PHILIPPINE NATIONAL STANDARD        PNS/BAFS _____  :2015  
Code of Good Warehousing Practices (GWP) for Grains  
 
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 SECTION 1 - OBJECTIVES  1 
This  Code aims  to provide specific guidance  for the appropriate handling,  storage 2 
andtransport of grains to ensure  prevention and reduction of physical, biological and 3 
chemical factors that contribute to the quality, quantity and safety of grains during storage.  4 
SECTION 2 – SCOPE, USE AND DEFINITION  5 
2.1 Scope  6 
This Code covers general warehousing  practices  relevant to handling storage  and transport  7 
ofgrains . It also considers the provisions of the Good Agricultural Practices (GAP) and Good 8 
Manufacturing Practices (GMP) to ensure food safety, quality of produce and work er’s 9 
health, safety and welfare . 10 
2.2 Use  11 
This Code considers the relevant provisions of the Republic Act 10 611: The Food Safety Act , 12 
National Food Authority (NFA)’s Revised Rules and Regulations on Grains Business  and other 13 
relevant national and private standards for the  handling, transport and storage of 14 
grains. This Sta ndard should be used in conjunction with the Good Agricultural Practices 15 
(GAP) for Corn (PNS/BAFPS 20:2007) and Rice (PNS/BAFS 141:2014 ). Moreover, this Code is 16 
consistent with the Philippine Agricultural Engineering Standard (PAES) _____:2015, 17 
Agricultural  Structures – Warehouse for Bag Type Storage for Grains .Relevant provisions 18 
that pertain to practices that ensure prevention and reduction of physical, biological and 19 
chemical factors that contribute to the quality, quantity and safety of grains during 20 
storage and promote agricultural product safe -keeping and quality preservation are 21 
expounded in this Code.  22 
 23 
2.3 Definition s 24 
For the use of this Code, the following terms should apply:  25 
Contamination  The introduction or occurrence of a hazard 
into the environment  
Farm  Any premise , or area  in which  crops especially 
grains   are grown and harvested  
Fertilizer  
 Includes any solid or liquid substance either 
organic or inorganic nutrient elements – singly 
or in combination with other materials, applied 
directly to the soil, foliage or plant for the 
purpose of promoting plant growth, increasing 
crop yield or improving  product q uality.  
Food  Any  substance or product whether processed, 
partially proce ssed or unprocessed that is 
intended for human consumption. It includes 
drinks, chewing gum, water and other 
substances which are intentionally 
incorporated into the food during its PHILIPPINE NATIONAL STANDARD        PNS/BAFS _____  :2015  
Code of Good Warehousing Practices (GWP) for Grains  
 
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 manufacture, preparation and treatment.  
Food safety    Assurance that food  will not cause harm to the 
consumer when it is prepared or eaten 
according to its intended use  
Good Manufacturing Practices  (GMP)  Quality assurance system aimed at ensuring 
that products are consistently manufactured, 
packed, repacked or held to quality standards 
appropriate for the intended use. It is thus 
concerned with both manufacturing and 
quality control procedure  
Grains  Shall mean the husked or unhusked, milled or 
unmilled, seeds or fruits of various food plants 
more specifically the cereal grasses.  
 
Milled Rice  Product obtained after the removal of husks 
and bran.  
 
Pest  An unwanted animal or plant  that affects the 
production, quality and safety of -food 
agricultural crops – for example, insects, 
diseases, weeds , rodents and birds  
Pesticide  Any substance or product, or mixture thereof, 
including active ingredients, adjuvants and 
pesticide formulations, intended to control, 
prevent, destroy , repel or mitigate directly or  
indirectly, any pest.   
Shelled Corn  Corn kernels, mainly either dent or flint 
varieties of the plant Zea mays . It is also known 
as ‘maize’ or ‘corn grain’.  
Warehouse  Building used for storing paddy, milled rice 
and other grains . 
Warehousing Practices  System  or procedure  of storing goods to ensure 
that these are always available, accessible and 
in good condition  
 26 
SECTION 3 – SITE LOCATION AND CONSTRUCTION  27 
This Section shall conform with the provisions ofthePhilippine Agricultural Engineering 28 
Standard (PAES)_____:2015, Agricultural Structures – Warehouse for Bag Type Storage for 29 
Grains . 30 
 31 
In addition to the requirements specified in PAES __ ____: 2015 standard, the following are 32 
additional considerations:  33 
 The warehouse should be constructed away from sources of potential contaminants 34 
that may affect the quality of produce and pose risk to  the worker’s health and 35 
safety.  36 
  The storage establishment should be located away from environmentally polluted 37 
areas and sources of industrial activities, flood prone areas, zones that may 38 PHILIPPINE NATIONAL STANDARD        PNS/BAFS _____  :2015  
Code of Good Warehousing Practices (GWP) for Grains  
 
