A liquid food that exhibits a finite yield stress $\tau_0$ and a flow behavior index $n < 1$ (shear thinning behavior once flow commences) is classified as a:
(B) Bingham plastic (e.g. toothpaste with linear $n = 1$)
(C) Dilatant fluid ($n > 1$)
(D) Newtonian fluid
Answer Key:
A
Step-by-Step Solution & Explanation
The Herschel-Bulkley model is $\tau = \tau_0 + K \dot{\gamma}^n$. When $\tau_0 > 0$ and $n < 1$, the fluid is yield-pseudoplastic (Herschel-Bulkley), characteristic of ketchup, mayonnaise, and purees.