Food Tests Lab Report
Food Test 1: Test for Glucose – with Benedicts solution
Benedicts solution is used to test for simple sugars, such as glucose. It is a clear blue solution of sodium and copper salts. In presence of simple sugars, the blue solution changes color to either green, yellow or brick-red, depending on the amount of sugar.
Method
1) Mix smalls amount of each food sample (i.e., Egg lumen, cylindrical piece of potato tuber, bread crump and crisps) in different test tubes with distilled water to make a liquid test. Take another test tube with glucose solution to act as a control so as to compare the difference in color after the completion of the experiment.
2) Label each of the test tubes with a marker for the substance.
3) Add 10 drops of Benedict's solution to each test tube.
4) Carefully heat the test tubes by suspending in a hot water bath using a 500 ml beaker at about 40-50 degrees Celsius for five minutes.
5) Note any color change.
Positive test for Glucose: If sugar is present solution will turn from blue to green, yellow, or brick-red, depending on sugar concentration.
A green precipitate means a little glucose was present.
A red precipitate means glucose is present in vast amounts.
Food Test 2: Test for Starch – with Iodine solution.
Iodine solution is used to identify the presence of starch- a complex carbohydrate. Iodine solution (potassium iodide solution) reacts with amylase – a type of starch – whereby a blue-black polyiodide complex is formed.
Method
1) Mix smalls amount of each food samples (i.e., Egg lumen, cylindrical piece of potato tuber, bread crump and crisps) in different test tubes with distilled water to make a liquid test. Take another test tube with starch solution to act as a control to compare the difference in color after the completion of the experiment.
2) Label each test tube with a marker for the substance.
3) Add 5 drops of iodine reagent solution to each test tube.
4) Note any color change.
Positive
Benedicts solution is used to test for simple sugars, such as glucose. It is a clear blue solution of sodium and copper salts. In presence of simple sugars, the blue solution changes color to either green, yellow or brick-red, depending on the amount of sugar.
Method
1) Mix smalls amount of each food sample (i.e., Egg lumen, cylindrical piece of potato tuber, bread crump and crisps) in different test tubes with distilled water to make a liquid test. Take another test tube with glucose solution to act as a control so as to compare the difference in color after the completion of the experiment.
2) Label each of the test tubes with a marker for the substance.
3) Add 10 drops of Benedict's solution to each test tube.
4) Carefully heat the test tubes by suspending in a hot water bath using a 500 ml beaker at about 40-50 degrees Celsius for five minutes.
5) Note any color change.
Positive test for Glucose: If sugar is present solution will turn from blue to green, yellow, or brick-red, depending on sugar concentration.
A green precipitate means a little glucose was present.
A red precipitate means glucose is present in vast amounts.
Food Test 2: Test for Starch – with Iodine solution.
Iodine solution is used to identify the presence of starch- a complex carbohydrate. Iodine solution (potassium iodide solution) reacts with amylase – a type of starch – whereby a blue-black polyiodide complex is formed.
Method
1) Mix smalls amount of each food samples (i.e., Egg lumen, cylindrical piece of potato tuber, bread crump and crisps) in different test tubes with distilled water to make a liquid test. Take another test tube with starch solution to act as a control to compare the difference in color after the completion of the experiment.
2) Label each test tube with a marker for the substance.
3) Add 5 drops of iodine reagent solution to each test tube.
4) Note any color change.
Positive