Oxidative and interfacial behavior of native oil bodies from walnut

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HAL Id: hal-02315046

https://hal.archives-ouvertes.fr/hal-02315046v2

Submitted on 17 Oct 2019

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Oxidative and interfacial behavior of native oil bodies

from walnut

Jeanne Kergomard, V. Vié, G. Paboeuf, Nathalie Barouh, Bruno Barea,

Pierre Villeneuve, Olivier Schafer, Tim Wooster, Claire Bourlieu-Lacanal

To cite this version:

Jeanne Kergomard, V. Vié, G. Paboeuf, Nathalie Barouh, Bruno Barea, et al.. Oxidative and interfa-cial behavior of native oil bodies from walnut. Euro Fed Lipid Seville 2019, Oct 2019, Séville, Spain. �hal-02315046v2�

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0 1 2 3 4 5 6 0 5 10 15 20 Con ce n tra tio n (mm o l MDA/kg o f o il)

Storage time (days)

TBARS value

Walnuts labmilk Isolated Native OB

OXIDATIVE AND INTERFACIAL BEHAVIOR OF NATIVE OIL BODIES FROM WALNUT

Jeanne Kergomard

1,2

_{, Véronique Vié}

2

_{, Gilles Paboeuf}

2

_{, Nathalie Barouh}

1

_{, Bruno Barea}

1

_{, Pierre Villeneuve}

1

_,

Olivier Schafer

3

_{, Tim J. Wooster}

3

_{, Claire Bourlieu}

1*

1

_{INRA-CIRAD Montpellier 1253 IATE, France;}

2

_{IPR Institute of Physics, Rennes University 1, France;}

3

_{IMS Nestlé Research,}

Lausanne, Switzerland

References

[1] D. Hayes, M. J. Angove, J. Tucci, C. Dennis, “Walnuts (Juglans regia) Chemical Composition and Research in Human Health”, Crit Rev Food Sci Nutr vol. 56:8, pp. 1231-1241, 2016

[2] V. Kapchie, L. Yao, C. C. Hauck, T. Wang, P. A. Murphy, “Oxidative stability of soybean oil in oleosomes as affected by pH and iron”, Food Chemistry v.141, pp. 2286–2293, 2013

[3] S-W. Huang, E. N. Frankel, J. B. German, “Antioxidant activity of alpha and gamma-tocopherols in bulk oils and in oil-in-water emulsions”, “J. Agric. Food Chem. Vol. 42, pp. 2108-2114, 1994

[4] G. Waschatko, B. Schiedt, T. A. Vilgis, A. Junghans, “Soybean oleosomes behavior at the Air-Water Interface”, J. Phys. Chem. B vol. 116, pp. 10831-10841, 2012

Walnuts are among the most widely consumed commercially grown tree nuts in the world. Indeed, their consumption is associated with

many health benefits, such as reducing the risk of cardiovascular disease, coronary heart disease and other neurological disorders. These

benefits are attributed to their fatty acid profiles, which is rich in polyunsaturated fatty acids (PUFA)

[1]

. As a result, walnuts are used in

several food products, such as walnut-based beverages, where fat is partly dispersed under the form of natural lipoproteic assemblies, which

are called oil bodies (OB).

What is OB?

O: Oleosins C: Caleosins S: Stereosins

Matrix triglycerides

(Neutral lipids)

Proteins

(Mainly oleosins)

Phospholipids

(Polar lipids)

Material and methods

Results - Interfacial behavior

Proteins, unsaturated TG and

phospholipids assembly

Phospholipids and saturated TG domain

Fresh Isolated Native OB

Oxidized Isolated Native OB

0 5 10 15 20 25 30 35 0 5 10 15 20 Con ce n tra tio n ( meq O 2 / k g o f o il)

Storage time (days)

PV value

Walnuts labmilk Isolated Native OB 0 2 4 6 8 0 10 v o lu m e ( % ) Size (µm)

73 µm

0 2 4 6 8 0 10 Size (µm)

Labmilk

Isolated Native OB

Results - Oxidative behavior

HHP*= High Pressure Homogenization

Labmilk Isolated Native OB

Matrix preparation

1

4% wt. of oil

2

Phospholipids Triglycerides Proteins Bimodal: 18.7 µm, 0.6 µm Trimodal: 7.6 µm, 0.6 µm, 2.8 µm

Phospholipids, saturated and

unsaturated TG domain

Proteins – oleosins

in solution

p

f

= 15 mN/m

Δ

f

= 5 °

Conclusion

: When OBs are intact, they open at the interface and spread out in domains and assemblies thanks to good cohesiveness between the

different molecules. Oxidation phenomenon modified the physical integrity of the OB, decreasing intermolecular forces, which resulted in a different

interfacial organization with a majority of lipids at the interface and solubilization of proteins.

Conclusion

: Walnuts OB were stable to oxidation on the short term (few days).

This phenomenon is related to the “assembly effect” of OB and to their

antioxidant content in vitamins E (41.0 ± 20.7 % wt.)

[3]

.

The stability of lipid dispersion was higher under “milk” form due to a complex

“matrix effect”.

50

0 n

m

–

2.5 µm

Size profile

The negative charges of oleosins at physiological

(neutral) pH trigger objet repulsion and avoid

coalescence phenomena in walnut system.

0 5 10 15 20 25 0 1 2 3 4

Fresh Isolated Native OB

PI (mN/m) DELTA PI (mN/m), D ELTA (° ) t (hours)

How does the structural changes of oxidized OB affect the behaviour at the interface?

0 5 10 15 20 25 0 1 2 3 4

Oxidized Isolated Native OB

PI (mN/m) DELTA PI (mN/m), DEL T A (°) t (hours)

Two questions remain pressing: what is walnut OB’s oxidative behavior and what are the consequences of oxidation on its interfacial reactivity?

(Waschatko et al, 2012, [4])

Formation of a thinner

monolayer at the interface

(Kapchie et al., 2013

[2]

)

Jeanne.kergomard@univ-rennes1.fr

1

2

Wilhelmy Balance p(mN/m) Ellipsometry Δ (°) Langmuir-Blodgett transfer

Atomic Force Microscopy

Tensiometry/Ellipsometry

Oxidative challenge test (PV, TBARS)

Confocal microscopy

Incubation

20 days 40°C

110 rpm

+ 3 fluorescent probes

p(surface pressure)is indicative ofprotein insertion

Δ(ellipsometric angle)is related to theamount of matter at the interface