Food groups and Food tests

LO: to sort food into food groups and carry out food tests

TASK: 1. Why do we need to eat food and plants don’t?2. Which food groups are in these pictures?3. What is an balanced diet? (not kfc everyday!)4. What happens to a human body if we don’t have

balanced diet?

What happens if you lack vitamins and minerals?

• Vitamins =A, B, C, D etc Fruit, Vegetables and cereal

• Minerals = Iron, Sodium, Calcium etc Meat, Milk, cereal

• If we don’t have enough of something we call it a deficiency

• Scurvy- lack of vitamin C found in oranges, lemons, fruit and vegetables.

• Rickets- lack of calcium and vitamin B

A Balanced diet• Balanced diet contains suitable proportions of each group of

nutrients – carbohydrates, fats, proteins, minerals, vitamins, water and fibre – and the correct amount of energy.

• A balanced diet may differ depending on a persons age sex and level of physical activity

Video: fast food vomit

starvation, coronary heart disease, constipation and obesity

1. Benedicts test for reducing sugars1. Add 2ml of unknown/control solution 2. Add 2ml of Benedict’s solution

(WEAR GOGGLES!!)3. Mix gently. Make sure tube is labeled on

the top – as the label will soak in water!4. Place test tube in a beaker and heat with

Bunsen burner for 10 minutes5.Record the color development after 10

minutes

3. Potassium Iodide test for Starch1.Add 1 ml of unknown/control in a spotting tile2. Add 1 drop (2mL) of Iodine solutionIf solution turns blue black, starch is present

Increasing concentration of reducing sugar

2. Emulsion test for lipids/fats1. Place the food sample into 2cm3 of ethanol.2. Pour the sample and ethanol into another test tube containing 10 cm3 of waterWhite emulsion/cloudy= presence of fats

4. Biuret test for Protein1. Add 2 mL of unknown/control solution to a test tube2. Add 4 drops of Biuret’s Reagent 1(NaOH) then 2 drops Biuret reagent 2(CuSO4) (WEAR GLOVES AND GOGGLES!!)3. Mix gently4. Record color development against a white background

Blue (-) Purple (+ test for protein)

FOOD TESTSDraw a neat results table in your book and remember All food samples must be grind up first

Foodsample

Colour after adding Reagent

Iodine test for Starch

Benedict test for Sugar

Biuret Test for Protein

Emulsion test for Fats

Apple

Bread

Potato chips

Milk

Steamed rice

Questions- answer in full sentences

1. Describe how you tested for starch2. Describe how you tested for sugar3. Describe how you tested for protein4. Explain how you tested for fats5. Which food contained sugar and which food

had the highest concentration of sugar?6. Which food contained protein and fat

Which chemical tested for which?

Iodine

Biuret solution

Benidict’s solution

Ethanol

Protein

Starch

Fat

Sugar

Copy and complete

• Starch will turn __________ from an _______________ colour to a _______________ colour

• _______________ will tune Biuret’s solution from a ___________________colour to a _________________ colour

• When heated with_____________ _______________ solution will turn ________________

• Fat will turn a water and ______________ mixture____________milky