Term
| Lipids are soluble in _____________. |
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Definition
| Lipids are soluble in organic solvents. |
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Term
Fats are _____ at room temp.
Oils are _____ at room temp.
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Definition
Fats are solid at room temp
Oils are liquid at room temp. |
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Term
| What happens if R1 and R3 on a triglyercide are the same? |
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Definition
| There are no chiral centers. |
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Term
| Where is the chiral center on a triglyercide? |
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Definition
| C2 from the carbon backbone. |
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Term
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Definition
| Stereospecific numbering. |
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Term
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Definition
N = # of carbons in chain
M = number of c=c bonds
(So, if M is 0, it is saturated. It M > 0, it is unsaturated) |
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Term
Δ
What does this indicate? Give example. |
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Definition
Position of double bond.
Ex: 18:1 Δ9
Means there is a double bond from C9 to C10. |
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Term
Normal numbering vs. nutritionist numbering of fatty acids.
For nutrition, what denotes double bond position? |
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Definition
Normal: from C=O end, where this C is C1.
Nutrition: other end first.
w symbol replaces Δ for double bond position (so 9, 12, 15 would become 3, 6, 9) |
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Term
Cis vs. trans.
Applies to what? |
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Definition
Cis: R groups are next to each other
Trans: R groups are diagonally across.
Applies to double bonds; they can be either cis or trans. |
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Term
Fatty Acid constituent names
4:0 |
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Definition
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Term
Fatty Acid constituent names
6:0 |
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Definition
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|
Term
Fatty Acid constituent names
8:0 |
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Definition
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|
Term
Fatty Acid constituent names
10:0
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Definition
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|
Term
Fatty Acid constituent names
12:0 |
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Definition
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Term
Fatty Acid constituent names
14:0 |
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Definition
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Term
Fatty Acid constituent names
16:0 |
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Definition
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|
Term
Fatty Acid constituent names
18:0
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Definition
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Term
Fatty Acid constituent names
18:1
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Definition
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|
Term
Fatty Acid constituent names
18:12Δ9,12
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Definition
9,12-Octadecadienoic
Linoleic |
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Term
Fatty Acid constituent names
18:3 |
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Definition
9,12,15-Octadecatrienoic
'
Linolenic |
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Term
Fatty Acid constituent names
20:0 |
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Definition
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Term
Fatty Acid constituent names
20:4 |
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Definition
5,8,11,14-Eicosatetraenoic
Arachadonic
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Term
Fatty Acid constituent names
22:1 |
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Definition
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Term
| _______ double bonds are lower in energy state. |
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Definition
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Term
| Common attributes of most fatty acids (3). |
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Definition
1. Even number of carbons
2. linear (not branched)
3. double bonds in nature are cis. |
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Term
| Name the components of a phospholipid. |
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Definition
--Glycerol backbone.
--2 fatty acid substituents
--the third attachment is a phosphate group. |
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Term
| Phospholipid heads are ____/__/___; tails are ___/___/___. |
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Definition
Heads: polar/charged/hydrophilic
Tails: nonpolar/neutral/hydrophobic |
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Term
What does amphiphilic mean? |
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Definition
Has both hydrophobic and hydrophilic properties.
Ex: Phospholipids |
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Term
| What does surface active mean? |
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Definition
| Phospholipids can sit between hydrophobic and hydrophilic phases (i.e. air/water, oil/water) |
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Term
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Definition
Esters
of long chain fatty acids
and long chain alcohols. |
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Term
|
Definition
--solid
--impermeable to water
--insoluble in water |
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Term
| Major functions of lipids in foods (3) |
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Definition
1. Energy & health
2. Food flavors
3. Texture |
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Term
| How do lipids influence food flavors? |
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Definition
--free fatty acids add flavors.
