Topic 3- 2-Food & Energy Tests

Question 1

What is the reagent used in the test for Starch and what colour will it go if there is Starch present

Answer 1

Iodine - yellow/brown solution

If starch is present it will turn from its original colour to a blue/black colour

Question 2

What is the reagent used in the test for (reducing) Sugars and what colour will it go if there is Sugar present

Answer 2

Benedict’s - Blue solution

No reducing sugar- same colour (blue)
Trances of sugar- green
Reducing Sugar is present- Orange
A lot of reducing sugar is present Brick red

Question 3

What is the reagent used in the test for Protein and what colour will it go if there is Protein present

Answer 3

Sodium Hydroxide + Copper Sulphate

Protein not present- Same colour (blue)
Protein is present- Lilac/purple

Question 4

What is the reagent used in the test for Fat and what colour will it go if there is Fat present

Answer 4

Ethanol

Fat not present- stay the same (colourless)
Fat is present- cloudy white emulsion in ethanol

Question 5

What is the equation used to calculate the amount of energy in a food sample

Answer 5

q = m x c x t

Energy in joules = mass of water x 4.2oC x change in temp