Healthy eating on a plate: eating for health made simple
Module 3: Cooking and Processing Methods
Module 3 – Cooking and Processing Methods, June 2013
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Healthy eating on a plate: eating for health made simple
Contents
Module 3: Cooking and Processing Methods .................................................................................... 1
Learning Outcomes ........................................................................................................................... 1
Key Message: .................................................................................................................................... 1
Checklist for session.......................................................................................................................... 1
Session outline: Cooking and Processing Methods ........................................................................... 2
Presenter notes for Module 3: Cooking and Processing Methods .................................................... 3
Which has more vitamins, frozen, canned or fresh? ......................................................................... 3
Fresh versus frozen or canned .......................................................................................................... 5
Reducing vitamin loss ....................................................................................................................... 6
Evaluation ......................................................................................................................................... 8
Group discussion & evaluation ......................................................................................................... 8
Fact sheet.......................................................................................................................................... 8
Website resources: ........................................................................................................................... 9
Appendix A – Resources ………………………………………………………………………………………………………10
Activity Sheet – ‘Circle the best choices to save vitamins’
Activity Sheet - Answers – ‘Circle the best choices to save vitamins’
Fact sheet – ‘Simple ways to reduce vitamin loss’
Appendix B – Script and flashcards…………………………………………………………………………….………14
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Healthy eating on a plate: eating for health made simple
Module 3: Cooking and Processing Methods
The best value for money is still to buy fresh produce in season, however depending on how the
produce is handled; it may not retain many vitamins by the time it gets to the table. In Australia,
modern processing practices, means that produce is canned or frozen very quickly after harvesting.
The freshness of the produce when it is frozen or canned offsets to a large degree losses during the
canning and freezing process. This module steps participants through practical ways to preserve
vitamins when storing, handling and preparing food in the home.
Learning Outcomes: By the end of the session participants will be able to:
• Understand how different food processing methods (frozen, canned, fresh) affect the
vitamin content of food
• Identify practical ways to prepare fruit and vegetables that will prevent vitamin loss during
food preparation and cooking.
Key Messages:
•
•
Buying fruit and vegetables in season is the best value for money
Frozen and canned fruit and vegetables are good alternatives if fresh produce is unavailable.
Checklist for session:
• Script and flashcard set for Module 3: Cooking and Processing Methods
• Knife and cutting board
• A fresh fruit or vegetable that will brown easily when cut (e.g. an apple)
• Lemon juice (about 1 teaspoon)
• Pot and access to a stove (this can be done ahead of time)
• 2 x clear containers suitable to pour hot water into (this can be done ahead of time)
• A vegetable that will lose colour quickly when boiled (e.g. broccoli, carrot)
• Plastic milk carton
• Activity sheet - ‘Circle the best choices to save vitamins’
• Answer sheet – ‘Circle the best choices to save vitamins’
• Factsheet - ‘Simple ways to reduce vitamin loss’
• Pens
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Session outline: Cooking and Processing Methods
Activity
2 mins
5 mins
10 mins
Activity
Introduction and overview of the session
• How different processing methods (with an emphasis on canning and
freezing) affect the vitamin content of food
• How different cooking methods affect the vitamin content of food
• How to prevent vitamin loss when buying, storing and preparing food in the
home.
Which has more vitamins – frozen, canned or fresh?
Discussion points:
• What affects the amount of vitamins in food?
• Which vitamins are affected most by processing and cooking?
• Fresh versus frozen or canned fruit and vegetables
• Good reasons to eat a variety of cooked and raw foods
Demonstration
Use different visual aids to show how water, light and air affect nutrients:
• Fruit goes brown quickly when cut
• Nutrient loss in water when vegetables are boiled
• Innovations that protect the vitamin content of food (dimples on the top of
a plastic milk carton reflect light and preserves vitamins)
Resources required
Flashcards:
‘What affects the
amount of vitamins
in food?’
