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Chemical indicators

Chemical indicators. How to detect macromolecules in food. What is a chemical indicator?. A substance that changes to indicate that a specific compound is in what you’re testing. The change can be color, temperature, odor, or production of bubbles. They are VERY specific!

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Chemical indicators

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  1. Chemical indicators How to detect macromolecules in food

  2. What is a chemical indicator? • A substance that changes to indicate that a specific compound is in what you’re testing. • The change can be color, temperature, odor, or production of bubbles. • They are VERY specific! • Easiest to use is color usually.

  3. Indicators we will use • Benedict’s Solution • Lugol’s Iodine • Biuret Solution • Sudan IV

  4. Benedict’s Solution • Used to test for monosaccharides • Normally light blue color • Mix it with your food, then heat it up • Change of color to green, yellow, orange, or red indicates monosaccharide is present greenorange red brown

  5. Lugol’s Iodine • Used to test for polysaccharide starch • Normally yellow to light brown in color • Mix with your food • Change of color to dark purple or black indicates starch is present

  6. Biuret Solution • Used to test for proteins • Normally light blue in color • Mix with food • Change of color to purple (light to dark range) indicates presence of a protein

  7. Sudan IV • Used to test for lipids, specifically fats • Normally red in color • Mix with equal parts food and water • A red-stained oil layer will separate out and float on the water surface if fat is present

  8. Procedure • First you need to perform the tests on control so that you know what a positive test looks like • Then test on unknown foods • Some foods will have more than one type of macromolecule

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