and stores are intended for the storage and physical protection of roots and tubers from 
adverse  weather  conditions , prevention of t he entry of pests as well as provision of  security. They also 
include materials and equ ipment required for inspection and proper handling of tubers and storage pest 
control.  
 
The structure should be properly built to provide good storage conditions, easy a ccess and safe working 
conditions, and should not provide harbourage for pests.  
 
In general, the condition of roots and tubers change slowly while in storage; the extent of any change 
depends on ambient conditions at harvest , handling and storage . Changes in moisture content and 
temperature are limited to the periphery of a bulk or to the outer bags of a stack, unless the storage period is 
prolonged or the root/tuber is adequately ventilated.  
 
Heavy infestations of insects, however, may cause a rise in tem perature in the root or tuber mass, possibly 
due to the development of fungi. Ideally, the warehouse should permit some control of temperature and 
humidity, to keep the tubers cool, dry and at a uniform temperature as much as possible.  
 
The objective of th is standard is to provide guidance to  the industry  regarding appropriate storage of roots 
and tubers in order to reduce on the level of post -harvest losses incurred in these commodities.  
 
This standard as well will be invaluable in promoting the Structure d Trading Systems (STS) in the region to 
promote both regional and International trade in roots and tubers. The standard will play a major role in the 
implementation of the Warehouse Receipt System (WRS) and the Commodity Exchange in the region . 
 
During th e preparation of this standard, reference was made to the following documents : 
KS ISO 2165 Ware potatoes - Guide to storage  
KS 26 57:2016 Warehouse  and warehousing for bagged storage of cereals and pulses  —Requirements   
 
Acknowledgement is hereby made for  the assistance derived from these sources . 
  
KENYA STANDARD                      DKS 2783:2018  
 
 
KEBS 2018  — All rights reserved    i Warehousing and storage of roots and tubers — Requirements  
 
 
1 Scope  
 
This Kenya Standard covers the location, structural, facility, safety and management requirements for a 
warehouse storing roots and tubers e ither bagged,  in crates or in bulk.  
 
 
2 Normative references  
 
The following referenced documents are indispensable for the application of this document. For dated 
references, only the edition cited applies. For undated references, the latest edition of the  referenced 
document (including any amendments) applies.  
  
 
KS EAS 778, Fresh  bitter Cassava -Specification  
 
KS EAS 748, Fresh  potato tuber (ware potato tuber) – Specification  
 
KS EAS 771, Fresh  sweet potatoes - Specification  
 
KS EAS 776, Production  and hand ling of fresh cassava - Code of practice  
 
KS EAS 775, Production  and handling of fresh ware potatoes - Code of practice  
 
KS 2077,  Seed  potato - Specification.  
 
3 Terms and definitions  
 
For the purpose of this standard, the following terms and definitions sh all apply.  
 
3.1 Warehouse  
Structure  for storage of roots and tubers  meant for trade, exchange and food security  
 
 3.2 Roots   
Underground part of a plant conveying water and nutrients to the rest of the plant and consumed as food . 
 
3.3 Tubers  
A much thicke ned, fleshy part of an underground stem, serving as a food reserve and bearing buds from 
which new plants arise.  
 
 
3.5 Pallet (spacers ) 
Wooden, plastic or any other suitable frames used on concrete floors for stacking bags  or crates to prevent 
direct conta ct between the roots and tubers and the floor  
 
3.6 Competent authority                                                                                                           DKS 2783:2018  
 
ii  KEBS 2018  — All rights reserved  Any person or organization that has the legally delegated or invested authority, capacity, or power to perform 
a designated function  
 
3.7 Warehousing  
Performance  of administrative and p hysical functions associated with storage of roots and tubers. These 
functions include cleaning and maintenance of a warehouse, inspection, drying, screening, sorting and 
grading of roots and tubers, stacking, pests prevention and control, records keeping and any other activity 
necessary to store roots and tubers safely . 
 
4 Location  
 
4.1 The location of a warehouse shall be authorized by competent authority (ies).  
 
4.2 The site shall be located at relatively high elevation to avoid water logging and safe fr om natural   
  flooding calamities.  
 