‘Fresh, canned or
frozen’
A vegetable that will
lose colour quickly
when boiled (e.g.
broccoli, carrot)
Flashcard:
‘Cooking vegetables:
boiling vs. steaming’
A fresh fruit or
vegetable that will
brown easily when
cut (e.g. an apple)
Flashcard:
‘Preparation of fruit’
5mins
3 mins
5 mins
Reducing vitamin loss
Discussion points:
• Cooking methods that are quick and use small amounts of water
• Simple ways to reduce vitamin loss
Recap of main points
In-class activity
• Participants will complete the activity sheet ‘Circle the best choices to save
vitamins’
• Discuss answers as a group.
Group discussion:
• Discuss what changes participants plan to make at home.
Module 3 – Cooking and Processing Methods, June 2013
Plastic milk carton
with dimples on the
top
Flashcard: ‘Milk’
Flashcards:
‘Cooking methods’
‘Simple ways to
reduce vitamin loss’
Activity and answer
sheets - ‘Circle the
best choices to save
vitamins’
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Healthy eating on a plate: eating for health made simple
Presenter notes for Module 3: Cooking and Processing Methods
Give an overview of what participants can expect to learn during the session.
• How different processing methods (with an emphasis on canning and freezing) affect the vitamin
content of food
• How different cooking methods affect the vitamin content of food
• How to prevent vitamin loss when buying, storing and preparing food in the home.
Display the ‘What affects the amount of vitamins in food’
flashcard
Which has more vitamins, frozen, canned or fresh?
‘What affects the amount of vitamins in food?’
Fruit and vegetables go through many processes on the way to our
table and vitamin loss can occur at any stage. The longer the produce
takes to get to our tables and the longer it is exposed to the elements
the more potential there is for vitamins to be lost. Vitamin loss is
affected by:
• heat
• light
• water
• air
• time from harvesting to the plate.
Note: minerals (e.g. iron and calcium are not affected)
Which vitamins are affected most by processing and cooking?
B-group vitamins and vitamin C are the vitamins most susceptible to
heat and light (and therefore transportation, processing and cooking).
Some vitamins are affected more than others.
These vitamins are termed unstable and include:
•
Folate
•
Thiamine (vitamin B12 or cobalamin)
•
Vitamin C.
Other vitamins affected by processing, but not to the same degree
include:
•
Niacin (B3)
•
Biotin (B7)
•
Pantothenic acid (vitamin B5)
•
Vitamin K & D.
Folate is a B vitamin and gets
its name from ‘folium’, which is
the Latin word for leaf. It is
found in leafy green
vegetables, fruit, dried peas
and beans. It is an especially
important vitamin for pregnant
women to ensure the baby
develops normally.
Folic acid is the synthetic
version of this vitamin found in
supplements and fortified
foods.
Phytochemicals are found in
plant foods – grains, fruits and
vegetables. (phyto means
plant).
There are thousands of
phytochemicals, but less than
200 have been studied in
depth. Those that have been
studied have shown many
health benefits.
If food has travelled long distances it can be weeks old before it reaches the table. Vitamin C is a very
unstable vitamin and fruit and vegetables can lose up to half of their vitamin C after just one week in
the fridge – let alone the time it takes to get to your fridge.
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Food cycle
The way in which food is grown, harvested, stored and prepared will affect its overall nutritional content.
fertilisers fertilisers tend to
reduce vitamin C
content - even
organic ones
milling - when
cereals are milled
the husk is
removed, which
contains most of the
fibre and B-group
vitamins
blanching - fruit and
vegetables are
heated very quickly
before canning or
freezing, which
tends to destroy
vitamin C and Bgroup vitamins
freezing - once a
food is frozen there
are no further
vitamin losses.
Losses will occur
again in the cooking
process
canning - food is
heated whilstinside
the can to destroy
micro-organisms.
High temperatures
may affect the foods
appearance and
those vitamins
affected by heat will
be reduced
dehydrating drying out foods
such as fruit, will
destroy some
vitamin C, however
concentrate other
nutrients, including
fibre
pasteurisation fruit juice and milk
are heated to
destroy organisms.
Some vitamin C may
be lost in fruit juice
preparation peeling and
trimming fruit and
vegetables will
reduce vitamins and
other nutrients,
such as fibre. Most
of the vitamins and
fibre lie just under
the skin
cooking - vitamins
that dissolve in
water will be lost
during cooking.
