Tests

Question 1

How do you find the presence of starch?

Answer 1

Put iodine on starch and the colour of iodine (Jod) will change from yellow-brown to blue-black.

Question 2

A solution is heated to 80℃ and froms an orange-red precipitate. What does this test indicate?

Answer 2

This indicates that we have a reducing sugar (DE: reduzierender Zucker) such as mono-or disaccharide. The solutions is called Benedict’s solutins (DE: Benedict-Reagenz) (alkaline copper sulfate).

Question 3

Some pale blue liquid is put on a food sample and it turns to lilac. What does this indicate?

Answer 3

This test indicates the presence of a protein and called the biuret test (DE: Biuret test). The liquid contains NaOH and copper sulfate.

Question 4

A sample is mixed with ethanol and poured into water. A cloudy white emulsion can be seen. What does this indicate?

Answer 4

It indicates the presence of lipids and called the ethanol emulsion test.