Extensional viscosity of some food hydrocolloids

Abstract Conventional rheological techniques such as steady shear viscosity and dynamic oscillatory rheometry have long been used to characterize differences between hydrocolloid solutions. Useful information on structure and conformation has been obtained in this way. A complementary method, extensional viscosity, is now available to study these solutions. The newly released Rheometrics Extensional Rheometer (RFX) measures extensional viscosity by means of an opposing jet design. The fluid being tested is drawn into two opposing nozzles from a test beaker. The area between the nozzles undergoes an extensional flow. Such instruments are called stagnation point devices and have been used to study molecular alignment via optical techniques. However, these devices were not able to quantitate the extensional viscosity.