Uss module 5 chpt 8 Food Health and Safety

Module 5:
Food Matters
Chapter 8 Food Health and Safety
1© Copyright Star Publishing Pte Ltd

8.1 Why is a balanced diet important?
8.2 What is the purpose of the nutrition label
and
how is it interpreted?
8.3 What are the consequences of a diet high
in fat, salt and sugar content?
8.4 How are simple food tests performed?
8.5 What are microbes and their effects on
food?
8.6 What are the ways to prevent food
spoilage?
8.7 What are food additives and their 2© Copyright Star Publishing Pte Ltd

Objectives
 Understand the concept of a balanced
diet as a diet supplying sufficient
quantities of carbohydrates, fats,
vitamins, mineral salts, fibre and water to
sustain a healthy life
 List the principal sources of
carbohydrates, fats, vitamin C, vitamin D,
mineral salts (calcium and iron), fibre
and water
 State the dietary importance of
carbohydrates, fats, vitamin C, vitamin D,
mineral salts (calcium and iron), fibre

What is a balanced diet?
 A balanced diet
refers to one with
the correct types
and amounts of
foods and drinks
which will provide
sufficient
nutrients and
energy to keep a
person’s body fit
and healthy.
© Copyright Star Publishing Pte Ltd 4
a balanced diet includes food
from all the food groups in the
right amounts.

What is a balanced diet?
 Eating a balanced diet is not enough. We need to
(a) eat foods in moderation. This means that
we do not over eat any type of food, and
(b) eat at regular intervals. This means that we
eat during proper meal times.

Functions of Nutrients
 Nutrients are chemical substances found in food.
 These nutrients are needed by our body and serve
many functions.
 Nutrients, water and dietary fibre are essential parts
of a balanced diet.
essential parts of a healthy diet

Carbohydrates
 Carbohydrates provide a source of energy for the
body. Examples of food which are high in carbohydrates
include rice, wheat, bread and potatoes.
foods that contain
carbohydrates

Proteins
 Proteins are needed for tissue growth and
repair.
 Examples of food which are rich in protein
include meat (lean), eggs, milk and fish.
foods that contain
proteins

Fats
 Fats provide a source of energy and act as a solvent
to absorb fat soluble vitamins in the body.
 Examples of food which are high in fat content include
cooking oil, peanuts, meat (fat) and butter.
foods that contain
fats

Vitamins
 Vitamins are needed in small amount to promote
good health in our body. Examples includes:
(a) Vitamin C:
Vitamin C strengthens the gums and prevents
them from bleeding, and boosts resistance to
infections.
Examples of food that provide a lot of Vitamin C
include citrus fruits such as oranges, lemons
and grapes.

Vitamin D
 Vitamin D helps to support the absorption of
calcium which strengthens the bones.
 Examples of food that are rich in Vitamin D
include cod liver oil, fish and eggs.
foods that have high
amounts of vitamins

Mineral salts
 Mineral salts are also important
in maintaining the general well-
being of our body.
 Calcium helps to build and
support the development of
strong bones and teeth. Food
such as milk, cheese, eggs and
soya beans are high in calcium.
 Iron is required in blood to carry
oxygen around the body. Iron is
also needed for respiration.
Food such as red meat, liver,
egg yolk and dark green leafy
vegetables are good sources of
iron.
foods that contain high
amounts of calcium and iron

Water
 Having enough water in our body
prevents dehydration and
constipation.
 It also protects the spine,
tissues and joints.
 Blood, which is made up of 85%
water, transports oxygen and
nutrients to the other parts of our
body.
 Besides drinking water, we can
take in water by consuming
fruits and vegetables.
it is recommended
we drink at least 8 glasses
of water daily

Dietary fibre
 Dietary fibre helps maintain a healthy digestive
system prevent constipation.
 Constipation refers to a condition whereby a person
finds it difficult and painful to pass solid faeces out
from the body.
 Examples of food high in dietary fibre include
vegetables, fruits and whole grain cereals.
food rich in dietary fibre helps
with bowel movement

My Healthy Plate
 Healthy eating is about
choosing the right
types and right
amounts of food.
 A healthy diet will
provide us with the
nutrients and energy
we need to support our
health and daily
activities.
 My Healthy Plate is a
guide to healthy eating
and aims to help
develop healthy
lifestyles.

