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24 Janvier 2019 Séminaire Denis Roux

Characterization of a model food crystal network oleogel formation an AGING

Jeudi 24 Janvier 2019 de 14h à 15h salle A.Rassat du bâtiment E de l’UFR de Chimie

Résumé :
Monoglycerides (MG) suspended in oil are very important systems in the cosmetic and food industries. Indeed their mechanical properties, bio-compatibility, weak susceptibility to microbial infection, and excellent emulsification properties make them ideal to tailor cream products for cosmetic and food applications. However, while MG in water systems have been studied in-extenso, MG in oil systems are less well known, in particular the aging of their physical properties.

In this work, we investigated the behaviour of an oleogel made from 10% commercial, distilled monoglycerides in sunflower oil. The gel was characterized in terms of crystal micro-structure, rheology, and polymorphic state as it was cooled to 25°C, and as a function of age for up to 8 weeks. As the solution was cooled from 95°C to 25°C, two distinct polymorphic events occurred : crystallization into the initial α phase, and a transition into the sub-α from ; both events were correlated with highly birefringent crystals and a large increase of visco-elasticity. Over 8 subsequent weeks the gels evolved from the initial polymorphic forms to the β polymorph, and the initial percolating crystal network transitioned into discrete, dense crystals, with an associated decrease in gel strength. During both cooling and aging, the polymorphic and rheological evolutions of the gel were correlated through crystal microstructure modifications. The observed coupling of polymorphic evolutions and rheological properties is hypothesised to be extendable to other lipid oleogel systems, providing important tools to predict gel properties, including gel collapse, in industrially interesting lipid-based materials.

D. C. D. Roux1,*, E. M. Spiden1, F. Caton1, N. Isobe1, O. Schafer2, J. Craven2, D. Z. Gunes2,*

1- Laboratoire Rhéologie et Procédés (LRP), Univ. Grenoble Alpes (UGA), France

2- Nestlé Research Center, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland
(*to whom correspondence should be addressed)

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