demonstrations:testing_foods_for_reducing_sugars

Testing Foods for Reducing Sugars

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required

Categories: Food Science and Nutrition

Alternative titles: Glucose Test with Benedict’s Solution

Summary

Benedict’s solution is used to test foods for the presence of reducing sugars such as glucose. When heated with a reducing sugar, the blue solution changes to green, yellow, orange, or brick red depending on the sugar concentration.

Procedure

  1. Place the food sample in a test tube.
  2. Add a few drops of Benedict’s solution.
  3. Heat the mixture in a boiling water bath for 2–3 minutes.
  4. Observe the color change: green/yellow/orange indicates some sugar, while brick red shows a strong positive result.

Biology - Reducing Sugars using Benedict's Reagent Demonstration - Bury College Official:


Benedict's Test for Reducing Sugars - JamJarMMX:


📄 Food test 2 - Benedict's test for Reducing Sugars - Biology Notes for IGCSE: https://biology-igcse.weebly.com/food-test-2---benedicts-test-for-reducing-sugars.html

Variations

  • Compare fresh fruit juice to processed drinks.
  • Test starchy foods before and after hydrolysis with amylase or acid.
  • Quantify results by comparing shades of color to a standard chart.

Safety Precautions

  • Use heat-resistant gloves or tongs when handling hot test tubes.
  • Avoid direct flame on Benedict’s solution—use a water bath for heating.
  • Dispose of test mixtures properly; do not ingest chemicals or tested food.

Questions to Consider

  • Why does Benedict’s solution change color when reducing sugars are present? (Copper(II) ions are reduced to copper(I) oxide, which forms a red precipitate.)
  • What foods are likely to contain reducing sugars? (Fruits, honey, soft drinks, some vegetables.)
  • Why must the mixture be heated for the reaction to work? (Heat provides the energy needed to drive the redox reaction.)