3.1.1 micro-organisms and enzymes 1 activity: crossword … 5... · 3.1.1 micro-organisms and...

© Illuminate Publishing Ltd AQA GCSE Food Preparation and Nutrition by Tull, Littlewood, Maitland, Worger

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3.1.1 Micro-organisms and enzymes

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1 Activity: Crossword 5a


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Clues across1 Wearing one of these when you cook prevents cross-

contamination from your clothes to the food you are preparing.

2 This type of poultry is often the cause of food poisoning.

6 This is one of the symptoms of food poisoning.

11 This is a type of food poisoning bacteria of which there are many types.

12 These foods can be a cause of food poisoning, especially when they are raw.

13 This type of food poisoning bacteria is especially dangerous for pregnant women.

15 Bacteria need enough of this to be able to grow and multiply.

17 These types of micro-organism are the most common cause of food poisoning.

20 This is one of the symptoms of food poisoning – it means a high body temperature.

21 These types of micro-organism also cause food poisoning and illness.

22 It is dangerous for babies and young children to get food poisoning because this part of their body is immature (2 words).

27 Food poisoning illnesses should be reported to this department.

29 This is what bacteria spores do when the conditions are right.

33 To prevent cross-contamination, this coloured chopping board should be used for fresh meat.

34 This type of food poisoning bacteria is found in raw poultry, meat, milk and dirty water.

38 Bacteria and other microbes also need enough of this to be able to grow and multiply.

39 The number of times that left-over food can be safely re-heated.

40 This is produced by some bacteria when conditions are not right for them to grow and multiply.

Clues down1 This is one of the symptoms of food poisoning

(2 words).

7 This food is often a cause of food poisoning (2 words).

2 These have a special bacteria culture added at the beginning of their production.

3 This is one of the symptoms of food poisoning – it means feeling sick.

4 Bacteria and other microbes need enough of this to be able to grow and multiply.

5 These bacteria causes food poisoning and is found in cooked rice (2 words).

8 These bacteria cause food poisoning and are found in cooked foods, water, milk, cheese, seafoods, salads, meat dishes and products.

9 These bacteria cause food poisoning and are found in human noses, mouths, skin, cuts and skin infections.

10 To prevent cross-contamination, this coloured chopping board should be used for fresh fi sh.

14 This cooked cereal can be a source of food poisoning.

16 This is what you should do to your hands before, during and after handling foods.

18 This is the name given to an animal or insect that contaminates food by urinating and defecating on it; or by landing on it, walking over it and eating it.

19 Listeria bacteria are dangerous for these women.

21 This is one of the symptoms of food poisoning.

23 This is used to preserve some foods.

24 Food poisoning can make you feel like this.

25 Bacteria need this to be just right to be able to grow and multiply rapidly.

26 You must do this thoroughly to frozen chicken before you cook it.

28 Raw meat, poultry, cream, fi sh, milk, eggs and shellfi sh are all this type of food, because bacteria easily grow in them (2 words).

30 This is another name for bacteria, moulds, yeasts and viruses.

32 & 31 These 2 words together mean the range of temperatures that are just right for bacteria to multiply.

35 These live in people’s homes, but should not be allowed to sit on the kitchen worktops or eat from the same dishes as their owners.

36 Another name for a poison that causes food poisoning.

37 Allow cooked food to do this before you put it in the refrigerator.

2 Activity: Crossword 5a


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ActivityEnzymic browning is the discolouration of certain fruits or vegetables due to a reaction of the enzymes they contain with plant cell substances and oxygen from the air.

The purpose of this activity is to observe and record the amount of enzymic browning that occurs in apple slices that are dipped into different solutions (liquids) over a period of time.

You will needfresh apple slices of approximately the same size (5 per group)lemon juicesugar syrup (made by heating sugar in water)vinegarwaterpaper towels

What to do1 Place an untreated apple slice on a paper towel. Label the paper towel ‘Control’.

2 Dip another apple slice into one of the test solutions for 30 seconds, then place it on the towel. Label the paper towel with the name of the solution.

3 Repeat the same procedure for the other three solutions.

4 Observe the apple slices every 10 minutes for one hour and record your observations.

5 Compare your results with those obtained by the rest of the class.

Time (minutes) Control Lemon juice Sugar syrup Vinegar Water

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Key1 No browning

2 Very little brown colouring or patches of colour

3 Half-covered light brown colour

4 Fully covered light brown

5 Completely dark brown

Follow upExplain the scientifi c principles of the results you have obtained.

