Postharvest and Food Safety Management for Improved Health and Income

International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

Postharvest and

Food Safety

Management for

Improved Health

and Income

Kerstin Hell


Outline

Introduction

Factors that influence post harvest quality

Research to address post harvest

constraints

- post harvest systems analysis

- control of pests

- diffusion and adoption of new

technologies

Mycotoxin research

Future needs


Food Systems

Large Scale and Regulated

– Developed countries

– Trade based

– Advanced infrastructure

– Capital intensive

Tim Williams, Peanut CRSP

Small Scale and Unregulated

– Developing countries

– Informal markets

– Subsistence

– High food insecurity


Post harvest systems in Africa - constraints

• Almost all operations are manual – leading to high

losses and poor quality

• Potential for rapid drying low – high moisture and

increased fungal development

• Storage structures open and often poorly ventilated -

increased losses due to pest and diseases

• Long holding periods in open stores – leading to

theft, infection with pests and diseases

• Poor to no access to storage insecticides

• Poor marketing system - leading to increased losses

and low prices low incentive for increased production


Evaluation of post harvest system

• Development of post harvest insects and fungi in three different traditional storage structures in Benin

• Vegetable material stores (VMS)

• Mud silo store (MSS)

• Polyethylene bag storage (PBS)

• 4 sites in different agroecological zones, monitored monthly for 7 months

• Serious levels of Sitophilus zeamais (highest in the south and in the VMS) and Prostephanus truncatus (high levels in the VMS and later in the season in the PBS)

• Highest moisture content in the coastal zone decreasing towards the north (16,5% south to 9,9% north)

• Most prevalent fungi were Fusarium spp. highest levels observed in Aplahoué (south), whereas Penicillium and Aspergillus spp. were found mostly in Ouessè (middle)

Hell et al. 2008 submitted to Journal of Applied Entomology


Effects of four temperatures (20, 25, 30 and 35 C) and two

relative humidity levels (44 and 80% RH) on development time,

survivorship, age-specific fecundity, sex ratio and intrinsic rate

of natural increase (rm) of S. cerealella• Minimum development

time occurred close to32 C and 80% RH forboth males and females.

• Development time offemales was significantlyshorter than that ofmales.

• Immature survivorshipwas highest between 25-30 C and 80% RH andlowest at 35 C.

• The greatest fecundity(124 eggs per female)occurred at 20ºC, 80%RH. The maximum rm -value was 0.086 d-1 at30 C and 80% RH, butthe growth rate declineddramatically at 35 C.

0

0,01

0,02

0,03

15 20 25 30 35 40

0

0,01

0,02

0,03

15 20 25 30 35 40

females

males

develop

ment

rate

(day-1)

ºC

High RH

Low RH

L. Stengård Hansen et al. 2004 Journal of Economic Entomology


Prostephanus truncatus

Prostephanus truncatus serious pest of stored maize and dried cassava roots

Quarantine pest affects international trade

Maize losses after 6 months from 11% before the introduction of P. truncatus to more than 35% afterwards

IITA had projects from 1990 till 2003 (estimated more than 10 mill $ were spent)

Predator released for the control

Impact of this effort was not evaluated

Teretrius nigrescens G.Goergen


Cassava chips stored for 5 months in mud silos and 50 adults of T. nigrescens added

Chip weight and number of holes on chips differed between treatments from 2 months of storage

After 3 months of storage, losses reached 40 to 50% without predator and 30 to 40% with T. nigrescens.

A farmer can increase his profit by 1437 fcfa/100kg and losses are reduced by 11%

Twice as many P. truncatus and holes on chips in stores where T. nigrescens was not released

Farmers were able to prolong storage period by 2 months.