My Healthy Plate
(a) Fruits and vegetables
Fill half of our plate with fruits and vegetables.
Fruits and vegetables are rich in dietary fibre,
vitamins and minerals. Eating more of fruits
and vegetables can lower the risk of developing
heart disease, stroke and cancer.
(b) Whole grains
Fill one quarter of our plate with whole grains.
Whole grain food such as brown rice, wholemeal
bread and oats contain vitamins and minerals.
Consuming whole grains can reduce the risk of
developing heart disease and diabetes.

Fruits and vegetables and Whole grains
whole grains
fruits and vegetables

Meat and other food rich in proteins
 Fill one quarter of our plate with meat and other food
that is rich in proteins such as fish, beans, tofu, nuts
and dairy products. Lean meat, beans, tofu, nuts and
dairy products such as milk and cheese contain
proteins that help to build and repair tissues in our
body.
meat and protein-rich foods

Healthier oils
 Healthier oils such as canola, olive, soybean
and sunflower oil, consist of healthy fats that
can decrease the risk of developing heart
disease.
 Nuts are also a good source of healthy fats.
foods that contain healthy fats

Plain water
 We should always
consume more water
instead of sweetened
drinks such as soft drinks
and syrup.
 Drinking too much sweet
drinks can lead to
obesity.
drink plain water instead
of sweetened drinks

Active lifestyle
 Being healthy is not just
about healthy eating. It
also involves being
physically active every
day.
 Examples of physical
activities include brisk
walking, cycling,
swimming and taking
the stairs.
 We should try to carry
out some of these
physical activities
every week. © Copyright Star Publishing Pte Ltd 21
keep an active lifestyle

Understanding My Healthy Plate guidelines

Recommended daily water intake and
physical activities
Activity Book Link
Activity 8.1
Diet Plans

8.2 What is the purpose of the nutrition
label and how is it interpreted?
food?
spoilage?
8.7 What are food additives and their
functions?

Objectives
 Identify the basic information found on
a food/nutrition label such as
carbohydrate, protein, fat and sodium
content, serving sizes, percentage
daily values and energy content
 Understand and calculate percentages
and total amount of a nutrient based
on serving sizes and percentage daily
values

Food labels
 The food we eat contains many
nutrients. These nutrients provide the
energy for our body to work, play,
keep us healthy and carry out various
life processes.
 We need to know more about the food
we eat. We should read the nutrition
labels on food carefully before
buying or consuming these food.

Nutrition labels
 Important information on the nutrition labels,
include
(a) nutritional values
(b) serving sizes
(d) serving suggestions
(c) expiry dates
expiry date on
a milk carton

Example of a nutrition label

Reading Nutrition Labels
 The nutrition label provides
important information of
the nutrients present in the
food.
 For food to be sold in
Singapore, the authorities
(Agri-Food & Veterinary
Authority of Singapore)
require the food
manufacturers to print the
nutrition labels on the
food packaging.
the nutrition label
of a can of pasta

 The main section of the nutrition label
contains important information about the
food product such as serving size, Calories
and a list of nutrients present in the food.
 The bottom part of the nutrition label
contains a footnote with daily values for
2000 and 2500 Calorie diets.
 This footnote provides daily recommended
dietary information for important nutrients
such as fat, sodium and fibre. This footnote
does not change for different food
products.

