FOOD ADDITIVES The GRAS list: ‘Generally Regarded as Safe’ List aking agents: Ca silicate SiO 2 Iron ammonium citrate bases/buffers: acetates, citrates (left) , lactates, phosp tartarates, sorbates (middle) fiers (surfactants): mono- and diglycerides of fatty acids alcohols like sorbitol (right):
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FOOD ADDITIVES The GRAS list: ‘Generally Regarded as Safe’ List Anti-caking agents:Ca silicateSiO 2 Iron ammonium citrate Acids/bases/buffers:acetates,
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FOOD ADDITIVES
The GRAS list: ‘Generally Regarded as Safe’ List
Anti-caking agents: Ca silicate SiO2 Iron ammonium citrate
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
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.)