According to the US Public Health Service (USPHS) standard for homogenized milk, after 48 hours of quiescent storage at $4^\circ\text{C}$, the fat percentage in the upper $100\text{ mL}$ of a $1\text{ quart}$ ($946\text{ mL}$) container is $4.2\%$, and the fat percentage in the remaining thoroughly mixed milk is $3.9\%$. Calculate the creaming index $\left(\frac{F_{\text{top}} - F_{\text{rem}}}{F_{\text{top}}} \times 100\right)$ in percentage.
Answer Key:
7.14
Step-by-Step Solution & Explanation
$\text{Creaming Index} = \frac{4.2 - 3.9}{4.2} \times 100 = \frac{0.3}{4.2} \times 100 \approx 7.1429\%$
(Since it is lt; 10\%$, the milk meets the USPHS homogenization standard).