9 protein intro

Question 1

what are proteins?

Answer 1

macromolecules comprised of amino acids bound by peptide bonds

Question 2

what’s the term for: providing a specific useful property or function in a food product

Answer 2

[protein] functionality

Question 3

what are some useful properties targeted in protein functionality?

Answer 3

• water binding capacity
• emulsification capactiy
• gel forming ability
• coagulating properties
• dough forming abilities

Question 4

soybeans form a curd called

Answer 4

tofu

Question 5

______ activity can be both beneficial and detrimental

Answer 5

enzymatic

Question 6

name some examples of enzyme

Answer 6

• protease - meat tenderizer
• lipase - flavor developer
• amylase - syrup/sugar manufacturing
• glucose oxidase - remove headspace of packaging

Question 7

what’s MSG?

Answer 7

monosodium glutamate - a flavor potentiator.

Question 8

what are some currently uncommon sources of protein in our culture?

Answer 8

• rapeseed
• beans
• peas
• leaves
• microorganisms

Question 9

pros and cons of using plant proteins?

Answer 9

pros: more abundant, cheaper
cons: lesser protein quality

Question 10

what is surimi?

Answer 10

imitation crab/scallop meat made from pollock

Question 11

what are the components of an amino acid?

Answer 11

amine (NH2), carboxylic acid (COOH), and side chain (R) groups attached to an alpha carbon

Question 12

at a low pH, an amino acid is

Answer 12

protonated (COOH/NH3+)

Question 13

at neutral pH, an amino acid is

Answer 13

zwitterion (COO-/NH3+); net neutral charge

Question 14

at a high pH, an amino acid is

Answer 14

unprotonated; net negative (COO-/NH2)

Question 15

what does the pKa tell you?

Answer 15

when a H will pop on or off

Question 16

a substance that can act as both an acid and a base is considered:

Answer 16

amphoteric

Question 17

1) a protein in its neutral form have the attributes of a:

2) some of these attributes include

Answer 17

1) salt

2) crystalline structure, water soluble, decomposition at high temps

Question 18

what is the only amino acid that is achiral?

Answer 18

glycine (R=H)

Question 19

what are optical isomers?

Answer 19

mirror images of a compound that can’t be superimposed

Question 20

asymmetry give a molecule the ability to rotate _____ ______ ______ in opposite directions

Answer 20

plane polarized light

Question 21

what compound is used as a reference for determining configuration?

Answer 21

glyceraldehyde

Question 22

it glyceraldehyde has its OH group on the right, what form does it have? what about left?

Answer 22

D or dextro; L or levo

Question 23

what group do we look at when determining an amino acid’s form?

Answer 23

NH3 (amine) group; if it’s on the left it’s L, if it’s on the right it’s D

Question 24

naturally, our amino acids come in what form?

Answer 24

L

Question 25

what are the 7 categories of amino acids?

Answer 25

1) aliphatic side chain 2) hydroxy side chain 3) carboxylic side chain 4) basic side chain 5) aromatic side chain 6) sulfur-containing 7) imino acids

Question 26

what are the aliphatic amino acids?

Answer 26

glycine, alanine, valine, isoleucine, leucine

Question 27

what are some attributes of the aliphatic amino acids?

Answer 27

- relatively unreactive | - as chain length increases so does hydrophobicity

Question 28

is glycine hydrophobic?

Answer 28

hell naw

Question 29

what are the hydroxy side chain amino acids?

Answer 29

Serine (Ser), Threonine (Thr), Tyrosine (Tyr)

Question 30

what are some attributes of the hydroxy side chain amino acids?

Answer 30

- OH can form ester linkage with a phosphate group - OH enables hydrogen bonding - OH is a very reactive moiety

Question 31

true or false: casein is heat stable

Answer 31

true

Question 32

O-glycosidic linkages are associated with what functional group?

Answer 32

OH

Question 33

what are the carboxylic amino acids?

Answer 33

aspartic acid, glutamic acid and their amides, asparagine and glutamine

Question 34

what are some attributes of the carboxyl amino acids?

Answer 34

- COOH is a very reactive group - at pH 7 they are negatively charged (polar) - tend to have LOW isoelectric points - play a role in non-enzymatic browning reactions - water soluble

Question 35

what serves as an attacking point for reducing sugars?

Answer 35

amide group

Question 36

N-glycosidic linkages are associated with what functional group?

Answer 36

amide

Question 37

what are the basic side chain amino acids?

Answer 37

lysine, histidine, arginine

Question 38

what are some attributes of amino acids with basic side chains?

Answer 38

- high isoelectric points

Question 39

how many amide groups does lysine have?

Answer 39

2

Question 40

arginine has a _____ group

Answer 40

guanadino

Question 41

histidine has a _____ group

Answer 41

imidazole group

Question 42

when a protein reaches its isoelectric point, this is its point of (highest/lowest) solubility in water

Answer 42

lowest

Question 43

what are the aromatic amino acids?

Answer 43

phenylalanine, tyrosine, tryptophan

Question 44

what are some attributes of the aromatic amino acids?

Answer 44

- can absorb UV light | - quite hydrophobic

Question 45

what are the sulfur containing amino acids?

Answer 45

cysteine, cystine (cysteine's dimer), and methionine

Question 46

a _____ _____ holds together two cysteine residues

Answer 46

disulfide crosslink

Question 47

1) cystein has a: | 2) this group is (acidic/basic)

Answer 47

1) sulfhydryl group (SH) | 2) basic

Question 48

what are the imino acids?

Answer 48

proline, hydroxyproline

Question 49

what makes imino acids different?

Answer 49

they lack an NH2 group. they have NH instead

Question 50

what are some attributes of imino acids?

Answer 50

- interrupt natural tendency to form alpha helix - found in collagen - can't form intramolecular hydrogen bonds

Question 51

what are the essential amino acids?

Answer 51

HPVL2IT2 - histidine - phenylalanine - valine - leucine - lysine - isoleucine - threonine - tryptophan

Question 52

what are the conditionally essential amino acids?

Answer 52

A2G2PST - arginine - asparagine - glutamine - glycine - proline - serine - tyrosine

Question 53

what are the nonessential amino acids?

Answer 53

- Alanine - Asparate - Glutamate - Cysteine (we don't need cancer)

Question 54

what are used extensively as flavoring agents to provide a meaty/brothy flavor?

Answer 54

hydrolysates

Question 55

what is an example of a hydrolysate that's made from fermented soybeans

Answer 55

soy sauce

Question 56

what do sulfur containing amino acids release to provide flavor due to their breakdown while being cooked?

Answer 56

H2S - hydrogen sulfide

Question 57

what is responsible for flavors?

Answer 57

- peptides

Question 58

the process of decay or rotting in a body or other organic matter is known as

Answer 58

putrefaction

Question 59

what causes odors and off flavors association with putrefaction?

Answer 59

- enzymatic deamination | - decarboxylation of free amino acids by microbial enzymes