Reducing the
amount of water by
using alternative
methods such as
grilling, roasting,
steaming, stir-frying
and microwaving
will reduce these
losses.
Vitamin C and some of the B-group vitamins are the most susceptible to processing and cooking, however losses can be minimised by using produce soon after it
is purchased, scrubbing vegetables instead of peeling them, reducing the amount of water used in cooking (microwave, steam, roast or grill instead of boiling)
and cooking foods as quickly as possible.
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Healthy eating on a plate: eating for health made simple
Display ‘Fresh, canned or frozen?’ flashcard
Fresh versus frozen or canned
The way fruit and vegetables are processed and cooked can make them safer and more palatable to
eat, however there is a perception that frozen and canned foods do not retain as many vitamins as
fresh produce.
Generally speaking, canned fruit and vegetables will taste and look different to fresh, however
vitamin loss is variable. A test conducted by Choice (2007) showed that there was very little
difference in the nutrient content of sweet corn, whether it was fresh, canned or frozen. In fact if
fresh produce is not stored correctly, it can actually contain less vitamins than canned or frozen
varieties.
Canning and freezing factories are generally close to where the food is harvested, so the amount of
time the food is exposed to the elements is limited. Once a product is frozen or canned, vitamin loss
is dramatically slowed down. More vitamins will be lost once the product is cooked.
During the canning process, vitamin C will be lost, however the cooking time is very short, so losses
are minimised.
Good reasons to eat a variety of cooked and raw foods
As well as destroying bacteria, cooking can also enhance flavour and
break down food so that it is easier to digest.
The best way to get a wide variety of nutrients is to eat a wide variety
of food. This includes both cooked and raw fruits and vegetables.
The body can actually use some nutrients more efficiently when food
has been cooked, such as the phytochemical lycopene.
Demonstrate how water, light and air can affect nutrients
Lycopene is found in tomatoes
and is thought to be protective
against heart disease and
prostate cancer.
The cooking process makes
more lycopene available for
the body to use, so canned and
cooked tomatoes (including
tomato paste) are higher in
lycopene than fresh tomatoes.
Display ‘Cooking vegetables: boiling vs. steaming’ flashcard
•
Vegetables - demonstrate the difference in vitamin losses between microwaving and boiling
vegetables (carrot or broccoli work well for this demonstration)
o Microwave the vegetable of your choice with very little water
o Boil the same vegetable on the stovetop covered with water
o Demonstrate how much colour (and vitamins) have been lost in the water when the
vegetable is boiled when compared to microwaving by pouring off the water into a glass.
Cooking the vegetables can be done ahead of time
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Display ‘Preparation of fruit’ flashcard
•
Fruit - demonstrate how quickly exposure to the air will turn fruit brown
o When fruits or vegetables are harvested, they start to deteriorate. This deterioration is
sped up once the skin is damaged, cut or exposed to the air in any way
o Cut an apple at the beginning of the session to demonstrate how quickly it starts to
deteriorate
NOTE: Putting lemon juice on half of the cut apple will stop the reaction as lemon juice is high in
vitamin C. This vitamin is an anti-oxidant (stops oxidisation). Even though apples contain vitamin
C, there is not enough to stop the browning reaction by itself.
An apple can be prepared before the session. Put lemon juice on one half to
demonstrate the antioxidant effects of vitamin C
Display ‘Milk’ flashcard
• Milk - demonstrate how food producers use innovation to protect the food supply
o Milk used to be sold in clear, glass containers. It is now sold in opaque containers (not
clear) so that light cannot pass through the glass. Light can partially destroy vitamins,
particularly riboflavin (vitamin B2). Another method used to reflect light (and slow down
the loss of vitamins) is the dimpling around the top of some plastic containers.
Reducing vitamin loss
As soon as fruit or vegetables are harvested they begin to deteriorate and lose vitamins. Loses will
depend on how long the produce has been exposed to heat, water, air and heat and how long it has
been in storage, in transit, sitting on supermarket shelves or in the refrigerator at home.
