Chapter 34Food Additives

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Chapter 34 Food Additives
34.1 Introducing food additives
34.2 Food colourings
34.3 Food flavourings
34.4 Food preservatives
34.5 Are food additives really safe?
CONTENTS OF CHAPTER 34
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34.1 INTRODUCING FOOD ADDITIVES PROCESSED
FOODS AND FOOD ADDITIVES Some of the foods we
eat are fresh. They are not processed. Most
foods, however, are processed.
34.1 INTRODUCING FOOD ADDITIVES
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Figure 34.1 Some unprocessed foods.
34.1 INTRODUCING FOOD ADDITIVES
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Figure 34.2 All the foods and drinks shown
here have been processed.
34.1 INTRODUCING FOOD ADDITIVES
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In food processing, small amounts of certain
chemicals are often added these are called food
additives.
A FOOD ADDITIVE is a chemical added to food to
improve it or to preserve it.
The main reasons for using food additives
are ? to colour food ? to flavour food ? to
change the texture (sponginess) of food ? to add
nutrients ? to preserve food
34.1 INTRODUCING FOOD ADDITIVES
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Figure 34.3 A fruit juice with the additive
vitamin C.
34.1 INTRODUCING FOOD ADDITIVES
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Figure 34.4 Would you like this soft drink if no
artificial flavouring and colouring had been
added to it? (a) The normal look of the soft
drink. (b) What the soft drink would look like if
no artificial colouring had been added.
34.1 INTRODUCING FOOD ADDITIVES
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CONTROL OF FOOD ADDITIVES The EU (European
Union) countries have drawn a list of 314 safe
food additives. Each of them is given an E
number.
Figure 34.5 The E number identifies an additive.
34.1 INTRODUCING FOOD ADDITIVES
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TYPES OF FOOD ADDITIVES
34.1 INTRODUCING FOOD ADDITIVES
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Table 34.1 Different types of food
additives.
34.1 INTRODUCING FOOD ADDITIVES
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INSPECTING FOOD LABELS FOR ADDITIVES
Figure 34.6 Can you list the basic
foodstuff and food additives in this food?
34.1 INTRODUCING FOOD ADDITIVES
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Figure 34.7 Can you list the food additives
in these chocolate beans?
34.1 INTRODUCING FOOD ADDITIVES
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A34.1
E110 is used as an artificial colouring. E201 is
used as a preservative. E320 is used as an
anti-oxidant. E322 is used as an emulsifier and
stabilizer.
A34.2
Colouring, preservative and flavouring.
34.1 INTRODUCING FOOD ADDITIVES
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34.2 FOOD COLOURINGS WHY USE FOOD
COLOURINGS? Food colourings are dyes. They are
added to food for the following purposes
? To give food an attractive colour, so as to
make it more appetizing and more saleable. ? To
restore the original colour which may be changed
or lost during food processing or storage. ? To
ensure colour consistency.
34.2 FOOD COLOURINGS
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Figure 34.8 When fruits are processed, their
colours change. Artificial colourings are added
to make them look like fresh fruits.
34.2 FOOD COLOURINGS
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ARE FOOD COLOURINGS ESSENTIAL? There is no
definite conclusion to this. But one thing is
certain most processed foods on market nowadays
contain colourings. NATURAL AND SYNTHETIC
COLOURINGS Synthetic colourings are more commonly
used. USE OF COLOURINGS WORLDWIDE In most
places nowadays, the use of food colourings is
under strict control by the government. ANALYSING
COLOURINGS BY CHROMATOGRAPHY Food colourings
can be analysed by chromatography.
34.2 FOOD COLOURINGS
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Paper chromatography of black ink..
34.2 FOOD COLOURINGS
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Figure 34.10 Colourful chocolate beans.
Figure 34.11 Chocolate beans become white when
the colourings are removed.
34.2 FOOD COLOURINGS
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Figure 34.12 A simple set-up for paper
chromatography of colouring on chocolate beans.
