Table 1 – Instructions for food tests Food test
Steps
starch
1. Put a small piece of the food to test on a spotting tile. 2. Add two drops of iodine solution to the food.
3. If the iodine goes blue-black, the food contains starch. glucose
1. Mix a small sample of the food with about 3 cm3 of Benedict’s solution in a boiling tube. 2. Heat the mixture in a hot water bath for 3 minutes.
3. If the solution goes a brick red colour, the food contains sugar. protein
1. Mix a small sample of the food with about 3 cm3 of biuret solution. 2. Leave for 2 minutes.
3. If the mixture goes a pale purple colour, the food contains protein. lipid
1. Mix a small sample of the food with about 1 cm3 of ethanol in a dry test tube. 2. Pour the ethanol into a test tube full of cold water.
3. If the water goes milky white, the food contains lipid. 3.
Record your observations in row 1 of Table 2.
4.
Repeat for four more food samples and record your observations in rows 2–5 of Table 2.
Record your results Table 2 – Results of food tests Observations Food sample Starch test
Glucose test
Protein test
Lipid test
1. ....................... 2. ....................... 3. ....................... 4. ....................... 5. .......................
AQA GCSE (9–1) Combined Science: Trilogy Required Practicals Lab Book
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