Display ‘Cooking methods’ flashcard
The longer fruit and vegetables are kept in water or subjected to heat, the
more vitamins are likely to be lost. So quick cooking methods that use very
little water are the best, such as:
•
•
•
Steaming
Microwaving
Stir-frying
•
•
Grilling
Roasting
Microwaves work by
causing the water
particles in food to
vibrate at very high
speeds. The friction
caused by the vibration
produces heat – so
microwaves actually cook
from the inside out.
Even if little water is used, if vegetables are over-cooked – that is subjected to heat for too long - the
benefits of using a small amount of water will be lost by prolonged exposure to heat. Vegetables
should be tender, not soft when cooked.
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Healthy eating on a plate: eating for health made simple
Display ‘Simple ways to reduce vitamin losses’ flashcard
As well as cooking vegetables quickly and using small amounts of water, other ways to reduce
vitamin losses include:
•
Washing and scrubbing vegetables instead of peeling off the skin
o Most vitamins are just under the skin and most of the fibre is in the skin as well
• Preparing fruit and vegetables as needed
o Sometimes in our busy lives it is necessary to prepare food ahead of time, however
soaking pre-cut vegetables in water means losing some of the precious vitamins
• Cutting vegetables into large pieces to cook
o The more cuts made in the fruit or vegetable – the more of the surface area is
exposed to air, heat, light and water – and the more vitamins are lost
• Using any leftover ‘vegetable water’ in soups, gravies or casseroles
o This is a great way to add back the vitamins that have been leached into the water
• Not adding baking soda when cooking vegetables in water
o This is a trick used a few years ago, however we now know that baking soda
preserves colour, but destroys vitamins
• Storing ripe fruit in the refrigerator crisper
o Fruit can be left at room temperature to ripen, however once ripe it should be
placed in the fridge to slow down the deterioration process. The skin of bananas will
go black if they are kept in the fridge, however the flesh is still good to eat
• Buying small amounts of fresh produce and using it soon after purchase
o Make sure the produce you buy is fresh. Produce that is colourful and looks fresh
will contain the most vitamins
• Choose frozen produce that is free of ice crystals. If the packet is ‘icy’ this may indicate it has
been partially unthawed and re-frozen
Recap main points:
• Frozen and canned fruit and vegetables are good alternatives to fresh. Vitamin losses from
canning and freezing are balanced out by the fact they are canned or frozen very soon after
harvest
• Eat a variety of fruit and vegetables, including raw and cooked
…and remember
• Choose canned fruits in natural juice instead of syrup
• Choose canned or frozen vegetables with no added salt if possible
These last two points don’t influence vitamin loss, but are healthier choices.
Distribute ‘Circle the best choices to save vitamins’ activity sheet to participants
Give participants enough time to complete the activity sheet and then go through
the answers. Clarify any points and collect the sheets. Make a note of how many
participants completed the activity sheet correctly.
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Healthy eating on a plate: eating for health made simple
Evaluation
Group discussion & evaluation
•
•
•
What will you take away from today’s session?
Do you feel more confident about how to prepare foods in a way that reduces vitamin loss,
than you were before?
What changes, if any, do you plan to make as a result of today’s session?
Make notes of comments throughout the session and questions asked during completion of the
activity sheet and during the demonstration
An overall evaluation will be conducted at the end of all the sessions.
Fact sheet
•
Distribute ‘Simple ways to reduce vitamin loss’
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Website resources:
Better Health Channel,
http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Food_processing_and_nutrition
‘Food processing and nutrition’. This website is funded by the State Government of Victoria and
provides easy to understand factsheets on a wide range of health issues. This fact sheet summarises
how the vitamins in food may be affected by food processing.
Choice, http://www.choice.com.au/reviews-and-tests/food-and-health/food-anddrink/nutrition/are-fresh-vegies-better.aspx . Are fresh veggies better? Choice is an independent
organisation that advocates for consumer rights. This article presents data from tests that Choice
conducted on a range of vegetables comparing canned, frozen and fresh to see which vitamins were
affected during processing and storage.
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Appendix A
Resources
Module 3: Cooking and processing
methods
Module 3 – Cooking and Processing Methods, June 2013
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Circle the best choices to save vitamins
Scrubbing vegetables or peeling them?
