Th3_Molecular features of protein and starch in African rice relate to their processing behavior

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)


Nature & abundance:

- SDS-PAGEHighlights species-specific differences

O. sativa O. glaberrima


Nature & abundance:

- SDS-PAGE (O. sativa)Highlights variety-specific differences

A B C D E F



- 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


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


- susceptibility to selective enzymatic activities

Pasting behaviour

- MVAG Brabender

Interaction with water in complex/competing systems:

- TGA & DSC



- susceptibility to selective enzymatic activities

Pasting behaviour

- MVAG Brabender

Interaction with water in complex/competing systems:

- TGA &DSC


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


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”

Th3_Molecular features of protein and starch in African rice relate to their processing behavior

Technology

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