Food Test Flashcards
What is the name of the test for starch?
The Iodine Test.
What is the name of the test for reducing sugars?
The Benedict’s Test.
What is the name of the test for proteins?
The Biuret Test.
What is the name of the test for fats?
The Emulsion Test.
What reagent is used to test for starch?
Iodine solution.
What color change indicates the presence of starch?
Brown/orange iodine turns blue-black if starch is present.
What reagent is used to test for reducing sugars?(e.g glucose)
Benedict’s solution.
What must be done during the Benedict’s test?
The mixture must be heated in a water bath.
What color change indicates the presence of reducing sugars?
Blue Benedict’s solution turns green, then yellow, then orange, and finally brick red depending on the amount of sugar present.
What reagent is used to test for proteins?
Biuret solution (a mixture of sodium hydroxide and copper sulfate).
What color change indicates the presence of protein?
Blue Biuret solution turns purple/lilac if protein is present.
What reagents are used to test for fats?
Ethanol and water.
What is the procedure for testing fats using the emulsion test?
Mix the food sample with ethanol, shake, then add water.
What positive result indicates the presence of fats/lipids?
A white/milky emulsion forms.
Which test involves heating?
The Benedict’s test for reducing sugars.
Which test produces a milky white emulsion as a positive result?
The emulsion test for fats.
Why are food tests important?
They help identify the presence of different nutrients in food, which is important for understanding nutrition and digestion.
Why is the Benedict’s test boiled?
Heat is required to activate the chemical reaction between reducing sugars and Benedict’s solution. Boiling allows the copper(II) ions in the solution to react with the sugar, forming a colored precipitate.
What does a brick-red precipitate mean in the Benedict’s test?
A high concentration of reducing sugars is present.
What if no color change happens in the Benedict’s test?
No reducing sugars are present.
Why must the food sample be in liquid form before testing?
So the reagent can mix properly and react with all the molecules in the sample.
Why do you need to shake the solution in the Emulsion test?
Shaking helps the ethanol and water to mix well and form a milky white emulsion if lipids are present.
What is the purpose of using ethanol in the Emulsion test?
Lipids dissolve in ethanol, and when water is added, they come out of solution, forming an emulsion.
