Raw milk contains fat globules with an average diameter of $4.0\ \mu\text{m}$. After high-pressure homogenization, the average diameter is reduced to $0.8\ \mu\text{m}$. By Stokes' law, the creaming velocity of the fat globules is reduced by a factor of:
Answer Key:
25.0
Step-by-Step Solution & Explanation
According to Stokes' law, terminal creaming velocity $v_t \propto d^2$:
$\frac{v_1}{v_2} = \left(\frac{d_1}{d_2}\right)^2 = \left(\frac{4.0}{0.8}\right)^2 = (5.0)^2 = 25.0$
The creaming velocity decreases by a factor of 25, preventing gravity separation of cream during storage.