Workshop: “Improving the composition of plant foods for better mineral nutrition”
Food and Agriculture COST Action FA0905: Mineral-improved
crop production for healthy food and feed
Claire Mouquet-Rivier & Christèle Icard-Vernière
UMR 204 NUTRIPASS, IRD, France
Nutrient ingestion, nutrient absorption
For all micronutrients,
The quantity absorbed by enterocytes in the small intestine is much lower
than the quantity ingested from the foods
Vitamins
Vitamin C: 85 % [75-100 %] depending on the intakes
Vitamin B9
Folic acid : 85 %
Food folate : 50 %
Minerals
Selenium : 90%
Calcium : 35-70 %
Zinc : 15-50 %
Iron : 2-35 %
Micronutrients and absorption
3 main factors
In the foods
In humans
Micronutrient
form
Nutritional and
physiological status
Food matrix
Iron
Zinc
Calcium
Origins of micronutrients in foods
Intrinsic
Extrinsic
Contamination
Different
forms of
minerals
naturally
present in
raw materials
Total
micronutrient
content
soil
cooking utensils
processing equipments
Fortification
Biofortification  Extra-micronutrient
-conventional breeding
-GMO
-Fertilizers
Different forms of minerals
The case of iron
2 main forms
third form?
Haem iron
Non haem iron
Ferritin-iron
Hoppler et al (2008)
Fe++
Heme
Myoglobin, hemoglobin
Flesh foods: meat and fish 40%
Mixt diet
Intake ≈ 10-15%  Absorbed > 40%
Zhao et al
(2010)
Mineral iron Fe+++ /Fe++
Animal source food:
-Meat and fish (60%)
-Milk, egg
Fe
Plant foods:
-Cereals
-Vegetables ; leafy vegetables
-Legumes
Interactions mineral  food matrix
influence on absorption
The example of iron
Hurrell et Egli (2010)
Activating factors
Inhibiting factors
Vitamin C
Phytates
-reducing/chelating
Polyphenols
-some phenolic acids
Chelating
-condensed
tanins
Iron
effect
Proteins
- animal: milk, egg
- soybean
Oxalates
Other organic
acids
Muscle proteins
Calcium
Competition?
Vitamin A,
carotenoïds ?
Non digestible
polysaccharides
 Possible utilisation at colonic level?
Processing effects
Watzke, (1988)
Two types of effect:
Food matrix changes
Mineral content
Other
micronutrients
-competition
« Retention »
Quantity
Chelating
factors
contents
Activating
factor
contents
Absorption
Quality
Changes in
the form :
oxydation,
denaturation
Processing effects
On the retention/content :
Losses
Gains
 processing including unit operation involving
fractionation (separating)
-Decortication
-Grinding (if followed by sieving)
-Soaking, blanching, boiling  leaching of minerals
 Contamination
-From soil : harvest or post-harvest treatments
-Mechanical grinding
-Cooking utensils, cooking in hard water
-Specific processing such nixtamalisation
 Formulation
[Fortification]
Processing effects
On bioavailability:
Changes in
chemical forms
 unit operations leading to denaturation
-Thermal treatment
- acidification ( fermentation ?)
unit operations leading to complexation
Release of Fe++
from
phytoferritin
Non-haem iron
pool
Formation of
soluble or
insoluble
complexes
(Chelation)
 complex effects
- Decortication : decrease mineral contents but also
phytate, polyphenols, fibres…
- Soaking, germination, fermentation: endogenous or
exogenous phytase activation
- Cooking : controversial effects
Some examples
Traditional food processing in Africa
Tô
- Cereal processing
Family dish in
Burkina Faso
- Preparation of sauces from leafy vegetables
Processing effect is linked to mineral distribution in plant tissues
pericarp
polyphenols
fibres
Aleurone layer
phytates
minerals
proteins
Endosperm
starch
phytates
scutellum
germ
lipids
minerals 72 %
phytates
© CIRAD J.F. CRUZ
Structure of millet grain
 Effect of decortication ?