The serving size and the number of servings
 The first step is to look at the serving size and the
number of servings in the package on the nutrition
label.
 The size of each serving is expressed in units such as
grams (g), millilitres (ml) or common household
measurements such as teaspoons and cups.
 One cup of canned pasta or one serving size is 252 g.
This can of pasta can serve 2 cups.
serving sizes

Calorie conversion guide
 Calorie is a measurement of energy we receive from the
food we eat. If we consume more Calories than what is
needed by our body, the risk of being overweight will
increase.
 Our body needs an average of 2000 to 2500 Calories daily.
 There are 270 Calories in one serving of canned pasta. Out
of the 270 Calories, 70 Calories come from fat.
 If you consume the whole can of pasta, you would have
taken 2 servings. This is equivalent to 270 × 2 = 540
Calories.
Calories information

List of nutrients
 The food label on the right shows the
key nutrients present in the food.
 Nutrients such as fats, cholesterol
and sodium should be taken in
small quantities. Eating too much
of these nutrients may increase the
risk of developing heart disease,
high blood pressure or cancer.
 Instead, we should eat food that
contains more dietary fibre,
Vitamins A and C, calcium and iron.
 Eating more of these nutrients can
improve our health and help reduce
the risk of developing diseases.
List of nutrients

Understanding the recommended
Daily Values (DV)
 The bottom section of the
nutrition facts label shows
a footnote that describes
the Daily Values (DV) for
each of the nutrient listed
based on the 2000 and
2500 Calorie daily diet.
 This information does not
change for the different
food products and it
serves as recommended
dietary advice by health
experts.
Percent Daily Values

Understanding how the percent Daily Values
(% DV) relate to Daily Value (DV)
 The % DV shows the amount of nutrient present based
on a 2000 Calorie diet serving.
 For example the % DV of total fat is obtained as follows:

Daily Values
 As a general rule of thumb, a % DV of 5 or less is
considered low, whereas a % DV of 20 or more is
considered high.
 Trans fat and sugars do not have a % DV listing
because it is recommended by health experts that we
should keep our intake for these nutrients to be as low
as possible as part of a nutritionally balanced diet.
 As for protein, % DV need not be listed unless there
is a claim of “high in protein” for that particular food or
if the food is meant to be consumed by infants.
Activity Book Link
Activity 8.2
Food Labels

and how is it interpreted?
8.3 What are the consequences of a diet
high
food?
spoilage?

Objectives
 State how some food with high fat, salt
and sugar contents can cause health
conditions such as obesity, high blood
pressure and diabetes

Why is food important?
 An excess of nutrients can harm the
body and result in diseases and other
health problems such as obesity, high
blood pressure and diabetes.
 Unhealthy food types include food with:
(a) a high content of cholesterol
(b) a high salt content
(c) a high saturated fats content
(d) a high sugar content

Eating too much unhealthy food can cause health
problems such as high blood pressure, diabetes and
obesity.
food with high levels of cholesterol food with high salt content
fried food is rich in saturated fats
food with high sugar content

High blood pressure
 High blood pressure can be caused by a diet high in
salt, fat and cholesterol.
 Food such as meat and shellfish (e.g. prawns, crabs
and clams) are high in cholesterol.
food such as meat and shellfish are high in cholesterol
food with high salt contentfood rich in fat
and cholesterol

High blood pressure
 Eating too much food high in cholesterol can lead to
fatty deposits on the inner walls of the arteries.
 The heart will need to pump harder to transport
blood around the body. This will lead to high blood
pressure.

A balanced diet and regular exercise
 To reduce the risks of high
blood pressure, we should
eat a balanced diet that is
low in sodium, cholesterol
and fat. Instead, we should
eat more fruits and leafy
green vegetables.
 Apart from a healthy diet, we
should also exercise
regularly, drink plenty of
water, and maintain a
healthy lifestyle to reduce
the risk of developing high
blood pressure.
a balanced diet and regular
exercise help us maintain a healthy
blood pressure

Diabetes
 Diabetes is a health condition where the level of glucose
in the blood cannot be properly regulated.
 A high level of glucose in the blood can cause damage
to our nervous system, eyes, kidneys, heart and limbs.
 Eating too much food high in sugar increases the risk of
developing diabetes. Patients who suffer from diabetes
have a higher risk of developing diseases such as
stroke, heart disease and kidney failure.
food high in sugar

Diabetes
 To reduce the risk of
diabetes, our sugar
intake should be
moderate.
 Alternatively, instead
of using sugar to
sweeten beverages,
artificial sweeteners
such as aspartame
can be used. We
should also maintain a
healthy lifestyle by
exercising regularly.
Aspartame, a commonly
used artificial sweetener

Obesity
 A diet high in fat and sugar and a lifestyle with little
exercise can cause obesity.
 Being obese can increase the risk of developing heart
disease, high blood pressure and diabetes.
 To prevent obesity, we should maintain a balanced
diet and a healthy lifestyle by exercising regularly.
eating too much fried food and food high in
sugar can lead to obesity
Activity Book Link
Activity 8.3
Dietary Health
Issues

food?
spoilage?
functions?

