Table Of ContentAT
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u and Storage
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in
TroDica'C
.
and
SubtroplcaJ-
Areas
by:
D.W. Hall
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United
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. *
HANDLING
AND STORAGE
0F FOOD GRAINS
IN TROPICAL
AND SUBTROPXCAL
AREAS
_ _ .._.
~-_
..-_-
_
7
I
__
FOOD
AND
AGRICULTURE
ORGANIZATION
OF THE
UNITED
NATIONS
This manual sets out the causes of
grain loss, deterioration and contam-
ination, methods of drying and stor-
age, the design of storage facilities,
and also methods of fungus, insect
and rodent control methods.
It 4s
=-imarily
-intended for agricultural
and public health oflkers, for those
responsible for designing storage and
marketing facilities, and for agricul-
tural
training
colleges. kt should
also be useful to those when may be
engaged in .greparing extension ma-
terial for welfare officers, warehouse-
men, traders and farmers in tropical
and subtropical countries.
HANDLING
AND STORAGE OF FOOD GRAINS
IN TROPICAL
AND &JBTROPICAL
AREAS
First printing 1970
Second priwing 1975
FAO Agricultural Development Paper
No. 90
HANDLING
AND STORAGE
OF FOOD GRAINS IN TROPICAL
AND SUBTROPICAL
AREAS
bY
D.W. HALL
FAO Consultant
Agrkultural
Engineering Sefvice
Agricultural Services Division
FOOD AND AGRICUJLTURE
ORGANIZATION
OF THE UNITED
NATIONS
ROME 1970
The information
contained in this manual is based on data
prepared for Informal Working Bulletin No. 24 in the series avail-
able from the Agricultural
Engineering Service of the .Qgricultural
Services Division of the Food and Agricuiture Organization of the
United
Nations.
While it represents knowledge obtaineli from
organizations concerned with technical problems of handling and
storing produce, it is not possible for FAO to assume responsibility
for statements contained herein.
Q FAO 1470
Prbrrted in Italy
PREFACE
This manual presents technical data on some of the principles
of handling and storing food grains in relation to local practices
in the tropics and subtropics, particularly
with reference to the
storage of cereals, iegumes and oilseeds. It has been written pri-
marily as a practical aid to agricuhural offi~s
and extension staff;
produce and marketing officers (inspection); public health officers,
teachers (training colleges, etc.); and especially to those who may
be engaged in preparing simple extension material for use by welfare
officers, warehousemen, traders and farmers in the tropical and
subtropical countries.
The subject is so broad that it has been necessary to select
and emphasize technical details of particular relevance to the pro-
vision of instructions for farmers and traders.
At the same time,
the manual is intended to provide helpful information for officials
having varied interests and ,for scientists who have little practical
experience of storage proble,(ns in the tropics.
Thus some repetition
of basic information occurs in the different chapters.
This work is based on valuable information provided by spe-
cialists in Africa and in 11 countries in other parts of the world,
and by organizations concerned with stored products problems.
Some of this information
appeared in the FAO Informal Working
Bulletin No. 24. The collator is Dr. D.W. Hall, Director, Tropical
Stored Products Centre, Tropical Products Institute, Ministry
of
Overseas Development, Slough, England.
The writer
wishes to
acknowledge the collaboration
received from the staff of the Pest
Infestation Laboratory, Agricultural
Research Council, and of the
Infestation Control Laboratory,
Ministry
of Agriculture, Fisheries
and Food.
He is also indebted to members of the staff at the
Tropical Stored Products Centre at Slough who assisted in the com-
pilation of data.
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~111
1. ~~~&)~
. . . . . ..*.....................................
1
FOOD AND ITS IMPORTANCE . . . . . . . . . . . . . . . . . . . . . . . ...*....
5
2. Tropics and subtropics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
LOCAL DIETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..A..
9
FOOD As A CASH CROP .*...*......................*......