0 0

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25

18

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31

50

41

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35

40

45

50

Lo

sse

s (

Kg

)

0 1 2 3 4 5

Month of storage

NoTn PlusTn

Augmented release

Hell et al. 2006 Journal of Stored Products Research


Bruchid control• Twelve indigenous and exotic isolates of

Beauveria bassiana and Metarhizium anisopliaewere evaluated

• Indigenous isolates from C. maculatus were more virulent in laboratory bioassays than exotic isolates from other insects.

• B. bassiana 0362 at both 1x107 and 1x108

conidia g-1 grain led to significant adult mortality and reduced F1 emergence relative to untreated

• Effect of the fungus persisted into the F1 generation. The net reproductive rates, R0, measured 26 days after insects were released were 5.16 and 7.32 for the high and low doses compared to 9.52 for the untreated control.

• No evidence that cadavers were sporulating in stored grain need for persistence would depend on initial inoculum

Most serious pest of cowpea

and beans in Africa

The development of a single

larva in a kernel can lead to

weight losses of 8–22%

Significant impact on

commercial value – price

reduced by 40%

Cherry et al. 2005 Journal of Stored Products Research & Cherry et al. 2007 Annals of Applied Biology


Impact of farmers’ socio-economic factors, technology characteristics and farm specific factors, on the adoption of improved mud silo

Farmers’ socio-economic factors such as the years of farming experience, access to extension service, were positively correlated with adoption.

Technology characteristics like cost affected adoption negatively and perceived durability of the store affected adoption positively

Adoption of Improved Mud Silo

Année d'adoption

1984 1988 1992 1996 2000 2005 2010 2015 2020

Nom

bre

de p

aysa

ns a

yant

adopté

le

gre

nie

r

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210 Courbe de diffusion du grenier fermé en terre amélioré

Yt=199/(1+ e-666,99691-0,33281*t

)

Hell et al. 2008 Submitted to Int. Journal of Postharvest Technology & Innovation


Adoption of cassava chipping equipment

Variables

β Coefficient

Standard Error

Probability

Gender

Sale

Education

Processing experience

Non-tuber incomes

Contact

Group Membership

Agro-Ecological zone

Average Income

Constant

0.291

-0.144

-1.246

-0.049

-1.945

1.814

4.274

-1.355

-1.221

0.439

0.769

0.673

0.827

0.028

1.108

0.748

0.886

0.648

0.798

1.742

0.705*

0.831

0.132

0.079*

0.079*

0.015**

0.000***

0.037**

0.126

0.801

Pourcentage de prédictions correctes : 89.6 % ; Constante = 0.46217 ; N=212

Ratio de maximum de vraisemblance = 69.218; Chi carré = 72.100***.

(***) : significatif à 1 % ; (**) : significatif à 5 %.

Allogni et al. 2008 Submitted to Bulletin de la Recherche Agronomique.


Mycotoxin R-4-D at IITA

Aspergillus and Fusarium species diversity and

mycotoxin profile in food baskets (USAID, BMZ, IFAR)

Breeding for resistance (US-FAS)

Biocontrol of aflatoxin (BMZ)

Low-cost detection of mycotoxin

Development and dissemination of mycotoxin

management strategies (BMZ, ADA)

Intervention study for the reduction of aflatoxin and

impact on nutritional situation (BMZ)

Awareness campaign (Rotary International)

Training & information exchange (USAID, BMZ, EU)


Major classes of mycotoxins

• Aflatoxins: Aspergillus flavus, A. parasiticus

• Trichothecenes: Fusarium spp, Stachybotrys

• Fumonisins: F. verticillioides etc.

• Zearalenone: F. graminearum

• Ochratoxins: Penicillium verrucosum,

A. ochraceous


Prevalence of Aflatoxins in Food

• Aflatoxins are toxic substances produced by highly prevalent

Aspergillus fungi

• High levels from Kenya, Benin, Burkina Faso, Cameroon, Gambia,

Ghana, Guinea, Mozambique, Nigeria, Senegal, South Africa,

Zambia…….

