Management of aflatoxin contamination in groundnut –

ICRISAT ApproachH Desmae

ICRISAT-WCA, Bamako, MaliJanuary, 2016

Outline

• Groundnut in Africa• Aflatoxin Contamination• Effects and Regulatory Limits• Aflatoxin Management Approach• Aflatoxin Diagnostic tools

GROUNDNUT IN AFRICA• Africa accounts for over 40% of groundnut area but

contributes only about 25% of world production • West & Central Africa (WCA) accounts for over 70%

groundnut production in Africa• It accounts for up 60% of cultivated area and

significant portion of export commodities in some countries

• Cash crop– Up to 50% crop value– Main source of income for women

AFLATOXIN CONTAMINATION: Groundnut

Source of the problem

• Caused by fungus, Aspergillus flavus/A. parasiticus

• Aspergillus flavus is the most important– produces Aflatoxin B1 which is a extremely high carcinogenic

• Grows over a wide range of temperature (10-40°C)• Thrives at high RH & kernel moisture content

of 10-30%• No growth at low RH or kernel moisture

contents <10%• Aflatoxins are heat resistant

Complexity of the problem

• Can occur at any time (pre and post harvest)• Cultivars and farming practices• Weather conditions

• Drought stress• Time of harvest / pod removal • Method of harvest / drying• Mechanical / insect damage• Storage conditions• Conditions of packing and distribution

EFFECTS AND REGULATORY LIMITS

Effects• Mycotoxins are considered part of the most significant food contaminants in terms of

impact on public health, food security and economy• Aflatoxin, along with low productivity & poor quality standard, has contributed for

significant decline of WCA share in global groundnut production and market in the last four decades– production 27% to 20% – oil export from 55% to 24%– Confectionary groundnut export by 50%

• It has detrimental effect on human nutrition & health• Aflatoxin is reported to cause

– Mycosis and allergies– Edema, hemorrhage and even immediate death at high concentration levels– Excessively carcinogenic and can cause various types of cancer in humans– childhood cirrhosis– Reduces the effectiveness of the immune system & increases susceptibility to infection and

cancer– reactivation of sub-clinical infections– disruption of vaccine efficacy & loss of therapeutic effect– Negative effects on development and reproduction

Regulatory limits Country Product Aflatoxin Maximum

allowable limit (µg/kg)

China, Japan, Thailand,Egypt, Turkey

Groundnuts Total 10

Indonesia, Malaysia,Taiwan province of China, Australia

Groundnuts Total 15

EU Groundnuts Total 4 (direct consumption)15 (further processing)

B1 2

Kenya Groundnuts Total 20Russia Groundnuts B1 5

Canada Nuts and Nut products Total 15

India All food products Total 30

Philippines Nuts and products Total 20

Singapore Nuts Total 5USA All foods except milk Total 20

Viet Nam Food stuffs Total 10

(CODEX ALIMENTARIUS COMMISSION, 2013)

A case study: Pre-harvest groundnut aflatoxin contamination in different districts of Mali during

2009 & 2010

Aflatoxin range (µg/kg) % of groundnut samples in each category/district

Kayes Kita Kolokani

0-4 41.1 36.7 34.4

5-10 26.7 2.2 15.6

11-20 10.0 6.7 5.6

21-35 3.3 11.1 8.9

36-100 8.9 24.4 12.2

101-500 10.0 18.9 17.8

>500 0.0 0.0 5.6

Post-harvest aflatoxin contamination in groundnut (2009 rainy season crop) in farmers’ granaries in different

districts of Mali, West Africa

AFLATOXIN MANAGEMENT APPROACH

The main issues concerning aflatoxin management, particularly in WCA

• Lack of awareness on the effects of aflatoxins on crops, nutrition and human health at all levels (producers, buyers, traders, consumers)

• Lack of knowledge on appropriate technologies to mitigate Aflatoxins on farms

• Lack of expertise and appropriate facilities in aflatoxin analysis

• Lack of knowledge in post-harvest and storage management of aflatoxin in groundnut attributed to insect infestation, Aflatoxins, general quality, harvesting and storage practices

• Lack of data on aflatoxin contamination along the value chain

• Lack of premium for aflatoxin-free groundnut, and lower income for farmers

Typical model of groundnut value chain

No-cost Low-cost High-cost

ICRISAT Approach

Host resistanceConventional breeding,

Transgenic approach with anti-fungal and anti-mycotoxin genes,

Genomics-assisted breeding

Pre- and Post-harvestAflatoxin Management

Global Approach

Devising Appropriate Regional Package and Promotion

Harvesting and Post-harvesting Technologies

Drying and Storage

Assessment / Implementation at Regional level

Technology Transfer /Socio-economic issues

Regional studies & monitoringPublic awareness

Trade implicationsAdvisory panels

Consultation to IndustriesTraining

Bio-control AgentsTrichoderma, Pseudomonads,

Atoxigenic strains

Cultural PracticesSoil amendments

(gypsum, compost)

