Please enable JavaScript.
Coggle requires JavaScript to display documents.
Food tests and Calibration Curves (Quantitative Benedicts test (Make…
Food tests and Calibration Curves
Food test-
Starch
-Add a drop or two of iodine potassium iodine solution to the food sutff
If starch is
absent
it will go orange/iodine colour.
If starch is
present
it will go blue/black
Food test-
Protein
-Using a pipette, add a few drops of Biuret Solution A to a test tube part-full of the protein solution.
-Next, add a few drops of Biuret solution B solution into the same test tube.
If protein is absent, it'll go blue.
If protein is present it'll go purple.
Food test-
Lipid
Add 2cm3 of ethanol to the foodstuff in a test tube.
Bung the tube and shake for 30 seconds
Pour into another test tube half-full of water.
If lipids are present there will be a cloudy white emulsion.
If lipids are absent there will be no emulsion
Food test-
Reducing sugar
Pour some test solution into a test tube.
Add an equal amount of Benedicts solution.
Shake and bring to the boil in a water bath.
If present there will be a red/orange precipitate
If absent there will be a blue solution.
Food test-
Non-reducing sugar
First do Benedict's test and obtain a negative result
Pour some test solution into a test tube.
Add an equal amount of dilute HCI solution and boil for 3 minutes in a water bath.
Neutralise with sodium hydrogencarbonate until the fizzing stops.
Perform Benedict's test as before.
If present there will be a red/orange precipitate
If absent there will be a blue solution
Quantitative Benedicts test
Make solutions of
known
concentrations and carry out Benedicts test on each.
Use colorimeter to measure light absorbance of each solution.
Use data to plot graph, with concentration on x-axis and absorbance on y-axis. Draw calibration curve.
Find unknown concentrations by reading their absorbances off the calibration curve.