Chapter 1

Question 1

What are microorganisms?

Answer 1

Tiny forms of life, both plants and animals. There are three groups: bacteria, mould and yeasts

Question 2

What is bacteria?

Answer 2

Single celled organisms that can only be viewed in detail under a powerful microscope e.g. salmonella typhi, staphylococcus

Question 3

What are some of the features of a bacteria that make it successful to cause food spoilage and food poisoning?

Answer 3

CAPSULE - protects bacteria from drying out and from chemicals that are meant to destroy them
PILI - enable bacteria to stick to food and the gut wall inside the body
FLAGELLUM - enables them to move through foods (especially fluids) and in the body

Question 4

What are the optimum conditions for bacteria to grow and multiply?

Answer 4

a suitable temperature and pH
a supply of moisture and nutrients (protein, fats, minerals and sugar particularly)
the right level of oxygen (aerobic bacteria require oxygen anaerobic don’t)
sufficient time

Question 5

What is the optimum range of temperatures and pH for bacteria to grow and multiply?

Answer 5

5 - 63 C = danger zone
most bacteria won’t grow at a pH below 4

Question 6

What are high risk and low risk foods?

Answer 6

High risk foods = foods that favour the growth and multiplication of bacteria e.g. meat, fish and eggs
Low risk foods = provide less favourable conditions for microbial growth and multiplication and include foods with a low moisture content and high concentration of salt e.g. jams, biscuits and cereals

Question 7

What are the key temperatures?

Answer 7

100 C = water boils (bacteria spores can survive very high temperatures)
75 C = reheat cooked foods or cook from raw (bacteria cells are dead)
63 C = keep food hot (bacteria starts to die)
5-63 C = danger zone (bacteria multiply rapidly)
0-5 C = chill food (bacteria multiply slowly)
-18–24 C = freeze food (bacteria don’t multiply they are dormant - alive but inactive)

Question 8

How do bacteria multiply?

Answer 8

In optimum conditions they multiply about every 20 minutes and each divides into two new bacterium cells by binary fission
1 bacteria- divides in half - two bacteria cells form - two bacteria cells separate

Question 9

What is a spore?

Answer 9

A protective outer coating to the bacteria cell in which the bacteria remains inactive until the right conditions return, then they germinate (the spore breaks open and the bacteria becomes activated again). As they germinate, the bacteria spores produce deadly toxins (poisons). They can be very resistant to heat and acids and so are difficult to destroy.

Question 10

What are moulds?

Answer 10

Moulds belong to the group known as fungi and they are small plants and when they grow on the surface of foods they are visible without a microscope as large colonies

Question 11

What are the optimum conditions for moulds to grow and multiply?

Answer 11

a suitable temperature (20-30C is optimum but they can grow in cooler temperatures )
a suitable pH
a supply of moisture
a supply of energy and nutrients
the right level of oxygen (some aerobic and some anaerobic)
sufficient time

Question 12

What is the lifecycle of moulds

Answer 12

1. the tiny spores travel through the air and land on the surface of the food
2. in optimum conditions, the spores germinate and the mould plants start to grow
3. a large interconnected web of hyphae called the mycelium develops in the food and sporangia start to grow
4. when they are ‘ripe’ the sporangia burst and release the spores they contain into the air

Question 13

What is the difference between aerobic and anaerobic?

Answer 13

Aerobic require oxygen to grow and multiply but anaerobic do not

Question 14

What is the effect of moulds on foods?

Answer 14

-Make it unfit to eat
-Some are used in production to enhance the flavour and texture e.g. blue cheese
-Some are dangerous to eat as they produce poisonous by-products called mycotoxins which are harmful to humans

Question 15

What are yeasts?

Answer 15

A single celled fungi

Question 16

What are the optimum conditions for yeasts?

Answer 16

a suitable temperature (25-30 C but can grow slowly in cooler conditions)
a suitable pH (4-4.5)
a supply of moisture
a supply of energy and nutrients (particularly carbohydrates)
right level of oxygen (some aerobic and some anaerobic)
sufficient time

Question 17

How do yeasts decompose foods?

Answer 17

Fermentation which breaks down carbohydrates into carbon dioxide gas and alcohol (ethanol)
C6H12O6 ——-> 2C2H5OH + 2CO2

Question 18

What is responsible for food poisoning and spoilage?

Answer 18

Microorganisms that cause food poisoning are pathogenic. Bacteria causes food spoilage and poisoning the most and yeast and moulds can when the conditions for bacteria aren’t optimum

Question 19

What it the lifecycle of yeasts?

Answer 19

-Wild yeast spores are found in the air and will settle on foods (sugars) and ferment them
-Under optimum conditions, yeasts reproduce by sending out a small bud from each yeast cell which enlarge and eventually break away and become separate yeast cells
-If conditions are unfavourable yeasts will form spores that germinate when favourable conditions return

Question 20

What are viruses?

Answer 20

Extremely small and are only visible using a powerful electron microscope
They consist of a nucleic acid molecule inside a coat made of protein

Question 21

How does a virus reproduce?

Answer 21

Inside the living cells of a host e.g. an animal, plant, bacteria etc and when infected the host cell will rapidly produce thousands of copies of the virus which will be passed to other hosts through various bodily fluids e.g. blood, sneezing spray, saliva etc

Question 22

What is food spoilage?

Answer 22

The food is unpalatable, unfit and unsafe to eat

Question 23

What is food spoilage caused by?

