Evaluating PICS for Groundnut Storage

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Evaluating PICS for Groundnut
H. Sudini 1, C.L.L. Gowda 1, V. Margam 2 and L.L. Murdock
3
1 International Crops Research
Institute for the Semi-Arid Tropics, Patancheru, India
2 Computational Biosciences Research Center, KAUST, Saudi Arabia
3 Dept. of Entomology, Purdue University, West Lafayette, IN, USA
Purdue Improved Crop Storage Workshop, April 10-12, 2012, Accra,
Ghana
Groundnut (Arachis hypogaea)
Groundnut (Peanut) is an important food
legume in semi-arid tropical countries
Grown in more than 100 countries
India alone ~5.6 M tons (FAOSTAT 2010)
Important post-harvest constraints
Aflatoxin contamination
Bruchid infestation
Mycotoxins
• Mycotoxins, the secondary metabolites of
Aspergillus, Fusarium, and Penicillium, are among the
most common natural contaminants of foods and
feeds
Factors affecting aflatoxin
contamination during postharvest
Abiotic
•Water activity
•Temperature
•Gas composition
Biotic
•Storage insect pests
Groundnut Bruchid
Caryedon serratus (olivier) is the most important storage
pest
The adult is reddish brown beetle
Female beetle attaches its eggs to the pod wall
The eggs are small and milky-white in color and hatch
about 8 days
Grubs are stout and fleshy and they complete four instars
in about 23 days
Full grown grub makes a round hole on the pod wall
through which it leaves the pod and pupate at the bottom.
Pupal period ranges between 14 and 16 days
Grubs bore through the pod wall, feed on the internal
contents of the seed and make them hollow
Pupa
Egg
Linkage
 Venu Margam from Purdue visited ICRISAT
during late 2010
 Capacity building
 Introduced to Dr. Murdock
 Developed a proposal to test the efficacy of
PICS bags for Groundnut storage
 Subsequently Purdue provided financial
assistance
PICS experiment on Groundnut
@ ICRISAT
Important underlying goals
To check bruchid damage levels
To monitor aflatoxin contamination levels
To test seed viability (Germination)
Two independent experiments with different moisture
levels
Ist Batch experiment- 4 months storage
Approximately 8% MC
Methodology
•A generalized experiment
with 3 replications
•25kg unshelled pods
•5% Groundnut Bruchid
infestation (approximately
1.25 kg of infested pods)
•On an average 6-8 adults per
every 100 grams of pod
Methodology
Observations recorded on
Gas composition at
regular intervals (O2/CO2
Analyzer-Mocon)
 Germination
percentage (seed
viability before and
after the experiment)
Aflatoxin levels before
and after the
experiment (indirect
competitive ELISA)
Sample Processing
 Representative sample
 100 g of subsample made into
powder
 20g of powder added to
100ml of 70% methanol
 Shake it for 30 min.
 After filtration, the methanol
extracts were stored at 4oC till
they used
ELISA Plate Design
• Read the plate at 405 nm
• Higher toxin concentration confer light color that leads to
low OD value and vice versa
Results-Gas composition
Infested
Uninfested
PICS 1
PICS 2
PICS 3
Gunny Bag 1
Gunny Bag 2
Gunny Bag 3
PICS 4
PICS 5
PICS 6
Gunny Bag 4
Gunny Bag 5
Gunny Bag 6
O2 Level
9.22
12.17
6.79
20.18
20.31
20.30
6.15
5.41
10.80
20.07
20.13
20.19
CO2 Level
7.04
5.65
8.27
0.15
0.13
0.17
8.84
8.32
4.94
0.15
0.13
0.12
Results-Insect damage levels
after opening the bags
Infested
PICS Bag 1
PICS Bag 2
PICS Bag 3
Rep 1
Damaged Un
pod
damaged
pod
16
84
56
44
20
80
Rep 2
Damaged
Un
pod
damaged
Pod
12
88
62
38
24
76
Rep 3
Damaged
Un
pod
damaged
Pod
19
81
55
45
22
78
Gunny Bag 1
Gunny Bag 2
Gunny Bag 3
73
86
87
27
14
13
72
92
83
28
8
17
74
89
82
26
11
18
Uninfested/Control
PICS Bag 4
PICS Bag 5
PICS Bag 6
3
7
4
97
93
96
5
6
2
95
94
98
3
4
3
97
96
97
Gunny Bag 4
Gunny Bag 5
Gunny Bag 6
79
38
24
21
62
76
82
43
25
18
57
75
72
48
33
28
52
67
Results-Germination levels
Infested
PICS 1
PICS 2
PICS 3
Gunny Bag 1
Gunny Bag 2
Gunny Bag 3
Uninfested/Control
PICS 4
PICS 5
PICS 6
Gunny Bag 4
Gunny Bag 5
Gunny Bag 6
Before starting the
experiment
After the experiment
94%
95%
98%
90%
97%
97%
92 %
91%
95%
94%
95%
94%
94%
97%
93%
95%
92%
98%
93%
96%
92%
97%
92%
91%
Results-aflatoxin levels
Before the experiment
Sample 1
Infested
PICS 1
PICS 2
PICS 3
Gunny Bag 1
Gunny Bag 2
Gunny Bag 3
Uninfested/Control
PICS 4
PICS 5
PICS 6
Gunny Bag 4
Gunny Bag 5
Gunny Bag 6
Sample 2
Aflatoxin content in ppb
after the experiment
Sample 1
Sample 2
1.4
823.8
1.7
33.6
0.0
5.6
18.1
1526.4
0.0
11.8
0.0
0.0
1.7
0.0
0.0
0.0
0.0
0.0
0.0
4.0
2.5
1.5
2.3
5.3
25.3
0.0
15.5
0.0
80.0
168.7
46.8
0.0
23.4
18.3
52.9
78.5
0.0
0.0
0.0
0.0
0.0
0.0
1.6
0.0
0.0
0.0
0.0
0.0
Visibility of bruchid damage
Conclusions
Large air spaces in the PICS bags with unshelled
pods could affecting the gas composition
Since aflatoxin contamination is also a preharvest issue, any toxin produced remains in the
produce
Sampling variation is a huge factor in assessing
aflatoxin levels
Activity2 – Farmer Trials
As part of an
IFAD project a
group of
groundnut
farmers and
extension agents
visited ICRISAT
on April 4th,
2012.
Conducted a
demonstration of
PICS bag usage.
Activity2 – Farmer Trials
Showed them the
trials setup in the
laboratory and
difference in the
control vs PICS
stored groundnut.
Convinced, the
farmers requested
bags for testing.
Feedback will be
obtained from them
after 4 months.
Lessons learned/Way Forward
Micro scale level studies are to be conducted to
understand the exact relationship between
hermetic storage principle (gas composition) and
Aspergillus flavus growth and subsequent
aflatoxin contamination
The Groundnut material representing different
components of resistance to aflatoxin
contamination need to be studied separately
(circumstantial evidence for varietal differences)
Thank you
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