Postdoctoral position OT-21725
Physical chemistry of soft matter for innovative food design
91120 Palaiseau
INRAE presentation
The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.
Work environment, missions and activities
The need for food tailored to individuals is manifold, ranging from the development of high-nutrient plant-based protein foods for a less meat-based diet to the medical constraints of patients with dysphagia. The control of rheology and mouthfeel strongly influence the appreciation of these foods. This postdoctoral project aims to understand the physicochemical origin of the rheological properties of dense suspensions of protein gel particles and to relate them to mouthfeel. Recent work by our team has highlighted the importance of adhesion in the oral processes of viscoelastic foods. They have also established a framework for studying these processes, particularly during swallowing and the high shear stresses associated with it, using an in vitro extensometry approach. However, the effects of the viscoelasticity of the continuous phase on the rheology of non-Brownian suspensions are still poorly understood. The first part of this work will therefore focus on studying the effect of the viscoelasticity of the continuous phase on the flow and texture of the suspension. Another way to control the flow and texture properties of dense suspensions is to modify the contact interactions between the particles. Rheo-thickening or rheo-fluidification of dense suspensions can be explained by the nature of the microscopic interactions. Rheo-fluidification of spherical frictional particles originates from the weakening of the inter-particle friction coefficient µp when the shear imposed on the sample increases. The origin of this decrease in µp is still debated, especially with regard to the characteristic scale of the contact between the particles. The second objective of this project will be to study the feasibility of generating suspensions with particles of controlled roughness. The production of the particles will be done in a hierarchical structure called Ramsden-Pickering. The study of each of these systems will benefit from the unit's experience in the production of microgel suspensions.
To carry out the project, you will:
1) Characterize the influence of the viscoelasticity of the carrier fluid on the rheology of a model suspension;
2) Control the roughness on the surface of the particles and characterize the effect on the rheology.
This project will thus explore two ways to control the texture of dense suspensions and their respective impacts on rheology, and will propose ways to improve the texture of food.
Your activity in the lab will also consist in interacting with the research colleagues from other teams within our Research Unit.
Your hosting team IHAC (Human-Food Interactions for Design) of research unit SayFood is located on the AgroParisTech/INRAE campus in Palaiseau (Université Paris-Saclay).
Training and skills
The candidate should have successfully defended a PhD within the past 3 years in physics, chemical engineering or in mechanics, preferably with experience in rheology, and will have a strong interest for inter-disciplinary research at the frontier with physiology.
INRAE's life quality
By joining our teams, you benefit from (depending on the type of contract and its duration):
- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.
How to apply
Please contact us by email with a CV and a letter of motivation. The title of the email should start with [INRAE JOBS].
Please do not hesitate to get in touch should you require further information.
All persons employed by or hosted at INRAE, a public research establishment, are subject to its internal regulations, particularly with regard to the obligation of neutrality and respect for the principle of secularism. In carrying out their functions, whether or not they are in contact with the public, they must not express their religious, philosophical or political convictions through their behaviour or by what they wear.