• Frequency of occurrence high

– >30% maize in stores with >20 ppb aflatoxin

– ~90% stores are contaminated with Afla fungi

– Up to 50% grain in households with aflatoxin

• Several African staple commodities affected – maize, groundnut,

cassava, sorghum, yam, rice, cashews

• Environmental conditions, traditional farming methods and

improper grain drying and storage practices


Aflatoxin and Fumonisin in W. Africa

Maize: aflatoxin – 2-560 ppb

fumonisin – 0-12 ppm

Cassava chips: 0,3-13 ppb

Cowpea: 0.9-18.6ppb

Cashew: 3.0-56 ppb

Egussi: 4.6-32 ppb

Dried vegetables – 3.2-6 ppb

Primary products

Maize beverage:

• aflatoxin <2ppb

• fumonisin <2ppm

Cassava flour: 0,3-4.4ppb

Food products


Aspergillus flavus

prevalence

differs between

zone and season

High risk zone

has been

identified

0

20000

40000

60000

80000

100000

120000

140000

160000

SS NGS SGS CS

Ecozones

cfu AFT

Aspergillus flavus prevalence in

maize in Benin

Tedihoue et al. 2008 Submitted to Plant Disease


High and low risk

zones have been

identified

Results vary

between season

and years

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SS NGS SGS CS

Ecozones

pp

bAflatoxines

Aflatoxin in maize in different

agroecological zones in Benin

Tedihoue et al. 2008 Submitted to Plant Disease


Mycotoxin risk in different agroecological

zones in Africa

High aflatoxin risk

zones: moist

savannas (with

bimodal rainfall

patterns) and hot dry

savannas

Fusarium toxin risk

zones: humid forest

and mid-altitudes

Aflatoxin

contamination

increase with storage

time especially in

drier savanna

Drier savanna

Moist savannaHumid forest

Moist midaltitude

Drier midaltitude

High altitude


Factors that influence mycotoxins

• Climatic (rain, relative humidity, temperature)

• Biotic (insects, damage, incomplete huskcover)

• Abiotic (stress, irrigation, rotation, variety, planting date,

harvest, storage conditions)

Trt Aspergillus spp. Fusarium spp.

Non-protected 3.95 0.82 a 36.05 3.38 a

Protected 2.33 0.62 b 16.62 1.47 b

P 0.0067 <.0001


Drought, high temperature stress and unseasonal rains increase aflatoxin in maize and groundnuts

>125 people died of aflatoxin poisoning in 2004, a drought year

Increase in duration and area under drought would further accentuate aflatoxin problem

Climate Change and

Aflatoxin in Kenya

The 2004 Aflatoxin

outbreak.

