Food Tests Flashcards
What is the purpose of food tests in biology?
To identify the presence of specific nutrients in food.
What reagent is used to test for reducing sugars?
Benedict’s solution.
True or False: The presence of starch can be tested using iodine solution.
True.
What color change indicates a positive test for starch with iodine?
Blue-black.
Fill in the blank: The test for proteins is known as the ______ test.
Biuret.
What is the initial color of Biuret reagent?
Blue.
What color indicates a positive protein test using Biuret reagent?
Purple.
Which nutrient is tested using ethanol and then water?
Lipids.
True or False: A cloudy emulsion indicates the presence of lipids.
True.
What is the first step in the Benedict’s test for reducing sugars?
Add Benedict’s solution to the sample and heat it.
What color change indicates a positive result in the Benedict’s test?
Green, yellow, orange, or brick-red, depending on the amount of reducing sugar.
Fill in the blank: To perform the starch test, you add ______ solution to the sample.
iodine.
What is the function of the control in food tests?
To ensure that the test is working correctly.
What type of macromolecule are enzymes classified as?
Proteins.
Which test would you use to confirm the presence of glucose specifically?
Benedict’s test.
True or False: Non-reducing sugars can be detected directly using the Benedict’s test.
False.
What is the procedure for testing non-reducing sugars?
Boil the sample with hydrochloric acid, neutralize with sodium hydrocarbonate, then perform the Benedict’s test.
What is the role of sodium bicarbonate in the non-reducing sugar test?
To neutralize the acid after hydrolysis.
Fill in the blank: Lipids are tested using the ______ test.
emulsion.
What is the appearance of a lipid emulsion?
A cloudy white suspension.
List one method to test for the presence of proteins.
Biuret test.
What color does the iodine turn if starch is absent?
Brown or yellow.
Which nutrient test requires heating the sample?
Benedict’s test for reducing sugars.
What type of sugars can Benedict’s test detect?
Reducing sugars.
What is the primary indicator for proteins in the Biuret test?
The presence of peptide bonds.
True or False: The emulsion test can be used to identify carbohydrates.
False.
What is the key reagent in the lipid test?
Ethanol.
In the starch test, what is the color of the iodine solution before adding it to the sample?
Brown.
What do you observe when testing for reducing sugars if the test result is negative?
No color change; the solution remains blue.
What is the expected result of a positive lipid test?
A cloudy emulsion forms.
What is a non-reducing sugar example?
Sucrose
What does it mean when lipids are non-polar?
Do not dissolve in water, but dissolve in organic solvents such as ethanol.
