A 1 L batch of fermented milk uses a starter culture containing Lactobacillus bulgaricus that ferments lactose at a rate of 0.02 g per litre per hour. If fermentation is carried out for 8 hours, how many grams of lactose are converted to lactic acid?
Answer
0.16 g
The correct answer is 0.16 g — Total lactose converted = 0.02 g × 8 h = 0.16 g.
Step-by-step solution
- Rate = 0.02 g (L·h)⁻¹.
- For 1 L, lactose converted per hour = 0.02 g.
- Fermentation time = 8 h.
- Total lactose converted = 0.02 g × 8 h = 0.16 g.
Common mistake: Multiplying rate by volume and time incorrectly (e.g., using 1000 mL instead of 1 L)
Concept tested: Rate of lactose fermentation
Published · How this solution was prepared and checked
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