The Chemistry of Food

• What are all carbohydrates made of?

  units of sugar
• How many units of sugar does glucose have?

  one
• How many units of sugar does sucrose have?

  two
• What are Glucose & Sucrose?

  Simple sugars
• What are starch & cellulose made of?

  long chains of simple sugar units that are bonded together - complex carbohydrates
• What are lipid molecules made of?

  three molecules of fatty acids linked to a molecule of glycerol
• What are proteins made of?

  long chains of amino acids
• What are proteins made of?

  Long chains of amino acids
• How do proteins achieve their specific shape?

  They are folded from long chains of amino acids
• What happens to a protein when it is heated?

  The shape is changed and the protein is denatured
• What is a specific function of some proteins?

  They serve as structural components of tissues
• What are some examples of protein functions?

  Hormones, antibodies, or enzymes
• What is the iodine test used for?

  To test for the presence of starch
• What color change indicates the presence of starch in the iodine test?

  Yellow-red iodine solution turns blue-black
• What does the Benedict's test detect?

  The presence of sugars
• What color change occurs in the Benedict's test when sugar is present?

  Blue Benedict's solution turns brick red on heating
• What does the Biuret test identify?

  The presence of proteins
• What color change indicates the presence of protein in the Biuret test?

  Blue Biuret reagent turns purple
• What does the ethanol test detect?

  The presence of lipids
• What result indicates the presence of lipids in the ethanol test?

  A cloudy white layer forms
• What safety precaution should be taken when using ethanol?

  Wear eye protection
• Why is ethanol considered hazardous?

  It is highly flammable and harmful
• What are the main food tests and their indicators?

  • Carbohydrates: Iodine test: yellow-red to blue-black for starch or Benedict's test: blue to brick red for sugars
  • Protein: Biuret test: blue to purple for proteins
  • Lipids: Ethanol test: cloudy white layer for lipids
• What would you expect if you tested egg white with iodine solution?

  No color change, as egg white does not contain starch
• What would you expect if you tested egg white with Benedict's solution?

  No color change, as egg white does not contain sugars
• What would you expect if you tested egg white with Biuret solution?

  It turns purple, indicating the presence of protein