Transcript Unit 12.3 web

Food Additives
Chapter 19
A food additive is anything intentionally added to
a food to produce a specific, beneficial result.
In Canada there are almost 3000 compounds(~ 1500
of these are 'flavours') deliberately added to foods*.
There are approximately the same number in other
developed countries but not always the same
compounds. Many have multiple uses.
*another ~5000 are accidentally added during
growing, harvesting and packaging
Since ~1960 all new food additives must undergo
safety testing, however additives that were used prior
to this date are 'grandfathered' unless new safety
issues are discovered.
The GRAS list is a list of food additives that are
generally recognized as safe by a panel of experts,
but that have not been subjected to laboratory testing.
Categories of Food Additives
Added to foods to:
Make more appealing - flavours (& enhancers),
colours, acidity
Make more nutritious - vitamins, minerals
Preserve freshness/keep unspoiled - preservatives,
antioxidants(sequestrants)
Make easier to process - anticaking agents,
humectants
Keep stable during storage - stabilizers, thickeners,
emulsifiers
Food Preservation
Oxidation and microorganisms (bacteria, fungi, other)
are the major causes of the decomposition of food.
Drying (grain, fruit, meat/fish) is one of the oldest
preservation techniques, since water is
necessary for both the growth of microorganisms and oxidation reactions.
Salting (meat/fish) and preserving in concentrated
sugar solution(fruit) also dehydrates(-H2O).
Other methods include: Pasteurization(heat to
~140oF)),
Smoking, Canning(remove O2), (vacuum)
Freezing(slow oxidation), Irradiation.
Preservation is effective if it prevents multiplication of
microorganisms during the shelf life of the product.
Sterilization( heat, radiation) or inactivation by
freezing are two common 'physical' techniques.
Two of the most common chemical preservatives in
packaged foods are:
sodium benzoate - fruit juices, margarine, pickles,
nonalcoholic beverages, olives,
salads, pie fillings, jams & jellies
sodium propionate - bread, chocolate products,
cheese, pie crust and fillings.
Chemical Preservatives
Chemical preservatives are usually derivatives of acids
that kill the microorganisms by increasing slightly the
acidity of the food. They can be:
Organic: Benzoates; Propionates; Sorbates :
antimicrobial agents-act vs. mould etc.
Inorganic: Sulfites (SO22-); Nitrites/Nitrates(NO2-/ NO3-)
for botulism
The nitrite dilemma (risk balancing)
• Sodium nitrite (NaNO2) : prevents growth
of the Botulinum toxin in meat (botulus L
sausage) and improperly canned fruits/vegs
• But it may also produce nitrosoamines
(potentially carcinogenic) in humans
• Pick your poison!
Antioxidants
The action of oxygen in the air is the chief cause of the
destruction of the fats in food. Oxidation produces a
complex mixture of volatile aldehydes, ketones and
acids that cause the rancid odor/taste.
Antioxidants can be:
Organic - Ascorbates
Butylated hydroxyanisole (BHA)
Butylated hydroxytoluence (BHT)
Lecithin (a 'natural' phospholipid)
Inorganic - Sulfur Dioxide and Sulfites
Common Synthetic Antioxidants (like Vit. E)
OH
BHA (Butylated
Hydroxy Anisole)
OH
OCH3
BHT(Butylated
Hydroxy Toluene
CH3
Sequestrants
Metals get into food from the soil and from the
machinery of harvesting and processing. Copper, iron
and nickel catalyze the oxidation of fats.
Sequestrants are able to bond with a metal ion
so firmly that it removes the metal from any
chemical reaction with other substances.
They have multiple 'arms'/functional groups to
'envelope' (or chelate) the metal atoms.
Common sequestrants are:
EDTA(ethylenediaminetetraacetic acid),
Citric acid, Pyrophosphate, Sorbitol
EDTA structure
• 4 arms!
pH Control in Foods
Weak organic acids when added to such foods as
cheese, beverages and dressings give a mild acidic
taste. They often mask undesirable aftertastes.
