9 protein intro Flashcards
what are proteins?
macromolecules comprised of amino acids bound by peptide bonds
what’s the term for: providing a specific useful property or function in a food product
[protein] functionality
what are some useful properties targeted in protein functionality?
- water binding capacity
- emulsification capactiy
- gel forming ability
- coagulating properties
- dough forming abilities
soybeans form a curd called
tofu
______ activity can be both beneficial and detrimental
enzymatic
name some examples of enzyme
- protease - meat tenderizer
- lipase - flavor developer
- amylase - syrup/sugar manufacturing
- glucose oxidase - remove headspace of packaging
what’s MSG?
monosodium glutamate - a flavor potentiator.
what are some currently uncommon sources of protein in our culture?
- rapeseed
- beans
- peas
- leaves
- microorganisms
pros and cons of using plant proteins?
pros: more abundant, cheaper
cons: lesser protein quality
what is surimi?
imitation crab/scallop meat made from pollock
what are the components of an amino acid?
amine (NH2), carboxylic acid (COOH), and side chain (R) groups attached to an alpha carbon
at a low pH, an amino acid is
protonated (COOH/NH3+)
at neutral pH, an amino acid is
zwitterion (COO-/NH3+); net neutral charge
at a high pH, an amino acid is
unprotonated; net negative (COO-/NH2)
what does the pKa tell you?
when a H will pop on or off
a substance that can act as both an acid and a base is considered:
amphoteric
1) a protein in its neutral form have the attributes of a:
2) some of these attributes include
1) salt
2) crystalline structure, water soluble, decomposition at high temps
what is the only amino acid that is achiral?
glycine (R=H)
what are optical isomers?
mirror images of a compound that can’t be superimposed
asymmetry give a molecule the ability to rotate _____ ______ ______ in opposite directions
plane polarized light
what compound is used as a reference for determining configuration?
glyceraldehyde
it glyceraldehyde has its OH group on the right, what form does it have? what about left?
D or dextro; L or levo
what group do we look at when determining an amino acid’s form?
NH3 (amine) group; if it’s on the left it’s L, if it’s on the right it’s D
naturally, our amino acids come in what form?
L
what are the 7 categories of amino acids?
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
what are the aliphatic amino acids?
glycine, alanine, valine, isoleucine, leucine
what are some attributes of the aliphatic amino acids?
- relatively unreactive
- as chain length increases so does hydrophobicity
is glycine hydrophobic?
hell naw
what are the hydroxy side chain amino acids?
Serine (Ser), Threonine (Thr), Tyrosine (Tyr)
what are some attributes of the hydroxy side chain amino acids?
- OH can form ester linkage with a phosphate group
- OH enables hydrogen bonding
- OH is a very reactive moiety
true or false: casein is heat stable
true
O-glycosidic linkages are associated with what functional group?
OH
what are the carboxylic amino acids?
aspartic acid, glutamic acid and their amides, asparagine and glutamine
what are some attributes of the carboxyl amino acids?
- 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
what serves as an attacking point for reducing sugars?
amide group
N-glycosidic linkages are associated with what functional group?
amide
what are the basic side chain amino acids?
lysine, histidine, arginine
what are some attributes of amino acids with basic side chains?
- high isoelectric points
how many amide groups does lysine have?
2
arginine has a _____ group
guanadino
histidine has a _____ group
imidazole group
when a protein reaches its isoelectric point, this is its point of (highest/lowest) solubility in water
lowest
what are the aromatic amino acids?
phenylalanine, tyrosine, tryptophan
what are some attributes of the aromatic amino acids?
- can absorb UV light
- quite hydrophobic
what are the sulfur containing amino acids?
cysteine, cystine (cysteine’s dimer), and methionine
a _____ _____ holds together two cysteine residues
disulfide crosslink
1) cystein has a:
2) this group is (acidic/basic)
1) sulfhydryl group (SH)
2) basic
what are the imino acids?
proline, hydroxyproline
what makes imino acids different?
they lack an NH2 group. they have NH instead
what are some attributes of imino acids?
- interrupt natural tendency to form alpha helix
- found in collagen
- can’t form intramolecular hydrogen bonds
what are the essential amino acids?
HPVL2IT2
- histidine
- phenylalanine
- valine
- leucine
- lysine
- isoleucine
- threonine
- tryptophan
what are the conditionally essential amino acids?
A2G2PST
- arginine
- asparagine
- glutamine
- glycine
- proline
- serine
- tyrosine
what are the nonessential amino acids?
- Alanine
- Asparate
- Glutamate
- Cysteine (we don’t need cancer)
what are used extensively as flavoring agents to provide a meaty/brothy flavor?
hydrolysates
what is an example of a hydrolysate that’s made from fermented soybeans
soy sauce
what do sulfur containing amino acids release to provide flavor due to their breakdown while being cooked?
H2S - hydrogen sulfide
what is responsible for flavors?
- peptides
the process of decay or rotting in a body or other organic matter is known as
putrefaction
what causes odors and off flavors association with putrefaction?
- enzymatic deamination
- decarboxylation of free amino acids by microbial enzymes
