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Food Additives

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Substances added to food that are not naturally present ... Guar gum, Locust Bean gum. Modified celluloses, methyl cellulose. Bacterial origin. Xanthan gum ... – PowerPoint PPT presentation

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Title: Food Additives


1
Food Additives
  • Foods, Facts Fallacies
  • YSCN 0006
  • http//web.hku.hk/lramsden/fff.html

2
Additives
  • What do we eat?
  • Fresh food versus processed food.
  • Changing patterns of food consumption.
  • Longer storage and processing
  • Need to maintain food quality

3
What are additives?
  • Substances added to food that are not naturally
    present
  • Not nutritive
  • Original aim usually preservation
  • Later to enhance food appearance
  • and enhance food quality

4
Types of Additives and their Functions
5
Food Regulation
  • US GRAS system
  • Generally Recognised As Safe
  • Introduced in 1958 to approve established food
    ingredients
  • New additives must be approved by FDA
  • Delaney Clause to prohibit any substance known to
    cause cancer

6
Additive Testing
  • Relies on animal tests to NOEL
  • No Observable Effect Level highest dose of
    additive with no effect on animal
  • Reduced by a factor of 100 to give safety margin
    for humans

7
E number system
  • European system for approved food additives
  • E classification shows the additive is safe for
    use in food
  • Internationally recognised and also used in other
    countries

8
E numbers
9
Earliest Additives
  • Preservatives
  • Sodium Chloride, Salt
  • Used for 10,000 years to preserve meat products
  • Salt reduces water availability for bacteria to
    grow
  • Crude salt is contaminated with sodium nitrate
  • Additional use of smoke

10
Traditional Additives
  • Used for thousands of year
  • Salt and saltpetre
  • Smoke
  • Honey
  • Vinegar
  • Herbs Spices
  • Natural food colourings
  • Calcium carbonate

11
E 250 Sodium Nitrite
  • Sodium nitrate contaminant of crude salt
  • Found to cause pinkish colour in meat
  • Sodium nitrite more effective
  • On high temp cooking can be converted to
    carcinogenic compounds nitrosoamines.
  • Potent inhibitor of anaerobic metabolism
  • Prevents growth of major food pathogen
  • Clostridium botulinum

12
Clostridium botulinum
  • Common soil bacteria
  • Anaerobe can only grow well when no oxygen
    present
  • Spores heat resistant to 120C for 3mins
  • Bacteria produces protein toxin
  • 1µg fatal, respiratory paralysis and cardiac
    failure

13
Meat colour
  • Fresh meat purplish red
  • Exposed meat, bright red oxymyoglobin
  • Later turns to metmyoglobin, gray or brown
  • Nitrite reacts to form nitrosomyoglobin
  • After cooking nitrosohaemochrome
  • pinkish red in colour

14
Cured meat
  • Pickled in salts,
  • Salt, sodium nitrite, ascorbic acid, sugar
  • Meat submerged in strong solution
  • Or injected by machines with multiple needles
  • 10 days at 4C

15
Smoking
  • Wood fire, produces anti bacterial compounds
  • Provides surface coating and protection
  • Colour and flavour
  • Hams, heated to 60C
  • Not sterile, must be refrigerated,
  • But can be eaten raw
  • Bacon, only heated to 52C
  • Cannot be eaten raw

16
Sausages
  • Ground meat, low quality off-cuts
  • Natural casing, eg. sheep intestine
  • Stuffed spices, salt, sugar, ice
  • Sodium nitrite to inhibit Clostridium botulinum

17
Frankfurters, hot dogs
  • Meat comminuted
  • Ground very finely to form meat emulsion
  • 30 fat, 10 water
  • stuffed in cellophane casings to form links
  • smoked or cooked to 75C
  • De-skinned, passed through hot water and skins
    peeled off by machine.

18
Spoilage
  • Become slimy
  • Surface growth of yeasts and bacteria
  • Turn green
  • lactobacter releasing hydrogen peroxide
  • Reacts with nitrosohaemochrome
  • oxidises it to a green colour

19
More Preservatives
  • E200 Sorbic Acid, soft drinks, yoghourt.
  • E210 Benzoic acid, jams, creams
  • E220 Sulphites, SO2 wine, vegetables, drinks
  • E230 Diphenyl, fruit
  • E234 Nisin, cheese
  • E239 Hexamine Fish
  • E280 Propionic acid Bread

20
Antioxidants
  • Chemical preservation
  • Most important for fats
  • E300 Ascorbic acid (vitamin C)
  • E306 Tocopherol (Vitamin E)
  • E320 BHA meat products, dairy products
  • E321 BHT meat products, dairy products

21
Flavour
  • Artificial Sweeteners
  • sucrose 1
  • cyclamate 30
  • saccharin 300
  • aspartame 180
  • sucralose 600
  • alitame 2000
  • thaumatin 2500

22
Artificial Flavours
  • Mimics of natural flavours using complex mixes of
    pure chemicals
  • Synthetic banana flavour
  • amyl acetate
  • amyl butartae
  • ethyl butartae
  • isoamyl acetate
  • isoamyl butarate
  • linalool
  • 15 others in lesser quantities

23
Flavour enhancer
  • E621 monosodium glutamate
  • amino acid - glutamine

24
19th century
  • Increased urbanisation food processing
  • Adulteration
  • Use of cheap substitutes
  • Colour flavour enhancers
  • Sometimes dangerous
  • 1857 survey of confectionary found colours
  • Lead chromate
  • Mercuric sulphide
  • Copper arsenite

25
Food Colours
  • Preserved Vegetables
  • Chlorophyll, green pigment in plants is unstable
  • Green colour from copper salts due to cooking
    under acid conditions in copper pans

26
Confectionary
  • Colouring to enhance consumer appeal
  • Natural
  • Inorganic
  • Synthetic

27
Natural Colours
  • Caramel, brown from burnt sugar,
  • most widely used colour,
  • not always classified as an additive
  • Carotenoids, orange/yellows
  • Anthocyanins, reds blues
  • Betalaines, red/purple
  • Turmeric, root of turmeric plant, yellow
  • Cochineal, insects from cactus, scarlet

28
Synthetic Colours
  • Yellow Tartrazine E102
  • Sunset yellow E110
  • Red Red 2G E128
  • Ponceau 4R E124
  • Amaranth E123
  • Blue Brilliant Blue FCF E133
  • Green Food Green S E142
  • Brown Chocolate Brown E155

29
Dye problem
  • Many organic chemicals with bright colours found
    to be carcinogenic
  • Flat shape allows them to interfere with DNA
    helix
  • Usually found by effects on people making them
    not those eating them
  • e.g. Butter yellow
  • Not allowed to be used in foods

30
Bread
  • Flour whitening
  • calcium carbonate
  • Anti caking agents
  • ammonium citrate
  • Dough enhancers
  • stearate
  • Leavening agents
  • baking powder

31
Emulsifiers
  • Stabilise mixtures of food components
  • Oil and water
  • Natural emulsifier - E322 lecithin
  • Synthetic
  • E 471 Glyceryl monostearate
  • E442 Ammonium phosphatide
  • E435 polysorbate

32
Thickeners
  • Non-starch polysaccharides
  • Bind water to form gels
  • Algal origin
  • Alginates, agar, carrageenans
  • Plant origin
  • Guar gum, Locust Bean gum
  • Modified celluloses,
  • methyl cellulose
  • Bacterial origin
  • Xanthan gum

33
Is It Safe
  • Better than the alternative
  • Food degradation by biological or chemical action
    - very unsafe!
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