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 encourage insect infestation and entry of stray animals and places  where waste 39 
either solid or liquid cannot be removed effectively.  40 
 The warehouse should be constructed where there is accessible road.  41 
  The load -bearing capacity, resistance to compaction and drainage  characteristics of 42 
soil in which the storage and warehouse is to be constructed should be determined.  43 
 The location and distance of the warehouse from other farm structures or the 44 
production area should also be considered during construction.  45 
 Other factors  that may be taken into account are the following: accessibility, ease of 46 
movement of stocks, and permission for vehicle movement and maneuvering.  47 
In terms of building specification, there should be sufficient area in the storage and 48 
warehouse that will al low handling and storage of grains in a manner that will not result to 49 
adulteration of stored grains . 50 
SECTION 4 - STORAGE WAREHOUSE DESIGN AND SPECIFICATION  51 
This Section shall conform with the provisions ofthePhilippine Agricultural Engineering 52 
Standard (PAES)_____:2015, Agricultural Structures – Warehouse for Bag Type Storage for 53 
Grains  and Food  and Agricultural Organization  (FAO) : The Purposes of Warehouses, and 54 
Basic Requirements . The succeeding sections provide additional parameters that should be 55 
taken into account.  56 
4.1 Ventilation  57 
Ventilation systems should be designed and constructed to provide proper aeration and to 58 
maintainthe desired temperature. Moreover, the ventilation systems should be maintained  59 
in normal conditions  and cleaned  regularly.  60 
4.2 Flooring  and Drainage  61 
The floors should be constructed to be  adequately strong , sufficiently above ground level  62 
and free from cracks  where moisture from the ground may affect  and/or contaminate  the 63 
stored grains . Itshould be made from  durable , impervious, non -toxic, and non -adsorbent  64 
materials . Proper drainage system should be installed to prevent water stagnation.  The 65 
drainage canals should be protected by a grille.  66 
4.3 Walls  and Ceilings  67 
All ceilings and w alls should be constructed and finished  so as to prevent condensation, 68 
leakage and formation of mold.  The walls and ceilings should be painted white or any light 69 
color ed material . Moreover, it should be made of smooth, durable, impervious, crack - 70 
resistant materials that can be cleaned easily.  71 
4.4 Openings/Doorways/Windows  72 
Openings leading to the exterior should be installed with mesh screen windows and tight - 73 
fitting doors , to prevent entry of unauthorized personnel, and stray animal sand pests . 74 
4.5 Lightings  75 
Adequate lightings should be provided to allow adequate and effective cleaning  of the 76 
warehouse facility  and to ensure that storage operations can be carried out in a hygienic 77 
manner. Shatterproof materials should be used to enclose the lightings fixtures inside  the 78 
warehouse to ensure that the grain s are protected by contamination due to breakages.  79 
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Code of Good Warehousing Practices (GWP) for Grains  
 
