Biology Food Tests

Emma Barrett
Flashcards by , created over 4 years ago

GCSE Useful Flashcards on Biology Food Tests, created by Emma Barrett on 03/17/2015.

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Emma Barrett
Created by Emma Barrett over 4 years ago
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Question Answer
Testing for fats Add the food sample to 2 cm3 of ethanol, shake well. Allow to settle in a test tube rack for 2 minutes for food to dissolve in ethanol. Empty any clear liquid into a test tube containing 2 cm3 of distilled H2O. A MILKY-WHITE EMULSION is a positive result: lipid is present. If the mixture remains clear, there are no fats present in the sample
Starch Test add Iodine solution to a solution or directly onto materials such as bread, potato, crackers... a BLUE-BLACK COLOR is a positive result: starch is present
Biurets Test (Protein) add an equal amount of NaOH to a solution of the food, mix carefully. add a few drops of 1% CuSO4, do not shake the mixture. a PURPLE/MAUVE COLOR is a positive result: protein is present.
Benedict's Test (reducing sugars) add a few drops of Benedict's solution heat the mixture for 2-3 minutes in boiling water bath a BRICK RED/ORANGE COLOR is a positive result: glucose is present The closer the color is to brick red, the more reducing sugar is present.
Benedict's test add a few drops of Benedict's solution heat the mixture for 2-3 minutes in boiling water bath a BRICK RED/ORANGE COLOUR is a positive result: glucose is present The closer the colour is to brick red, the more reducing sugar is present.
Starch Test add Iodine solution to a solution or directly onto materials such as bread, potato, crackers... a BLUE-BLACK COLOR is a positive result: starch is present
Emulsion (ethanol) test for Fats Add the food sample to 2 cm3 of ethanol, shake well. Allow to settle in a test tube rack for 2 minutes for food to dissolve in ethanol. Empty any clear liquid into a test tube containing 2 cm3 of distilled H2O. A MILKY-WHITE EMULSION is a positive result: lipid is present. If the mixture remains clear, there are no fats present in the sample
Biuret test for Proteins add an equal amount of NaOH to a solution of the food, mix carefully. add a few drops of 1% CuSO4, do not shake the mixture. a PURPLE/MAUVE COLOUR is a positive result: protein is present.