4.3 The orientation of the warehouse shall be such that radiant heat gain from the sun is minimal.  
 
4.4 The warehouse shall be accessible by road.  
 
4.5 The warehouse shall have facilities such as clean water , power suppl y, handling and  
              communication facilities.   
     
4.6         The warehouse shall be secured  
 
4.6 Warehouse shall not be located near the site for waste disposal and surroundings shall be kept clear     
of vegetation and rubbish.  
 
4.7 The ware house shall not be near any facility where the danger of fire is constantly present  
 
4.8 Warehouses shall not be located near busy public facilities such as schools, or hospitals. Existing    
              warehouse s near public facilities shall take neces sary measures to mitigate the effects of their  
              operations.  
 
4.9 There should be ample space to facilitate movement and parking of transport.  
 
4.10   The warehouse for storing roots and tubers should be constructed  with care to avoid cross    
           contamination of pests and diseases between ware and seed potatoes.  
 
 
5 Structural requirements  
 
5.1 General  
 
5.1.1  The construction and building materials shall conform to the National Building Regulations and  
              relevant standards.  
 
5.1.2  The material shall be durable, nontoxic, wind  and water tight  
 5.1.3     The structural materials used for construction of warehouse should assist  to regulate internal     
              temperature and humidity.    
                                                                                              DKS 2783:2018  
KEBS 2018  — All rights reserved    iii  
5.2 Foundation  
 
The found ations shall be of adequate strength to take the weight of the structure and of the roots and tubers 
under storage.  
 
5.3 Floor  
 
5.3.1  The floor shall be adequately strong and capable of withstanding heavy loads and vibrations.  
 
5.3.2  The floor shall be ele vated or constructed higher than the existing ground.  
 
5.3.3  The floor shall be easy to clean  and not slippery . 
 
5.3.4  The floor shall be free from cracks where moisture from the ground may affect the stored roots and     
              Tubers  
 
5.3.5  Genera l warehouse space may be floored with appropriate flooring to carry wheel loads and  
              withstand the friction from abrasion generated by the continual use of hard rubber and steel -  
              wheeled forklift and trucks where necessary.       
  
5.4 Walls  
 
5.4.1  The internal surfaces of the walls shall be smooth and free from projections to eliminate dust -laden  
              surfaces, facilitate cleaning of the store and avoid interference with other operations.  
 
5.4.2  The junction between w alls and roof sha ll be well sealed in order  to prevent  birds and rodents from   
              accessing the store rooms while providing adequate ventilation.  
  
5.5 Roofs  
 
5.5.1  Roof design shall be in a way that facilitates pest control and other stock mana gement procedures.  
 
5.5.2  Internal pillars supporting roof frames should be avoided as much as practicable.  
 
5.5.3  Roof s shall be provided with the necessary lateral and vertical wind brace to resist forces due to  
              strong winds and earthquake s. 
 
5.5.5  The inclination of the roofs shall be sufficient to drain rainwater quickly, taking into account that the  
              water may be forced up by the wind.  
 
5.5.6  Roofs shall be watertight and gulleys kept clear of debris and leaves.  
 
5.5.7  The roofs shall be a good thermal insulator, not affected by condensat ion, and give protection   
              against attack by pests and moulds.  
 
5.5.8  The roofs shall be designed so as not to provide harbourage for birds, bats, insects , mites  and  
              rodents. An internal ceiling is not advised, as it may provide harbourage for predators.  
 
5.5.9  All drain pipes from roof gutters shall be external, well fitted and shall have mesh baffles fitted inside  
             their lower open ends.  
                                                                                                          DKS 2783:2018  
 
iv  KEBS 2018  — All rights reserved  5.6 Doors  
 
5.6.1  The door shall fit tightly for insect  and pests  control and fumigation.  
 
5.6.2  The door shall be made or reinforced with rodent or pest resistant  material  
 
5.6.3  The door shall be provided with a secure locking system.  
 
5.6.4  The size of the entran ce shall depend on loading and unloading operations.  
 
5.7  Ventilation  
 
5.7.1  Vents shall be provided near the floor level in the wall, at the top of the walls near the grid line. A  
              suitable meshed ventilation duct should be placed in each g able so that warm air accumulating  
              under the roof can escape.  
 