Increasing aflatoxin

in market maize in

brown. Blue circles

– aflatoxin deaths

INCREASING RISK OF

AFLATOXIN OUTBREAKS IN

MAKUENI AND MACHAKOS


Associated insect species

• Insects play a big role in the

propagation and distribution of

the fungal spores

• High correlation between certain

insect species and fungi

• Pest pressure was low

• To protect cobs from fungal

infestation a reduction of 40%

aflatoxin

• Cobs with more than 10% of

damage by insects had aflatoxin

contamination of 388 - 515 ppb

Correlation between mean number of insects and toxigenic

fungal species on maize

A. flavus A. parasiticus F.verticillioides

Prostephanus 0.36* 0.12 0.23

Sitophilus -0.21 0.39* -0.17

Cathartus 0.32* 0.18 -0.31*

Carpophilus 0.21 0.13 0.08

Tribolium 0.33* 0.48** 0.08

Palorus 0.23 0.42** -0.03

Cryptolestes -0.08 0.40** 0.09

Gnathocerus 0.23 0.24 0.04

* Significant at P = 0.05 and ** P = 0.01

Hell et al., 2004Hell et al. 2000 African Entomology


Local variety

Gbogbe had

much lower toxin

levels than

TZSR-W

No effect of

intercropping

with cowpea0.0E+00

2.0E+02

4.0E+02

6.0E+02

8.0E+02

1.0E+03

IV0

IV1

IVCP0

IVCP1

LV0LV1

LVCP0

LVCP1

Afl

ato

xin

(p

pb

) AFB1

AFB2

Effect of maize variety, and cowpea intercropping

on aflatoxin production during storage

Tedihoue et al. 2008 Manuscript in preparation


Beninese maize and F. verticilliodes infection

0

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AC

R20

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R94

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Inoculation

Control

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bc

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A & C 2003 B & D 2004

Dewaminou et al. 2008 submitted to Journal of Phytopathology


0

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1200

1400

1600

1800

Afla

toxi

n (p

pb)

TZM

I102

1368

1823

TZM

104

TZM

I502

Inbred Lines

Field-03 Field-04 KSA

Aflatoxin Resistance in Maize Inbreds


Mycotoxin Monitoring Tools

• Simple and low-cost diagnostic tool (ELISA)

• Polyclonal antibodies for aflatoxin

– Low-cost (US$ 1-2 per sample analysis)

– Simple procedure, qualitative and

quantitative

– Results comparable to HPLC

– High throughput analysis possible

(100-400 samples/day)

– Less dependency on commercial

equipment

– Ideal test for aflatoxin estimation in

developing countries


Aflatoxin Tested Pet Food

in Nairobi


Mycotoxin Management

Strategies• Awareness

• Host plant resistance

• Biological control

• Time of harvest

• Grain drying method

• Storage structure

• Storage form

• Sorting and processing

• Insect control


Insect control

Mihinto & Hell 2008 Manuscript in preparation

• Cobs were protected with mosquito netting, natural or artificial infestation

In protected cobs Pt levels were low rising to means of 1.8 under natural and

14.2 under artificial infestation

Aspergillus and Penicillium incidence was highest on Mussidia nigrivenella,

Carpophilus sp., Prostephanus truncatus and Sitophilus sp. While Fusarium spp.

was mainly associated with the field pests Eldana saccharina and Sesamia

calamistis

Low aflatoxin 0.21 0.16 ppb in T0, whereas insect infestation resulted in 22.74

p 6.99 ppb aflatoxin in T1, and 27.37 7.83 ppb in T2.

Treatment A. flavus A.

parasiticus

Insect.

damage

Grain

losses

Fungal

damage

Fungal

losses

Total

aflatoxin

Cobs

protected(T0)

8.17±0.86a 0.22±0.14a 10.48±1.4a 4.68±1.03a 6.43±0.44a 0.92±0.24a 0.22±0.16a

Natural

infestation(T1)

37.11±1.44b 0.11±0.00a 41.01±2.6b 19.65±1.9b 10.56±0.7a 1.57±0.69a 22.74±6.99b

Artificial

infestation(T2)

47.60±1.50c 0.33±0.14a 50.34±2.9c 27.47±2.4c 9.72±0.67a 1.12±0.49a 27.37±7.83b

p 0.0001 0.42 0.0001 0.0001 0.99 0.98 0.002


Aflatoxin management

Occurrence (%) of various toxigenic fungal species in maize grains after a 7-day

drying period using different drying methods

Drying method Aspergillus Fusarium Penicillium Others

Cobs on stalk in the field 4.7ab1 98.3a 1.7a 5.3a

Sun drying cobs dried on the ground 21.0a 95.3a 43.7a 10.0a

Sun drying cobs dried on a platform 2.0b 86.3b 4.7b 2.7a

Sun drying cobs dried on a plastic sheets 18.3a 33.3c 9.7b 0.7a

1Means within a column followed by the same letter do not differ significantly from each other (P < 0.05)

Hell et al. 2008 Mycotoxin Book


• Four storage systems of maize commonly used by farmers in Benin, West Africa, were tested to determine their impact on infection of maize by Fusarium and fumonisins.