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  81 
4.6 Roof  82 
Roof frames should be designed in a way that it can transfer the weight of the roof to the 83 
supporting  columns (in framed buildings), or to the walls f or small warehouses. The 84 
materials to be used in the construction of these roof frames should be made of  steel or  85 
wood that is well dried and chemical treated .  86 
There should be no opening between the wall and the roof  to avoid entry of pests and to 87 
minimize contamination. In the event that the existing warehouse s havegaps between the 88 
roof and the wall, a mesh should be installed to prevent entry of animals, and pests.  89 
SECTION 5 -PILING SYSTEM  90 
To provide aeration and avoi d contamination, pallets , square timbers  or any local 91 
substitute  shall be used as the base of all the stocks of grains. The pallets may be covered 92 
with clean and new empty sacks or plastic sheetsto prevent accumulation of spilled grains 93 
beneath the pallets. The floor sheets may be used for fumigation purposes.  94 
In terms of moisture content, grains shall be stored and piled following  the 95 
recommendations in the table below : 96 
Table 1 - Storage and  Piling System for Grains in reference to its Moisture Content (MC)  97 
 98 
All grains above 14% moisture content should be  subjected to further drying operations 99 
prior to storage.  100 
The piles shall be  stacked in a  tight, neat and squared off  manner .The stack heights  and 101 
stacking density  should conform with the recommended provision s of the Philippine 102 
Agricultural Engineering Standard (PAES)_____:2015, Agricultural Structures – Warehouse 103 
for Bag Type Storage for Grains . 104 
Atleast one-meter space shall be provided between piles, between piles and walls , and 105 
between piles and posts to facilitate cleaning and application of pest control measures. An 106 
updated bin card  shall be attached to every pile. The standard information in the bin card 107 
shall be the followi ng:  108 
a. Date received ordateprocured  109 
b. Source of stock  110 MC 
(%) Storage and 
Piling System  Description  Remarks  Illustration  
≤14  Block or 
Chinese 
Method  1 layer  after the 
other  --- 
 
 Japanese 
Method  
 1 layer  after the 
other with hole 
in the middle for 
aeration  Temporary piling 
only  
 
PHILIPPINE NATIONAL STANDARD        PNS/BAFS _____  :2015  
Code of Good Warehousing Practices (GWP) for Grains  
 