--lipids can act as solvents, carry hydrophobic flavors/aromas |
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Term
| What determines attributes of food lipids? |
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Definition
| Types and positions of fatty acids. |
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Term
| What does the plant triglyceride bar graph mean? |
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Definition
Column 1:Tells what % of sn1is comprised of 16:0 fatty acid
Column 2: Tells what % of sn2 is comprised of 16:0 fatty acid.
etc.
If you add up all the left columns, you get 100% of sn1 (add %16:0, %18:0, %18:1, etc.) |
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Term
Mostly saturated or unsaturated?
Cocoa butter
Peanut oil
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Definition
Cocoa butter: sat'd
Peanut oil: unsat
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Term
| _________ has many types of triglycerides, whereas the triglycerides in ___________ are much more homogeneous. |
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Definition
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Term
Compare fatty acids in cocoa butter and tallow.
Mostly ___ at sn2? |
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Definition
There is a similar composition of fatty acids, but the way these fatty acids are arranged at the sn1, sn2, and sn3 positions makes them have different triglycerides.
Cocoa = mostly U at sn2
Animals = mostly S at sn2 |
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Term
| What causes milk rancidity? |
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Definition
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|
Term
| What types of fatty acids are in marine/fish oils? |
|
Definition
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Term
|
Definition
-sn1 and sn2 are hydrolized to release fatty acids.
-rearranged to make triglycerides
-transported by chylomicrons to liver
-liver synthesizes other lipoproteins
-Shorter chain fatty acids are not made into triglycerides. They go directly to the blood. |
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Term
| Describe the different lipoproteins. |
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Definition
1. chylomicrons: large, least dense, mostly lipid (low protein content)
2. VLDL: smaller, more dense, become
3. LDL: smaller, more dense
4. HDL: smallest, most dense
From top to bottom: decreasing size, increasing density |
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Term
Where do LDL and HDL carry cholesterol?
High ____ ratio is good. |
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Definition
LDL: from liver to cells/arteries
HDL: from cells/arteries to liver (good)
High HDL/LDL ratio.
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Term
| Effects of triglycerides on cholesterol type (for sat'd, trans, & unsat'd) |
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Definition
sat'd: all increase
trans: LDL up, HDL down
unsat'd: HDL up, LDL down |
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Term
| Saturated fatty acids are absorbed better from _____________. |
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Definition
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|
Term
Flavor contributed by free fatty acids?
Examples? |
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Definition
bitter/soapy
ex: rancid milk, strong cheese
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Term
| Which flavors do lipid oxidations reactions produce (examples)? |
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Definition
-smelly fish
-refried fat |
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Term
| ____-chain fatty acids = stronger flavor |
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Definition
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Term
| Crystallization is a balance between... |
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Definition
entropic considerations & attractive intermolecular forces.
(close packing is favored, even though disorder is favored...65L) |
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Term
| Name attractive (2) and repulsive (2) forces. |
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Definition
Repulsive:
-electrostatic (i.e. Na+ and Na+)
-steric interactions (think stereochemistry...crowding of particles/atoms = repulsion)
Attractive
-H bonds
-Van der Waals
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Term
| Where do VdW forces occur? |
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Definition
-primary attraction btwn nonpolar lipid molecules
-attractive force between any two molecules
-stronger attraction when molecules are similar |
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Term
When are VdW forces strongest?
Ex? |
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Definition
When molecules are closer together, packed closely
Ex: long, strain chain molecules pack the best --> strongest VdW forces |
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Term
| At molecular level, causes of melting? (2) |
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Definition
1. weak intermolecular interactions
2. higher entropy |
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Term
| Low temp characteristics (entropy, enthalpy, crystallization, melting pt) |
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Definition
1. weak entropy
2. strong enthalpy ("can win"--maximized attractive VdW forces)
3. crystalline solids
4. MP depends on enthalpic interactions |
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Term
Long vs short chain fatty acids
Unsat vs. Sat
Cis vs trans
Which packs better?
Which has higher melting pt? |
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Definition
Long chain packs better, has higher MP.