• Fusarium incidence was significantly higher when maize was stored on a cemented floor in a house, a non ventilated facility (40.3 17.4%), than in the other tested systems (p < 0.05).

• The lowest Fusarium incidence was recorded when maize was stored in a bamboo granary (25.5 13.5%) (p < 0.05).

• All maize samples from the tested storage systems were found to be fumonisin-positive, with levels ranging from 0.6 to 2.4 mg/kg.

Mycotoxin management

Fandohan et al. 2006 African Journal of Biotechnology


Mycotoxin management

Oils from Cymbopogon citratus,

Ocimum basilicum, and Ocimum

gratissimum were the most

effective in vitro, completely

inhibiting the growth of F.

verticillioides at lower

concentrations over 21 days of

incubation

These oils reduced the incidence

of F. verticillioides in corn and

totally inhibited fungal growth at

concentrations of 8, 6.4, and 4.8

ųL/g, respectively, over 21 days.

Further studies are in progress to

evaluate the toxicological effects

of these plant substances.

Fandohan et al. 2004 Journal of Agricultural and Food Chemistry

Treatments

Control (no oil)

O. gratissimum

O. bas ilicum

C. citratus

Me

an

to

tal fu

mo

nis

in le

ve

l (u

g/g

)

1.6

1.4

1.2

1.0

.8

.6

.4

Storage conditions

Closed

Open


Simple management practices during

processing

• Sorting followed by winnowing of naturally contaminated maize grains resulted in a mean reduction of 59% and 69% in aflatoxin and fumonisin levels, respectively (Fandohan et al., 2005).

• Similar losses of aflatoxins (37%) and fumonisins (51%) to wash water have been reported when maize was processed into derived products in Benin (Fandohan et al., 2008)

• Small reductions in mycotoxin levels (18% for aflatoxins and 13% for fumonisins) also have been observed following lactic fermentation when preparing ogi (fermented maize dough) (Fandohan et al., 2005).

• A reduction of mycotoxin levels was observed during the preparation of adoyo (86 % of aflatoxins and 65 % of fumonisins). (Fandohan in preparation)

Infected Healthy


Maize sorting before

storage resulted in

an important

reduction of aflatoxin

level from 45461.22

ppb to 1811.775 ppb.

Calculated financial

losses were 40.75

FCFA for maize

sorted before

storage and 52.52

FCFA for non-sorted

maize.

0

50000

100000

Maize sorted Maize no-sorted

experimented technologies

afl

ato

xin

levels

in

pp

b

Aflatoxin levels after six months

Losses after six months

Poverty reduction through a better

post harvest management of maize


Atoxigenic Strain Identification

Strain characterization

cnxnia-D

Unknown

Unknown

nia-Dcnx

-

+

VCG

Toxin assay

Field

Competition assays

Lab

Field release


How does Biocontrol Work?

Broadcast

@ 10kg/ha 20-30

days after sowing

Sporulation on wet soil

Spores

Insects

Inoculum on

sorghum grain carrier

3-20 days

Wind

Soil

colonization


Steps in Aflatoxin Biocontrol R-4-D

• Collection and identification of isolates

• Characterisation of isolates

• Identification of atoxigenic strains

• Determination of genetic and molecular diversity in the

atoxigenic strains

• Ensuring biosafety of the atoxigenics

• Developing methods for mass multiplication of

inoculum for field application

• Testing efficacy of atoxigenics in field trials

• Sensitisation of growers, consumers and regulatory

agencies about potential of biocontrol

• Registration of the atoxigenic strains as biopesticides

• Upscaling and outscaling to wider areas


Awareness campaign & capacity building

More than 10 millionpeople in Benin, Togo and Ghana are now aware of the dangers of aflatoxin-contaminated feed/foods.