Activity: Investigation into the enzymic browning of apples 5b


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3.1.2 The signs of food spoilage

You’ve been asked to take over from a friend who is not available to prepare the food for a big party. When you look in the refrigerator to check the food that is going to be used, you fi nd the following items. Explain in detail, with reasons, what has happened to the food and then decide if it is safe to use or serve.

Some soft and very red tomatoes.

A bunch of bananas that have just about turned black.

Bread that has a few blue/green, hairy spots on its base.

The chopped ingredients for a fruit salad, in which much of the fruit has turned brown.

A cheese with mould growing on one surface.

A punnet of raspberries that seem to have a faint brown dust on them.

Activity: Signs of food spoilage – should I eat it? 5c


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4 Examples of foods that discolour include apples,

mushrooms, bananas and .

6 Foods containing sugar, such as fresh and dried fruits,

can be spoiled by wild .

7 are a type of micro-organism that,

when they grow on the surface of food, have a furry

appearance.

8 One way to prevent fruit from discolouring is to add an

acid, for example, juice.

Down

1 Fruits discolour when they are ripened. This is caused by

.

2 The process by which a fruit or vegetable matures so

that it is ready to eat is known as .

3 When yeasts settle on foods, they start to grow and

the sugar to produce carbon

dioxide.

5 Moulds multiply by sending out .

Activity: Signs of food spoilage crossword 5d


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There are a number of ways in which food can spoil. Explain fully each of these terms and describe what you would (or wouldn’t) see.

Term Explanation What you would see

Enzymic ripening

Enzymic browning

Mould

Mycelium

Spores

Yeast spoilage

Activity: Signs of food spoilage 5e


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3.1.3 Micro-organisms in food production

Research taskUsing the internet or textbooks, carry out research to fi nd out how yeasts, moulds and bacteria are used in the production of one food. Prepare a slide (PowerPoint) or storyboard presentation and produce a handout to present to the class.

Activity: Research task 5f


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Below are several sets of information and pictures outlining the importance of micro-organisms in food production.

• For each type of food production, read the paragraphs carefully, look at the pictures and decide what are the most important points, words or phrases from each section.

• Then, in your own words, construct a paragraph about each micro-organism, explaining how it works in food production.

Bacteria in food productionBacteria are used in making a wide range of food products. The most important bacteria in food manufacturing are Lactobacillus species, also called lactic bacteria.

In cheese production in the dairy industry• It is necessary to use a starter culture of non-pathogenic

(non-harmful) bacteria to make cheese.

• The starter culture of bacteria converts the sugar (lactose) in the milk into lactic acid.

• The lactic acid allows the cheese to develop the correct level of acidity/pH.

• It is also important for the moistness of the cheese.

• During the ripening process, the culture helps to create the smell, taste and texture of the cheese.

• The bacteria culture can also be responsible for the characteristics of specifi c cheeses, for example, the holes in cheeses such as Emmental. It is very important to get the right mixture of starter for the characteristics of individual cheeses.

In yogurt production• The starter culture for fermented milk products such

as yogurt gives the food its characteristic fl avour and sensory qualities.

• Controlling the level of acidity will provide variations in the strength of fl avours, for example, a mild or strong taste.

• The thickness and viscosity (the rate at which the yogurt fl ows when poured) can also depend on the use of starches, gums and other complex carbohydrates.

• Probiotic cultures (another name for bacteria cultures) in drinks such as yogurt drinks have increased in popularity.

• These cultures can also be added to breakfast cereals.

• There is some evidence that they can improve digestion.

Yogurt making

coagulate

Streptococcus thermophilus

Lactobacillus bulgaricus

Milk

Lactose Lactic acid

1 Activity: Case studies 5g


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In the meat industry• Bacteria cultures are used to make dried, fermented

meats such as salamis, pepperoni, and dried ham to give them characteristic fl avours and textures. The fl avour and colour of each product is produced by lactic bacteria.

• Special non-pathogenic moulds are sometimes seen on the surface of sausages. These act as a preservative, helping to ripen the product and improve the quality.

Yeasts in food productionYeasts can be used in two ways for food production – in fermenting alcohol and raising bread.

Baking bread• Yeast is the raising agent in bread.

• Sugars from fl our and additional added sugars feed the yeast, producing carbon dioxide and alcohol.

• Bubbles of carbon dioxide within the dough expand the gluten and bread structure.

• Fermentation of the yeast within the bread dough can be affected by additional ingredients, for example, fat, fruit and eggs can slow down the process.

Moulds in cheese• Stilton and other blue cheeses, and soft ripened cheeses,

gain their characteristic fl avours and textures from the use of non-pathogenic moulds in their production.

• Spores of mould are added to the milk with the bacteria culture.

• As the cheese matures, the mould grows.