Cutting fruit as needed or preparing in advance?
Boiling vegetables or steaming them?
Cutting vegetables into smaller pieces or larger pieces
to cook?
Cooking vegetables for a long time or a short time?
Storing ripe fruit in the fridge crisper or storing ripe fruit in a bowl?
Answer sheet - Circle the best choices to save vitamins
Scrubbing vegetables or peeling them?
Most of the vitamins are just under the
skin of fruit and vegetables and the skin
is where most of the fibre is.
Cutting fruit as needed or preparing in advance? The longer fruit is
exposed to air and light the quicker it deteriorates and loses vitamins
Boiling vegetables or steaming them? More water means more opportunity for
precious vitamins to end up in the water – an down the drain! Any water from
cooking can be used in gravies, casseroles or soups.
Cutting vegetables into smaller pieces or larger pieces to cook?
The more cuts that are made the greater the surface area of
the fruit or vegetable is exposed to air and light and potentially
water while cooking, which means more vitamins are lost.
Cooking vegetables for a long time or a short time? The
longer fruit and vegetables are cooked the longer the
exposure to water and heat – and the more vitamins are lost
Storing ripe fruit in the fridge crisper or storing ripe fruit in a bowl? Fruit can be
stored in a bowl until it is ripe, however once ripe it should be placed in the crisper
in the fridge to slow down the deterioration process and minimise exposure to
light, heat and air.
Simple ways to reduce vitamin loss
Vitamins are essential for good health and one of the best sources of
vitamins is fruit and vegetables. However, it is important to remember that
as soon as fruit and vegetables are picked (harvested), they begin to
deteriorate and lose vitamins. The way in which fruit and vegetables are
processed (including how they are stored, handled and cooked at home)
after they are harvested can influence how much of the vitamins are still in
the food once they reach the table.
To make the most of fruit and vegetables, they need to be prepared and stored in a way that
slows down the loss of vitamins. This means reducing the amount of time they are exposed
to heat, water, air and light.
Make the most of your fruit and vegetables by:
1. Reducing the cooking time - fruit and vegetables should be tender not soft
2. Using small amounts of water – steaming or microwaving are the best methods
− roasting or grilling vegetables are also good alternatives to boiling
3. Washing and scrubbing vegetables instead of peeling off the skin
− along with the vitamins and the fibre
4. Preparing fruit and vegetables as needed
− and avoiding soaking pre-cut vegetables in water
5. Cutting vegetables into large pieces to cook
6. Using any leftover ‘vegetable water’ in soups, gravies or casseroles
7. Not adding baking soda to cooking water
− Baking soda preserves colour, but destroys vitamins
8. Storing ripe fruit in the refrigerator crisper
9. Buying small amounts of fresh produce and using soon after purchase.
…and remember
•
•
•
•
Frozen and canned fruit and vegetables are good alternatives to fresh
Choose canned or frozen vegetables with no added salt if possible
Choose canned fruits in natural juice instead of syrup
Eat a variety of fruit and vegetables, including raw and cooked.
Appendix B
Script & flashcards
Module 3: Cooking and processing
methods
This page has been left blank intentionally
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Script for Module3: Cooking and Processing Methods
Today we are going to be talking about cooking and processing methods. We’ll be looking at:
Module 3
Cooking and Processing
Methods
• How different food processing methods (frozen, canned, fresh) affect the vitamin content of fruit and
vegetables
• Practical ways to prepare fruit and vegetables that prevent vitamin loss during food preparation and cooking
• Nutritious alternatives when fresh fruit and vegetables are not available
Food processing is any process that a food undergoes from the field to the plate. In Australia, almost all food has
undergone some sort of process before it is eaten. For example milk is fermented into yoghurt, meat is dissected and
vegetables are washed.
