# Structuration and Rheological Properties of Gels made from Gluten Proteins

Mohsen Dahesh, Amélie Banc, Agnès Duri-Bechemilh, Marie Helene Morel, Laurence Ramos

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Mohsen Dahesh, Amélie Banc, Agnès Duri-Bechemilh, Marie Helene Morel, Laurence Ramos. Structuration and Rheological Properties of Gels made from Gluten Proteins. 9. Annual European Rheological Conference (AERC 2014), Apr 2014, Karlsruhe, Germany. hal-01606436

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# STRUCTURATION AND RHEOLOGICAL PROPERTIES OF GELS MADE FROM GLUTEN PROTEINS

Mohsen Dahesh ¹,³

Amélie Banc¹,², Agnès Duri³, Marie-Hélène Morel³ and Laurence Ramos¹,²

<figure><img src="image_1.png" /></figure>

1) Laboratoire Charles Coulomb UMR 5221, Université Montpellier 2, 34095 Montpellier, France

2) CNRS, Laboratoire Charles Coulomb UMR 5221, 34095 Montpellier,

3) Ingénierie des Agropolymères et Technologies Emergentes UMR 1208, INRA, 34000 Montpellier, France

<figure><img src="image_2.png" /></figure>
Thursday 10:00 Clubraum

BF17

Rheological properties of Costa Rican guava (Psidium friedrichsthalianum (O. Berg) Niedenzu) pulp

Daniel A. Mendez*¹, Lina M. García¹, Alfredo A. Ayala², José A. Muñoz¹, Henry A. Váquiro¹, José F. Solanilla¹
damendezre@ut.edu.co

¹Universidad del Tolima, Agronomic Engineering Faculty, Ibague, Colombia, ²Universidad del Valle, Engineering Faculty, Cali, Colombia

Costa Rican guava is a tropical fruit more aromatic and sour than the common guava, native from the seasonally flooded forest from south Mexico to northern South America. The interest for better understanding of processing and properties of this and other exotic fruits has been increasing due to their nutraceutical benefits [1]. An important tool for unit operations design and process optimization is the rheological characterization, which has not been studied yet for this exotic fruit. In the present work the dynamic shear rheological properties of Costa Rican guava (Psidium friedrichsthalianum (O. Berg) Niedenzu) pulp has been evaluated. Pulp samples were reconstituted with distilled water to 10 °Brix, from lyophilized and milled pulp. Flow behavior of the samples was measured at temperatures between 0-80 °C and evaluated using the Casson (C), Herschel-Bulkley's (HB), Mizrahi-Berk (MB), Bingham (B) and power law (P) models. The yield stress was calculated by extrapolation from experimental data for the C, HB and MB models. The models best described the flow behavior were the P and the HB models (R2>0.95). The consistency coefficient (CC) and flow behavior index (F) of these models were described as function of temperature by Arrhenius (R2>0.95) and linear (R2>0.89) equations respectively. The results showed that CC decreased when temperature increased, with a significant change between 40 and 60 °C (16.99-7.96 Pa sn). The F was in the range of 0.27-0.32 and 0.31-0.41 for P and HB models, respectively. The temperature effect on yield stress was not significant for both models. The parameters of HB and P models of guava pulp were influenced by temperature; however yield stress of pulp could be affected by milling process. The obtained data are useful for future studies on food properties.

[1] Flores, G.; Dastmalchi, K.; Wu, S.-B.; Whalen, K.; Dabo, A. J.; Reynertson, K. A.; Foronjy, R. F.; D'Armiento, J. M.; Kennelly, E. J. Food Chem. 2013, 141, 889-895.

