A quart container of homogenized milk is stored quiescently at $5^\circ\text{C}$ for 48 hours. After storage, the top $100\text{ mL}$ is decanted and tested to contain $3.55\%$ fat, while the remaining thoroughly mixed milk contains $3.30\%$ fat. The USPHS homogenization index ($\frac{\text{Fat}_{top} - \text{Fat}_{rem}}{\text{Fat}_{top}} \times 100$) in percentage is ________ (round off to 2 decimal places).
Answer Key:
7.04
Step-by-Step Solution & Explanation
The United States Public Health Service (USPHS) Homogenization Index is:
$\text{Index} = \frac{\text{Fat}_{top} - \text{Fat}_{rem}}{\text{Fat}_{top}} \times 100$
$\text{Index} = \frac{3.55 - 3.30}{3.55} \times 100 = \frac{0.25}{3.55} \times 100 = 7.04225\% \approx 7.04\%$