Which reagent turns from orange-brown to blue-black when starch is present in a food sample?
Answer and explanation
Correct answer: C. Iodine solution
- Step 1: Each food test uses a reagent that gives a colour change for one nutrient. Step 2. Iodine solution gives a blue-black colour with starch. Answer: iodine solution. Why not the others: Benedict's solution tests for reducing sugars, biuret reagent for protein and the ethanol emulsion test for fats.
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