Food is processed for a variety of reasons including:
o To make it last longer (e.g. canned or frozen food)
o To kill bacteria or germs (e.g. pasteurising milk)
o To change the flavour, texture or colour of the food (e.g. homogenising milk, so the fat doesn’t rise to the top)
o To reduce preparation time (e.g. cutting raw oats into smaller bits that cook quicker)
o To restore or raise the nutrient level of food (e.g. vitamins added back to bread)
Food processing can impact on the amount of vitamins in food. Particularly foods that contain vitamins that are
more susceptible to food processing – like fruit and vegetables. Today we are going to discuss ways to reduce the
amount of vitamins lost, so that we get the most out of our food.
Page | 1
Module 3
Cooking and Processing
Methods
Page | 2
Script for Module3: Cooking and Processing Methods
‘What affects the amount of vitamins in fruit and vegetables?’
Fruit and vegetables go through many processes on the way to our table and vitamin loss can occur at any stage.
The longer the fruit and vegetables take to get to our tables and the longer it is exposed to the elements the more potential there
is for vitamins to be lost. Vitamin loss is affected by:
• heat
• light
• water
• air
• time from harvesting to the plate.
Note: minerals (e.g. iron and calcium are not affected)
B-group vitamins and vitamin C are the vitamins most susceptible to heat and light ( and therefore transportation,
processing and cooking).
If food has travelled long distances it can be weeks old before it reaches the table. Vitamin C is a very unstable vitamin and fruit and
vegetables can lose up to half of their vitamin C after just one week in the fridge – let alone the time it takes to get the food to your
fridge.
Page 2
What affects the amount of vitamins in food?
Light
Water
Time on the shelf
Page 3
Air
Time being transported
Heat
Script for Module3: Cooking and Processing Methods
Which has more vitamins, frozen, canned or fresh?
The way fruit and vegetables are processed and cooked can make them safer and more pleasant to eat,
however many people think that frozen and canned foods don’t have as many vitamins as fresh fruit and
vegetables.
Generally speaking, canned fruit and vegetables will taste and look different to fresh, however the vitamin content can vary. For
example, tests show that there is very little difference in the vitamin content of sweet corn, whether it is fresh, canned or frozen. In
fact if fresh sweet corn is not stored correctly, it can actually contain less vitamins than canned or frozen varieties
Canning and freezing factories are generally close to where the food is harvested, so the amount of time the food is exposed to
heat and light is limited. Once a food is frozen or canned, vitamin loss slows down dramatically – and then vitamins are lost again
once the produce is thawed or cooked.
During the canning process, vitamin C will be lost, however because this process is very short, the losses are small.
Good reasons to eat a variety of cooked and raw foods
As well as destroying bacteria, cooking can also make food taste better (for example cooking potatoes) and start the process of
breaking down the food so that it is easier to digest.
It’s a good idea to eat a wide variety of foods to get a wide variety of nutrients. This includes both cooked and raw fruits and
vegetables. Sometimes nutrients are trapped in food and cooking them allows the body to use them better.
For example tomatoes contain a substance called lycopene that has been shown to protect against some cancers – lycopene can
actually be used by the body better when tomatoes have been cooked (canned tomatoes, tomato sauce, tomato paste)
Page 3
Fresh, canned or frozen?
Frozen or canned within a
few hours of harvesting
Canning – overall cooking time is less
(salt may be added)
Freezing – stops any further
loss of vitamins
Page 4
Demonstration
Script for Module3: Cooking and Processing Methods
How does water affects vitamin loss?
Sometimes you can see how vitamins are lost during preparation and cooking.
Different cooking methods can lead to more vitamin loss than others.
Vitamins leaching from
vegetables
Firstly, let’s look at how water affects vitamin loss.
(**hold up vegetables that have been boiled**)
These vegetables have been boiled on the stove in a pot of water for
about 10 to 15 minutes.
(**pour water from boiled veg into a clear glass and show to
participants**)
If you look at the water you will see that it is quite strongly coloured.
When vegetables lose colour they also lose vitamins.
(**hold up the vegetables that have been steamed in the microwave**)
These vegetables have been steamed in a small amount of water in the
microwave for about three minutes.
(** pour water from steamed veg into clear glass and show to
participants**)
Notice how there is less water and not as much colour (and therefore
vitamins) have been lost in the water using this method.