34.2 FOOD COLOURINGS
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To separate dyes in the colouring of a Smarties
chocolate bean.
34.2 FOOD COLOURINGS
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34.3 FOOD FLAVOURINGS WHY USE FOOD
FLAVOURINGS? Flavourings are added to food for
the following purposes
? To enhance flavour of food ? To restore the
original flavour which may be lost during food
processing ? To add flavour to foods which are
tasteless themselves (e.g. ice cream, jelly)
34.3 FOOD FLAVOURINGS
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Figure 34.14 The flavour of an ice cream is due
to the flavourings added.
34.3 FOOD FLAVOURINGS
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COMMON FLAVOURINGS Flavourings make up the
largest class of food additives. Both
natural and artificial flavourings are used.
34.3 FOOD FLAVOURINGS
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Figure 34.15 Common flavourings.
34.3 FOOD FLAVOURINGS
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A34.3
Synthetic esters are widely used as fruit
flavours in drinks, ice creams and sweets.
Monosodium glutamate Monosodium glutamate is a
white solid. It possesses little flavour of its
own, but it can bring out the flavour of foods.
It is therefore actually a flavour enhancer.
34.3 FOOD FLAVOURINGS
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Figure 34.16 Monosodium glutamate is a
widely-used flavour enhancer.
34.3 FOOD FLAVOURINGS
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Figure 34.17 Instant noodle supplied with
the packet of flavouring (mainly MSG).
34.3 FOOD FLAVOURINGS
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34.4 FOOD PRESERVATIVES TO PRESERVE FOOD Food
spoilage is mainly due to micro-organisms
(microbes). Thus there are two ways to preserve
food ? Kill the microbes in food ? Keep food in
conditions where the microbes cannot multiply
34.4 FOOD PRESERVATIVES
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Figure 34.19 Three main types of
micro-organisms (a) Bacteria
(b) Mould
(c) Yeast
34.4 FOOD PRESERVATIVES
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Common methods to preserve food Common methods to
preserve food include ? Canning Cook food and
then seal it in tin cans under sterile
conditions. ? Drying Dry food in the sun or
in special ovens. Drying takes away the water
needed by microbes. ? Freezing and
refrigeration Freeze food quickly. Freezing
turns liquid water into ice, thus controlling the
growth of microbes. Refrigeration slows down
biochemical changes of microbes.
34.4 FOOD PRESERVATIVES
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? Irradiation Expose food to gamma rays from
certain radioactive isotopes for a short time.
The microbes are killed at once. ? Using
preservatives
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Figure 34.20 Foods preserved by different
methods (a) Canned foods. (b) Dried
fruits. (c) Frozen foods. (d) Irradiated
strawberries (compared with non-irradiated ones)
34.4 FOOD PRESERVATIVES
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A34.4
(a) Drying (b) Canning
PRESERVATIVES AND THEIR FUNCTIONS We add
preservatives to food to kill microbes or inhibit
their growth, so that the food spoils less
quickly. Common food preservatives are common
salt, sugar, vinegar, sulphur dioxide, benzoic
acid and sodium nitrite.
34.4 FOOD PRESERVATIVES
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Common salt and sugar Salting and sugaring are
two of the oldest methods of preserving food.
Figure 34.21 Using salt to preserve fish.
34.4 FOOD PRESERVATIVES
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Figure 34.22 Fruits preserved in strong
sugar solution.
34.4 FOOD PRESERVATIVES
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A34.5
(a) Osmosis. (b) Salting and sugaring.
Vinegar Pickling in vinegar is a common method of
preserving onions, cucumbers and beetroot.
34.4 FOOD PRESERVATIVES
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Figure 34.23 Onion is pickled in vinegar.
34.4 FOOD PRESERVATIVES
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Sulphur dioxide Sulphur dioxide has been used in
wine-making for hundreds of years to control the
growth of unwanted microbes. A wide range of
other foods, such as fruit juices and dried
fruits, also have sulphur dioxide added as a
preservative.
