Unit 34 Food Additives

1
Unit 34 Food Additives
34.1 Why using food additives (PAT) 34.2 Main
classes of food additives (Big 7) 34.3 Colourings
and paper chromatography 34.4 Preservatives
(Salt/vinegar/SO2/benzoic acid/nitrite and
nitrate) 34.5 Flavourings and MSG(??) 34.7 The
E-number (1 to 6) 34.8 Common methods of
preserving food (4 methods) 34.9 Food additives
and health
2
34.1 Why using food additives (PAT)
Preserving Attractive Tastier
3
34.2 Main classes of food additives (Big 7)

• Colourings
• Preservatives(???)
• Flavourings
• Emulsifiers and stabilizers(Stabilize oil-water
  mixtures like ice-cream)
• Acids, bases and buffers(Control the pH value of
  food)
• Sweeteners(To sweeten food without using sugar)
• Nutrients

4
34.3 Colourings and paper chromatography
5
34.4 Preservatives

• Salt
• vinegar
• SO2 (alcoholic drinks, fruit juices and dried
  fruits)
• benzoic acid (oyster sauce, jams)
• Nitrite(NO2-) and nitrate(NO3-)
• (cured meatsprevent botulism and maintain the
  pink colour)

6
(No Transcript)
7
???? ???????????,?????????,???????????????????
Some chemistry thinking NaNO2 ???? NaOH HNO2
? NaNO2 H2O
8
1. After an experiment for separating the
colouring in chocolate beans by paper
chromatography, the following results are found

• Draw a chromatogram.
• Suggest a solvent.

1 NaCl solution can be a solvent.
9

• Discuss the advantage(s) and the disadvantage(s)
  of using nitrite additives.

Advantages Decreases the risk of botulin toxin
formation.(botulism) Maintain a pink colour of
meat.
Reproductive capacity impairment, reduce life span
Disadvantages Decreases level of haemoglobin in
the blood. Malnutrition. Growth retardation./ may
cause cancer.
10
3. Suggest the uses of sulphur dioxide as food
additives.

• Acts as a preservatives for
• dehydrated fruit and vegetables.
• wine(the fermented juice of fresh grapes)
• non-alcoholic beverage(drinkable liquid)

11
4. Write a short essay on the monitoring the
use of additives.

• By Public Health and Municipal Services
  Ordinance. Government can
• make sure food label on package.
• check food processing
• can seize(take possession) and destroy food
• prosecute the companies using non-permitted
  additives.

12
In Hong Kong, the Department of Health is
empowered under the Public Health and Municipal
Services Ordinance. For example, they legislate
permissible additives and maximum limits of
additives in particular foods, require supply of
information as to composition of substances used
in the preparation of food, check on food
labelling, inspect food-processing industries,
take sample for chemical analyses on food and
food additives, seize and destroy food and
prosecute false labelling, advertiment, using
non-permitted additives or additives, beyond the
permissible limits. (by Chow Hoi Ki)
13
34.5 Flavourings and MSG(??)
Used to enhance natural flavours e.g.. sugar,
salt, vinegar, monosodium glutamate (MSG)
14
34.7 The E-number (1 to 6)
is a coding system that is used on food
manufactured in EU countries.

• Colourings (1)
• Preservatives(???) (2)
• Flavourings (none)
• Emulsifiers and stabilizers (3 or 4)
• Acids, bases and buffers (5)
• Sweeteners (4 or 6)
• Nutrients (none)

15
34.8 Common methods of preserving food (4 methods)

• against
• bacterial action and
• 2) chemical changes (e.g. oxidation of oil)

• Dehydration
• Why? pulls the water out of the bacterial cell
• How? by drying, salt or sugaring
• Examples Bacon(??)
• Unfavourable medium for the bacterial growth
• Examples pickling, SO2 and benzoic acid, NaNO2
• 3. Using antioxidants such as BHA and BHT

16
34.9 Food additives and health
Allergies (??) Hyperactivity (????) e.g.
E102 Long-term illness (such as cancer)

• Chinese Restaurant Syndrome(???????)
• headache, asthma(??), faint(??) or even death
• MSG
• burning sensations, thirst, vomiting(??)

17
Questions
1. Look at these two food labels.
(a) Which of the two foods contains artificial
colouring? List all these colouring. (b) Which
additive prevents the growth of micro-organism?
18
Question

• A can of fizzy drink includes the following
  ingredients
• carbonated water, sucrose, vitamin C, butyl
  butanoate, citric acid
• In the drink, vitamin C is used as an
  anti-oxidant.
• Why is an anti-oxidant used?
• Suggest another reason for including vitamin C in
  the drink.
• Name ONE other anti-oxidant that can be used.
• Why is butyl butanoate used in the drink?
  (2001Q.3)

19

• Which of the following statements concerning
  monosodium glutamate is correct?
• It sweetens food.
• It prevents food from being oxidized.
• It emulsifies oil and water in food.
• It enhances the flavour of food.

• Which of the following substances are commonly
  found in canned grapefruit juice?
• citric acid. (2) benzoic acid (3) ethanoic acid
• (1) and (2) only
• (1) and (3) only
• (2) and (3) only
• (1), (2) and (3)