IB Chemistry 2
Name:__________________
Date:________Period:_____
Food Chemistry Notes
I. Rancidity
A. Hydrolytic Rancidity—
Definition: The breaking down of a lipid into ________ _______ and ______________.
Sped up by:
1. ______________
2. ______________
3. ______________
Example—Deep frying
B. Oxidative Rancidity/ __________ __________________-Definition--___________ ___________ chains oxidized by the addition of
_____________ across the __________ bond in an ________________________ fatty
acid.
Sped up by:
1. _________________
2. _________________
3. _________________
Examples—
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Mechanism of oxidative rancidity—
___________ - _______________ chain mechanism
B. Common synthetic antioxidants
1. ________ butylated hydroxyanisole
2. _______ butylated hydroxytoluene
3. ______ progyl gallate
4. ________ trihydroxybutyrophenone
5. _________ tert-butylhydroquinone
All contain a_______________ group, and many a tertiary butyl group.
Antioxidants found in traditional foods
1.
2.
3.
4.
5.
6.
All of these are linked to ________________________ and ____________________
levels, reducing ___________________________, and preventing the development of
____________.
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II. Dyes & Pigments
A. Definitions-A dye is a
A pigment is a
B. Why are pigments colored?
C. Naturally occurring pigments and their sources
1. Anthocyanins
a. the most widely occurring pigments in ____________________.
b. responsible for
c. found in
2. Carotenoids
a. the most ______________________ pigment in nature
b. often produced by
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c. acts as a
d. colors range from
e. found in
f. red astaxanthin, ________________ with _____________ and has a
________ or ________ color found in ________________ and ______________, and the
___________ color of ______________.
3. Chlorophyll
4. Heme
a.
b.
D. Color stability of naturally occurring pigments
1. Four general factors affecting color stability
A.
B.
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C.
D.
2. Anthocyanins--
In aqueous solution, ______________________________ exists between
________ different structural forms, depending on ________ and
___________________.
Anthocyanins are less stable when exposed to __________, leading to
Anthocyanins form deeply colored ____________________ with _____ and
_______.
Why might canned fruit become discolored?
3. Carotenoids--
Caretonoids are _________________________, containing many
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The double bonds can be ________________________. The oxidation is sped up
by
A.
B.
C.
Oxidation results in
A.
B.
C.
Carotenoids are stable


Would carotenoids be degraded by typical processing? Why or why not?
The naturally occurring ___________ isomer rearranges to the _______ isomer
upon heating.
4. Chlorophyll-Chlorophyll can be ____________________ by _______, but this depends on the
____.
In a basic solution…
In an acidic solution…
When heated, the cell membrane…
Then the magnesium atom is displaced by
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The resulting complex is
The cell membrane damage during heating also makes the chlorophyll susceptible
to
5. Heme--
In Mb and MbO2 the iron is in the _____ state and is readily oxidized to an _____
state in MMb.
Interconversion occurs readily between all three forms shown above.
Auto-oxidation and undesirable ___________ can be minimized by
III. Synthetic colorants and Safety
A. International concerns
1.
2.
3.
B. Example: 4-dimethylaminoazobenzene
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IV. Non-enzymatic browning of food-A. Maillard Reaction
1. Chemical composition of the foods affected
2. Examples--
3. Products of the process include
A.
B.
B. Caramelization
1. Chemical composition of the foods affected
2. Factors that increase the rate of reaction
3. Examples
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4. Products of the process include
V. Texture
A. Dispersed System in Food
Definition: A dispersed system is a ____________________ ______________ mixture
of ________ _____________ in another largely ____________________ phase.
Some Background Definitions—
1. Homogeneous
2. Immiscible
3. Miscible
4. Kinetically Stable
Food often appears ____________________________ when the food particles are
actually in different _______________. (______________________)
Why?
B. Types of Dispersed Systems
1.
2.
Example:
3.
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Example:
C. Emulsifiers
1. Types of emulsions a)
b)
2. Emulsifying agents






3. Making an Emulsion
To make an emulsion ___________________ energy is also
_________________.
4. Stabilizers
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VI. Genetically Modified Foods—
A. Definition—
A genetically modified food is…
It can be different or the same as the original food in terms of …
B. Benefits and Concerns of using GM foods.
1. Potential Benefits—
a. Crops
b. Animals
c. Environment
2. Potential Concerns
:
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