11
3.Lmw?sofstoredfood
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
bVEI23 AT WHICH LOSSES OCCUR . . . . . . . . . . . . . . . . ..*........
14
TYPES OF LOSSES .........................................
16
Loss of weight .........................................
18
Food loss ...............................................
25
Loss of quality
..........................................
26
Monetarvloss ...........................................
32
Loss of goodwill ........................................
35
Seed loss ..............................................
35
STANDARD PACKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36
4. Factors affecting food v&e and deterioration ................
38
PROPERTIES OF FOOD GRAINS ..............................
39
Respiration .............................................
39
Moisture ................................................
40
Conductivity ............................................
41
Flow.. .................................................
41
Pressure ................................................
41
Physical and chemical nature of surface ...................
42
VIII
HAXDLING
AND
STORAGE
OF FOOD GRAINS
TEMPERATURE.. ..........................................
44
MOIS~JRJZ ...............................................
47
Types of water ..........................................
48
Moisture content/relative humidity ........................
48
Moisture content for safe storage .........................
51
Measurement of moisture ................................
55
Moisture movement in storage ............................
62
PROCESSING ..........................
..k .................
Harvesting ..............................................
Threshing and shelling ...................................
Drying .................................................
cooling .................................................
Water treatments ..............
: .........................
Cleaning ................................................
Milling .................................................
Conveying ..............................................
65
66
68
68
72
73
74
75
76
BIOLOGICAL AGENTS ......................................
79
Fungi ..................................................
79
Mites ...................................................
82
Insects ..................................................
83
EFFICIENCY GF INSPECTION METHODS.. .....................
Sampling ................................................
RODENTS ................................................
CLIMATE ................................................
Hot dry areas ..........................................
Hot damp areas .........................................
Cool areas ..............................................
97
99
104
107
111
111
111
5. Design of stores . . . . . . . . . . . . . . . . . . . ..*.................
113
BUILDINGS FOR BAG STORAGE ..............................
113
Importance of moisture ..................................
115
Importance of temperature ...............................
117
Constructional details ....................................
119
CONTENTS
IX
BUILDINGS FOR BULK STORAGE .............................
Plinth construction .......................................
Constructional details for small silos and pits ..............
HYGIENE AND ORGANIZATION ..............................
CHEMICAL TREATMENTS ....................................
6. Drying *methods .........................................
NATL.
DRYING ........................................
Methods to be encouraged ...............................
ARTIFICIAL
DRUG
......................................
Effect of barometric pressure on drying. ...................
Methods to be encoumged ...............................
Cost of drying ..........................................
COST OF DIWING .........................................
7. Storage methods .........................................
TRADITIOIUL
STORAGE ....................................
Types in use..............-
..............................
MODERN STORAGE ........................................
Trader storage ..........................................
Central storage ..........................................
GENERAL CONSIDERATIONS .................................
Reception procedure .....................................
Storage procedure .......................................
Issue procedure ..........................................
8. Insect control methods ..................................
TRADITIONAL
METHODS ....................................
Regular sunning.. .......................................
Smoking ................................................
Admixture of local plants ................................
Admixture of local dusts .................................
CHEWCAL METHODS ......................................
Contact insecticides ......................................
Problems relating to the use of insecticides ................
Insecticide formulations ..................................
127
128
130
135
139
141
141
143
146
149
150
154
154
156
157
157
172
172
175
188
191
194
197
199
199
199
199
200
200
201
201
204
209
X
HANDLING
AND
STORAGE
OF rXbOD GRAINS
Admixture of insecticides directly with food products . . . . . . .
219 ’
Admixture of insecticides for the protection of seed .......
Residual spraying of storage buildings and vehicles .........
Treatment of bag stacks. .................................
Fumigation ...........................
..............
.....
Fumiga$s used in storage and infestation work ...........
Application of liquid fumigants ...........................
Application of aluminium phosphide ......................
Application of methyl bromide ...........................
Gasproof sheet fumigation ................................
In-bag or in-drum fumigation ............................
