FOOD ADDITIVES

The GRAS list: ‘Generally Regarded as Safe’ List

Anti-caking agents: Ca silicate SiO2 Iron ammonium citrate

Acids/bases/buffers: acetates, citrates (left) , lactates, phosphates,tartarates, sorbates (middle)

Emulsifiers (surfactants): mono- and diglycerides of fatty acidsalcohols like sorbitol (right):

Preservatives: benzoates, propionates, sorbates, ‘parabens’

Anti-oxidants: ascorbic acid, BHA, BHT,

lecithin, SO2 and sulphites

Flavour enhancers: MSG, maltol

Sweeteners: Aspartame, Mannitol, Saccharin, Sorbitol

Flavourings: amyl butyrate (pear), carvone (spearmint), citral (lemon),Ethyl vanillin (vanilla), geraniol (rose), methyl anthranilate (grape), methyl salicylate (wintergreen), eugenol (allspice)

PRESERVATIVES: prevent bacteria and oxidation dry and/or use salt/sugar OR add a BACTERICIDE

SODIUM BENZOATE ≤ 0.1%Used under acidic conditions

pie fillings, jams, syrups, pickles, relishes, olives, margarines, jellies, non-alcoholic beverages (found naturally in cranberries)

COO- Na+

SODIUM PROPANOATE (PROPIONATE) ≤0.3%

CH3CH2COO- Na+ Used under non-acidic conditions

bread, chocolate, cheese, pie-crusts (found naturally in Swiss Cheese)

ACTION OF BOTH: coats cell walls, stop passage of nutrients in orout, microbe dies from starvation

BACTERIOSTATS (FUNGISTATS) Prevent the growth, don’t kill

SORBIC ACID AND THE SORBATES

COOH (or COO- K+)

used in breads, muffins, cheese, paint, rubber, fish products, carbonated drinks...

PARABENS are used more in Europe

HO COOR NH2 COOH

R = methyl, propyl,... PABAeg propylparabens

probably get incorporated in to Folic acid instead of PABA

very widely used in cosmetics: lipsticks, under-arm deodorants

PRESERVATIVES FOR MEATS:

NITRITES sodium nitrite NaNO2 ≤ 200 ppmLD50 0.18 g/kg (= 20 g or so for me)

Used: in processed meats like wieners, bologna, salami...

NO2- inhibits botulinus bacteria: botulism toxin

and also reacts with myoglobin in meat to give a bright pink color

No nitrite, meat turns grey over time (no harm in this)need about 10x amount for pink than for botulinus inhibition

Nitrates (NaNO3) present in a wide variety of foods and water, also can produce NO2

- in presence of reducing bacteria (see below)

Controversy:

In the stomach: HNO2 forms, can react with amines (R2NH) to produce NITROSAMINES, R2N-NO

Nitrosamines are highly carcinogenic (to rats and other animals)

Is this a major risk? Probably NOT:

risk from botulism is much higher and food contains some nitratesnaturally (lettuce, spinach, beetroot, celery @ ~1000 ppm; peas, beans, onions @ ~200 ppm and beer @ ~25 mg per beer)

Average daily intake ~100 mg of nitrates, which on reduction gives ~5 g/mL of nitrite in saliva and about 5 mg of nitrite in the gut!

IRRADIATION

60Co -emitter: produce hydroxyl free radicals that kill most micro-organisms and inhibit many enzymes, prevent sprouting and ripening

FRUITS SO2 (sulfur dioxide) gas OR sulphite salts

Used: in dried fruits, wines, syrups, jellies, dehydrated potatoesacts both as a bleach and to kill bacteria

ANTI-OXIDANTS: many are phenols

OH OH

OMe

HOOH

OH

COOPr

BHT BHA propyl gallate

used in foods containing oils and fats, up to 0.02% (egs. Chips, cereals, breads)

FLAVOURS: FRUITY are all esters, same as natural ones

HCOO CH3COO CH3COO

CH3COO

HCOO

CH3CH2CH2COO CH3CH2CH2COO

SCH3CH3CH2CH2CO

raspberries pears bananas

orangespineapples

rum

apricots

strawberries

CH3COO

bananas

CH3CH2COO

rum

CHO

almonds, marishino cherries

COOCH3

NH2

grape

CHO

CH3O

HO

vanilla

OH

COOCH3

wintergreen

CHO

cinnamon

HO

menthol

SS

garlic

FLAVOUR ENHANCERSPotentiators: don’t have taste themselves, but enhance the flavour of othersMSG Monosodium glutamate (0.2-0.9%) NH2

COONa

COOH

Sodium salt of the natural amino acid, made by fermenting sugar beet molasses: widely used in meats, veg products, soya sauce, oriental food

‘Chinese Restaurant Syndrome’: sensitivity to MSG (purportedly) causing weakness and headaches

recent evidence suggests it might be histamines in the foods

So in part because of this see the 5'-nucleotides used:

sodium inosinate, sodium guanylate

O

HO OH

H2PO4 N

N

N

N

OH

O

O

OH

inosinic acid, Maltol (from pine needles)used as sodium salt

are used, look for them in soups, savoury type foods.