Per year:

About 10 students

1 training course on post-harvest pests and diseases

Individual training


Africa Conference

109 participants, 28 countries in Africa (15), Europe, Asia, North America and South America

Participants: Scientists, parliamentarians, heads of institutions, policymakers, trade and health specialists

13-16 Sept 2005

Accra Ghana

http://mycoglobe.ispa.cnr.it/


Impact of awareness campaign

Aflatoxin awareness amongst target groups before (Pre-C) and after (Post-C) awareness campaign in Benin, Ghana and Togo

Respondents aware of aflatoxin (%)

Farmers Traders Consumers Poultry farmers

Awareness

indicator†

Pre-C Post-C %

change Pre-C Post-C

%

change Pre-C Post-C

%

change Pre-C Post-C

%

change

Informed 20.8 53.2 32.4*** 26.7 56.9 30.2*** 25.2 63.5 38.3*** 60.0 60.9 0.9 ns

Believed 54.6 76.9 22.3*** 58.5 78.1 19.6*** 60.0 84.3 24.3*** 83.0 91.2 8.2 **

Adopts 51.1 75.7 24.6*** 55.4 91.8 36.3*** 81.3 84.5 3.2 ns 48.9 68.8 19.9***

James et al. 2007 Food Additives & Contaminants


Trade Losses due to Aflatoxins

• Export compliance with food safety

and quality standards.

• Some countries active to meet

standards by putting in place relevant

institutions

• Best quality exported; poorer quality

consumed domestically.

• Need to evaluate the economic impact

of aflatoxin on health and trade, and the

economic benefit the deployment of

aflatoxin management can have.

Peanut

Maize

Coffee

Cocoa


Figure 1: Prevalence (%) of malnutrition by agro-ecological zone

37

.01

28

.12

0

30

.13

27

.44

4.4

1

31

.58

27

.6

3.9

3

38

.56

32

.18

7

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5

10

15

20

25

30

35

40

45

Stunting Underweight Wasting

% o

f un

de

rno

uri

she

d c

hild

ren

Zone 1 (N=45)

Zone 2 (N=113)

Zone 3 (N=76)

Zone 4 (N=88)

Honfo et al. to be submitted to International Journal of Food Safety, Nutrition and Public Health

Nutritional status of children aged 18-36 month

in four agro-ecological Zones in Benin


Figure 2: Proportion of children covering at least 100% of the nutritional

needs

37

.8

55

.6

51.3 61.9

64.3

60.5

36.8

71.9

62.3

52.5

78.2

48

.9

0

20

40

60

80

100

Energy Proteins Iron

Pro

port

ion

Zone 1(N=45)

Zone 2 (N=113)

Zone 3 (N=76)

Zone 4 (N=88)

Honfo et al. to be submitted to International Journal of Food Safety, Nutrition and Public Health

Nutritional status of children aged 18-36 month

in four agro-ecological Zones in Benin


Summary

• Food supplies in Africa are precarious

• High losses of foods both in Quality (mycotoxins, chemical residues, hygiene) and in Quantity (mostly due to pest)

• Need for improved storage structures and methods to reduce these losses (up to 30%)

• Need improved access to markets

• Need improved processing and packaging methods to maintain quality

It’s not possible that people go hungry and we have more than 30% of the children showing signs of malnutrition


New research opportunities

• Quality in horticultural food chains (risk assessment, technology options)

• Scaling up and out of mycotoxin management using different partnership models

• Economic impact of mycotoxin management on improved health and income

• Study other mycotoxins eg. Fumonisin, OchratoxinA (diagnostic capacity has to be established)

• Mycotoxins and climate change

• Monitoring and testing of product quality at different steps in commodity chain using appropriate analytical tools (mycotoxins, pesticide residues, other microbes)

• Development of options for quality approaches & Market Access (Technologies, Methodologies, Training)

• Food/nutrition/health especially focusing on child health

Postharvest and Food Safety Management for Improved Health and Income

Technology

Transcript of Postharvest and Food Safety Management for Improved Health and Income