• Blue veins are created as the cheese matures and the mould weaves its way through the cheese.

• Mould grows on the outside of soft cheeses such as Brie and Camembert, allowing them to age from the outside in.

• A soft, white crust covers the cheese and the inside is runny with quite a pungent (strong, characteristic) smell and strong taste.

2 Activity: Case studies 5g


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Across

2 In blue cheeses such as Stilton and Gorgonzola,

are used to give the blue colour.

4 Mould spores are either sprayed on or the cheese is

dipped into them when making .

9 In making Cheddar cheese are

used.

10 Cheese is left to ripen and develop its fl avour. This is also

known as .

11 The whey is used to make cheese.

12 When the milk mixture has set, the solid part, known as

the , is cut up fi nely with special

knives.

Down

1 Milk that is forced under high pressure through a

fi ne sieve, in order to break up the fat, is known as

milk.

3 Micro-organisms that are harmful to humans are known

as .

5 An enzyme called is used to

coagulate the protein when making cheese.

6 The micro-organism used to make bread is

.

7 In making yogurt, the bacteria ferment the lactose sugar

in the milk and produce acid.

8 Yogurt is made from milk that has been

.

Activity: Micro-organisms in food production crossword 5h


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3.1.4 Bacterial contamination

Read the following account and identify ten instances when food safety was threatened by poor attention to personal hygiene or correct food safety procedures.

Kelly ran the last few hundred metres. Late again. Once she’d hung up her coat and made her way into the kitchen she noticed that Mrs Price, her boss, wasn’t there. Phew. It looked like Kelly had got away with it this time.

Grabbing her dirty chef’s whites from her locker, Kelly took off her shoes and put them on the worktop. She was pleased to get her kitchen clogs on; her street shoes pinched a bit. Swiftly clearing everything back into her locker she arrived at her station just 10 minutes late.

She picked up one of a hundred onions and began to chop. She was still hot from her run and ran her fi ngers through her hair. She didn’t like looking sweaty.

The onions chopped, Kelly now began work on the chicken livers and looked over to smile at Grace. Grace was such a good friend and had remarked on how cool Kelly’s new bracelet was. Kelly thought it looked pretty good too and she jangled it whilst she worked.

‘Can you give me a hand with these tomatoes whilst I go to the loo?’ asked Grace. Kelly put down her knife and walked round to help her friend, who had a mountain of preparation still to do.

When Grace returned, wiping her hands on her tunic, Kelly had made a good impression on the pile of tomatoes. She was a quick worker. She returned to the chicken livers and continued to work on them. They were a bit slippery so Kelly embedded her long fi ngernails in them to get a better grip. It made the job such a lot easier.

Activity: Hygiene in the kitchen 5i


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Which bacteria are associated with which foods and liquids?

Draw lines from each type of bacteria to the foods it is found in.

Salad vegetables Minced beef Raw meats and poultry

Eggs Dairy products

Chicken Cold cooked meats

Soft cheeses Pâté

Raw milk Cheese made from unpasteurised milk

Dirty water

E. coli

Listeria

Campylobacter

Salmonella

Staphylococcus aureus

Activity: Potential bacteria in foods and liquids 5j


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A dirty and untidy kitchen can create a huge number of hazards to our health. In the picture below, fi nd and fully explain 10 potential hazards, and then explain what you would do to remove their threat.

Activity: Keeping a clean kitchen 5k

There are several steps in the recipe below. Identify the food safety measures you would need to follow in each one, to ensure that you minimise any risk. The fi rst has been done for you.

Step Action you need to take

1 Chop and peel the onions. Cut into dice.

Wash your hands.

Use a brown chopping board – make sure it’s clean before you begin.

Use a vegetable or chef’s knife – make sure it’s clean before you begin.

Check the onions are fresh and unblemished.

Dispose of waste immediately afterwards.

2 Peel and dice the carrots.

3 Trim the beef of any excess fat.

4 Cut the beef into 2cm cubes.

5 Heat a tablespoon of oil in a frying pan; place the meat in the pan and sear it.

6 Transfer the meat to a dish.

7 Now fry off the onions and carrots in the same pan.

No specifi c action required.

8 Peel and mince a clove of garlic and add to the vegetables in the pan.

9 Add the meat, vegetables and garlic to a casserole dish and pour in the stock. Stir well. Bring to a simmer.

10 Place the lid on the casserole and place in an oven at 180°C for 30 minutes. Then turn it down to 140°C for 2 hours.

11 Prepare a green salad.


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3.1.4 Bacterial contaminationActivity: Principles of food safety 5l

3.1.1 micro-organisms and enzymes 1 activity: crossword … 5... · 3.1.1 micro-organisms and...

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