11
Effect of decortication on iron and zinc contents
of millet and sorghum
100
90
80
70
60
50
40
30
20
10
0
-10 0
Iron
Gampela millet
White sorghum
y=x
5
losses (% DM)
losses (% DM)
Abrasive decortication
Zinc
100
90
80
70
60
50
40
30
20
10
0
-10
Gampela millet
White sorghum
Y=X
0
10 15 20 25 30 35 40 45 50 55
5
y=x
5
10 15 20 25 30 35 40 45 50 55
extraction rate (%)
losses (% DM)
losses (%DM )
White sorghum
Millet
10 15 20 25 30 35 40 45 50 55
Lipid
Phytate
Gampela millet
Decorticated
extraction rate (%)
extraction rate (%)
100
90
80
70
60
50
40
30
20
10
0
-10 0
Whole
100
90
80
70
60
50
40
30
20
10
0
-10
-20
Whole
Decorticated
Gampela millet
White sorghum
y=x
Sorghum
0
5
10 15 20 25 30 35 40 45 50 55
extraction rate (%)
12
Hama et al, (2011)
Corundum grindstone
Metallic grindstone
Total iron content
Mortar/pestle
12
b
mg/100g DM
10
8
6
b
a,b
4
Porridge
b
Pancakes
a
a
Tô
2
0
Raw
millet
grains
Washed
Decorti
cated
Processing steps
Ground
Dishes
Total iron content
Intrinsic/extrinsic
parts
12
Contaminant
iron?
10
mg/100g DM
Food
composition
tables ?
8
≈ intrinsic iron
6
porridge
4
pancakes
2
Tô
0
Raw
millet
grains
Washed
Decorti
cated
Ground
Processing steps
Dishes
Nutritional interest
of contaminant
iron ?
Adish, 1999 / Hooda, 2004
Bioaccessibility of iron in millet tô
Millet flour: 3.7 mg/100 g DM
4
3
Iron content
(mg/100g
DM)
2
1
0
Total
Dialysable Soluble Insoluble
ND
Bioaccessibility of contaminant iron in millet tô
Non contaminated flour : 3.7 mg/100 g DM
Contaminated flour : 8.8 mg/100 g DM
10
non contaminated
contaminated
8
Iron
content
(mg/100g DM)
6
- Most part insoluble
4
- Small part soluble : could be
bioavailable?
Degradation of chelating
factors
Increase or protection of
activators
2
0
Total
Dialysable Soluble ND
Insoluble
50
mg/100 g DM
Work on spinach
Nafir-Zenati et al, 1992
Ashes
25
40
30
Cu (x10)
20
Fe
10
Fe
0
20
crude leaves
Cu (x10)
boiled leaves
g/100g DM
15
steamed leaves
10
Ca
Na
4
0
crude leaves boiled leaves
steamed
leaves
Important leaching during boiling
(one third)
g/100g DM
5
3
2
1
Na
0
crude leaves
Variable magnitude according to the mineral
-Solubility
-Involvement in complexes
Ca
boiled leaves
steamed
leaves
80
Total iron
70
Dialysable iron
60
50
iron content 40
(mg/100g DM)
30
High variability
• In content
• In behaviour during in
vitro digestion
20
10
0
roselle
amaranth
jute
spinach-BF
cleome
salt
19
% Dialysable iron
20
18
16
14
12
% 10
8
6
4
2
0
Slimy sauce
Leaves Sauce
roselle
Leaves Sauce
amaranth
Leaves Sauce
jute
Leaves Sauce
spinachcleome
Processing effects
on mineral content (‘retention’):
-quite simple
On mineral bioaccessibility
-Complex and numerous
 versatile behaviour
Difficulty to
develop
predictive
models
Biofortification : some questions arising
Side-effects of biofortification on factors influencing bioavailability of
minerals?
Fate of extrinsic mineral through processing ?
-contamination
-biofortification /GMO-conventional breeding –fertilization: localisation
of extra-mineral?
Determining ideal processing intensity?
- unit operations, method used and their parameters : t, T, yield, pH, etc.
- mineral form