5.7.2  Ventilation openings shall be fitted on the outside with anti -bird grills and on the inside with insect  
             screens, which will deter entry of birds,  rodents and  insects.   
 
5.7.3  In addition to natural ventilation, exhaust and fans  may be introduced for forced ventilation.  
 
5.7.4  Windows should be kept to a minimum or avoided. They should be left open as little as possible.  
             Windows shall be protected  by mesh grills to keep birds out when the windows are open . 
 
5.8  Illuminations temperatures and relative humidity,  
 
5.8.1  The lighting should be maintained according to the requirements of  specific root and tuber crops  
 
 a) Ware potato, shall be mainta ined in darkness  
 
                           b)  Seed potato store should be maintained under diffused light  
 
5.8.2  Artificial lighting is preferable for the interior of the warehouse  
 
5.8.3   T emperature and relative humidity  
 
 5.8.3.1       Roots and tu bers shall be stored at a temperature of about 5°C to 20°C. And a relative humidity  
                    of above 85%          
 
 5.8.3.2        Sweetpotatoes should not be stored at temperatures below 10 °C 
 
5.9  Fence  
 
5.9.1  The site shall be secured agains t the unauthorized entry of persons and animals.  
 
5.9.2  Gates shall be adequate for their purpose and wide enough to allow easy vehicle  access.  
 
6  Facility requirements  
                                                                                       DKS 2783:2018  
KEBS 2018  — All rights reserved    v  Where annex rooms  are present , they shall be separate  from the roots/tubers storage areas and may 
include the facilities for reception, offices, laboratory, equipment and chemical store, toilets and urinals, 
changing room and showers.  
 
6.1  Office space and related facilities  
 
The office space shall be:  
 
a) easily accessible for staff and  other visitors;  
 
b)  clearly signposted;  
 
c)  well aerated;  
 
d)  safe and unobstructed; and  
 
e)  clean, naturally well -lit and suitably furnished.  
 
6.2  Toilets and urinals  
 
6.2.1  The floor of the toilets and urinals shall be non -absorbent, washable and n on-slip materials.  
 
6.2.2  The wall shall be constructed from non -absorbent, light coloured  material, , up  
             to a height of 2 m, smooth , without crevices and shall be easy to clean and  
             disinfect.  
 
6.2.3  The toilets and urinals shall  be furnished with hand washing facilities . 
6. 2. 4    Toilets shall not be constructed in the  warehouse operation area  
 
6.2.5  For commercial warehouses, the number of toilets shall be adequate for the number of employees.  
               The number of toi lets may be determined using Table 1.        
 
Table 1 — Number of toilets and urinals in Warehouse and warehousing for storage of roots  
                  and tubers  
 
SL No  Number of employees  Number of toilets and urinals  
i) 1 – 15 1 
ii) 16 – 35 2 
iii) 36 – 55 3 
iv) 56 – 80 4 
v) 81 – 110 5 
vi) 111 – 150 6 
 
NOTE Over 150 employees, one additional fixture for each additional 40 employees.  
 
 
 
6.3 Changing rooms and showers  
 
6.3.1    Commercial  warehouse shall provide suitable changing room s furnished w ith labelled lockers.   
                                                                                                          DKS 2783:2018  
 
vi  KEBS 2018  — All rights reserved  6.3.2  All cleaning materials shall be provided.  
 
6.4 Equipment store  
 
6.4.1  Equipment such as for fumigation, sampling, cleaning may be provided in the warehouse. Such  
             equipment shall be appropriately stored and separat e from the roots and tubers storage and  
              chemical storage areas.      
 
6.4.2  The floor shall be  easy to clean  and not slippery.   
6.4.3       The equipment store shall be secured  
 
6.5  Chemical store  
 
6.5.1  Chemicals such as pesticide, rodentic ides, fumigants may be stored at the warehouse. Such  
              chemicals shall be stored in a separate room under lock and key.  
 
6.5.2  Chemicals shall be clearly labelled for easy identification.  
. 
6.5.3  The floor shall be easy to clean and not slippe ry.  
6.5.4       The chemical  store shall be secured  
 
6.5.5  Chemical store shall be clearly identified as such.  
 
 
6.6  Laboratory  
 
6.6.1  The warehouse may be provided with laboratory for internal control.  
 
6.6.2  The laboratory shall have facilities to under take basic tests such as moisture content, organoleptic  
             test and grading.  
 
