Safety precaution to maintain grain quality - implementer induction training

www.iita.orgA member of CGIAR consortium Date: 19-June-2014
Safety Precaution to Maintain Grain
Quality
Lawrence K. Kaptoge
Adebowale Akande
Joseph Atehnkeng
Joao Augusto
Ranajit Bandyopadhyay

Introduction – Health & Economic Losses
• The 2004 outbreak (317 cases reported, with 125 deaths) resulted from widespread
aflatoxin contamination of locally grown maize, which occurred during storage of the
maize under damp conditions. Aflatoxin poisoning likely will continue to be a public
health problem until culturally appropriate storage methods for dry maize are
implemented by the local population
• Evidence that this outbreak resulted from aflatoxin poisoning included:
1. High levels of aflatoxin (up to 8,000 ppb) in maize samples collected from patient
households
2. Clinical illness consistent with acute aflatoxin poisoning
3. Clustering of cases among residents of the same household and
4. Reports of deaths among animals known to have eaten the same maize as the
patients during the same period.
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5334a4.htm.

Introduction – Health & Economic Losses

Introduction
Small-scale grain
farmers in Kenya risk
losing out from the
World Food Program
maize purchase deal
due to contamination
of grain by aflatoxin.
On Tuesday, the
government raised
the red flag after
samples from last
season’s harvest
were found to be
contaminated.
http://www.nation.co.
ke/business/Aflatoxin
-to-hurt-farmers-
prospects-/-
/996/918918/-
/f07g2c/-/index.html

Introduction
• The National Cereals and Produce Board has re-opened its depots in Eastern and Coast
provinces to buy maize with aflatoxin. A major alert was issued by the government last
week in connection with 2.3 million bags of contaminated maize in the two provinces.
http://www.nation.co.ke/news/Cereals-board-moves-to-buy-bad-maize--/-
/1056/934812/-/5y2gn3/-/index.html
• Change of fortunes as sweet harvest turns suddenly sour
Tests reveal that slightly over 60 per cent of the maize tested in the larger Makueni
District is infected with the poisonous aflatoxin.
http://www.standardmedia.co.ke/article/2000010754/change-of-fortunes-as-sweet-
harvest-turns-suddenly-sour

• Highly toxic metabolite produced
by the ubiquitous Aspergillus
flavus fungus
• The fungus infects crops and
produces the toxin in the field and
in stores
• Fungus carried from field to store
• Contamination possible without
visible signs of the fungus
• Some predisposing factors:
– pre-harvest high temp and
drought stress
– wet conditions at harvest and
post-harvest periods
– insect damage
Aflatoxin Facts

Out line
• Sampling.
• Moisture content
• Fumigation.
• Drying.
• Cleaning.
• Storage
• Steps for good storage practices

Out line
Sampling is important for checks and testing for a range of
properties; moisture content, infestation viability, weight etc.
• Done periodically to check on the viability and general
deterioration of the crop.
1. In the field to determine MC, maturity, infestation etc.
2. On arrival at the store for MC, infestation, quantity etc
3. During storage for continual quantity monitoring
4. On despatch from store where it is weighed out and samples
retained in event of subsequent disputes
5. On arrival at the purchaser’s store for required quality attributes.

Sampling
Sampling points: A 5; B 8; C 11.

Aflasafe sampling – Raw Sorghum
Consignme
nt Date/
2014
# Bags
Registers
Clean Grain
(kg)
Waste
Material
(kg)
Total of
Grain (kg)
% of Grain
(kg/Bag)
09/05 310 26,265.0 1988.5 28,253.5 91.5
10/05 303 24,451.00 2,533.00 26,984.00 89.0
22/05 320 29,055.00 1,453.00 30,508.00 95.5
TOTAL 933 79,771.00 5,974.50 85,745.50 92
% of grain 93 % 7 % 100 %

Aflasafe sampling – Raw Sorghum
Consignment Date/
2014
# Bags with high
fungus contamination
Total of Grain (kg)
09/05 7 655.0
10.05 4 354.0
22/05 3 285.0
TOTAL 14 1,294.0
Finished Product – every 100 packets I sample collected

