Question Bank • QB_APE_PROC_001 NAT • 2 Marks

Section 6: Agricultural Process Engineering

Processing of Agriculture Produce

Subtopic: Processing of seeds, spices, fruits and vegetables

Question Statement:

A mechanical screw expeller processes $1500\text{ kg}$ of mustard seed containing $36.0\%\text{ (w/w)}$ oil. The expeller produces oil and a press cake containing $8.0\%\text{ (w/w)}$ residual oil. Assuming moisture content remains constant and no solid losses occur, the mass of oil extracted in $\text{kg}$ is ________ (round off to two decimal places).

Answer Key:

456.52

Step-by-Step Solution & Explanation

Multi-Approach Solution: **Method 1: Non-Oil Solids Conservation** 1. In feed: Total mass $F = 1500\text{ kg}$, oil fraction $x_F = 0.36$. $M_{\text{oil, in}} = 1500 \times 0.36 = 540\text{ kg}$ $S = \text{Non-oil solids} = 1500 - 540 = 960\text{ kg}$ 2. In cake: Non-oil solids constitute $100\% - 8.0\% = 92.0\%$ of the cake mass. $C = \text{Cake mass} = \frac{S}{1 - x_C} = \frac{960}{1 - 0.08} = \frac{960}{0.92} = 1043.478\text{ kg}$ 3. Oil remaining in cake: $M_{\text{oil, cake}} = 1043.478 \times 0.08 = 83.478\text{ kg}$ 4. Oil extracted: $M_{\text{oil, extracted}} = 540 - 83.478 = 456.522\text{ kg} \approx 456.52\text{ kg}$ **Method 2: Direct Formula** $M_{\text{oil, extracted}} = F \times \frac{x_F - x_C}{1 - x_C} = 1500 \times \frac{0.36 - 0.08}{1 - 0.08} = 1500 \times \frac{0.28}{0.92} = 456.52\text{ kg}$
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