Thursday 10:20 Clubraum

BF18

Structuration and Rheological Properties of Gels made from Gluten Proteins

Mohsen Dahesh¹, Amélie Banc*¹, Agnès Duri², Marie-Hélène Morel², Laurence Ramos¹
amelie.banc@univ-montp2.fr

¹CNRS and University Montpellier 2, Laboratoire Charles Coulomb UMR5221, Montpellier, France, ²CIRAD, INRA, Montpellier SupAgro and Université Montpellier 2, Ingénierie des Agropolymères et Technologies Emergentes UMR 1208, Montpellier, France

Wheat gluten proteins are among the most complex protein networks in nature, due in particular to their poor solubility in water and to their viscoelastic behavior. Gluten networks are often considered as transient networks comprising extensible biopolymer segments of flexible or semiflexible chains between junction points. However, the exact structure of the network, the nature of the junction points, its mechanical properties and the way it gets structured under shear remain to be clarified.

Here we report the visco-elastic behavior of model systems composed of gluten proteins near gelation. We build model systems by dispersing in ethanol-water mixtures two major protein groups, gliadins and glutenins that we have purified from gluten. Rheological properties show a slow evolution over time scales of the order of days of the linear frequency dependence complex modulus of the samples, with a concentration-dependent liquid to solid transition. Interestingly, we find that all data acquired at different protein concentrations and different times after sample preparation (different sample ages) can be scaled onto a master curve, showing a cross-over from a soft solid behavior at low frequency to a visco-elastic fluid at higher frequency, and revealing the self-similarity of the gels. Rheological data are completed by scattering experiments in order to elucidate the complex structure of the materials. For gel samples, the scattering profiles display at small length scales features typical of semi-dilute polymer solutions. At larger length scale a fractal structure is measured, that we interpret as being due to the highly disordered spatial organization of the junction points, at the origin of the solid behavior.
Wheat, Rye, Barley

<figure><img src="image_3.png" /></figure>

<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /></figure>

**GLUTEN**

**Unique** visco-elastic network !

Role of kneading (transient network)

<figure><img src="image_7.png" /><figcaption>Bread with no gluten</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>Cystein C</figcaption></figure>

⇒ Disulfide bonds
(intra or inter-molecular)

More than 50 proteins, classification:

<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /></figure>

<figure><img src="image_11.png" /><figcaption>Repetitive domain</figcaption></figure>

Proline P

<figure><img src="image_12.png" /></figure>

⇒ Structural disorder

Glutamine Q

<figure><img src="image_13.png" /></figure>

⇒ H-bonds

Non soluble in water

Prolamins: soluble in water/ethanol – acetic acid
GLUTENIN CONTRIBUTION TO
ELASTICITY

<figure><img src="image_14.png" /></figure>

Cornec et al, J. Cereal Sci. 1994

PARTICLE GEL

<figure><img src="image_15.png" /></figure>

Don et al, J. Cereal Sci. 2003

Glutenin macro polymer

1.5% SDS

<figure><img src="image_16.png" /></figure>

POLYMERIC GEL

<figure><img src="image_17.png" /></figure>

Ng et al, J. Rheol. 2008

Critical gel

Water
## I- System

## II- Structure

- Dilute regime

- Concentrated regime

## III- Rheology

- Concentration dependence

- Ageing effect
# Model system: fraction enriched in glutenins

<figure><img src="image_18.png" /><figcaption>## GLUTEN SOLUBILISED IN WATER/ETHANOL (50/50)</figcaption></figure>

Like a glue!

<figure><img src="image_19.png" /></figure>

<figure><img src="image_20.png" /></figure>

Very large
linear regime.
## I- System

## II- Structure

- Dilute solutions

- Concentrated regime

## III- Rheology

- Concentration dependence

- Ageing effect
STATIC LIGHT SCATTERING

<figure><img src="image_21.png" /></figure>

Zimm analysis

Debye model => **polymeric structure**

$M_{w \text{ app}}$=27 000 000 g/mol

$R_g$ app= 150 nm

Very large polymeric objects:
several proteins
MULTI-ANGLE DYNAMIC LIGHT SCATTERING