6.6.3  The laboratory shall have sufficient area for  staff, reagents, equipment, and testing  operations . 
              These equipment   may include but not limited to  moisture meters, grading racks, weighing balance.   
 
6.6.4  The floor and the walls shall be easy to clean and not slippery.  
6.6.5       The laboratory  shall be secured  
 
6.6.6 The testing area shall be sufficiently lit.  
 
 
7  Safety requirements  
 
7.1 Warning  signs or boards shall be fixed in hazardous/dangerous areas such as chemical storage, wet 
floor, laboratories  
 
7.2 Firefighting equipment in working condition (fire extinguishers, fire hydrants) shall be provided and  
             be installed in a conspic uous and accessible location . 
 
7.3 There shall be provisions for first aid facilit y placed in a conspicuous and accessible location.  . 
                                                                                       DKS 2783:2018  
KEBS 2018  — All rights reserved    vii 7.4 Safety signs, fire exits  and assembly points , eyewash and emergency shower stations, shall be 
indicated.  
 
 
 
8.0     Harv est and post -harvest handling practices  
 
 8.1   Harvesting  
  
8.1.1   Roots and tubers  for storage shall be harvested after attaining specified product maturity   
 
8.2   Curing  
 
8.2.1  The roots and tubers meant for storage shall be cured after cut back of ab ove foliage for a specified  
          period to allow development of a thick enough skin to avoid peeling off and rotting.  
 
8.2.2  Harvesting  shall be done on a dry day and gently not to puncture, pierce or bruise  the roots and  
          tubers.  
 
8.2.3  Freshly  harvested roots and  tubers shall be stored in a dry  and cool place for the skin to cure for longer  
          keeping.  
 
8.2.4  After curing excess soil clinging to roots and tubers may be brushed off, packaged in the correct      
            materials  followed by storage in a cool, dry, and dark place while observing the specific ideal  
             temperature and humidity requirements  
 
8.3 Proper packaging and handling  
 
8..3.1  Roots and  tubers shall be packaged in bags or crates in accordance with re commended practices to  
           protect the produce from damage during handling, transport and storage. Strong , uniformly sized, well  
           ventilated and easy to clean packages should be used for ease of stacking, handling, stocking in  
           quantity, weighing and economical use of transport.  
 
8.4   Loading, Transportation and Unloading  
 
8.4.1  Loading   
 
8.4.1.1  Roots and tubers packaged in bags, crates or bulk shall be loaded in stacks or gently placed to 
recommended height not to damage und erlying fresh produce into a transport vessel  
 
8.4.2   Transportation  
8.4.2.1 Roots and tubers shall be  transported in clean  covered or closed vessel to avoid airborne 
contaminants, water and direct sunlight likely to negatively affect the produce.  
 
8.4.3 U nloading  
8.4.3.1  The roots and tubers shall be unloaded for storage with avoidance of stepping on the fresh produce 
and rough handling likely to cause bruises while ensuring placement of the unloaded produce on 
pallets.  
  
8.5 Management of post -harvest pes ts & diseases                                                                                                           DKS 2783:2018  
 
viii  KEBS 2018  — All rights reserved  8.5.1    Roots and tubers harvested from a clean crop field shall be stored in properly cleaned, disinfected 
and dry stores,  they shall be gently  handled to avoid bruising and regular inspection shall be 
conducted to isolate and dispose any ro tting material.  
 
 
9 Management requirements  
 
9.1  Cleaning and maintenance  
 
9.1.1 The buildings, equipment, utensils and all other physical facilities of the establishment, including  
              drains, shall be maintained in good  orderly  working condi tion. 
 
9.1.2 The store shall be cleaned and treated prior to any storage operation.  
 
9.1.3 The store and environment of the warehouse shall be kept clean and shall be disinfected regularly  
              to prevent insect s, rodents and mites infestation.  
 
9.1.4 Waste from sorting and screening shall be disposed in such way that does not  cause contamination,   
              harbour rodents and Pests or generate obnoxious smell.   
 
