6.3 Food Tests

Question 1

glucose

Answer 1

glucose test strip
procedures:
1. dip the test strip into the sample
results:
v: distinctive colour change
x: no colour change

Question 2

protein

Answer 2

protein test strip
procedures:
1. dip the test strip into the sample
results:
v: distinctive colour change
x: no colour change

Question 3

vitamin c

Answer 3

dcpip solution
procedures:
1. add the sample drop by drop into the blue dcpip solution
results:
v: distinctive colour change (colourless)
x: no colour change (blue)

*comparison?
- compare the number of drops used
- the more drops used, the less amount of vitamin c present

Question 4

lipids

Answer 4

grease spot test
procedures:
1. rub/ add the sample drop by drop onto the filter paper
2. treat with organic solvent (ethanol) and observe against light
results:
v: oil forms a translucent spot on filter paper –> spot remains after drying –> after treatment with organic solvent, translucent spot disappears

Question 5

reducing sugars (monosaccharides, disaccharides x sucrose)

Answer 5

benedict’s test
procedures:
1. add benedict’s solution into equal volume of the sample
2. heat in water bath for five minutes
results:
v: brick-red precipitate
x: blue

Question 6

starch

Answer 6

iodine test
procedures:
1. add iodine solution drop by drop into sample
results:
v: blue-black
x: brown