Answer 23

-Enzymes(ripening, colour, texture and flavour changes)
-Micro-organisms(bacteria, moulds, yeasts and viruses)
-Pests(insects, animals)
-Physical spoilage(bruising, freezer burn, dampness)
-Oxidation(rancidity)

Question 24

What is an enzyme?

Answer 24

Natural catalysts that speed up chemical reactions and cause foods e.g. fruit and veg to ripen which change their colour, flavour and texture

Question 25

How do enzymes cause food to become unfit to eat?

Answer 25

Ripening occurs before decomposition which is the breakdown of large, complex molecules inside plants and animals into smaller molecules that are then absorbed and used by bacteria and other microbes

Question 26

What is enzymic browning?

Answer 26

When you cut open a food e.g. apple the cut surface becomes brown/black. The food is safe to eat but the colour will make it less appetizing

Question 27

How to delay/prevent enzymic browning?

Answer 27

-Adding an acid e.g. lemon juice which denatures the enzyme protein -Cooking the food so that the heat denatures the enzyme protein -Putting the food in cold water so oxygen doesn't mix with the enzymes -Blanching vegetables before they are frozen to denature the enzyme protein

Question 28

What are pests?

Answer 28

Animals that cause food spoilage and contamination. They include vermin such as insects, flies, rats etc. Insects spoil food by laying eggs which hatch into larvae e.g. maggots from flies. The larvae, vermin and birds eat the food and contaminate it with their waste products

Question 29

What is bruising?

Answer 29

Physical damaging of foods by it being dropped/crushed.

Question 30

What is the structure of a plant cell?

Answer 30

Plant cells contain storage vacuoles in the centre which contain a variety of natural substances and around the outside is cytoplasm which contains enzymes.

Question 31

What is freezer burn?

Answer 31

When food is frozen, the water molecules form ice crystals and the water molecules gradually move out of the food to the coldest place in the freezer which causes the food to become dehydrated e.g. meat/poultry a pale brown/white spotted appearance

Question 32

What do the molecules of water leaving the food get replaced with?

Answer 32

Oxygen (oxidation) which causes unpleasant changes to the flavour and texture of the food

Question 33

Dampness

Answer 33

Foods that are stored in damp conditions (particularly dry foods) will absorb the moisture which will alter the texture of the food. It also encourages the growth of moulds.

Question 33

How to avoid freezer burn?

Answer 33

1. not freezing the food for too long 2. wrapping the food tightly in heavy-gauge plastic bags/ storing it in containers that do not let water molecules through

Question 34

What happens when cells are broken open due to bruising?

Answer 34

The enzymes in the cytoplasm and oxygen from the air mix with the substances in the vacuole which makes the substances join together and change colour (oxidation).

Question 35

How does oxidation occur in foods containing fats?

Answer 35

Fat molecules can be broken down to free fatty acids by microorganisms and enzymes. The free fatty acids will pick up oxygen atoms which causes rancidity and the foods will develop off flavours and odours

Question 36

What is contamination?

Answer 36

A food contains something that is harmful to health if the food is eaten

Question 37

What are the ways foods can become contaminated?

Answer 37

-by the growth of micro-organisms that have been transferred through cross contamination -by the growth of pests which have hatched out of the eggs that were previously laid in the food by an insect e.g. maggots (larvae of flies) -by the addition of a chemical toxin to the food e.g. cleaning chemicals - addition of harmful objects e.g. glass

Question 38

What is food poisoning?

Answer 38

Unpleasant and severe illness that can lead to serious health complications or even death in certain vulnerable groups of people e.g. babies, elderly

Question 39

What is the cause of food poisoning?

Answer 39

-mainly by pathogenic bacteria that have contaminated and multiplied into very large numbers in some food -toxins produced by marine animals that get into the food chain -chemicals and metals e.g. cleaning fluid -mycotoxins from moulds -natural poisons in plants e.g. wild mushroom -natural poisons in animals e.g. puffer fish

Question 40

What are the effects of pathogenic bacteria?

Answer 40

They irritate, poison and interfere with the gut and its microbiota and causes a variety of symptoms e.g. vomiting, nausea, fever, headache and diarrhoea Most people recover after a few days but can take longer or the victim could die

Question 41

How to treat food poisoning?

Answer 41

Allow the natural processes of vomiting and diarrhoea to remove the pathogenic bacteria from the body. The body will continue to excrete these bacteria for several days after the symptoms have gone e.g. extra diligence with washing hands etc

Question 42

Foodborne diseases

Answer 42

Only a few bacteria can cause the illness and the food is a vehicle by which they enter the body rather than where they multiply. The bacteria can also come from other sources e.g. dirty water, sewage etc

Question 43

What are implications of food poisoning for the consumer?

Answer 43

-unpleasant illness -loss of pay due to absence from work -loss of confidence in eating food that is not cooked at home -possible long term health issues

Question 44

What are the implications of food poisoning for business owners?

Answer 44

-possible closure of business by EHO -loss of business and damage to reputation -financial costs due to payment of fines, penalties, costs of improvement etc -loss of food if spoiled -staff turnover will increase

Question 45

What are the implications of food poisoning in a food business?

Answer 45

-employees may be prosecuted if they haven't followed food hygiene regulations -loss of earnings if the business is closed -loss of jobs if the business is closed permanently -possible difficulty finding employment and negative reactions from future employers