Question Bank • QB_DFE_EXP_068 NAT • 2 Marks

Section 7: Dairy and Food Engineering

Heat and Mass Transfer

Subtopic: Material and energy balances in food processing systems

Question Statement:

Whole milk containing $4.0\%$ fat is separated in a centrifugal cream separator into cream containing $40\%$ fat and skim milk containing $0.05\%$ fat. For $1000\text{ kg}$ of whole milk feed, calculate the yield of cream in $\text{kg}$.

Answer Key:

98.87

Step-by-Step Solution & Explanation

Overall mass balance: $M = C + S \implies S = 1000 - C$. Fat balance: $1000 \times 0.04 = C \times 0.40 + S \times 0.0005$ $40 = 0.40 C + 0.0005(1000 - C)$ $40 = 0.40 C + 0.5 - 0.0005 C$ $39.5 = 0.3995 C$ $C = \frac{39.5}{0.3995} \approx 98.873\text{ kg}$
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