Question

Potato slices weighing 50 kg are dried from 60% moisture content (wet basis) to 5% moisture content (dry basis). The amount of dried potato slices obtained (in kg) is ................. (Answer in integer).

Hint:

Always convert moisture contents carefully: - Wet basis → relative to total mass. - Dry basis → relative to dry solids. The dry solid mass remains constant throughout drying.

Answer 1

Correct Answer: 21

Step 1: Moisture content conversions.
- Wet basis (wb): \[ M_{wb} = \frac{W_w}{W_t} \] where \(W_w = \text{water weight}, W_t = \text{total weight}. \] - Dry basis (db): \[ M_{db} = \frac{W_w}{W_s} \] where \(W_s = \text{dry solid weight}. \]

Step 2: Find dry solid weight initially.
Given: total weight \(= 50\) kg, \(M_{wb} = 0.60\). \[ W_w = 0.6 \times 50 = 30 \; \text{kg} \] \[ W_s = 50 - 30 = 20 \; \text{kg (constant during drying)}. \]

Step 3: Final condition (5% dry basis).
Let final water weight = \(W_{wf}\). \[ M_{db} = \frac{W_{wf}}{W_s} = 0.05 \] \[ W_{wf} = 0.05 \times 20 = 1 \; \text{kg} \]

Step 4: Final total weight.
\[ W_f = W_s + W_{wf} = 20 + 1 = 21 \; \text{kg} \] Final Answer: \[ \boxed{21 \; \text{kg}} \]