Uss module 5 chpt 8 Food Health and Safety

Module 5:Food MattersChapter 8 Food Health and Safety

© Copyright Star Publishing Pte Ltd

Chapter 8 Food Health and Safety8.1 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 functions?


ObjectivesUnderstand 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 and water


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.


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 containcarbohydrates

ProteinsProteins are needed for tissue growth and

repair.

Examples of food which are rich in protein include meat (lean), eggs, milk and fish.


foods that containproteins

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 containfats

VitaminsVitamins are needed in small amount to promote

good health in our body. Examples includes:

(a) Vitamin C:

Vitamin C strengthens the gums and preventsthem from bleeding, and boosts resistance toinfections.

Examples of food that provide a lot of Vitamin C include citrus fruits such as oranges, lemons and grapes.


Vitamin DVitamin 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 highamounts 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. © Copyright Star Publishing

Pte Ltd

foods that contain highamounts 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 recommendedwe 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 fruitsand vegetables can lower the risk of developingheart disease, stroke and cancer.

(b) Whole grains

Fill one quarter of our plate with whole grains.Whole grain food such as brown rice, wholemealbread and oats contain vitamins and minerals.Consuming whole grains can reduce the risk ofdeveloping 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 oilsHealthier 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 lifestyleBeing 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.


keep an active lifestyle

Understanding My Healthy Plate guidelines


Understanding My Healthy Plate guidelines


Recommended daily water intake and physical activities


Activity Book LinkActivity 8.1Diet Plans

Chapter 8 Food Health and Safety8.1 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



ObjectivesIdentify 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 labelsThe 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 ona 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 labelof a can of pasta

Reading Nutrition LabelsThe 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.


Reading Nutrition Labels


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 recommendedDaily 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 LinkActivity 8.2Food Labels


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



ObjectivesState 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 healthproblems such as high blood pressure, diabetes andobesity.


food with high levels of cholesterol food with high salt content

fried food is rich in saturated fatsfood 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 fatand 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 regularexercise 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

DiabetesTo 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 commonlyused 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 balanceddiet and a healthy lifestyle by exercising regularly.


eating too much fried food and food high in

sugar can lead to obesity

Activity Book LinkActivity 8.3Dietary Health Issues


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



ObjectivesUnderstand 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 LinkActivity 8.4Food Tests






ObjectivesState what microbes areDescribe 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 FoodMicrobes 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 breadBread 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 sourBacteria 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 usNot 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 LinkActivity Book LinkActivity 8.5Souring of Milk




food? 8.6 What are the ways to prevent food

spoilage? 8.7 What are food additives and their functions?


ObjectivesState that to preserve food there is a need

to reduce microbial activityDescribe 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 TemperaturesFood preservation methods include using

high temperatures.


SterilisationSterilisation 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.


SterilisationMilk 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 lastlonger than pasteurised milk

PasteurisationThere 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

PasteurisationPasteurisation

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


dairy products

PasteurisationIn 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.


CanningIn 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

CanningCanning 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. © Copyright Star Publishing

Pte Ltd

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 freezercompartment

Reducing water contentThere are 3 methods of reducing

water content in food:

(a) Freeze drying(b) Dehydration(c) Using chemical preservatives


Freeze dryingTo 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 preservationsSometimes 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 preservationsSalt 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 ofvegetables

Reducing Oxygen SupplyRemoving 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 SupplyIn 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 sausages

Activity Book LinkActivity 8.6Browning of Apples




food? 8.6 What are the ways to prevent food spoilage? 8.7 What are food additives and their

functions?


ObjectivesDescribe why some food additives are

necessaryGive 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 additivesFood 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 additivesFood 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


PreservativesPreservatives in food can reduce

microbial activity by:

(i) Killing the microbes (ii) Lowering the water content(iii) Lowering the pH of food


Killing the microbesSulfur dioxide is used in the

manufacture of dried fruits as it can destroy and kill microbes.


Lowering the water contentSalt 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 foodVinegar used for pickling

vegetables lowers the pH of food.


Nutrient supplementsNutrient 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’sdiet 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 AdditivesWhile 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 usein Singapore


Excessive consumption of permitted food additivesEating 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 LinkActivity 8.7Food Preservatives

permitted food additive


Education

Uss module 5 chpt 8 Food Health and Safety