Page 4
Demonstrate how water, light and air can
affect nutrients
• Vegetables - demonstrate the difference in
vitamin losses between microwaving and boiling
vegetables
(carrot or broccoli work well for this
demonstration)
o Microwave the vegetable of your choice
with very little water
o Boil the same vegetable on the stovetop
covered with water
o Demonstrate how much colour (and
vitamins) have been lost in the water when
the vegetable is boiled compared to
microwaving by pouring the water into a
heatproof glass container.
Cooking vegetables: boiling vs. steaming
Less water
Shorter cooking time
Less leaching of vitamins
Steaming
More water
Longer cooking time
More leaching of vitamins
Page 5
Boiling
Script for Module3: Cooking and Processing Methods
How does air affect vitamins?
As we mentioned earlier, exposure to air is one of the factors
that affects the amount of vitamins in our food. Once the skin
of fruit and vegetables is cut the flesh is exposed to air and
this starts the food deteriorating – and losing vitamins.
(**hold up the apple (or whatever you have decided to use)
that was cut at the beginning of the session**)
This apple was cut at the beginning of the session. Notice how
the flesh has turned brown? This is because the air has
reacted with substances in the fruit and caused it to go
brown. This process is call oxidisation. As the fruit turns
brown, vitamins are also being lost. Vitamin C will stop the
browning process – so the fresher the apple and the more
vitamin C it contains – the slower this process will be –
because vitamin C is an anti-oxidant.
• It is best to cut fruit and vegetables just before eating or
cooking them to reduce the amount of time they are
exposed to the air.
• If you are preparing fruit ahead of time, squeeze some
citrus juice such as lemon or orange juice on it. The extra
vitamin C in the lemon or oranges will help slow down
the oxidation or browning process.
Page 5
Demonstration
How air affects the
vitamins in fruit
An apple can be prepared before the
session. Put lemon juice on one half to
demonstrate the anti-oxidant effects of
vitamin C
• Fruit - demonstrate how quickly exposure to the
air will turn fruit brown
o When fruit or vegetables are harvested, they
start to deteriorate. This deterioration is
sped up once the skin is damaged, cut or
exposed to the air in any way
o Cut an apple at the beginning of the session
to demonstrate how quickly it starts to
deteriorate
NOTE: Putting lemon juice on half of the cut
apple will slow down the reaction as lemon juice
is high in vitamin C. This vitamin is an antioxidant (stops oxidisation). Even though apples
contain vitamin C, there is not enough to stop the
browning reaction by itself.
Preparation of fruit
Fresh fruit
• Flesh exposed to the
air over a period of
time
• Browning of flesh due
to oxidation
• More vitamin loss
Prepared prior to eating
Page 6
• Flesh received
minimal exposure to
air
• Flesh is not brown
• More vitamins
Cut just before eating
Script for Module3: Cooking and Processing Methods
How does light affect vitamins?
Food producers are constantly trying to find ways to improve
the food we eat and stop vitamins from being lost.
Milk is an example of this. It used to be sold in clear, glass
containers. It is now sold in opaque containers (not clear) so
that light cannot pass through. This is because some of the
vitamins that milk contains can easily be destroyed by light,
such as vitamin B2 (riboflavin).
(** hold up the milk container and highlight that it is not
clear and that is has dimpling around the top to reflect the
light**)
Some milk is also produced in plastic containers with dimpling
around the top. The dimpling is designed to reflect light and
therefore slow down vitamin loss.
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Demonstration
How light affects vitamins and why
milk containers are dimpled
Milk - demonstrate how food producers use
innovation to protect the food supply
o Show 2 litre milk containers with the dimpling around
the top.
Milk
Milk was previously packaged in
glass containers. It was often
delivered and left outside.
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Milk is now either packaged in
cardboard cartons or opaque (not clear)
plastic containers.
Script for Module3: Cooking and Processing Methods
Reducing vitamin loss
Remember that as soon as fruit or vegetables are harvested (picked) they begin to deteriorate. The greater the
length of time fruit and vegetables are in storage, in transit and sit on supermarket shelves, the greater the vitamin losses.