Jun 06: vine ripe tomatoes (“taste better”) have more msg and 5’nucleotides than gas ripened supermarket types! (Chem World)

SWEETENERS

Lead acetate is sweet but toxic!! Pb(OCOCH3)2 - sugar of lead

Not much logic as to why things taste sweet

SACCHARIN discovered 1879 300x sweeter than sucrose

SO2

NHCO

‘Sweet & Low’ (US): granulated sugar substitute – dextrose (3.6%) and saccharin (36 mg per 1g packet), cream of tartar and calcium silicate (an anti-caking agent)

Banned in Canada since 1977 for causing cancer in rats BUT

Study used saccharin as 5% of diet (equiv to 800 cans/pop per day!)

3/100 got bladder cancer; 14/100 2nd generation

Use was >200,000 kg/year in Canada in soft drinks at time of ban

Not banned in US (already had banned cyclamates)

Some get a very bitter after-taste and can tell immediately if saccharin has been used!

CYCLAMATE (1930)30x sweeter than sucrose, but no after-taste

NHSO3

2

2-

Ca2+

Reached peak in 1969 with 7 Mkg /y (US) soft drinks

Banned in US (1969) but not in Canada: rats got bladder cancer at absurdly high doses

Still approved in Canada, though not used in soft drinks Sugar Twin = sodium cyclamate in Canada BUT saccharin in US

ASPARTAME (1965)180x sweeter than sucrose, texture of sugar

NHCO

COOCH3 NH2

COOH

phenylalanine aspartic acid

It is a peptide of the naturally occurring amino acids phenylalanine and aspartic acid: Use ~ 100mg (4 kcal/g) = 0.4 kcal)

Some people (1 in 10,000) cannot metabolise phenylalanine (phenylketonuria): gives high levels of neurotransmitters, headaches

Use: 10 Mkg/yr in NA, 80% of NA market (70% of use in soft drinks)Not so useful in cooked goods100’s of web sites with ‘information’!BEWARE SOURCES!!!

Can Chem News June 06: Not carcinogenic – Nat Canc Inst (US) study

NEOTAME (made by NutraSweet, 2002) ~104 x sweeter than sugar

NHCO

COOCH3NHCH2CH2C(CH3)3

COOH

HEAT STABLE: useful in baking http://www.cfsan.fda.gov/~lrd/tpneotam.html

ACESULFAME-K (1967) 200 x sweeter than sugar (sold as Sunett)

Used in drugs, toothpaste, mouthwashes...approved for foods, HEAT STABLE

popular in Europe for decades but only approved for general use in US in 2003

http://www.caloriecontrol.org/acesulf.html

SUCRALOSE 600 x sweeter than sugar

Can (91) FDA (98) WHO (91)

‘Chlorinated galacto-sucrose’ i.e. Gal-Fru

More than 100 studies indicate no adverse affects at very high and prolonged dosages: Can. Diabetes Assoc. guidelines 1.65 g/d for life (for someone of my weight) with no adverse effects (= 1 kg sugar/d)

Fat insoluble so does not bio-accumulate but may accumulate in the environment

COLORS FD&C (Food, drugs and cosmetics approved)Purely cosmetic, slowly being reduced in number ~ 30 left, ½ natural, ½ synthetic

They are all highly conjugated so that they absorb visible light in 400-700 nm region – we see the complimentary color

eg. -carotene absorbs blue-violet so we see orange-red

Older coal tar dyes now synthesised with water solubilizing groups:SO3

-, COO- or OH so that dye is excreted without metabolizing

Most of older fat soluble dyes have been eliminated (carcinogenic): egs. butter yellow, yellows 3&4, orange 1, reds 2&4, violet 1

Sudan Red G (an example of an azo dye) caused a large food recall in UK in 2005: No longer used - carcinogenic

Cochineal (Carminic acid) comes from driedpregnant scale insects of Mexico, Peru andthe Canary Islands: highly valued dye incolonial Mexico; farmed in Australia

ADDITIVES TO CONTROL ACIDITY

Fruit acids: citric, tartaric, malic and lactic acid are used in fruit drinks

Phosphoric acid (H3PO4) is used in ‘cola’ type drinks

HO COOH

COOHHOHO COOH

COOH

COOH

CH3

OH

COOHHO COOH

COOHH

malic acid tartaric acid citric acid lactic acid (apples) (grapes) (lemons) (milk)

In candy manufacture, acid converts sucrose to softer invert sugar:LOW ACID gives hard (crystalline) candiesHIGH ACID gives softer, chewy (less crystalline) candies

BUFFERS usually sodium or potassium salts of di or tri-acids eg. potassium acid tartrate:

HO COO-

COOKHO

HO COOH

COOKHO

HO COOH

COOHHO

base acid

Buffer

ANTI-CAKING AGENTS: prevent moisture from forming lumps1% magnesium silicate in saltsodium aluminosilicate in non-dairy creamersilicon dioxide (silica) in soups (same stuff in those little bags thatcome with electronic equipment etc.)