title: Crystallization and polymorphism of triacylglycerols contribute to the rheological properties of processed cheese.
abstract: The thermal, rheological, and structural behaviors of a spreadable processed cheese were studied by complementary techniques including differential scanning calorimetry (DSC), rheology, and X-ray diffraction as a function of temperature. In this product, fat is present as a dispersed phase. Thermal and rheological properties were studied at different cooling rates between 0.5 and 10 degrees C min(-1) from 60 to 3 degrees C. Crystallization properties of fat were monitored at a cooling rate of -2 degrees C min(-1) from 60 to -10 degrees C. Fat triacylglycerols (TGs) crystallized at 15 degrees C in a triple-chain length 3Lalpha (72 A) structure correlated to exothermic events and to the sudden increase in the rheological moduli G' and G''. Upon heating at 2 degrees C min(-1), the polymorphic transition of TGs evidence the melting of the 3Lalpha structure and the formation of a 2Lbeta' (36.7-41.5 A) structure. Melting of the latter follows. These transformations coincide with thermal events observed by DSC and the decrease in two steps of the rheological moduli. The influence of fat crystallization, melting, and polymorphism upon the viscoelastic properties is clearly demonstrated upon both heating and cooling.
authors.affiliation: Equipe Physico-Chimie des Systèmes Polyphasés, UMR 8612 du CNRS, Chatenay-Malabry, France.
authors.forename: Hela
authors.initials: H
authors.lastname: Gliguem
authors.forename: Dorra
authors.initials: D
authors.lastname: Ghorbel
authors.forename: Christelle
authors.initials: C
authors.lastname: Lopez
authors.forename: Camille
authors.initials: C
authors.lastname: Michon
authors.forename: Michel
authors.initials: M
authors.lastname: Ollivon
authors.forename: Pierre
authors.initials: P
authors.lastname: Lesieur
mesh_terms: D002152:Calorimetry, Differential Scanning; D002611:Cheese / Q000032:analysis*; D055598:Chemical Phenomena; D003460:Crystallization; D004548:Elasticity; D011110:Polymorphism, Genetic; D012212:Rheology; D013816:Thermodynamics; D014280:Triglycerides / Q000032:analysis / Q000737:chemistry*; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D014280:Triglycerides