Sampling

Fumigation
• Fumigation - method of pest control that completely fills an area with gaseous pesticides
or fumigants to suffocate or poison the pests within.
• Used for control of pests in buildings (structural fumigation), soil, grain, and produce & during
processing of goods to be imported or exported to prevent transfer of exotic organisms.
• It involves:
• Covering the area to be fumigated to create a sealed environment;
• Releasing of fumigant into the space to be fumigated;
• Holding the pace for set period while the fumigant gas percolates through the space and
acts on and kills any infestation in the product and finally
• Ventilation of the space to allow poisonous gases escape and render it safe for entry.
• If successful, the fumigated area is now safe and pest free.
• Widely used fumigants include:
o phosphine
o 1,3-dichloropropene
o chloropicrin
o methyl isocyanate
o hydrogen cyanide
o sulfuryl fluoride
o formaldehyde
o Iodoform

Fumigation

Moisture Content
Moisture content
Definition
It is the amount of moisture (water) the seed contains.
2 methods of expressing moisture content:
1. Wet Basis
2. Dry Basis
Moisture content determination methods:
1. Direct methods determine the amount of water in the seeds
by removing them.
2. Indirect methods require the use of a meter to measure the
property of the seed that can be related to the moisture
content

Moisture Content
Source: Transactions of ASABE 3330337

Drying
o Physiological maturity - high moisture e.g. maize 35 %, highest quality, greatest vigour
and germination potential.
o Duration of safe storage dependent on the condition the crop was harvested and the
type of storage facility being utilized.
o Drying - Removal of high moisture to low levels for safe storage.
Drying, Aeration and Dehydration.
Drying permits a reduction of losses in storage from causes such as:
• Premature and unseasonable germination ,
• Development of moulds,
• Proliferation of insects.
Recommendation: Harvesting early MC >20%, quickly dry to safe MC <13%.
Drying may be effected by any of the following methods:
1. Field drying
2. Sun drying
3. Drying with forced artificially heated or unheated air,
4. Use of desiccants to dehumidify the air and
5. Drying with infrared light rays.

Drying
Reasons for drying.
o Retard or stop the development of bacteria, fungi, mites and
insects during storage.
o Make further processing easier.
o Prevent germination.
o Produce uniformly high quality crop/seed with high vigour and
germination.
o Reduced damage in processing operations, especially in
shelling in the case of maize, to elevators and cleaners.
o Increased quality of harvested grain by reducing crop
exposure to weather.
o Harvesting can be done early and in a controlled way.
o Harvesting operations can be scheduled to obtain more
efficient use of labour and available equipment.
o Allows more time for post-harvest fieldwork.
o Reduced potential for weather and pest related field losses.

Importance of drying
http://www.nation.co.ke/news/regional/Sh760m-given-to-fight-maize-poisoning-/-/1070/936196/-/h322gm/-/index.html

Drying

Cleaning
• After threshing, grains (or shells, in the case of groundnuts) are contaminated by
impurities (earth, small pebbles, plant and insect waste, seed cases, etc.)
• These impurities hinder drying operations and make them longer and more costly.
• Traditional methods: Simplest cleaning method, known as winnowing, consists of
tossing the grain into the air and letting the wind carry off the lightest impurities.
• Although widespread does not eliminate all impurities.
• Air Screen Cleaning:

Storage
• Storage - produce kept in condition to guarantee food security other than during
periods of agricultural production.
• Main objectives of storage:
i. At the food level – use on annual/multiannual
ii. At the agricultural level –Availability of seed for crop cycles to some
iii. At the agro-industrial level - guarantee regular and continuous supplies of raw
materials for processing industries;
iv. At the marketing level - to balance the supply and demand of agricultural
products, thereby stabilizing market prices.
• To attain above general objectives, necessary to adopt measures aimed at preserving
the quality and quantity of the stored products over time.
• Storage in bag or bulk; sealed or unsealed structure.
• Effect of environmental factors and Agents causing deterioration – microorganisms,
insects and rodents

Storage
• Influences of environmental factors
• long-term storage, degradation processes must be slowed down or even
stopped.
• Degradation of grains during storage depends principally on a
combination of three factors:
o Temperature,
o Moisture,
o Oxygen content.
• Temperature and moisture
• Direct influence on the speed of development of insects and
microorganisms (moulds, yeasts and bacteria), and on the premature
and unseasonal germination of grain.
• Moisture content of stored grain, depends on the relative humidity of the
air,
• Temperature sensors in silos