Weak acids react with bicarbonate to form CO2 in
the baking process. Acid and buffer examples:
acetic acid, citric acid, phosphoric acid( & salts),
lactic acid(& Ca salt), potassium acid tartrate
These versatile acidulants also function as antimicrobial agents, antioxidants(to prevent rancidity
and browning)and viscosity modifiers in dough.
Stabilizers/Thickeners/Emulsifiers
Stabilizers and thickeners(to improve the texture and
blends of foods) are usually polysaccharides. The
hydroxyl groups, using H-bonds, provide a more even
blend of the water and oils in the food. Stabilizers and
thickeners are particularly effective in icing, frozen
desserts, whipped cream, confections and cheeses.
Eg. agar, algins, carrageenan. “Phycocolloids”
Emulsifying Agents (detergent-like) keep oil/water
mixtures, ie. peanut butter, salad dressing, from
separating. They are mono - and diglycerides of fatty
acids.
Phycocolloids
•
•
•
•
Carrageenan, agar, alginates
All come from red and brown algae
Polysaccharides (lots of H bonds)
Help blend water and oil
Monoglyceride
• Hydrophobic and hydrophilic parts-good
emulsifier
Anticaking Agents / Humectants
Anticaking agents react readily with water. They are
added, (1% or less), to hygroscopic foods, eg. table
salt, which absorb water from the air. This prevents
'caking' of such foods in humid weather.
Anticaking Agents:
Silicates, Silicon Dioxide, Iron ammonium citrate
(Table salt has NaCl, KI and SiO2)
Humectants do the opposite, ie. keep foods “moist”,
by 'interfacing' with both the food & water, eg.
glycerine(shredded coconut), glycerine
monostearate(marshmellows)
Presence of one additive leads to
another!
• Table salt: 4 ingredients: NaCl, KI, SiO2 and
sodium thiosulfate
• Sodium thiosulfate is present to stabilize the
iodide-ie keep salt from discoloring if salt
gets wet!
Food Flavours
Much of the sensation of taste in food is from our
sense of smell. Natural 'flavours, like coffee or apple
juice, are determined largely by mixtures of 100's of
small, volatile compounds. Most flavor additives and
perfume ingredients originally came from plants.
Today synthetic preparations of the same flavors are
common food additives. Some examples:
iso(banana)pentyl(pear) ethanoate, iso(strawberry)
butyl(raspberry)ethanoate, methyl butanoate
(pineapple), ethyl formate/butyl propanoate(rum)
Ethylbutyrate: Oranges –in flavor packs
(processed OJ: CBC 2009)
Some Natural Flavours
O
O
O
OCH3
H
OCH3
almond
NH2
OH
grape
wintergreen
OH
CH2 CH CH2
HO
CH3O
O
cloves
peppermint
H2C CH CH2 S S CH2 CH CH2
garlic
O
CH CH
cinnamon
H
O
HO
CH3O
H
vanilla
Flavour Enhancers
Compounds that have little/no flavour themselves
but that amplify/enhance the flavours of other
compounds, or can cover unwanted flavours.
First used in meat/fish but now present in vegetables,
baked goods, fruits, beverages. Some examples:
Monosodium glutamate - the MSG of Chinese
restaurants
(also present in Parmesan cheese!)
5'-Nucleotides (for meat, salt)
Artificial Sweeteners: Why?
• Weight reduction
• Dental health
• More variety in food for diabetics
• But…….recent study………….
Feb 11/08 Study on Rats
• Those fed artificially sweetened yogurt
gained more weight than those on yogurt
with sugar!!
• Seemed to be an appetite stimulating effect
of saccharin!
• Q: is the obesity epidemic related?
How Sweet It Is!
World-wide the artificial
sweetener market is $1
billion(US). Aspartame
had ~75% of that (2004)
Nutrasweet/Equal =
aspartame
Splenda =
sucralose
Artificial Sweeteners
Compound
Index
Sorbitol
Glucose
Xylitol
Sucrose
Fructose
Cyclamate
Aspartame
Acesulfame
Saccharin
Sucralose
Alitame
P-4000
0.6
0.7
0.8
1.0
1.7
30
160
200
500
600
2000
4000
The Saga of Sweeteners in NA
Saccharin(1879) was first banned in ~1905 but
reinstated during World War 1. Cyclamate(1937) when
combined with saccharin leaves no bitter aftertaste.
