food tests

Question 1

what do you do first to the food sample?

Answer 1

take the food sample and grind this with distilled water using a mortar and pestle.- make a paste

Question 2

what do you do once you make a paste?

Answer 2

transfer the paste into a beaker and add more distilled water. stir so the chemicals in the food dissolved in water

Question 3

once the chemicals dissolve in water what do you do?

Answer 3

filter solution to remove suspended food particles

Question 4

what is the Benedict test for?

Answer 4

sugars (reducing sugars)

Question 5

what are sugars?

Answer 5

small units that all carbohydrates are made od

Question 6

what is the first step for the benedicts test?

Answer 6

.Set up your traditional water bath set up using a Bunsen burner.

Question 7

what is the second step for the benedicts test?

Answer 7

put 5cm^3 of food sample into test tube

Question 8

once you put food sample in test tube for benedicts test what do you do?

Answer 8

Add a few drops of Benedict’s solution to the sample in the test tube.

Question 9

what is the final step?

Answer 9

Put the test tube in the water bath at a minimum of 80 °C/65 degrees for about 5 minutes.

Question 10

what do you use to put test tube in water bath?

Answer 10

place test tube holder in the water bath

Question 11

what colour does solution change to if sugar present?

Answer 11

changes to green, yellow or brick red depending on how much sugar present.
If no sugar present , solution remains blue

Question 12

what does iodine test for?

Answer 12

starch

Question 13

first step for the iodine test for starch

Answer 13

put 5cm ^3 of food sample into a test tube

Question 14

second step for the iodine test for starch

Answer 14

Add a few drops of Iodine solution. shake slightly

Question 15

what is the colour change of the solution if starch is present?

Answer 15

solution goes from brown colour to blue-black colour

Question 16

what does biuret test for?

Answer 16

proteins

Question 17

what is the first step for test for protein

Answer 17

add 2cm^3 of food sample into test tube. Then add 2cm^3 biuret soltuion

Question 18

what colour does biuret solution turn sample and if protein is present whats the colour change?

Answer 18

goes from blue to pink/ turns purple / lilac

Question 19

what does test for lipids use?

Answer 19

ethanol

Question 20

what are the steps for test for lipids?

Answer 20

1. Put some of the food sample into a test tube.
2. Add a few drops of distilled water.(2cm^3)
3. Add a few drops of ethanol. (2cm^3)
   Shake the solution gently.

Question 21

why can ethanol be dangerous and what should you do?

Answer 21

Ethanol is highly flammable. Keep the solution away from any flames

Question 22

how do you know if lipids is present?

Answer 22

solution turns cloudy