food tests

• what indicator do you use for the sugar food tests

  benedicts reagent
• what colour will the solution go if sugar is present


  brick red
• what colour will the solution go if sugar isnt present


  stays light blue
• describe the test for reducing sugars


  you would add a few drops of benedicts reagent to your solution and heat in a water bath at 75 degrees for five minutes
• what are the colours that a solution positive for sugars will go once mixed with benedict's reagent


  green , yellow , orange then brick red
• describe the test for non-reducing sugars


  add hydrochloric acid to the solution and boil for a few minutes in order to hydrolyse any glycosidic bonds and then add hydrogen carbonate powder and benedict's reagent and then boil
• what is a negative result for a non reducing sugars test


  there will be no colour change
• what is the difference between reducing and non-reducing sugars


  a reducing sugar can lose a oh group
• describe the test for starch


  add 5 cm^3 of iodine solution to a solution and wait for a colour change
• what is the positive result for a starch test


  orange turned blue-black
• describe the test for proteins


  add biuret regant to the solution
• what is the positive test for proteins


  it will turn light purple
• describe the tests for lipids


  mix absolute alcohol(ethanol) with the solution and shake gently
• what is the positive result for a lipid test


  a white cloudy percipitate will form