Storage
• Oxygen content
• Like grain, micro-organisms and insects are living organisms that need
oxygen. Storage of grain in places that are low in oxygen causes the
death of insects, cessation of development of micro-organisms, and
blockage, or slowing down, of the biochemical phenomena of grain
degradation. This favours the conservation of grain, but may affect its
germinating power. CA Storage.
• PICS bag storage - Purdue Improved Crop Storage (PICS2) -
http://www.entm.purdue.edu/PICS2/

Steps for Good Storage Practice

Agents causing deterioration of
stored grain
• The principal enemies of stored grain are micro-organisms, insects and
rodents.
• Micro-organisms
• Micro-organisms (moulds, yeasts, bacteria) are biological agents present
in the soil which, when transported by air or water, can contaminate
products before, during and after the harvest.
• Their presence and growth cause severe changes in the nutritive value
and the organoleptic features of grain (taste, smell, aspect).
• They are responsible for formation of dangerous poisons.
• Impurities and cracked or broken grains, foster the development of
micro-organisms.
• Temperature and humidity have a determining influence on the growth
rate of these degradation agents.
• On the contrary, atmospheres that are low in oxygen help check the
development of these degradation agents.

Agents causing deterioration of
stored grain
Insects
• Insect infestations occur either in the field, before harvest or in storage.
• Their biological activity (waste production, respiration, etc.) compromises
the quality and commercial value of the stored grain and fosters the
development of micro-organisms.
• Insects can live and reproduce at temperatures between 15 & 35 0C.
• Low humidity slows or even stops their development, and a low supply of
oxygen rapidly kills them.
Rodents
• Rodents invade and multiply in or near storage places, where they can find
abundance of food. They also cause serious damage to packaging and
storage buildings.
• Prolonged attacks result in serious quantitative losses of stored products.
• Their filth (excrement, secretions) is responsible for decrease in quality of the
foodstuffs
• This contamination is as important from the marketing standpoint as it is for
hygiene and health. Rodents are often the vectors of serious diseases
(rabies, leptospirosis).

Good Post Harvest Practices
For best storage performance:
• Clean the grain to remove chaff, weed seeds, and broken kernels
• Handle grain gently to minimize cracked and broken kernels.
• Dry to the safe storage moisture 10-12 % for cereals; 7-9% for oil seeds
• Aerate to maintain cool, uniform recommended temperature.
• Properly clean and disinfect the storage structures.
• Chose storage structure that does not permit contact/exchange with
outside humid air.
Requirements for good storage
• Provide maximum possible protection from ground moisture, rain, insect
pests, moulds, rodents, birds etc.,
• Provide the necessary facility for inspection, disinfection, loading,
unloading, cleaning and reconditioning.
• Protect grain from excessive moisture and temperature favourable to
both insect and mould development.

Ideal Storage Conditions

Ideal Storage Conditions
Figure 2. Storage Risk Increases with Temperature, Moisture and Time.

Pests
Stored product pests can be managed either behaviouraly (traps ) or with
several preventive and curative measures (both chemical and non-
chemical methods).
Steps.
1. Before storage
• Check for leakage of rain water and sufficiency of drainage facilities
• Cleanliness of the facility and environment
• Pesticidal treatment – e.g. application of Actellic dust
• Security and fire fighting arrangements and
• Repairs to available equipment
2. After receipt
• Inspection for variety and soundness of quality
• Carefully inspection for infestation and when present, type and extent of
infestation,
• Inspection whether grain has excess moisture, any grain rendered wet or
damaged to be segregated and salvaged with facilities available and
check the weight received

3. During storage
• Maintenance of cleanliness
• Ensuring aeration where necessary
• Check for leakage after rains
• Inspection for insects, rats and mites at fortnightly intervals
• Watch for advancement in deterioration, if any,
• Arrangement for segregation, salvage and processing, wherever,
damage owing to leakage of water and other causes might have
taken place.

www.iita.orgA member of CGIAR consortium Date: 02 – May - 2013

Safety precaution to maintain grain quality - implementer induction training

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