Food Chemistry Test 2

Front 1

Aliphatic AAs

Back 1

-Glycine (Gly)
-Alanine (Ala)
-Valine (Val)

-unreactive
-limited flexibility, molecular stability
-apolar face of alpha helix and b sheet and in core globular proteins
-Leucine (Leu)
-Isoleucine (Iso)

Front 2

Aromatic AAs

Back 2

-Phenylalanine (Phe)
-Tyrosine (Tyr)
-OH group makes it very reactive
-Tryptophan (Trp)
-used to quantify proteins because it can adsorb @ 280nm

Front 3

Proline

Back 3

-breaks alpha helix

Front 4

Sulfur Containing AAs

Back 4

-Cystine (Cys)
-2 cysteine sulfides are oxidized to form Cystine
-Methionine (Met)

-Cysteine and disulfide bonds, impact thermostablity and folding confirmations
-at neutral and alk pH rapid exchange of thiols

Front 5

Polar AAs

Back 5

-Serine (Ser)
-Threonine (Thr)

-amide groups of asn and gln are labile at extreme pH

Front 6

Basic AAs

Back 6

-Histidine (His)
-Lysine (Lys)
-Arginine (Arg)

-charged in foods: lys and arg
-salt bridge interactions

Front 7

Acidic AAs

Back 7

-Aspartate (Asp)
-Glutamate (Glu)
-Aspargine (Asn)

-chelate metal ions; calcium binding
-H donors
-salt bridge interactions
-Glutamine (Gln)

Front 8

pH < pKa

Back 8

AA is (+)

Front 9

pH > pKa

Back 9

AA is (-)

Front 10

Primary Structure

Back 10

-Ala-Glu-Val-Thr-

Front 11

Secondary Structure

Back 11

-Alpha helix
-Beta sheet

Front 12

Tertiary Structure

Back 12

Domains

Front 13

Quaternary Structure

Back 13

-comprised of subunits
-hydrophobic patches lead to quaternary structure
-Myosin (functional protein in muscle) has 6 subunits

Front 14

Disulfide

Back 14

-covalent bond b/w cys residues
-restricts number of confirmations that proteins can assume

Front 15

Bond Energies

Back 15

-C-C
-S-S
-H bond
-Salt ionic
-Hydrophobic
-Van der Waals

Front 16

Urea

Back 16

-causes proteins to unfold and break sulfide bridges

Front 17

Forces that stabilize protein structure

Back 17

- H bonds
-Electrostatic interactions
-depends on charge
- charges is on surface usually but inside structure its stabilizing
-Hydrophobic interactions
-No net attraction
-thermodynamically driven; H20
-Dipole-Dipole
-Disulfide linkage

Front 18

Hydrophobicity and proteins

Back 18

-not true bonds
-food proteins tend to hbp
-can lead to quarternary structure when there are hydrophobic residues on surface
-more hpb, more tend to aggregate
-can serve as good gelling, water holding and fat holding agents

Front 19

Functional proteins in eggs

Back 19

-ovalbumin
-responsible for foaming

Front 20

Functional proteins in meat

Back 20

-Myosin
-highly functionally
-responsible for quality of meat

Front 21

Protein solubility important in...

Back 21

-beverages
-protein concentrates

Front 22

Protein water holding capacity important in....

Back 22

-meats
-cheese
-yogurt
-surimi

Front 23

Protein gelatin is important...

Back 23

-comminuted meat
-custards
-scrambled eggs
-yogurt
-tofu

Front 24

Protein emulsification is important in

Back 24

-mayo
-salad dressing
-gravies
-ice cream

Front 25

Protein foaming is important in

Back 25

-whipped toppings
-meringues
marshmellows

Front 26

Salting in

Back 26

-increasing protein solubility by addition of salt

Front 27

Salting out

Back 27

-precipitating proteins
-decreasing of protein solubility
-increase NaCl; increase net solubility at PI

Front 28

PI

Back 28

-no net charge on protein
-max protein interactions
-less likely to be soluble at PI

Front 29

pH = pKa

Back 29

aa has no net charge

Front 30

pH < PI

Back 30

-net charge on protein is (+)

Front 31

pH > PI

Back 31

-domains of

Front 32

Shear Stress

Back 32

-force put on an object at an angle

Front 33

Shear Strain

Back 33

-how a product deforms

Front 34

NaCl

Back 34

-increases protein solubility
-used as an control

Front 35

KSCN

Back 35

-enhances protein-solvent interactions
-get looser gel

Front 36

(NH4)2SO4

Back 36

-enhances protein-protein interactions
-get more solid gel

Front 37

Myosin quarternary structure

Back 37

-2 heavy chains
-forms alpha helical tail
-4 light chains in globular head
-ATP activity is centered
-cause traction and relaxation (movement)

Front 38

Myofibril

Back 38

-G-actin (globular) polymerizes to form F-actin (fibrous)

Front 39

Power stroke of muscle and motility

Back 39

1. energized myosin on signal from regulatory protein; binds ADP,Pi

2. myosin makes contact with G-actin

3. confirmations change in myosin moves actin

4. release of bound ADP, Pi; cleavage of ATP changes myosin t original position

Front 40

Structural hierarchy of muscle

Back 40

-fiber bundles: form muscle structure

-myofilament
-contain myosin and actin (salt soluble)
-contains structural and functional proteins

-Sarcoplasma proteins
-catalytic proteins
-surrounds fiber bundles
-myosin inches down actin chain w/energy

Structure
fiber bundles -> myofibrils ->myofilament ->sarcoplasma

Front 41

TEM of muscle structure

Back 41

-regular repeating highly ordered structure
-myofibril, Z-line, A band, I band Sacromere

Front 42

Thick and thin filaments

Back 42

-lil hairs where catalytic activity takes place (contractions)
-arrangement of filaments in skeletal muscle.
-thick is myosin
thin is actin

Front 43

Water Soluble Proteins (WSP)

Back 43

-not functional for whipping etc.
-not useful in food science
-contains sacroplasmic enzymes

Front 44

Salt Soluble Proteins (SSP)

Back 44

-want to maintain quality of these proteins
-functional proteins

Front 45

Fresh muscle, rigor and quality

Back 45

-@ slaughter theres a depletion of energy stores
-increase in lactic acid
-decrease in glycogen
-anaerobic stiffening
-myosin binds to actin and won't unbind until relaxation (post rigor)

Front 46

Gelling

Back 46

Association of dispersed polymer chains in solution to form a 3d continuous network, immobilizes liquid in interstatial structures, resists flow

Front 47

Phosphates

Back 47

-disrupt sarcomere by breaking down ordered structuure by making it hold H2O better.