Coupling between flow, heat transfer and transformation during phase change of a liquid food complex - application to the control of the texture

Couplage entre ecoulements, transferts thermiques et transformation lors du changement de phase d'un produit alimentaire liquide complexe - application a la maitrise de la texture

Anis Haddad Amamou

THIS STUDY FOCUSES ON THE FREEZING STAGE DURING THE PROCESSING OF A COMPLEX LIQUID SUCH AS SORBET OR ICE CREAM. THIS STEP TAKES PLACE IN SCRAPED SURFACE HEAT EXCHANGERS (SSHE) OR FREEZERS. DURING THIS STAGE, THE ORIGINAL MIX IS SUBJECTED TO SEVERAL PHENOMENA: HEAT TRANSFER, CRYSTALLIZATION OF WATER INTO ICE AND SHEAR. THIS PREDISPOSES THE FINAL QUALITY OF THE PRODUCT, ESPECIALLY ITS TEXTURE. THIS STUDY AIMS TO BETTER UNDERSTAND THE EVOLUTION OF THE PRODUCT DURING THE FREEZING AND TO CHARACTERIZE THE INFLUENCE OF PROCESS VARIABLES AND FORMULATION ASPECTS ON THE TEXTURE OF THE PRODUCT, AND PARTICULARLY ON CRYSTAL SIZE AND VISCOSITY. OUR APPROACH HAS COMBINED THE EXPERIMENT (AT THE LABORATORY SCALE) AND MODELLING (KINETICS OF CRYSTALLIZATION AND NUMERICAL SIMULATION OF FLOW AND HEAT TRANSFER). THE EXPERIMENTAL STUDY WAS PERFORMED AT THE LABORATORY SCALE (IN A SSHE SIMULATOR) UNDER CONTROLLED THERMAL AND MECHANICAL CONDITIONS. THIS WORK ALLOWED TO MONITOR THE STRUCTURAL (SIZE ...) AND RHEOLOGICAL (VISCOSITY) EVOLUTIONS OF THE PRODUCT DURING THE CRYSTALLIZATION. THEN, A MODEL COUPLING THE HEAT TRANSFER AND CRYSTALLIZATION WAS DEVELOPED TO BETTER UNDERSTAND THE MECHANISMS AND ALLOW THE SIMULATION OF THE PRODUCT EVOLUTION DURING THE FREEZING STEP.

CETTE ETUDE S'INTERESSE A L'ETAPE DE GLAÇAGE LORS DE LA CONGELATION D'UN PRODUIT LIQUIDE COMPLEXE, DE TYPE SORBETS OU CREME GLACEE. CETTE ETAPE A LIEU DANS DES ECHANGEURS DE CHALEUR A SURFACE RACLEE (ECSR) OU FREEZERS. AU COURS DE CETTE ETAPE, LA FORMULE INITIALE OU LE MIX EST LE SIEGE DE PLUSIEURS PHENOMENES : LES TRANSFERTS THERMIQUES, LA CRISTALLISATION DE L'EAU EN GLACE ET LE CISAILLEMENT. CETTE ETAPE PREDISPOSE LA QUALITE FINALE DU PRODUIT, NOTAMMENT SA TEXTURE. L'ETUDE ENTREPRISE LORS DE CE TRAVAIL DE THESE A POUR OBJECTIF DE MIEUX COMPRENDRE L'EVOLUTION DU PRODUIT DURANT LE GLAÇAGE ET DE CARACTERISER L'INFLUENCE DES VARIABLES DU PROCEDE ET DE CERTAINS ASPECTS DE FORMULATION SUR LA TEXTURE DU PRODUIT. POUR CELA, ON S'EST INTERESSE PLUS PARTICULIEREMENT A LA TAILLE DES CRISTAUX ET A LA VISCOSITE. NOTRE APPROCHE A COMBINE L'EXPERIMENTATION (A L'ECHELLE DU LABORATOIRE) ET LA MODELISATION (CINETIQUE DE CRISTALLISATION ET SIMULATION NUMERIQUE DES ECOULEMENTS ET DES TRANSFERTS THERMIQUES). L'ETUDE EXPERIMENTALE A ETE REALISEE A L'ECHELLE DU LABORATOIRE (DANS UN SIMULATEUR D'ECSR) DANS DES CONDITIONS THERMIQUES ET MECANIQUES CONTROLEES. ELLE A PERMIS DE SUIVRE L'EVOLUTION STRUCTURALE (GRANULOMETRIE

Mots clés: Crystallization; Scraped surface heat exchanger; Ice crystal size; Viscosity; Modelling

Mots clés: Cristallisation; Glace; Echangeur de chaleur à surface raclée; Taille des cristaux; Viscosité; Modélisation

Domaines: Chimie

Anis Haddad Amamou. Coupling between flow, heat transfer and transformation during phase change of a liquid food complex - application to the control of the texture. Chemical Sciences. AgroParisTech, 2009. English. ⟨NNT : 2009AGPT0023⟩. ⟨pastel-00005395⟩