Paper Number
SM30 

Session
Polymers Solutions, Melts, and Blends

Title
Extensional rheology and pinching dynamics of polysaccharide food thickener

Presentation Date and Time
October 13, 2021 (Wednesday) 10:15

Track / Room
Track 1 / Ballroom 5

Authors (Click on name to view author profile)

  1. Suresh, Karthika (University of Illinois Chicago)
  2. Boehm, Michael (Motif FoodWorks, Inc.)
  3. Baier, Stefan (Motif FoodWorks, Inc.)
  4. Sharma, Vivek (University of Illinois at Chicago, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Karthika Suresh1, Michael Boehm2, Stefan Baier2 and Vivek Sharma1
1Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607; 2Motif FoodWorks, Inc., Boston, MA

Speaker / Presenter 
Suresh, Karthika

Keywords
experimental methods; polymer solutions; rheology methods

Text of Abstract
Foods are multicomponent soft materials that often contain dispersed drops, bubbles, particles, or proteins. Often protein-based foams, emulsions, suspensions, and pastes contain polysaccharides that act as binders, thickeners, gelling agents or rheology modifiers, and influence shelf-life, rheology, processability as well as control over fiber, fat, salt, calorie count, texture, and mouth-feel. Stream-wise velocity gradients associated with extensional flows spontaneously arise during extrusion, calendaring, coating, dispensing, bubble growth or collapse as well as consumption including swallowing and suction via straws. Even though shear rheology response is fairly well characterized and utilized in food industry, elucidating, measuring and harnessing the extensional rheology response have remained longstanding challenges. The characterization challenges include the lack of robust, reliable and affordable methods for measuring extensional rheology response, whereas the product design challenges stem from the difficulties in assessing or predicting the influence of macromolecular properties on macroscopic rheological behavior. In this contribution, we address the characterization challenges for specific case of xanthan gum thickener by using dripping-onto-substrate (DoS) rheometry protocols that we developed that rely on analysis of capillary-driven thinning and break-up of liquid necks created by releasing a finite volume of fluid onto a substrate. The DoS rheometry protocols emulate the heuristic tests of thickening, stickiness or cohesiveness based on dripping a sauce from a ladle or dispensing from a nozzle onto a substrate. We investigate the concentration-dependent variation in shear and extensional rheology of xanthan gum solutions. We show that changing salt concentration can be used for tuning the pinch-off dynamics, extensional rheology response, and processability of solutions of xanthan gum.