food tests practicals

Question 1

how do you prepare food sample?

Answer 1

get the food, crush up the food, add food into beaker with distilled water, stir with glass rod until some dissolves, filter solid bits of food out.

Question 2

glucose(reducing sugars)

Answer 2

benedict’s text
add a few drops of benedict’s solution to the substance
heat the test tube in a water bath
colour change: blue to orange-red

Question 3

protein

Answer 3

biuret test
use biuret solution
some shi about adding copper sulphate solution and sodium hydroxide solution
colour change: pale blue to purple

Question 4

fats (lipids)

Answer 4

ethanol test
add a few drops of ethanol
shake and allow to stand for one min
pour ethanol into test tube of water
colour change: colourless to cloudy

Question 5

starch (non-reducing sugars)

Answer 5

iodine test
add a few drops of iodine solution to substance
colour change: orange to blue-black