RP4 Food tests

Question 1

describe how you would prepare a sample of food to be tested

Answer 1

grind up food samples using pestle and mortar
mix with water
filter with funnel and filter paper

Question 2

describe how you would test for the presence of starch in a sample

Answer 2

add iodine solution to sample
if starch is present, solution turns from brown to blue-black

Question 3

describe how you would test for the presence of a reducing sugar in a sample

Answer 3

add Benedict’s reagent to sample
boil test tube in a hot water bath
if reducing sugar is present, a brick red precipitate forms. if not, the solution remains blue

Question 4

describe how you would test for the presence of lipids in a sample

Answer 4

add ethanol to the sample
add water to sample
shake test tube
white emulsion formed if lipid present

Question 4

describe how you would test for the presence of protein in a sample

Answer 4

add Biuret reagent (potassium hydroxide and copper (II) sulphate)
shake mixture
if protein is present, solution turns from blue to purple