Transcript 17 Food Additives

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 acids
alcohols 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
COO- Na+
pie fillings, jams, syrups, pickles, relishes, olives, margarines,
jellies, non-alcoholic beverages (found naturally in cranberries)
SODIUM PROPANOATE (PROPIONATE)
CH3CH2COO- Na+
≤0.3%
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 or
out, 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
R = methyl, propyl,...
eg propylparabens
COOH
NH2
PABA
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 ppm
LD50 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 nitrates
naturally (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 mg/mL of nitrite in saliva and about 5 mg of nitrite in the gut!
FRUITS
SO2 (sulfur dioxide) gas OR sulphite salts
Used: in dried fruits, wines, syrups, jellies, dehydrated potatoes
acts both as a bleach and to kill bacteria
IRRADIATION
g-emitter: produce hydroxyl free radicals that kill most microorganisms and inhibit many enzymes, prevent sprouting and ripening
60Co
ANTI-OXIDANTS: many are phenols
OH
OH
OH
HO
OMe
BHT
BHA
OH
COOPr
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
CH3COO
HCOO
raspberries
CH3COO
pears
bananas
CH3CH2CH2COO
CH3CH2CH2COO
pineapples
apricots
CH3CH2CH2CO SCH3
bananas
CH3COO
oranges
HCOO
strawberries
CH3CH2COO
rum
rum
CH3O
CHO
almonds,
marishino cherries
CH3COO
COOCH3
HO
CHO
NH2
vanilla
grape
HO
OH
CHO
S
S
COOCH3
wintergreen
cinnamon
menthol
garlic
FLAVOUR ENHANCERS
Potentiators: don’t have taste themselves, but enhance the flavour of
others
MSG 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
OH
N
H2PO 4
O
N
N
O
N
OH
O
HO OH
inosinic acid,
used as sodium salt
Maltol (from pine needles)
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
CO
NH
SO2
discovered 1879
300x sweeter than sucrose
‘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)
NHSO3
30x sweeter than sucrose,
but no after-taste
2Ca
2+
2
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
COOCH 3
ASPARTAME (1965)
NH 2
NHCO
180x sweeter than sucrose,
texture of sugar
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 goods
100’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
HEAT STABLE:
useful in baking
http://www.cfsan.fda.gov/~lrd/tpneotam.html
COOCH3
NHCH2 CH2 C(CH3 )3
NHCO
COOH
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 400700 nm region – we see the
complimentary color
eg. b-carotene absorbs blueviolet 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 dried
pregnant scale insects of Mexico, Peru and
the Canary Islands: highly valued dye in
colonial 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
HO
COOH
COOH
HO
H
COOH
malic acid
(apples)
HO
COOH
tartaric acid
(grapes)
COOH
COOH
citric acid
(lemons)
COOH
CH 3
OH
lactic acid
(milk)
In candy manufacture, acid converts sucrose to softer invert sugar:
LOW ACID gives hard (crystalline) candies
HIGH ACID gives softer, chewy (less crystalline) candies
BUFFERS usually sodium or potassium salts of di or tri-acids
eg. potassium acid tartrate:
HO
COO-
HO
COOK
base
HO
COOH
HO
COOK
acid
HO
COOH
HO
COOH
Buffer
ANTI-CAKING AGENTS: prevent moisture from forming lumps
1% magnesium silicate in salt
sodium aluminosilicate in non-dairy creamer
silicon dioxide (silica) in soups (same stuff in those little bags that
come with electronic equipment etc.)