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Problem Set

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sodium benzoate - fruit juices, margarine, pickles, nonalcoholic beverages, olives, ... one controversy concerns MeOH metabolic product (but apple juices have 2x) ... – PowerPoint PPT presentation

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Title: Problem Set


1
Problem Set 5
  • Chapt 19 1, 5, 10, 17

2
Food Additives Chapter 19
3
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
4
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.
5
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

6
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 micro-
organisms and oxidation reactions. Salting
(meat/fish) and preserving in concentrated
sugar solution(fruit) also
dehydrates(-H2O). Other methods include
Pasteurization(heat), Smoking,
Canning(remove O2), (vacuum)
Freezing(slow oxidation), Irradiation.

7
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.
8
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 for
molds Inorganic Sulfites (SO22-)
Nitrites/Nitrates(NO2-/ NO3-)
for
botulism
9
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!

10
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) Inorga
nic - Sulfur Dioxide and Sulfites
11
Common Synthetic Antioxidants (like Vit. E)
BHA (Butylated Hydroxy Anisole)
BHT(Butylated Hydroxy Toluene
12
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
13
EDTA structure
  • 4 arms!

14
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 anti- microbial agents,
antioxidants(to prevent rancidity and
browning)and viscosity modifiers in dough.
15
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. Emulsifying Agents (detergent-like)
keep oil/water mixtures, ie. peanut butter, salad
dressing, from separating. They are mono - and
diglycerides of fatty acids.
16
Monoglyceride
  • Hydrophobic and hydrophilic parts

17
(No Transcript)
18
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)
19
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)
20
Some Natural Flavours
almond
grape
wintergreen
cloves
peppermint
garlic
vanilla
cinnamon
21
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)
22
Artificial Sweeteners Why?
  • Weight reduction
  • Dental health
  • More variety in food for diabetics
  • But.recent study.

23
Feb 11/08 Study on Rats
  • P1 Ottawa Citizen/Globe (Erin Westby 2)
  • 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?

24
How Sweet It Is! Artificial Sweeteners
Compound Index Sorbitol 0.6
Glucose 0.7 Xylitol
0.8 Sucrose 1.0 Fructose
1.7 Cyclamate 30 Aspartame
160 Acesulfame 200 Saccharin
500 Sucralose 600 Alitame
2000 P-4000 4000
World-wide the artificial sweetener market is 1
billion(US). Aspartame had 75 of that
(2004) Nutrasweet/Equal
aspartame Splenda sucralose
25
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.
26
Artificial Sweetners
saccharin
cyclamate
aspartame
sucralose
xylitol
acesulfame
sorbitol
27
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)

28
Other issues with Aspartame
  • Aspartic acid (humans biosynthesize it)
  • Phenylalanine (an essential a.a.)
  • Some children (1/20,000) cannot metabolize
    phenylalanine
  • Phenylketonurea (Follings disease) results

29
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 supps

30
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

31
Synthesis of Sucralose
  • Sucrose gtgtgtgtgt 5 step synthesis gives
    trichlorosucrose
  • Metabolism controversial!!
  • Partially broken down (20) remainder is
    excreted unchanged
  • Questions are the chlorofructose metabolic
    products harmful?

32
Advantage to sucralose!
  • Can withstand the high temps used in cooking and
    baking!
  • Market share is increasing (2008)

33
Decision
  • Court ruled no unfair advantage to sucralose
    makers
  • No damages awarded to makers of aspartame

34
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

35
Sorbitol is everywhere!
36
Sweetners of the Future?
P-4000 (extremely sweet)
Cmpd I (tasteless)
Cmpd. II (bitter)
Alitame
37
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

38
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!

39
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 (yellow5 corn, cheese, pasta)
erythrosine (red3 cherry pie, ice
cream) amaranth(red2
candy, jello, orangeskins)
allura red (red40 cereals, " ", puddings)
sunset yellow (yellow6
soft drinks) indigotine
(blue2 soft drinks, 'koolaid')
40
Synthetic Food Colours recently banned in USA
Orange 1
Yellow 3
Yellow 4
Red 2
41
Why do you think these were banned?
  • Look at the nature of the structures (planar)?
  • DNA Intercalators?

42
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).
43
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.

gt gt

44
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)
45
Yum, Yum Breakfast !
Scrambled Eggs ovalbumin, ovomucoid, mucin,
amino acids, globulins,
lipovitellin, cholesterol, lecithin,
lutein, triglycerides, fatty acids, butyric acid,
acetic acid, sodium chloride,
zeaxanthine, vitamin A, B, E,
Ham(sugar-cured) actomysin, myogen,
nucleoproteins, peptides, amino
acids, myoglobin, lipids, fatty
acids, lecithin, sucrose, ATP, glucose, collagen,
elastin, creatine, sodium chloride,
sodium nitrate/ nitrite, sodium phosphate.
46
Lutein and zeaxanthin in eggs
  • Both are carotenes provide colour to yolk and
    may protect vision
  • Zeaxanthine tablets are new eye supplements
  • Possibly protect vs. macular degeneration age
    relatedlight sensing cells in the central area
    of vision (macula) degrade and then die

47
Yum, Yum Breakfast(contd) !
Toast/Coffee Cake gluten, 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.
48
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
49
Problem Set 6
  • Chapt 19 2, 11, 46
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