Enzymes + food tests

• Enzymes are biological catalysts that speed up chemical reactions in the body
• Enzymes break down the food so it can be absorbed through the small intestine
• Large proteins are made up of long chains of aminos acid chains that can fold into unique shapes
• Induced fit models are more accurate than the lock and key model
• Enzymes and substrates are complimentary to each other

  they are very specific so that the catalyst doesn't speed up the wrong reaction
• Factors that affect enzyme reactions are

  •temperature ( over 40 degrees Celsius they become denatured )

  •pH levels
• Preparing a food sample

  •break up food with mortar and pestle

  •put into beaker with distilled water

  •stir with glass rod until some dissolve

  •filter out the solids and use the left over solution as the sample
• Carbohydrates ( starch ) are broken down by amylase into maltose
• Amylase are produced in the salivary glands , pancreas and small intestine
• Proteins are broken down by protease into amino acids
• Protease are produced in the stomach , pancreas and small intestine
• Lipids ( fats ) are broken down by lipases into glycerol and fatty acids
• Lipases are produced in the pancreas and small intestine
• The Benedict's test , tests for reducing sugars only
• Benedict Test requires a water bath a 75 degrees celsius
• 10 drops of Benedict solution
• from least amount of sugar to most amount of sugar conc. the sample will turn

  blue

  green

  yellow

  red
• the iodine test is the test for starch
• If starch is present , the food sample will turn from a brown / orange to a blue-black.
• The biuret test is for proteins
• when biuret solution is added, food sample will turn a light purple if proteins are present
• Three drops of sudan solution is needed for the sudan test
• The sudan III test is for lipids
• If lipids are present a layer of red will appear on top of the solution

  this is because lipids are insoluble oils
• For the sudan III test the food sample must not be filtered