Biological Molecule: - Non- Reducing Sugar Test

- Test For Non-Reducing Sugars - 

Test for non-reducing sugars: some disaccharides are reducing sugars and we can use Benedict's test to detect them. Sucrose is known as a reducing sugar because it doesn't change the colour of Benedict's reagent when heated with it.

1. Liquify sample.
2. Add 2cm³ of the food sample to 2cm³ of Benedict's reagent.
3. Place the test tube in a gently boiling water bath for 5 minutes. If the Benedict's reagent does not change colour then a reducing sugar is not present.
4. Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube in gently boiling water bath for 5 minutes. The hydrochloric acid will hydrolyse any disaccharides present into its constituent monosaccharides.
5. Add sodium hydrogen carbonate solution to neutralise the hydrochloric acid. Test with pH paper to check that solution is alkaline
6. Retest the resulting solution, if non reducing sugar present the sample would turn orange-brown colour