Saturated
Trans |
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Term
| What reaction increases the MP? |
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Definition
| Hydrogenation--turns plant oils into semisolid. |
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Term
Melting point trends with regard to:
-chain length
-degree of saturation
-cis/trans |
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Definition
-longer chain = higher MP
-more saturated = higher MP (HUGE effect!!)
-trans = higher MP
sat'd = 18:1, 18:2, 18:3, etc... anything that doesn't end in :0 |
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Term
Compare melting/crystallization of lard and cocoa butter.
Describe consistency. |
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Definition
Lard: Heterogeneous, so MELT, this breaks all triglycerides apart. As you cool it, sat fat crystallize at highest temp, then the ones with most sat fatty acids. Crystallization occurs over a range of temperatures. Makes it greasy. (Mixture of sold + liquid)
Cocoa butter: they all crystallize at same temp. So it's either solid or liquid. |
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Term
| What does rapid cooling do? What's the opposite of this? |
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Definition
Rapid cooling: traps fats in a higher energy crystal form.
Controlled cooling: tempering. |
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Term
What's it called when fats rearrange into a new crystal form?
How does this happen? |
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Definition
Polymorphism
Heating fat just to melting pt. |
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Term
| How does polymorphism occur in chocolate? |
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Definition
| Upon heating. Develops bloom. |
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Term
CHAIN LENGTH PACKING
1. If sn2 is similar to sn3?
2. if sn2 is different from sn3? |
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Definition
1. double chain length packing
2. triple chain length packing (sandwich the sn2's) |
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Term
List the 3 crystal packing forms
-from least stable to most stable
-from least ordered to most ordered
-lowest to highest energy |
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Definition
a (alpha): least stable, least ordered
B (Beta)
B': most stable, most ordered
a: highest energy
B
B': lowest energy |
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Term
What is hydrolysis of lipids called?
What is the basic reaction? |
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Definition
Lipolysis.
triglycerides <--H20--> diglycerides, monoglycerides, glyerol, + fatty acids |
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Term
| Name 4 lipid hydrolysis reactions. Briefly describe. |
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Definition
1. saponification (base catalyzed)
2. acid catalyzed (lipase catalyzed)
3. esterification (reverse rxn)
4. interesterificaiton (randomization) |
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Term
| What products does hydrogenation of unsat'd lipids create? (2) |
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Definition
sat'd lipids
trans isomers |
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Term
| Which lipid hydrolysis method does not occur spontaneously and what is it used for? |
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Definition
Based-catalyzed/saponification.
Used on purpose to free up fatty acids to make soaps/cleaning products. |
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Term
What's the significance of the sn2 position with regard to digestion? |
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Definition
-The sn2 chain is largely conserved.
-What you eat at the sn2 position with be delivered to your cells at the sn2 position (sn2 fatty acid in food triglycerides enters stays there when it becomes a triglycerides that goes into your body) |
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Term
| Which lipid hydrolysis mechanisms occur naturally during digestion and in foods over time? |
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Definition
| acid- and enzyme- catalyzed. |
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Term
|
Definition
Lipase produces small quantities of fatty acids -->
creates a protein film around a gas bubble
--uhh...caused by surfactants, which are amphiphilic (interact with both hydrophobic and hydrophilic environments...) |
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Term
| What causes off flavors in milk, vegetables, and fruits, as well as strong flavors in cheese? How do you prevent these off flavors? |
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Definition
Free fatty acids.
Blanching. |
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Term
| 3 things that are surface active and amphiphilic |
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Definition
monoglycerides, diglycerides, and fatty acids.
But not triglycerides! |
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Term
What is the basic structure of Olestra?
Is it digested? Why or why not? |
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Definition
fatty acids attached to sucrose.