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 c. Moisture content  111 
d. Quantity of bags  112 
e. Variety or code  113 
f. Pest control measures applied and date of application  114 
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SECTION 6  – GOOD WAREHOUSEKEEPING  116 
6.1 Warehouse Maintenance  117 
There should be monthly scheduled inspection of roofs for the presence of any holes, 118 
leakages or damages in the roofing system. The Warehouse officer shall immediately act 119 
upon any report of leaks or damage . Structural defects in gutters  and downspouts sha ll be 120 
immediately and properly repaired. In case of cracks and crevices, cement plaster shall be 121 
used  to properly fill up the damage . 122 
6.2 Warehouse Hygiene and Sanitation  123 
Prior to storage, the  warehouse and its immediate surroundings shall bethoroughly  124 
cleaned . The warehouse must be free from unnecessary materials like pieces of lumber  and 125 
old machine s.After cleaning, residual spraying shall be applied to the entire storage 126 
structure , which includes walls, floors and posts. The entire warehouse structure must be 127 
cleaned and brushed down at least once a month to prevent contamination from dirt.  128 
Moreover, t he surrounding areas of the warehouse should be weed -free.  129 
Machines must be cleaned to avoid accumulation of grain residues, dust and waste. A 130 
weekly cleaning of the periphery of the piles should be done to remove dust and webs and 131 
to eliminate the possible breeding place of rats, birds, and insects. Damaged or gnawed 132 
sacks should be immediately mended to avoid spillages, collapse  of the pile , and further 133 
attack from pests. Warehouse including pallets must  be cleaned immediately upon grain 134 
disposal to remove accumulated grain residues, dust, and cobwebs .Unused pallets 135 
andempty sacks should be  cleaned and  properly stored.  136 
If possible, bags or containers should not be re-used since use of returned sacks is a  serious 137 
source of insect infestation . However, if sacks are intended to be used again, immediate 138 
cleaning and fumigation should be done after each use with particular at tention to the 139 
seams where pockets of grains may lodge. Unserviceable empty sacks  and totally damaged 140 
grains should  be properly disposed.  141 
A separate room should be provided for pesticides and cleaning materials. Sacks and 142 
pallets should be properly stored  in a separate portion of the warehouse and stacked 143 
neatly and orderly and provided with a physical separator .Proper signage should be 144 
provided for all rooms.  Moreover, no portion of the warehouse should be used as living 145 
quarters.  146 
6.3 Stock Maintenance and  Preservation Standards  147 
Representative sample s shall be taken randomly from a batch of bagged grains and 148 
measured using calibrated moisture meters . Newly received grains with moisture content 149 
above 14 % shall be temporarily stored and subjected to drying to 14% MC and below . Dried 150 
stocks may be grouped according to their varietal characteristics . 151 
Laborers shall be discouraged and prevented from using hook or “gancho” to maintain the 152 
integrity of thebags and avoid spillages. The spillages shall be immediately collected . These 153 PHILIPPINE NATIONAL STANDARD        PNS/BAFS _____  :2015  
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 collected grains may be either be  sacked and piled separately or cleaned and added to 154 
busted bags.  155 
At least 100 g sampleof every variety of stocks  of milled rice  or shelled corn  stored in the 156 
warehouse should be maintained at the warehous e office for easy reference .It shall be 157 
packed in plastic containers or sample bottles with proper identification . Warehouse 158 
temperature/humidity as well as grain temperature must be measured daily. Grain 159 
thermometer and thermohygrometershould be installed for monitoring purposes.  160 
 Warehouse atmosphere must be controlled by  either  opening or closing windows/doors 161 
or installing ventilation fans. Windows and doors must be opened during  daytime for 162 
proper aeration of stocks. All windows and other openings excep t doors must be screened 163 
to avoid pilferages  and entry of pests.  164 
Damaged grains that  are no longer fit for consumption shall be disposed immediately . Daily 165 
inspection of stocks shall be done to detect signs of infestation in order that  pest control 166 
measures can be recommended and effected.  167 
6.4 Pest Control Administration  168 
A pest monitoring and inspection program must be in place to prevent harborage and 169 
breeding of pests on the grounds and within the wa rehouse facility.Whenever stocks are 170 
disposed and the warehouse is vacated , residual spraying of the whole or sections of the 171 
storage structure should be carried out after thorough cleaning. Space treatment should be 172 
conducted at dawn or dusk when flying insects are most active. For crawl ing insects, 173 
external stock treatment consisting of spray application to the four sides and the top 174 
surface of the pile should be conducted regularly. For heavily infested stocks, fumigation , 175 
conducted by licensed fumigators only , should be done as a remedial measure to control 176 
internal infestation. Rodent control through the use of traps or poison baits should be 177 
carried out regularly.  178 
 179 
Only pesticides for stored products approved by the competent authority shall be used.  180 
Monitor ing of the efficacy of the treatment used should be done at least one week after the 181 
application.  182 
 183 
6.5 Transport  184 
The harvested grains or stored grains should be transported using clean vehicles or other 185 
appropriate mode of transportation. Transport vehicle s should be cleaned before and after 186 
usage to avoid contamination and residual infestation.  187 
 188 
SECTION 7: WORKER’ S HEALTH, WELFARE AND TRAINING  189 
7.1 Personnel Hygiene  190 
There shall be a strict observance of the “no smoking”, “no spitting” and “no eating” policy 191 
inside the warehouse since this practices will induce contamination. Any person who has 192 
or appears to have an infectious disease, open lesion, including boils, sor es, or infected 193 
