th3_molecular features of protein and starch in african rice relate to their processing behavior
DESCRIPTION
3rd Africa Rice Congress Theme 3: Rice processing and marketing Mini symposium: Adding value to Africa’s rice: rice-derived products Author: BarbiroliTRANSCRIPT
Molecular features of protein and starch in
African rice relate to their processing behavior
Stefania IamettiAlberto Barbiroli, Francesco Bonomi, Alessandra Marti, Mauro Marengo,
Maria Ambrogina Pagani, John Manful#
DeFENS, University of Milan, Italy # Africa Rice, Benin
The targets
To investigate the properties of starch and protein in rice
varieties popularly cultivated in Africa
To identify which varieties/species could be most suitable
for developing various specific food products
Structural and physical properties of starch and
proteins were studied by using a multidisciplinary
approach
STRUCTURAL CHARACTERIZATION OF PROTEINS
Nature & abundance:
- SDS-PAGE
Structural organization:
- Solubility (also in denaturing/dissociating media)
Reactivity:
- Exposure of possible reticulating moieties: thiols (-SH)
STRUCTURAL CHARACTERIZATION OF PROTEINS
Nature & abundance:
- SDS-PAGEHighlights species-specific differences
O. sativa O. glaberrima
STRUCTURAL CHARACTERIZATION OF PROTEINS
Nature & abundance:
- SDS-PAGE (O. sativa)Highlights variety-specific differences
A B C D E F
STRUCTURAL CHARACTERIZATION OF PROTEINS
Structural organization:
- Solubility (also in denaturing/dissociating media)
protein solubility in the presence/absenceof dissociating and reducing agents
pro
tein
, m
g/g
ric
e
0
10
20
30
40
50
60
sativa 1 sativa 2sativa 3glaberrima
buffer only + urea + urea & DTT
Highlights species-related differences, and also differences related to agronomical issues
STRUCTURAL CHARACTERIZATION OF PROTEINS
mic
rom
ol -
SH
/g r
ice
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
sativa 1 sativa 2sativa 3glaberrima
buffer + urea
conditional accessibility of protein thiols
Highlights species-related differences, but also differences related to agronomical issues (in particular when considering their relative protein content)
Reactivity:
- Exposure of possible reticulating moieties (-SH)
STRUCTURAL CHARACTERIZATION OF STARCH
Structural organization:
- susceptibility to selective enzymatic activities
Pasting behaviour
- MVAG Brabender
Interaction with water in complex/competing systems:
- TGA & DSC
STRUCTURAL CHARACTERIZATION OF STARCH
Structural organization:
- susceptibility to selective enzymatic activities
Pasting behaviour
- MVAG Brabender
Interaction with water in complex/competing systems:
- TGA &DSC
STRUCTURAL CHARACTERIZATION OF STARCH
Structural organization: as detected by susceptibility to selective enzymatic activities, followed by GPC/MALS
Starch degradation by endogenous enzymes results in a different pattern of breakdown products in different rice samples
GLAB 766NERICA
WITA8
The effects of purified pullulanase highlight a different sensitivity of starch components in each variety/species towards debranching
GLAB 766
WITA8
NERICA
STRUCTURAL CHARACTERIZATION OF STARCH
0
200
400
600
800
1000
1200
0 5 10 15 20 25 30 35 40 45 50 55 60 65
Time (min)
Vis
co
sit
y (
B.U
.)
0
20
40
60
80
100
Te
mp
era
ture
(°C
)
Glaberrima 766 Sativa 4 Sativa 5Sativa 1 Sativa 3 Temperatura (°C)
sativa
glaberrima
Pasting behaviour
- MVAG
CONCLUDING REMARKS
The approaches presented here seem able to provide
useful insights as for the structural characteristics of
starch and proteins in various African rice varieties
Further studies will have to verify whether the
“molecular-based” information we are gathering will be
able to define proper processing and the possible end
uses of some of the materials investigated here
PEOPLE THAT MADE IT POSSIBLE
Students & post-docs DeFENS
Prof. Dimitrios Fessas DeFENS
Partners & Funding from GRISP project “New Products”