Biology B2- Food tests

what are food tests for

to identify what type of food molecules a sample contains

how do you prepare a food sample for any test?

1.) get a piece of food & break it up using a pestle and mortar

2.) transfer the ground up food to a beaker and add some distilled water

3.) stir mixture with glass rod - to dissolve some of the food

4.) filter the solution - to get rid of solid bits of food

What does Benedict's test test for?

Reducing sugars (in foods such as biscuits, cereal, or bread)

explain the steps of the benedict test

1.) prepare a food sample & transfer 1-2cm cubed to a test tube

2.) prepare a water bath so that it's set to 75 degrees

3.) add some benedict solution to test tube (around 10 drops)

4.) place test tube in water bath using test tube holder, leave for 5 mins, ensure test tube is turnt away from you

describe the colour changes when peforming the benedict test

test tube will change from normal blue colour to green, yellow, or brick-red (depending on how much sugar is in the food)

What does the Iodine solution test for?

starch

foods that contain lots of starch

Pasta, bread, potatoes, rice

explain the steps of the iodine solution test

1.) make food sample and transfer 1-2cm cubed of it into test tube

2.) add a few drops of iodine solution, gently shake the tube to mix the contents

describe the colour changes when peforming the iodine solution test

if sample contains starch, colour of solution will change from browny-orange to black or blue-black

What does the Biuret test test for?

Proteins

type of foods that contain protein to test on?

meat, cheese

explain the steps of the biuret test?

1.) Prepare a sample of food and transfer 2cm cubed of sample to test tube

2.) add 2cm cubed of biuret solution and mix by shaking tube

describe the colour changes when peforming the biuret test

if food sample contains protein solution will change from blue to pink or purple