Food tests

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Food tests

  1. 1. Food Tests<br />
  2. 2. Test for Starch<br />Place a little starch powder in a depression on a spotting tile.<br />Add a few drops of iodine.<br />Positive Result : <br />Blue/Black colour<br />Negative results: <br />Browncolour<br />
  3. 3. Test for Glucose<br />Take 10ml of glucose solution in a test tube.<br />Add 5 drops of Benedict’s solution to the test tube.<br />Lower the test tube into a water bath kept at 70oC.<br />
  4. 4. Test for Glucose<br />Strong Positive Result : <br />Brick Red precipitate<br />Medium Positive Result<br />Yellow orange precipitate<br />Weak Result<br />Green colour<br />Negative results: <br />Blue colour<br />
  5. 5. Test for proteins<br />Dissolve a little milk powder in a test tube.<br />Add a few drops of Biuret reagent<br />Positive Result : <br />Purple Colour<br />Negative results: <br />Blue colour<br />
  6. 6. Test for oil and fat<br />Place about 1cm3 of ethanol in a test tube.<br />Add a few drops of oil and mix by shaking.<br />Add an equal amount of water and shake again.<br />Positive Result : <br />A cloudy emulsion forms<br />Negative results: <br />Liquid remains clear<br />Note<br />Food with solid fats can be tested <br />by crushing them in ethanol.<br />

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