How to Measure Sugar in Potatoes
- 1). Put on your protective safety goggles. Pour 4 ml of the potato juice into the test tube. Potato juice can be collected from raw grated potatoes. Put the grated potatoes into a small sieve and press the potato into the sieve to release the juice.
- 2). Add 1 ml of Benedict's reagent to the raw potato juice. This reagent is typically available at local pharmacies. The solution is a mixture of sodium citrate, copper sulfate and sodium carbonate.
- 3). Mix Benedict's reagent and the raw potato juice together. Thoroughly blend the two by whirling the tube or stirring with a glass rod.
- 4). Place the test tube in a container with boiling water high enough to cover the level of the solution in the test tube. A canning jar or Pyrex container can be used to hold the boiling water safely . Baby food jars are also good for 50 to 100 ml.
- 5). Leave the test tube in the boiling water for 2 to 3 minutes. Return the hot tube to the test-tube rack using the test-tube holder.
- 6). Look for color changes in the solution. The substance in your test tube will change color if it contains glucose. Using a white paper as a background, hold the test tube to determine the color.
A blue color indicates no sugar.
A blue-green color indicates a trace of sugar.
A green color indicates a little sugar.
A yellow color indicates some sugar.
An orange-red color indicates a large amount of sugar.
