Food Tests Flashcards
how can you test for sugars?
1)Prepare a food sample and transfer 5 cm to a test tube.
2)Add some Benedict’s solution to the test tube using a pipette.
3)Place the test tube a water bath using a test tube holder and leave it in there for 5 minutes. Make sure the tube is pointing away from you
4)If the food sample contains a reducing sugar, the solution in the test tube will change from the normal blue colour to green, yellow or red depending on how much sugar is in the food.
how can you test for starch?
1) Make a food sample and transfer 5 cm of your sample to a test tube.
2) Then add a few drops of iodine solution and gently shake the tube to mix the contents. If the sample
contains starch, the colour of the solution will change from browny-orange to black or blue-black.
how can you test for proteins?
1)Prepare a sample of your food and transfer 2 cm of your sample to a test tube.
2) Add 2 cm of biuret solution to the sample and mix the contents of the tube by gently shaking it.
3) If the food sample contains protein, the solution will change from blue to purple. If no protein is present, the solution will stay blue.
how can you test for lipids?
1)Prepare a sample of the food you’re testing (but you don’t need to filter it).
Transfer about 5 cm° into a test tube.
2) Use a pipette to add 3 drops of Sudan Ill stain solution to the test tube and gently shake the tube.
3)Sudan IIl stain solution stains lipids. If the sample contains lipids, the mixture will separate out into two layers. The top layer will be bright red. If no lipids are present, no separate red layer will form at the top of the liquid.
how can you prepare a food sample?
1) Get a piece of food and break it up using a pestle and mortar.
2) Transfer the ground up food to a beaker and add some distilled water.
3) Give the mixture a good stir with a glass rod to dissolve some of the food.
4) Filter the solution using a funnel lined with filter paper to get rid of the solid bits of food
what is the test for sugars called?
the Benedict’s test
what is the test for proteins called?
The Biuret Test
what is the test for lipids called?
The Sudan III Test
what solution can be used to test for protein?
biuret solution
what solution can be used to test for lipids?
Sudan III
what solution can be used to test for sugars?
benidicts solution
what solution can be used to test for starch?
iodine solution
