title: Microwave heating effect on rheology and microstructure of white sauces.
abstract: The microstructure and rheological properties of white sauces formulated with different starches were analyzed after being microwave-heated for different times. Significant differences (P < 0.05) in rheological parameters analyzed-storage modulus (G'), loss modulus (G″), and loss tangent (tanδ)-were obtained for sauces made with different starches. Microwave reheating did not affect G' and G″ values until water evaporation became significant. In addition, tanδ values did not change significantly (P < 0.05) even during long reheating times showing that sauce viscoelastic properties did not change after microwave irradiation. However, microstructure assessed by confocal laser scanning microscopy showed changes in fat globule and protein. These microstructural changes did not seem to have a significant effect on rheological measurements since starch and ι-carrageenan are mainly responsible for the viscoelastic behavior of the sauces. Practical Application:  The development of products appropriate to microwave heating is constantly rising in food industry. It is necessary to understand the behavior of the ingredients and the final product to microwave heating in order to choose those ingredients which will develop the best performance. Starches are common ingredients in industrial sauces, and rheological and microstructural techniques have shown their usefulness in characterization of starch-based systems.
authors.affiliation: Dept. de Tecnología de Alimentos, Grupo de Microestructura y Química de Alimentos, Univ. Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain. luiguaex@upvnet.upv.es
authors.forename: Luis M
authors.initials: LM
authors.lastname: Guardeño
authors.forename: Teresa
authors.initials: T
authors.lastname: Sanz
authors.forename: Susana M
authors.initials: SM
authors.lastname: Fiszman
authors.forename: Amparo
authors.initials: A
authors.lastname: Quiles
authors.forename: Isabel
authors.initials: I
authors.lastname: Hernando
mesh_terms: D002351:Carrageenan / Q000737:chemistry; D003296:Cooking / Q000379:methods*; D005502:Food; D005511:Food Handling / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D018613:Microscopy, Confocal / Q000379:methods; D008872:Microwaves; D012212:Rheology; D013213:Starch / Q000737:chemistry*
chemical_list: D002351:Carrageenan; D013213:Starch