Objectives
 Understand the use of simple food
tests on (i) starch [iodine test] (ii)
protein [biuret test] (iii) oil [blot test]

Testing for Starch (Iodine
Test)
 The presence of starch in sample of food can be
detected by adding a few drops of iodine.
 Iodine is a yellow brown liquid and will turn the
food materials blue-black when starch is
present.

Testing for Proteins (Biuret
Test)
 The Biuret test is used to test for the
presence of proteins in food.

Testing for Oil (Oil Blot Test)
 If oil is present in the food, oil spots will
form and remain on the filter paper with the
food sample being pressed on it.
Activity Book
Link
Activity 8.4
Food Tests

food?
spoilage?
functions?

Objectives
 State what microbes are
 Describe the action of microbes on
food (e.g. mould on bread and
bacteria on milk)

What are microbes?
 Microbes are tiny living organisms
around us that are too small to be
seen with our eyes without a
microscope.
 Examples of microbes include:
(a) Bacteria
(b) Fungi such as yeasts and moulds

Classification of microbes

Action of Microbes on Food
 Microbes are present in the air and these
microbes can cause food to be spoilt.
 Eating food contaminated with these
microbes can cause severe food
poisoning.
 The symptoms of food poisoning include
stomachache, vomiting, diarrhoea and
fever.

Formation of mould on bread
 Bread can only be kept fresh for
a short period of time.
 When the bread has been kept
past the expiry date, moulds
may begin to grow on it.
 These moulds would produce
enzymes that convert starch
into sugar and water.
 Hence, the bread turns bad and
has an unpleasant smell.
a slice of fresh bread
a slice of mouldy bread

How milk turns sour
 Bacteria present in the milk produces
enzymes which would change the
flavour and texture of the milk.
 An acid is produced that causes the
milk to turn sour and lumpy.

Microbes can be useful to us
 Not all microbes are harmful. Microbes
can be used in making of bread,
cheese and yoghurt.
 Microbes (bacteria) in human intestines
also help in the digestion of food.
 Yoghurt contains good bacteria and
helps to promote good intestinal
health.
Activity Book Link
Activity Book Link
Activity 8.5
Souring of Milk

food?
spoilage?
functions?

Objectives
 State that to preserve food there is a
need to reduce microbial activity
 Describe briefly the following methods of
preventing food from getting spoilt (i)
using high temperature [e.g. sterilisation,
pasteurisation, canning] (ii) using low
temperature [e.g. freezing] (iii) reducing
the water content [e.g. freezing,
dehydration, use of chemical
preservatives] (iv) lowering the pH [e.g.
pickling] (v) reducing the oxygen supply
[e.g. bottling, packaging]

What causes food spoilage?
 Microbial activities can cause food
spoilage. Hence, there is a need to
preserve our food and make it safe for
consumption.
 Microbial activity is affected by factors
such as temperature, water content,
pH and oxygen supply.

What causes food spoilage?
 Microbes are most active at a
temperature range of 37°C to
40°C.
 At very low and high
temperatures, microbial
activities are reduced.
 At -10°C, microbial activity is very
low. Most of the microbes stop
growing and reproducing.
 Above 60°C, microbial activity is
also significantly reduced as
most microbes are killed.
microbial activity is affected
by temperature

Using High Temperatures
 Food preservation methods include using
high temperatures.

Sterilisation
 Sterilisation involves heating food to
above 100°C to kill the microbes. The
food is then packed into sterilised
containers.
 Sterilisation is commonly used to
preserve fresh milk.
 Fresh milk can be heated to between
135°C and 150°C for 1 to 3 seconds.

