How to Test for the Presence of Lipids

Written by andrew copley
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How to Test for the Presence of Lipids
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Lipids are a non-water-soluble organic compound that are found in many foods. If you are concerned about excessive fats in your diet you can check for lipids to reduce your intake. There are two ways you can test to see if lipids are present, and they are the grease spot test and the Sudan red test.

If lipids are in a sample that is placed on a piece of non-coated paper, the paper will look like it is wet or oily. Sudan Red is a dye that turns red when it comes into contact with lipids from a sample.

Skill level:
Moderately Easy

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Things you need

  • Test samples
  • Small, glass test container
  • Cotton swabs
  • Non-coated paper
  • Sudan Red
  • Water

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    Grease Spot Test

  1. 1

    Put the test sample in a small glass dish.

  2. 2

    Moisten a cotton swab with the liquid of the test sample and apply a small amount to a piece of non-coated paper such as plain writing paper or a brown paper bag.

  3. 3

    Allow the sample on the paper to fully dry for several minutes.

  4. 4

    Hold the sample paper up to allow light to shine through. If there is a grease spot on the paper, lipids are present.

    Sudan Red Test

  1. 1

    Add 2ml of your test sample and 2ml of water to your test container.

  2. 2

    Add one to five drops of Sudan Red to the test container.

  3. 3

    Gently shake the test container to mix the ingredients up. If the mixture turns red, lipids are present.

Tips and warnings

  • Make sure work area is clean and free from clutter.
  • Make sure sample on paper is fully dry.
  • Do not use a plastic container with Sudan Red as plastic is porous and can absorb the dye.
  • Avoid dripping Sudan Red on anything other than your test sample as it will stain.
  • Make sure test container is clean and dry before each test.

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