9.1.5 Waste from the warehouse shall be collected and disposed in environment fr iendly manner.  
 
9.1.6 Changing facilities and toilets shall be kept clean.  
 
 
9.2  Inspection  
 
9.2.1    Inspection  operations shall be carried out in a clean and sanitary manner. Only clean, sound product   
         shall be stored.  
 
9.2.2   The general appe arance of the products shall be observed during the process of unloading; if the  
            Roots or tubers  are moist , injured , insect infested, insect damaged, or contain an unusual  amount of   
           dirt, debris or other  foreign material.   
 
9.2.3    If the observations from organoleptic analysis do not allow taking the decision, a sample from the  
            suspected lots shall be taken and accurate tests conducted before any acceptance of the lot.   
 
9.3  Loading and unloading  
 
9.3.1 Loading and unloading may be done mechanically or manually.  
 
9.3.2 If manual loading and unloading is used, the floor should be 1 -m above the ground to permit easy  
             loading or unloading into trucks at the sides of the warehouse . 
 
9.3.3 Loading and unloadin g shall not take place in open area when it is raining. A canopy should be  
            constructed over every entry door to allow continuous loading and unloading even when it rains.  
 
9.4  Provision of spacers  
 
9.4.1 The spacers (pallets) shall be used to  avoid the sacks being in direct contact with the ground.  
                                                                                       DKS 2783:2018  
KEBS 2018  — All rights reserved    ix 9.4.2 Spacers should be standard pallets, of manageable size, and therefore easy to lift. spacers shall be  
              treated with pesticides and stacked neatly when not in use.  
 
9.5  Stacking  
 
While deciding the whereabouts of bag or crate stacks the following shall be considered:  
 
a)  Bags  or crates  of roots  or tubers in each lot shall be stacked in basic patterns of cluster formation so 
that bags  or crates can be easily c ounted, and quality m aintained;   
 
b)  The bag  or crates  stack shall be arranged  in a manner that allow s inspection and fumigation   
 
c)  When using jute or sisal bags, the bag stack can be built to around 8 layers, any higher th an that  
there is a risk to stability and it is difficult for storage worker  
 
d)  Different commodities, different consignments (new and old) should be placed in different stacks i.e. 
separated in batches based also on the time of their reception in store, as far as the available space 
will allow.  
 
9.6  Pests prevention and control  
 
9.6.1 Pests can be prevented and controlled by : 
 
a)  keeping roots  or tubers below the temperature or the humidity necessary for increase in pest 
numbers (for example drying, aerated storage, refrigerated storage);  
 
b)  sprayin g the floors and walls with pesticides;  
 
c)  dusting of roots and tubers by pesticides; and  
 
d)  fumigation.  
 
9.6.2 Where control is by fumigation, the following provisions shall apply:  
 
a)  fumigants shall only be used by properly trained and authorized p ersons, who know the hazards and 
the necessary safety  precautions.  
 
b)  there shall be no human habitations within 100 m of the planned fumigation; if there are, the 
arrangements shall be made for people to be relocated during the treatment.  
 
c)  fumigated  piles shall be kept closed and warning signs displayed until the gas concentration goes 
below  the levels which do  not cause any adverse  effect to the workers.  
 
d)  the stacks shall be well sheeted and there shall be no store imperfections, including  but n ot limited to 
cracks  in the floor, unfilled floor joints  and roof leaks, which  might jeopardize  the success of the 
fumigation.  
 
e)  at the end of the fumigation, warehouse shall be aerated carefully to minimize hazards.  
 
 
9.7  Record keeping  
                                                                                                          DKS 2783:2018  
 
x  KEBS 2018  — All rights reserved  Warehouse sha ll keep records of:  
 
a) origin, history of and volume of each lot of roots or tubers  
 
b) Dates of receipt and batch number.  
 
c) laboratory tests carried out;  
 
d) names of chemicals used for pest control;  
 
e) fumigation detailing the fumigant used, the date and method of fumigation, person or company;  
 
f) names of employees and training undertaken;  
 
g) authorization by Environmental agency;  
 
h) servicing and calibration of all equipment;  
 
i) cleaning; and  
 
j) pest control detailing the pesticide used, the date and method of spray/dusting , person or company.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
    © KEBS   First Edition  
 
 
 
                                                                                       DKS 2783:2018  
KEBS 2018  — All rights reserved    xi