34.4 FOOD PRESERVATIVES
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Figure 34.24 Sulphur dioxide is a common
preservative for dried fruits.
34.4 FOOD PRESERVATIVES
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Benzoic acid Benzoic acid (or sodium benzoate)
is a preservative commonly used in fruit juices
and other drinks. It is able to stop the growth
of bacteria and yeasts.
34.4 FOOD PRESERVATIVES
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Figure 34.25 Fruit juices usually contain small
amounts of benzoic acid (or sodium benzoate) as
preservative.
34.4 FOOD PRESERVATIVES
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Sodium nitrite In the process of manufacturing
ham, bacon and sausages, the meats are soaked in
a solution containing sodium chloride, sodium
nitrate and sodium nitrite. This is called curing.
34.4 FOOD PRESERVATIVES
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Figure 34.26 Luncheon meat and ham contain
sodium nitrite as preservative.
34.4 FOOD PRESERVATIVES
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Table 34.2 Main functions of food
preservatives.
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A34.6
(b) B, C (c) B (d) A, D (e)
A, C (f) D
34.4 FOOD PRESERVATIVES
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34.5 ARE FOOD ADDITIVES REALLY
SAFE? DIFFERENT OPINIONS ON SAFETY OF FOOD
ADDITIVES It is hard to draw general rules to
control food additives which would apply to all
people.
34.5 ARE FOOD ADDITIVES REALLY SAFE?
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Activity 4
Some guiding questions for this discussion
are ? Selecting one or two food items, try to
decide what the food would be like without the
additives. For example, what would
vanilla-flavoured ice cream be like without
colouring? Without flavouring? Without
emulsifiers and stabilizers? ? For the same food
items, would you still buy them without the
additives? Or would you buy another different
food instead? ? Are some types of additives more
useful than others? If so, which ones? Could we
do without any additives?
34.5 ARE FOOD ADDITIVES REALLY SAFE?
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? Should we worry about the possible effect of
food additives on health? ? Without food
additives, the variety of food available in shops
would be much smaller (just imagine potato crisps
with no flavour). Would this have a great impact
on sales? ? A list of ingredients is not found
in some foods, e.g. fresh fruit, vegetables and
alcoholic drinks. Why do you think this is so?
Should all foods have ingredient lists?
34.5 ARE FOOD ADDITIVES REALLY SAFE?
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POSSIBLE HAZARDS OF FOOD ADDITIVES Possible
hazards of some food additives to our health
are ? Hazards of colourings Food colourings
permitted by law may not be really safe. ?
Hazards of MSG Some people are allergic to MSG.
34.5 ARE FOOD ADDITIVES REALLY SAFE?
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Figure 34.27 All these contain much MSG.
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? Hazards of preservatives Sulphur dioxide
would cause breathing difficulties and stomach
upset in some asthma patients. Besides, sodium
nitrite is suspected of causing cancer.
34.5 ARE FOOD ADDITIVES REALLY SAFE?
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SUMMARY
1. A food additive is a chemical added to food to
improve it or to preserve it. 2. The main reasons
for using food additives are ? To colour food
(by colourings) ? To flavour food (by
flavourings) ? To keep oils and water mixed in
food (by emulsifiers and stabilizers) ? To
add nutrients ? To preserve food (by
preservatives)
SUMMARY
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3. Food additives approved by the EU countries
often have an E number. (See Table 34.1 on p.
305.) 4. Paper chromatography can be used to
separate the dyes in food colourings. 5. Common
food flavourings include common salt, sugar,
vinegar and synthetic esters. MSG is a flavour
enhancer. 6. Food spoilage is mainly due to
micro-organisms (bacteria, fungi, yeast). 7. Food
preservatives include common salt, sugar,
vinegar, sulphur dioxide, benzoic acid and sodium
nitrite. 8. Food preservatives can function as
such because they either kill microbes or inhibit
their growth.
SUMMARY
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9. Some food additives such as tartrazine (E102)
and sodium nitrite are hazardous to health.
SUMMARY