The Science Behind Non-Newtonian Noodles
19th September 2018
Traditionally, elastic fei chang fen noodles are made of sweet-potato starch reserved in a steaming-hot broth with pig intestines. The resulting noodle soup is then garnished with bean sprouts, scallions, peanuts, chili oil, and vinegar.
It is the unique preparation, however, by which the street vendor creates his noodles that caught our attention. By combining starch and liquid, he creates a non-Newtonian fluid: a liquid that does not flow with constant viscosity but with a viscosity that changes in response to shear forces, which are forces that push in opposite directions along two distinct parallel lines. Simply put, non-Newtonian fluids can behave as both a liquid and solid. When you apply shear forces to non-Newtonian fluids, you’re met with resistance—try punching such mixtures, and you might come away with a bruise or two. In contrast, Newtonian fluids (like water) have a relatively constant viscosity, despite shear forces and flow rates, which allow them to flow in predictable ways.
I’ll bet you didn’t know that.