Animal studies in Canada & US in 60s & 70s
implicated both as cancer causing. Cyclamates were
banned in US (not Canada or 40 other countries) in
1969 but when FDA tried to ban saccharin the public
forced US Congress to allow it, with warning labels.
Aspartame approved in early '80s, acesulfame in '96,
sucralose in '98 in US (Canada always ~2 years later).
The 'sugar alcohols' sorbitol & xylitol are not broken
down in the mouth, thus used for chewing gum.
Artificial Sweetners
H
+
Na
SO
O
3
N
+H
H3N C
O
CH2
-
-
O
H
N C
H
CH2
OMe
saccharin
aspartame
CH2OH
O
N Na
SO2
COO
cyclamate
Cl
CH2OH
CH2OH
CHOH
CHOH
CHOH
CHOH
ClCH2
OH
O
+
O
HO
CH2Cl
O
+
N-K
OH HO
sucralose
S
H3C
O
O
O
acesulfame
CHOH
CHOH
CH2OH
sorbitol
CHOH
CH2OH
xylitol
Aspartame
• The most widely researched food additive
ever!
• Cannot be used in cooked or baked foods:
breaks down and thus loses its sweetening
power
• one controversy concerns MeOH metabolic
product (but apple juices have 2x)
Other issues with Aspartame
• Aspartic acid (humans biosynthesize it)
• Phenylalanine (an essential a.a.)
• Some children (1/20,000) cannot metabolize
phenylalanine
• Phenylketonurea (Folling’s disease) results
PKU (Phenylketonurea)
• Symptoms in infants: lethargy, poor feeding
“mousy” urine odour
• Enzyme is lacking for phenylalanine
metabolism; thus accumulates in blood
• Can lead to mental retardation
• Also low tyrosine levels: use tyrosine supp’s
Sweetener Wars (2007)
• Companies duke it out over Splenda ads!
• “unfair advantage in advertising” to Splenda
• “Splenda is made from sugar, so it tastes
like sugar” –ad misleads customers into
thinking that it is more “natural” than
Aspartame
Synthesis of Sucralose
• Sucrose >>>>> 5 step synthesis gives
trichlorosucrose
• Metabolism: controversial!!
• Partially broken down (20%) : remainder is
excreted unchanged
• Questions: are the chlorofructose metabolic
products harmful?
Advantage to sucralose!
• Can withstand the high temps used in
cooking and baking!
• Market share is increasing (2008)
Decision
• Court ruled no unfair advantage to sucralose
makers
• No damages awarded to makers of
aspartame
Sorbitol in your chewing gum
•
•
•
•
Sorbitol ~same sweetness index as sucrose
Not metabolized
Stimulates colonic movement
Pro-anorexia websites tout it as weight-loss
aid
• 20 sticks of sugar free gum/day. 25% loss/yr
• But..severe abdominal pain, diarrhea
Sorbitol is everywhere!
Sweetners of the Future?
OCH2CH2CH3
NH2
OCH2CH2CH3
NO2
OCH2CH2CH3
NO2
NO2
NH2
NO2
P-4000
(extremely sweet)
Cmpd I
(tasteless)
O
HOOC
H
CH2 C
Cmpd. II
(bitter)
CH3
N
H
CH
NH2
N
H
O
Alitame
S
Q: What makes a molecule taste
sweet?
• Huge research area (BIG$$)
• Molecule needs both a H bond donor and an
acceptor
• Molecule must have a hydrophobic (water
repelling) part
• “handedness” may be important: (L!)
• X-ray crystal structures of aspartyl based
sweeteners compared
Looking at Compd II
•
•
•
•
Has only H bond acceptors!
Bitter taste
Position is imp (Compd I vs. P-4000)
Alitame and P-4000 look promising!
Food Colouring It's Everywhere!