wounds, or any other abnormal source of microbial contamination must be excluded from 194 
any operations.  Hygienic practices  through established/documented procedures including 195 
specific instructions should be made for all personnel.  196 PHILIPPINE NATIONAL STANDARD        PNS/BAFS _____  :2015  
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 Grain handl ers should follow personal hygiene  recommendations  as indicated in 197 
FDA/BFAD Revised Guidelines on Current Good Manufacturing Practice in Manufacturing, 198 
Packing, Repacking or Holding Food (AO No. 153 s.2004) or the latest issuance and Codex 199 
Recommended International Code of Practice General Principles of F ood Hygiene 200 
(CAC/RCP 1 -1969,Rev. 4 -2003) or the latest issuance.  The following recommendations 201 
should include but not limited to:  202 
7.1.1 Wearing of appropriate clothing and shoes applicable to the operation and can serve 203 
as protection for food contamination  and an aid on the workers health and welfare.  204 
7.1.2 Wearing appropriate masks during handling and transport of grain produce.  205 
7.1.3 Washing of hands thoroughly and sanitizing, if necessary, in the appropriate hand - 206 
washing facility before the start of any handling operation, after each absence from the 207 
work station and at any given time when possible contamination can be encountered by 208 
the worker.  209 
 210 
7.2 Personnel Training  211 
Before a job is assigned, the  training background and ability of the personnel shall be  212 
considered. Training and re -orientation of the warehouse personnel should be done at least 213 
every two (2) years. The following trainings recommended for the personnel specific on 214 
his/her assigned task  are the following:  215 
7.2.1 Inventory and management  216 
7.2.2 Acquisition and purchasing  217 
7.2.3 Supply chain and logistics  218 
7.2.4 Transportation and freight operations  219 
7.2.5 Personnel hygiene and food safety  220 
 221 
SECTION 8: MANAGEMENT AND SUPERVISION  222 
Grain operators should have adequate knowledge o nfood hygiene principles and practices 223 
to be able to assess potential risks, take appropriate preventive and corrective action, and 224 
ensure that effective monitoring and supervision is carried out. Formal training on food 225 
safety ( GMP/GHP ) is necessary and fu rther trainings in HACCP are extremely helpful.  226 
Trainings on food safety for grains businessmen, grains operators and warehouse 227 
personnel should be conducted.  228 
 229 
SECTION 9: DOCUMENTATION AND RECORDS  230 
All cleaning and pest management activities should be proper ly documented  in a 231 
recommended form . 232 
Appropriate records from all warehousing practices should be kept and retained for a 233 
period that exceeds the shelf life of the product. Records should be to facilitate recalls and 234 
product safety investigations, if required.  235 
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  237 
SECTION 10:  TRACEABILITY  238 
Proper packaging and labeling for grains  should conform with the provisions stated under 239 
the revised edition of the National Food Authority’s Primer on Philippine Grains 240 
Standardization Program. The labeling informatio n should contain the following whenever 241 
applicable: Classification (ie. well milled, regular milled or under milled for rice and white 242 
or yellow cor n and flint or dent corn for shelled corn), variety, grade(optional except for 243 
special rice), net weight, na me and address of the Miller and in case of custom milling, 244 
name and address of owner.  245 
Proper labeling and record keeping should be made to facilitate any forward or backward 246 
tracing of food products. Records of deliveries should be kept (delivery receipt, personnel 247 
from in and out of the warehouse, date of delivery, and classification of goods delivered) . 248 
 249 
SECTION 11: RECALL P ROCEDURES  250 
Warehouse o perators should ensure that effective procedures are in place to deal with any 251 
food safety hazard and to enable the complete, rapid recall of any implicated lot of the 252 
finished food from the market in case of complaint or issues regarding product quality and 253 
safety . Where a product is withdrawn because of an imm ediate health hazard, other 254 
products which are produced under similar conditions, and which may present a similar 255 
hazard to public health, should be evaluated for safety . The need for public warnings 256 
should be considered.  257 
Recalled products should be held u nder supervision until they are destroyed, used for 258 
purposes other than human consumption, determined to be safe for human consumption, 259 
or reprocessed in a manner to ensure their safety.  260 
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 References:  285 
Agricultural Machinery Testing and Evaluation Center.(AMTEC). Philippine Agricultural 286 
Engineering Standard (PAES)_____:2015, Agricultural Structures – Warehouse for Bag Type 287 
Storage for Grains.  288 
Bureau of Agricultural and Fisheries Standards (BAFS).PNS/BAFS 10:2004 ICS 65.020.20 289 
Grains - Corn ( Zea mays indenta Linn, Zea mays indurate Linn.  and Zea mays ceritina  K. Sturt. 290 
Syn.  praecox ) – Grading and Classification  291 
Bureau of Agricultural and Fisheries Standards (BAFS).PNS/BAFPS 20:2007 ICS 65.020.20 292 
Code of Good of Agricultural Practices for Corn (GAP Corn).  293 
Bureau of Agricultural and Fish eries Standards (BAFS).PNS/BAFS 141:2014  ICS 65.020.20 294 
Code of Good of Agricultural Practices for Rice  (GAP  Rice ). 295 
Codex Recommended International Code of Practice General Principles of Food Hygiene 296 
(CAC/RCP  1-1969,Rev. 4 -2003)  297 
Food and Drug Administration (FDA) /Bureau of Food And Drug (BFAD) Revised 298 
Guidelines on Current Good Manufacturing Practice in Manufacturing, Packing, Repacking 299 
or Holding Food (AO No. 153 s.2004)  300 
Food Agricultural Organization.The Pu rposes of Warehouses, and Basic 301 
Requirements.Retrieved on May 28, 2015 at 302 
http://www.fao.org/docrep/t1838e/t1838e16.htm . 303 
National Food Authority.  2006. Revised Rules and Regulations on Grains Business. Council 304 
Resolution No. 301 -2K6 -K. 305 
National Food Authority. 2013. Primer on Philippine Grains Standardization Program. 306 
Revised Edition. Circular Number AO – 2013 -04-003  307