© OUP: To be used solely in purchaser’s school or college Food Tests Food Tests Review.

© OUP: To be used solely in purchaser’s school or college

Food Tests

Food Tests Review

© OUP: To be used solely in purchaser’s school or college

Food

Food Tests

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What do we need food for?

Energy to do things

8A Food – who needs it?

Raw materials to grow larger

Raw materials to repair damaged body parts

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Proteins

8A So what’s in food?

Food is a complicated mixture of different chemicals. We can sort these chemicals into different types. What are the main types?

Fats

Carbohydrates (starch and sugars)

Vitamins

Minerals

Water

Can you make up a sentence with words starting with the same letters – a mnemonic?

Roughage

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8A Which food contains which chemical?

Which foods belong to which food groups?

Proteins

Fats Carbohydrates Water

Proteins

Water Carbohydrates

Fats

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8A What’s in food?

We can test foods to find out what chemicals they contain.

Orangey-brown iodine turns blue-black when it reacts with starch.

drop iodine solution onto the food

black = starch

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8A What’s in food?

Blue Benedict’s solution turns orangey-red when it is boiled with glucose.

blue turns orange/red= glucose

heat

chopped up food

hot water

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8A What’s in food?

In the Biuret test the solution turns purple.

chopped up food

potassium hydroxide

shake

coppersulphate

purple = protein

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8A What’s in food?

Fats go cloudy white when they are mixed with ethanol and water.

Now see if you can use these tests to identify the food chemicals on the next slides.

grind food with ethanol

add waterfilter

cloudy = fat

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8A What’s in food?

For each food, decide on the chemicals found in them.

Fats Protein Starch Glucose

Food sample Test Result

Iodine solution orangey-brown

Benedict’s test blue

Biuret test purple

Ethanol test cloudy white

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8A What’s in food?

For each food, decide on the chemicals found in them.

Fats Protein Starch Glucose

Food sample Test Result

Iodine solution blue-black

Benedict’s test blue

Biuret test blue

Ethanol test clear

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8A What’s in food?

For each food, decide on the chemicals found in them.

Fats Protein Starch Glucose

Food sample Test Result

Iodine solution orangey-brown

Benedict’s test orangey-red

Biuret test blue

Ethanol test clear

© OUP: To be used solely in purchaser’s school or college

8A What’s in food?

For each food, decide on the chemicals found in them.

Fats Protein Starch Glucose

Food sample Test Result

Iodine solution orangey-brown

Benedict’s test orangey-red

Biuret test blue

Ethanol test clear

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8A Vitamins

Vitamin Found in Gives you

A

B2

C

D

Liver, butter, green vegetables

Cheese, milk, liver, eggs, green vegetables

Citrus fruits, green vegetables, potatoes

Fish liver oil, eggs, sunlight on the skin

Healthy skin and teeth

Healthy skin

Healthy teeth and gums, without it you get scurvy

Healthy bones – without it you get rickets (soft bones)