Not digested --not large for lipolysis |
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Term
| What's are the two basic steps of interesterification? |
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Definition
1. hydrolyze to remove fatty acids
2. reattach fatty acids by esterification |
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Term
| What is one potential purpose of interesterification? |
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Definition
| Create different triglycerides so that the trigs. have a more similar melting point, and improve the properties of food. |
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Term
| Which form of saturated fat occurs naturally? |
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Definition
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Term
| What is required in order for a hydrogenation reactions to occur? |
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Definition
| Metal catalyst, i.e. nickel, copper |
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Term
| Hydrogenation is a ____________ reaction of lipids. It __________ the melting point. |
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Definition
Hydrogenation is a reduction reaction of lipids. It raises the melting point.
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Term
| What does "partially hydrogenated" mean? |
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Definition
| Some of the double bonds are removed, but not all. |
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Term
What are semisolids?
Give 4 examples. |
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Definition
Mixture of solid and liquid triglycerides.
Crisco
lard
butter
margarine |
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|
Term
Basic steps of hydrogenation...
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Definition
trienes--> dienes (quick)
dienes--> monoenes (quick)
monoenes -->no double bonds/fully sat'd (slow)
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|
Term
|
Definition
| Unsaturated fatty acid groups containing trans double bonds. This only occurs when fats have been partially hydrogenated. (Only Cis occurs in nature) |
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Term
| What are the 3 main phases of lipid oxidation? |
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Definition
Initiation
Propagation
Termination |
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Term
| What are the 3 mechanisms of initiation of oxidation? |
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Definition
1. Photooxidation
2.Enzymatic--lipoxygenases
3. Metal ions |
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Term
| _______ is a solvent for hydrophilic flavors |
|
Definition
|
|
Term
| Aw/deterioration relationship |
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Definition
| As Aw increases, deterioration increases |
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Term
| Water has a strong ___________ moment. |
|
Definition
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|
Term
| What types of molecules does water H bond with? Why? |
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Definition
| Sugars, proteins, polysaccharides--because they are polar |
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Term
| When water molecules interact strongly with a small number of hydrophilic solute particles, this is called ______________ or ___________ |
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Definition
bound water
water of hydration |
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Term
| What is a property of water of hydration/bound water? |
|
Definition
| Hindered mobility, less capable of deterioration reactions |
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Term
|
Definition
|
|
Term
|
Definition
p/po
p= vapor pressure of water above food
po = vpor pressure above pure water
(relative humidity!)
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|
Term
| (lower, higher) MW solutes have a stronger effect on aw |
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Definition
| lower molecular weight = stronger effect |
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|
Term
| Does high aw means lots of solute or little solute? |
|
Definition
high aw = little solute
low aw = lots of solute |
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|
Term
| if aw is close to 1 , is that large or small |
|
Definition
large
can't be bigger than 1 |
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Term
| 3 ways to lowe water activity |
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Definition
decrease moisture (dehydration
increases solutes (i.e. add salt)
freeze |
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Term
|
Definition
aggregation
make gels, fibers, particles
ex: proteins polysaccharides |
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|
Term
| 2 types proteins in 3 structure |
|
Definition
globular
hydrophobic residues out inside, hydrophilic inside
fibrous
more hydrophilic, less compact |
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Term
| Water is attracted to _________ groups |
|
Definition
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|
Term
| Upon denaturation of proteins, what is exposed |
|
Definition
Internal residues
(exposes hydrophobic patches --> causes protein-protein attraction) |
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|
Term
|
Definition
Critical temperature
at which proteins denature |
|
|
Term
| What can cause denaturation? |
|
Definition
pH! ionization of amino acids
temperature
solvents
salts |
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|
Term
| What are salting out and salting in? |
|
Definition
salting out --> promotes denaturation
salting in --> prevents |
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|
Term
|
Definition
hydrolysis: makes amino acids and peptides
redox reactions: affects disulfide bonds, inter and intramolecular interactions
Maillard browning |
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|
Term
| How do you increase Tg and why do you want to? |
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Definition
Increases stability.
add hydrophilic polymers, increase solute concentration |
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Term
| Oxidation: what creates the bad smell? |
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Definition
| Hydroperoxides decompose into shorter chain aldehydes |
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