Food tests Flashcards
what does the Starch-Iodide Test test for
starch
what are the results when starch is present
the iodine turns from yellowish-orange to blue-black
what are the results when starch is absent
the mixture remains yellowish-orange
what does the Biuret Test test for
protein
what are the results when protein is present
the mixture turns from blue to violet/lilac
what are the results when protein is absent
the mixture remains blue
what does the Benedict’s Test test for
reducing sugar
what does it mean when a brick red precipitate was obtained from a blue mixture
a large amount of reducing sugar is present
what does it mean when an orange precipitate was obtained from a blue mixture
a moderate amount of reducing sugar is present
what does it mean when a yellow precipitate was obtained from a blue mixture
a low amount of reducing sugar is present
what does it mean when a green precipitate was obtained from a blue mixture
a trace amount of reducing sugar is present
what does the Ethanol Emulsion Test test for
lipids/fats
what does it mean when a white emulsion is formed when water was added
fat/lipid is present
what does it mean when the mixture remained clear when water was added
fat/lipid is absent
description of starch-iodide test
add 1 drop of iodine solution on white tile, followed by 1 drop of test solution and mix well. Observe any colour change
description of biuret test
add test solution to test tube, add biuret reagant to test solution. shake to mix and observe for colour change
description of Benedict’s test
add test solution to test tub, add Benedict’s solution to test tube and swirl. leave test tube in a boiling water bath for 3 min and observe for formation of precipitate (colour change)
description of ethanol emulsion test
add ethanol to test solution in a test tube. mix well and allow to stand for 2 min. decant the ethanol into another test tube containing water. mix well. observe for white suspension.