Fumigation chambers ....................................
Fumigation in ships, barges and railway trucks ............
INSPECTION AND REPORTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
239
COSTS 02 PESTICIDE CONTROL METHODS . . . . . . . . . ..I.........
240
PHlfSICAL CONTROL METHODS ..............................
241
Airtight storage ......................
. ..................
241
Insect-proof containers ....................................
242
irradiation ..............................................
242
Sound ..................................................
242
Percussion ...............................................
243
9. Rodent control methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROOFING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..a.....<...
244
REPELLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
245
POISONING ..............................................
Types of poison for use in baits ..........................
Choice of bait ..........
................................
Baiting technique.. .... . .................................
10. Some economic aspect.s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COOPERATIVE AND PRODUCE BOARD MARKETING . . . . . . . . . . . . . .
254
ROLE OF STORAGE IN IMPROVED MARKETING ..................
255
J3zonomic principles of storage ............................
256
Storage costs ...........................................
257
Location, size and operation of storage facilities ...........
261
222
222
225
227
228
230
230
231
233
236
237
238
244
245
246
246
247
248
251
co.-
xl
A.
B.
c.
D.
E.
F.
G.
H.
1.
J.
Specialists on African storage problems who contibuted data
to FAN Working Bulletin No. 24 . L........................
A selection of store products legislation in tropical and sub-
tropical countries . . . . . . . . . *.....*........................a
Assessment of insect infestation: standardized procedure. . . .
Major considerations in minimizing the incidence of toxins
in produce (particularly groundnuts) by inspection . . . . . . . . . .
Outline of measures for rodent-proofing storage buildings . . .
Bushel and standard bag weights of certain produce . . . . . . .
Loads imposed by stored grain . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of the psychrometric chart in grain drying . . . . . . . . . . . .
Temperature measuring equipment and methods . . . . . . . . . . . .
Sampling grain stored in bulk . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I&x
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
270
273
295
298
304
309
310
317
320
327
334
345
LIST OF ILLUSTRATIONS
Fipre
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Comparison ol’ estimated daily per caput calorie supplies
in terms of food types’for developed and developing areas
Exampies of types of damage .to produce. . . . . . . . . . . . . . .
Increase in fat acidity of groundnuts following infestation by
two spies
of beetles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Increase in fat acidity of stored maize meal . . . . . . . . 1 . . .
Consumption of maize meal in relation to milling maize
after storage and with increased free fatty content. . . . . .
Comparative rates of carbon dioxide production by some
cerealsand oilseeds at 38*C. . . . . . . . . . . . . . . . . . . . . . . . . . . ,
General limits of temperature and relative humidity for
the multiplication of biological agencies.. . . . . . . . . . . . . . . .
Moisture content/relative humidity equilibrium curves. . .
Values of temperature, relative humidity and moisture
content for safe storage, insect and fungal heating and
fall in germination . . . . . . . . ..-.........................
Moisture movement within bulk of grain due to differences
between the temperature of outside air and of stored grain
Spoilage of grain due to temperature gradients, movement
of moisture and localized development of fungi and insects
Effect of temperature and relative humidity on certain
species of fungi. - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Example of interaction of temperature and relative humid-
ity on the development of species of insect pest. . . . . . . . .
Callosobrdzw madams F. - pulse beetle . . . . , . . . . . . . . .
Ephestia cautella Walker - tropical warehouse moth . . . . .
BIateZZa germanica L. - Gelman cockroach. . . . . . . . . . . . . .
Sampling spears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Simple types of sampling methods . -. . . . . . . . . . _ . . . . . . . .
Rattzls (Mastomys) natalensis Smith . . . . . . . . . . . . . . . . . . . .
Cricetomys gambianus Watfrhouse with oil palm fruit . . .
Rattus ruttus L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mus musculus L. . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . , . . . .
7
17
29
29
30
40
46
49
52
64
64
81
88
94
94
94
100
103
106
106
108
108
