Food tests Flashcards
(14 cards)
What is the iodine test used for?
Testing for starch
The iodine solution changes color in the presence of starch.
What color indicates a positive result for starch in the iodine test?
Blue-black
A blue-black color signifies the presence of starch.
What color indicates a negative result for starch in the iodine test?
Brown/orange
A brown/orange color indicates the absence of starch.
What is the Benedict’s test used for?
Testing for glucose
The test detects reducing sugars like glucose.
What is the required condition for a positive Benedict’s test?
Benedict’s + heat
Heating the mixture is essential for the reaction.
What color change occurs in the Benedict’s test from green to brick-red?
Indicates increasing glucose concentration
A transition from green to brick-red shows higher levels of glucose.
What color indicates a negative result in the Benedict’s test?
Blue
A blue color indicates no reducing sugars are present.
What is the Biuret test used for?
Testing for protein
The Biuret test identifies the presence of peptide bonds in proteins.
What color indicates a positive result for protein in the Biuret test?
Purple/lilac
A purple or lilac color signifies the presence of proteins.
What color indicates a negative result in the Biuret test?
Blue
A blue color indicates no protein is present.
What is the emulsion test used for?
Testing for lipids
The emulsion test detects the presence of fats and oils.
What is the key reagent used in the emulsion test?
Ethanol + water
Mixing ethanol and water helps form an emulsion with lipids.
What color indicates a positive result for lipids in the emulsion test?
Milky/cloudy white
A milky or cloudy appearance indicates the presence of lipids.
What color indicates a negative result in the emulsion test?
Clear
A clear solution indicates no lipids are present.
