Required practical 4

• Describe the test for sugars (a type of carbohydrate)

  1. Grind up food and add Benedict’s reagent

  2. Boil / heat (above 65 oC) in a water bath

  3. Sugar turns solution (from blue to) green / yellow / orange / brick red
• Describe the test for starch (a type of carbohydrate)

  1. Grind up food and add iodine solution
  2. Starch turns solution (from orange / brown to) blue-black
• Describe the test for lipids (fats)

  1. Grind up food and add ethanol, then add water
  2. Fat turns solution milky / cloudy white
• Describe the test for proteins

  ● Grind up food and add Biuret reagent

  ● Protein turns solution (from blue to) purple / lilac
• RP4 Describe any safety precautions you would take and why you would take them. (2)

  ● Wear goggles to protect eyes

  ● Clean up spills immediately as Biuret is an irritant / corrosive / poisonous
• A student investigated the sugar content of mycoprotein sausages and meat sausages. Describe a method to compare the amount of sugar in the two types of sausage. (6)

  ● Grind up each sausage and add to test tubes with water

  ● Add same mass of each sausage

  ● Add same volume of Benedict’s solution to each test tube

  ● Place test tubes in a heated water bath

  ● For same length of time

  ● Repeat test for each sample

  ● Record colour change - green / yellow / orange / brown / red if sugar present (or blue if no sugar present)

  ● The closer the colour to red, the more sugar presen