ICRISAT employs Integrated Approach to Mitigate Aflatoxin Contamination (Waliyar, 2015)

Aflatoxin Management Options(Waliyar et al., 2013)

Pre-harvest Management options

• Use of A. flavus resistant/tolerant varieties • Selection of healthy seeds• Early planting• Avoidance of mono-cropping• Application of Trichoderma at 1 kg/ha• Plowing before sowing• Appropriate weeding• Application of farmyard manure at 2.5

tons/hectare before planting • Treatment of foliar diseases using 1–2

sprayings Application of lime or gypsum at 400 kg/ha at flowering

• Mulching with crop residues at 40 days after planting

• Maintenance of optimal density of plants in the field

• Avoidance of end-of-season drought through irrigation (if possible)

• Removal of dead plants from the field before harvest

At-harvest and post-harvest Management options

• Harvesting the crop at the correct maturity• Use of water-harvesting to preserve available

moisture• Use of A. flavus resistant/tolerant varieties• Avoidance of damage to pods during harvest• Avoiding long-term contact of groundnut

pods with soil after harvest • Drying of groundnut pods on tarpaulin

sheets rather than on bare ground• Drying seed to 8 percent moisture level• Stripping the pod immediately after drying• Removing immature pods attached to the

haulms• Removing damaged, shriveled, and

immature pods• Not mixing clean harvested pods with

gleaned pods• Avoidance of re-humidification of pods

during shelling or in storage• Fumigation of pods with insecticide to avoid

insect damage during storage

Some ExamplesHost plant resistance

• Breeding for short duration & drought tolerant varieties

• Drought is an important predisposing factor. Short duration varieties escape end-of-season (terminal) drought while drought tolerant varieties minimize the effect of drought (e.g. ICGV86124,86024, 86015…)

• Breeding for varieties with low aflatoxin infestation to minimize infestation and infection

Screening of various germplasm sets (core/mini core collections)

Testing advanced breeding lines in Asia and Africa• ICGV 91324, 94434, 94379,91278, 91279, 91328, 93279, ...etc

• Incorporation of “R” through hybridization

Cultural Methods

• Adjusting planting dates Proper planting time enables good plant growth as well as avoids terminal

drought stress

• Box ridges for moisture retention• Soil amendments

• FYM• cereal crop residues• Gypsum/Lime

Gypsum enhances shell integrity in pods and minimizes A. flavus fungus penetration and infestation

• Conjunctive use of FYM, Gypsum & cereal crop residues reduces infestation more

Improved soil fertility supports healthy plant development

Influence of agronomic/cultural practices in aflatoxin reduction

Agronomic practice Aflatoxin reduction (%)

Cereal crop residues (CCR) (2.5 t/ha) 28

Farmyard Manure (FYM) (2.5 t/ha)42

Lime (400 kg/ha)72

FYM + CCR53

Lime + CCR 82

FYM + Lime + CCR83

FYM + Lime 84

Waliyar et al., 2006 & 2007

Post-harvest management in reducing aflatoxin contamination

• Post-harvest management techniques reduce the incidence and infection of groundnut with aflatoxin by creating unfavorable condition for the fungus growth

Introduction of simple pod stripers could help reducing aflatoxin infestation by enabling timely pod striping

Awareness creation is very important

Improved Batch Drying

•Drying pods: facing the Sun

• Improved Batch Drying

(Pods facing the sun)

Traditional drying practices

Simple change in drying practice of pods

Improved granary for reducing aflatoxin contamination

Smoke passage

Kitchen Granary

Improved granary structure – attached to kitchen

Farmer granary

AFLATOXIN DIAGNOSTICS TOOLS

Analytical techniques

Immunological methods are advantageous over chromatographic and other methods. Because they are:

•Simple•Cost-effective•Sensitive•Rapid•Versatile

ICRISAT has developed competitive ELISAs with the help of in house raised antibodies

• Indirect competitive ELISA• Direct competitive ELISA

The analytical techniques for assaying mycotoxins include chromatographic methods (TLC, HPLC, GC), biological (qualitative test) and Immunological (ELISA).

LOOKING AHEAD

There is a need for continuous effort in:– Generation of new technologies

• Improved varieties• Pre-& post-harvest management technologies

– Developing fast and affordable testing kits– Strong awareness creation across the value chain actors

• ICT & other communications tools need to be exploited• Capacity building

– Transfer of available aflatoxin management technologies• Formulating technology packages• Demonstrating & popularizing

ICRISAT is a member of the CGIAR Consortium

Thank you!