<figure><img src="image_22.png" /></figure>

Monoexponential decay at low angles

Cumulant analysis
$\Gamma_1 = - \lim_{t \to 0} d(g_2-1)/dt$

Monodisperse objects with an
internal dynamic

<figure><img src="image_23.png" /></figure>

<figure><img src="image_24.png" /></figure>

Crosslinked - Branched
polymeric structure
STATIC X-RAY AND NEUTRON SCATTERING

<figure><img src="image_25.png" /></figure>

$d_f$: fractal dimension
(spatial concentration fluctuations)

$\xi$: correlation length = blob size
(time dependent concentration fluctuation)

$l_0$: persistence length

S: average distance between atoms

<figure><img src="image_26.png" /></figure>

=> Polymeric network with a fractal organisation at larger scale
STATIC X-RAY AND NEUTRON SCATTERING

<figure><img src="image_27.png" /></figure>

<figure><img src="image_28.png" /></figure>

Model derived from polymeric gels:

Falcao et al, *Macromolecules* 1993

$$I = a_1 \frac{(1+q\xi)^{1/3}}{(1+q^2\xi^2)} [1 + a_2q^{-d_f}]$$
$$d_f=2 \qquad \xi=f(C)$$

Semi-dilute regime of a polymer
in a good solvent:

$$\xi = l_0 \cdot \phi^{-3/4}$$

$l_0=0.6$ nm

comparable to unstructured proteins

<figure><img src="image_29.png" /></figure>

=> Polymeric network with a fractal organisation at larger scale
## I- System

## II- Structure

- Dilute solutions

- Concentrated regime

## III- Rheology

- Concentration dependence

- Ageing effect
# C° and time dependent rheological properties

## LINEAR RHEOLOGY

<figure><img src="image_30.png" /><figcaption>Ageing effect
(317 mg/ml)</figcaption></figure>

<figure><img src="image_31.png" /></figure>

Sol-gel transition with ageing time and concentration
## Master curves

<figure><img src="image_32.png" /></figure>

<figure><img src="image_33.png" /></figure>

**Critical gel: G'~G''~ω''** Winter-Chambon gel point criterion, 1986

$n_{exp}=0.8 \Rightarrow$ consistent with percolation theory: $n=0.75$

**Time-ageing-concentration superpositions**
**Self similar structures below and above critical gel**
<figure><img src="image_34.png" /></figure>

<figure><img src="image_35.png" /></figure>

* Exponential evolution: atypical - meaning?
<figure><img src="image_36.png" /></figure>

<figure><img src="image_37.png" /></figure>

Induction time,
Auto-catalytic
crosslinking?

<figure><img src="image_38.png" /></figure>

* Exponential evolution:
atypical - meaning?
Origin of ageing?

N-Ethylmaleimide (NEM): blocks thiol groups:

<figure><img src="image_39.png" /></figure>

<figure><img src="image_40.png" /></figure>

Formation of covalent polymeric
species with ageing time.

Disulfide bond shuffling
participate in ageing.

<figure><img src="image_41.png" /></figure>
# Origin of ageing?

<figure><img src="image_42.png" /></figure>

$t^{1/2} \Rightarrow$ Fickian motion

<figure><img src="image_43.png" /></figure>

Gel structure held by glutenins and ω-gliadins (no cystein).
⇒ Non covalent bonds also participate in ageing.
Gluten model system in water-ethanol:

-Structure and dynamics well described by **crosslinked polymer models**.

-Time and concentration dependent gelation.

-Covalent and non-covalent crosslinking.

<figure><img src="image_44.png" /></figure>
## TECHNICAL SUPPORT:

J. Bonicel (HPLC)

P. Dieudonné (SAXS)

## LARGE SCALE FACILITIES:

<figure><img src="image_45.png" /></figure>

P. Kwasniewski

<figure><img src="image_46.png" /></figure>

FRM II
Forschungs-Neutronenquelle
Heinz Maier-Leibnitz

M.S. Appavou

Z. Fu

## FINANCIAL SUPPORT:

<figure><img src="image_47.png" /></figure>

Institut National de la Recherche Agronomique

<figure><img src="image_48.png" /></figure>

LABEX NUMEV