Natural: -carotene, beet juice, saffron, paprika
Synthetic:
Inorganic - titanium dioxide(white frosting),
iron oxide(egg shells, food colouring)
Organic - tartrazine (yellow#5; corn, cheese, pasta)
erythrosine (red#3; cherry pie, ice cream)
amaranth(red#2; candy, jello, orangeskins)
allura red (red#40; cereals, " ", puddings)
sunset yellow (yellow#6; soft drinks)
indigotine (blue#2; soft drinks, 'koolaid')
Synthetic Food Colours – recently banned in USA
NH2
HO
N N
SO3Na
N N
Orange #1
HO
NaO3S
Yellow #3
SO3Na
N N
NH2
H3C
N N
Yellow # 4
Red # 2
SO3Na
Why do you think these were
banned?
• Look at the nature of the structures (planar)?
• DNA Intercalators?
Vitamins & Minerals - Nutritional Additives
Some of the essential micronutrients are added, by
law, to 'basic' foods to enrich / fortify our diet as a
public health / preventative measure.
Vitamins: vit. D / vit. A(milk), carotene (margarine),
B-complex, ie. B1, B2, B3, sometimes B6, B9(flour).
Minerals: calcium(milk), iodine ('iodized' salt).
Others are added for various reasons, eg. labeling
regulations (mandatory / voluntary).
Good Food ? Bad Food ?
Some possible definitions A junk food is a food that supplies a large
number of calories but few micronutrients.
That means Empty calories are contained in foods, such as
highly refined sugar, that provide many calories
but few or no micronutrients to accompany them.
=> =>
The larger the variety and amount of micronutrients
provided by a food and the fewer calories, the more
healthful it is.
A healthy food supplies a large number of
micronutrients compared with its calories.
(ie. green vegetables: spinach)
Yum, Yum – Breakfast !
Scrambled Eggs: ovalbumin, ovomucoid, mucin, amino
acids, globulins, lipovitellin, cholesterol, lecithin,
lutein, triglycerides, fatty acids, butyric acid, acetic
acid, sodium chloride, zeaxanthin, vitamin A, B, E,
Ham(sugar-cured): actomycin, myosin(muscle proteins),
nucleoproteins,
peptides, amino acids, myoglobin, lipids, fatty
acids, lecithin, sucrose, ATP, glucose, collagen,
elastin, creatine, sodium chloride, sodium
nitrate/ nitrite, sodium phosphate.
Lutein and zeaxanthin in eggs
• Both are carotenes: provide colour to yolk
and may “protect vision”
• Zeaxanthin tablets are new “eye
supplements”
• Possibly protect vs. macular degeneration
age related:light sensing cells in the central
area of vision (macula) degrade and then die
Yum, Yum – Breakfast(cont’d) !
Toast/Coffee Cake: gluten(protein in wheat, barley, oats,
amylose, amino acids, iron,
methyl ethyl ketone, dextrins, starches, sucrose,
thiamine, triglycerides, sodium chloride, riboflavin,
phosphates, calcium, mono-/diglycerides, niacin,
ethyl lactate, pantothenic acid, vitamin D, maltol,
acetic/propionic/butyric/valeric/caproic acids,
ethyl acetate.
Coffee: caffeine, essential oils, methanol, acetaldehyde,
methyl formate, ethanol, dimethyl sulfide, butanol,
acetone, propionaldehyde, methyl acetate,
(methyl)furan, isoprene, pentanol.
Our Daily Prayer !
To the editor of Times Union (Albany, New York):
Give us this day our daily calcium propionate(spoilage
retarder), sodium diacetate(mold inhibitor), calcium
phosphate monobasic(dough conditioner), chloramine T
(flour bleach), monoglyceride (emulsifier), potassium
bromate(maturing agent), aluminum potassium sulfate
(acid baking powder), sodium benzoate (preservative),
butylated hydroxy anisole (antioxidant), mono-isopropyl
citrate (sequestrant), plus synthetic vitamins A & D.
Forgive us, O Lord, for calling this stuff BREAD!
from J. H.Read
End of material covered on Friday June 12,
2009 Midterm!! (Azrielli Theatre (AT) 101)
5-7 PM