Whilst these conditions are out of our control, once we have purchased the fruit and vegetables there are things that we can do
to minimise vitamin loss. For example, there are certain cooking methods that reduce vitamin loss.
Cooking methods which are quick and that use very little water are the best, such as:
•
•
•
•
•
Grilling
Microwaving
Steaming
Roasting
Stir-frying
Even if a little water is used, if vegetables are over-cooked – that is subjected to heat for
longer than necessary - the benefits of using a small amount of water will be lost as heat also
destroys vitamins – this is why it is best to use quick methods as well as those that use little
water.
Remember - vegetables should be tender, not soft and mushy when cooked.
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How do microwaves work?
They cause the water
particles in food to vibrate
at very high speeds. The
friction caused by the
vibration produces heat –
so microwaves actually
cook from the inside out.
Cooking methods
Roasting
Grilling
Steaming
Microwaving
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Stir-frying
Script for Module3: Cooking and Processing Methods
As well as cooking vegetables quickly and using small amounts of water, other ways to reduce vitamin
losses include:
• Washing and scrubbing vegetables instead of peeling off the skin
• Most vitamins are just under the skin and most of the fibre is in the skin as well
• Preparing fruit and vegetables as needed
• Sometimes in our busy lives it is necessary to prepare food ahead of time, however soaking pre-cut vegetables in water
means losing some of the precious vitamins
• Cutting vegetables into large pieces to cook
• The more cuts made – the more of the surface area of the vegetable is exposed to air, heat, light and water – and the
more vitamins are lost
• Using any leftover ‘vegetable water’ in soups, gravies or casseroles
• This is a great way to add back the vitamins that have been leached into the water
• Not adding baking soda when cooking vegetables
• This is a trick used a few years ago, however we now know that baking soda preserves colour, but destroys vitamins
• Storing ripe fruit in the refrigerator crisper
• Fruit can be left at room temperature to ripen, however once ripe it should be placed in the fridge to slow down the
deterioration process. The skin of bananas will go black if they are kept in the fridge, however the flesh is still good to
eat
• Buying small amounts of fresh produce and using it soon after purchase
• Make sure the produce you buy is fresh. Produce that is colourful and looks fresh will contain the most vitamins.
• Choose frozen produce that is free of ice crystals. If the packet is ‘icy’ this may indicate it has been partially
unthawed and re-frozen – and vitamins have been lost.
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Simple ways to reduce vitamin loss
Swap long for short cooking times – less heat
Swap peeling for scrubbing – more fibre and vitamins
Swap small pieces for large pieces – less exposure to the air
Swap boiling for steaming, roasting or grilling – less water
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Add any ‘vegetable water’ to soups, gravies or casseroles
Brightly coloured fresh produce will have more vitamins
than produce that looks old
Prepare fruit and vegetables as needed – less exposure to
the air
Store ripe fruit and vegetables in the refrigerator – less
exposure to light and heat
Script for Module3: Cooking and Processing Methods
Explain the activity sheet to participants.
Distribute activity sheets and factsheet
Circle the preparation method that will preserve the most
vitamins
 Give participants them about 3 minutes to
complete the activity and then discuss the
answers as a group.
Recap main points:
• Frozen and canned fruit and vegetables are good
alternatives to fresh. Vitamin losses from canning and
freezing are balanced out by the fact they are canned
or frozen very soon after harvest
• Eat a variety of fruit and vegetables, including raw
and cooked
…and remember to
• Choose canned or frozen vegetables with no added
salt if possible
• Choose canned fruits in natural juice instead of syrup
These things don’t affect vitamin loss – but are healthier
choices
Group discussion
What will you take away from the session?
Do you feel more confident about how to prepare foods
in a way that reduces vitamin loss, than you were before?
What changes, if any, do you plan to make as a result of today’s
session?
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Circle the best choices to save vitamins
Scrubbing vegetables or peeling them?
Boiling vegetables or steaming them?
Cutting vegetables into smaller pieces or larger pieces to cook?
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Cutting fruit as needed or preparing in advance?
Cooking vegetables for a long time or a short
Storing ripe fruit in the fridge crisper or storing ripe fruit in
a bowl?
Script for Module3: Cooking and Processing Methods
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