Testing for non-reducing sugars

• What is step 1?

  First add 2 cm cubed of the food sample (a liquid) to 2cm cubed of Benedict’s reagent in a test tube and filter.
• What is step 2?

  Place the test tube in a gently boiling water bath for 5 minutes. If the solution doesn’t change colour, then a reducing sugar is not present.
• What is step 3?

  Add another 2 cm cubed of the food sample to 2 cm cubed of dilute hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 minutes. The dilute hydrochloric acid will hydrolyse any disaccharide present into any monosaccharides.
• What is step 4?

  Slowly add some sodium hydrogen carbonate solution to the tube in order to neutralise the hydrochloric acid. Test with pH paper to check that the solution is alkaline.
• What is step 5?

  Re-test the resulting solution by heating it with 2 cm cubed of benedict's reagent in gently boiling water for 5 mins.
• What is step 6?

  If a non-reducing sugar was present in the original sample, the Benedict’s reagent will now turn orange—brown. This is due to the reducing sugars that were produced from the hydrolysis of the non-reducing sugar.