Sterilisation
 Milk preserved this
way is called Ultra
High Temperature
(UHT) milk.
 UHT milk has a
shelf life of about 6
to 8 weeks
without
refrigeration.
UHT milk is able to last
longer than pasteurised milk

Pasteurisation
 There are 2 main ways of
pasteurising food:
(a) Heating food to
between 70°C and
80°C for 15 seconds.
(b) Heating food to
between 60°C and
65°C for 30 minutes
and then cooling the
food rapidly to -10°C.
pasteurised milk can be used
to make products such as
cheese and yoghurt

Pasteurisation
 Pasteurisation
can be used to
preserve dairy
products like
milk, cheese
butter, yoghurt,
fruit juices and
coconut milk.
dairy products

Pasteurisation
 In pasteurisation, food is heated to a
temperature lower than that in
sterilisation.
 Hence, not all the microbes in the food
are killed. For this reason, pasteurised
food does not have a long shelf life.
 Pasteurised milk can remain fresh for
only a week even when refrigerated.

Canning
 In canning, the food
and containers are
heated under
pressure to kill the
harmful microbes.
The food is then
packed into the
containers. The
temperature during
heating can be as
high as 140°C.
canning of food

Canning
 Canning can be
used to preserve
many different
types of food that
include
vegetables,
seafood, poultry
and fruits.
 Canned food
usually has a shelf
life of two or more
years.
canned food

Using Low Temperatures
 Freezing involves rapidly cooling
food to temperatures below 4°C. It
is best to freeze food to -18°C or
below.
 Solid carbon dioxide (dry ice) may
be used to further lower the
temperature of the food.
 Freezing reduces microbial activity in
food because microbial growth is
slowed down at low temperatures.
 Freezing, however will not kill all the
microbes present in the food. Once
the frozen food is thawed, the
microbes will grow and multiply
again.
keeping food fresh at low
temperatures

Using Low Temperatures
 Freezing also helps preserve
food by reducing the water
content of food as the water
has become solid ice. Hence,
water is no longer available
for microbial activity to take
place.
 Freezing is used to slow
down microbial activities
so that food can be kept
fresh longer. We can keep
our food in the freezer
compartment of the
refrigerator for a few days.
food in the freezer
compartment

Reducing water content
 There are 3 methods of reducing
water content in food:
(a) Freeze drying
(b) Dehydration
(c) Using chemical preservatives

Freeze drying
 To keep food longer, the food industry
uses the freeze drying method which
removes water from the food.
 The freeze dried food is then vacuum
packed and may be kept
unrefrigerated for several years.

Freeze drying

Dehydration
 Dehydration is a process of
removing water from food by
using heat.
 The cheapest way to dehydrate
food would be to spread the food
out under the sun to dry or to let
the wind evaporate the water in
the food.
 Some other common
dehydration methods include
drying the food in ovens,
smoking (e.g. Smoked salmon)
and vacuum-drying.
dehydrated food

Use of chemical preservations
 Sometimes food
packaging comes
with small packets of
dehydrating agents
to keep the air in the
food packaging dry.
No microbes can
survive as there is no
moisture to support
microbial activities.
dehydrating agent packets
in a box of mooncakes

Use of chemical preservations
 Salt and sugar are also commonly used
to reduce water content in food.
 Other chemical preservatives such as
sulfur dioxide, benzoic acid and
sodium nitrite reduce microbial
activity by killing the microbes in food.
Chemical preservatives are also called
food additives.

Lowering pH
 Pickling is preserving food in a
solution of an acid and salt. The
acid used can be vinegar or
citric acid.
 The acid lowers the pH of the
food and thus reduces microbial
activity.
 Sugar may also be added to add
taste to the food. Pickles are
preserved vegetables ( such as
such as cucumber and cabbage )
and fruits ( like mango and
papaya ).
pickling of
vegetables

Reducing Oxygen Supply
 Removing the
oxygen supply in
food packaging will
reduce the
microbial activity in
food.
 Examples of
removing the oxygen
supply include
bottling and
vacuum packing.
bottling removes oxygen
supply in the red wine

Reducing Oxygen Supply
 In vacuum packaging,
air and water vapour
are removed from the
packaging and sealed.
 Moulds and bacteria
cannot grow on the
food. Hence, the food
will not spoil easily
and can have a long
shelf life.
vacuum sealed chicken
cheese
vacuum packed sausagesActivity Book Link
Activity 8.6
Browning of Apples

food?
spoilage?
functions?

Objectives
 Describe why some food additives are
necessary
 Give examples of common food
additives (i) preservatives [e.g. vinegar,
salt, sugar, sulfur dioxide] (ii) nutrient
supplements [e.g. vitamins, mineral
salts] (iii) texture and appearance
modifiers [e.g. starch, food colourings]
 Describe the dangers using non-
permitted additives (e.g. carcinogens,
heavy-metal poisons) or adding
excessive levels of permitted additives in
food production

Food additives
 Food additives are
substances added to
food to improve the
flavour, taste,
appearance, texture,
nutritional value and/or
shelf life of food.
 In the past, before
refrigeration was invented,
additives such as salt and
vinegar were widely used
to keep food edible for long
periods of time. These
additives prevented food
from spoiling.
spices are commonly added
to food for additional flavour

Examples of common food additives
 Food additives are often used by food
manufacturers for three main
purposes:
(a) As a food preservative
(b) As nutrient supplements
(c) As texture and appearance
modifiers

Preservatives
 Preservatives in food can reduce
microbial activity by:
(i) Killing the microbes
(ii) Lowering the water content
(iii) Lowering the pH of food

Killing the microbes
 Sulfur dioxide is used in the
manufacture of dried fruits as it can
destroy and kill microbes.

Lowering the water content
 Salt in salted fish
products lower the
water content in
food
 High sugar
concentration in
bottled fruit jams
lowers the water
content

Lowering the pH of food
 Vinegar used for pickling vegetables
lowers the pH of food.

Nutrient supplements
 Nutrient supplements are added to
food to:
(i) Replace nutrients that are lost
during the processing and
manufacturing of food
(ii) Enrich the vitamin or mineral
contents of food

Vitamins and Mineral salts
 Vitamins are essential for
the overall health of
a person.
 Any vitamin deficiency in
a person’s
diet can be supplemented
with pills or food
additives.
 Mineral salts deficiency
will lead to a number of
health problems.
 Our diet may not provide
us with all the essential
salts.
 We can take some mineral
salts such as iron and
calcium supplements.

Texture and appearance modifiers
 Food with a smoother texture and a more attractive
appearance tends to be more appetising.
 Some common texture and appearance modifiers
include starch and food colourings.
 Starch is commonly used as bakery fillings and in
fishball making.
starch is used in making fishballs

Texture and appearance modifiers
 Food colourings are also important in
food industries.
 Like in bakeries, cupcakes are often
made with colourful food colourings.

Dangers of Using Food
Additives
 While food additives are important to the food
industries, proper checks and regulations
are needed to prevent the use of or
excessive use of non-permitted food
additives.
 In Singapore, the use of food additives is
regulated by the Agri-Food & Veterinary
Authority of Singapore (AVA) which
ensures that food additives in food are kept
within the legal limits. Consuming non-
permitted food additives can cause harm to
our health.

Food additives permitted for use
in Singapore

Excessive consumption of permitted
food additives
 Eating food that contain too much of a
permitted food additive can be harmful to our
health.
 It is advisable to consume permitted food
additives in moderation.

Consumption of non-permitted food
additives
 Non-permitted food additives are
toxic to human health. Consuming
these carcinogenic food additives
can cause cancer and poisoning
(heavy-metal poisoning).
 Non-permitted food additives may
contain heavy metals such as
mercury and lead which are toxic
when consumed. These additives
are banned.
Activity Book Link
Activity 8.7
Food Preservatives
permitted food additive

Uss module 5 chpt 8 Food Health and Safety

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