Topic 3B Flashcards
(102 cards)
1
Q
what are the roles of PRO in food?
A
water binding gel formation thickening emulsion foam formation Maillard rxn
2
Q
what elements do PROs contain?
A
C H O N S
3
Q
how many AAs are there?
A
20
4
Q
how many AAs are essential?
A
9
5
Q
how many AA are conditionally essential?
A
1
6
Q
how do AAs differ from among each other?
A
side chain
7
Q
What is unique about a PRO?
A
AA sequence
8
Q
the balance of AAs in a PRO determines what about its quality?
A
biological value
nutritional quality
9
Q
what does it mean when a PRO has a high biological value?
A
complete PRO contain adequate amounts of essential AAs
10
Q
complete PRO
A
contains all essential AAs
11
Q
what foods contain PROs of high biological value?
A
animal products (ex: milk, eggs, cheese, meat & poultry)
12
Q
how does a vegan lifestyle acquire a complete PRO source?
A
combination of diff plant PROs
13
Q
primary structure
A
series of AAs
14
Q
what determine the primary structure of a PRO?
A
genetics
15
Q
secondary structure
A
side chains of AA interact with one another in the PRO molecule
16
Q
tertiary structure
A
alpha helices & beta sheets interact with one another
17
Q
what structure creates the 3D shape of the PRO?
A
tertiary
18
Q
quaternary structure
A
multimeric PROs
19
Q
what type of envr will cause denaturation of a PRO?
A
acidic
20
Q
PRO shape can be:
A
globular
fibrous
21
Q
buffering
A
resist change in pH
22
Q
amphoteric
A
same molecule can take & donate protons in nature
23
Q
PROs are more soluble at what pH? & why?
A
PROs are more soluble at alkaline pH b/c there are more net OH- ions & thus more interactions with water (H-bonds) remain dissolved in water
24
Q
what groups on the PROs accept & donate H+?
A
amine = accept
carboxyl = donate H+
25
what is an ex of PRO buffering in humans?
blood carrying various substances altering the pH which could be harmful
the blood buffers the pH
26
denaturation
interactions b/w side chains have changed thus, causing the PRO to acquire a new shape
27
what structures are disrupted during the denaturation of a PRO?
tertiary & quaternary
28
what causes denaturation?
change in the envr --> acids, alkalis, alcohol, heat, heavy metals (ex: Hg), UV radiation
29
how does denaturation affect the solubility of PROs?
reduces, form aggregations
30
when is denaturation desirable? & how is this accomplished?
digestion & by gastric acid containing HCl, causes the side chains to open up & enables enzymes to break them down
31
when is denaturation undesirable?
transport of harmful materials in the blood
32
foaming & how does this happen?
PROs form films around air bubbles
films have repulsive interactions & don't let the air bubble coalesce stabilizing the foams
33
PRO films are line with what kind of charge in foaming?
negative
34
gelation
PROs can form a gel matrix balancing PRO-PRO interactions & PRO-solvent (water) interactions
35
water holding capacity
the amount of water it can bind to without the water leaking away from it
36
what factors affect the water holding capacity of a PRO?
pH
salt
temp
37
when does a PRO have the least water holding capacity?
isoelectric pH
PRO is compact & not interacting with PRO molecules (insoluble)
38
isoelectric pH
pH where the PRO has a net charge of 0
39
what causes the increase in WHC?
addition of salt
& increase in temp up to a certain point in gel-forming PROs
40
how does an isoelectric pH affect a PRO's solubility?
insoluble
41
how does a pH above the isoelectric pH affect a PRO's charge? how does this affect solubility?
net negative charge
increases
42
how does a pH below the isoelectric pH affect a PRO's charge? & how does this affect solubility?
net positive charge
increases
43
emulsification
ability to keep oil & water mixed
44
what type of PROs are good emulsifiers?
PROs with both hydrophobic & hydrophilic properties
45
what is the pH of milk PRO?
6.6
46
what are the PROs included in milk PRO?
casein alpha, beta & kappa
47
kappa
keeps alpha & beta-casein from precipitating
48
what causes alpha & beta to precipitate?
pH change causing casein to become non-functional
49
what are the whey PROs in milk?
Lactoalbumin, Lactoglobulin, lactoferrin, lysozyme, lactoperoxidase
50
what are 2 high PRO products made from milk?
whey PRO isolate
whey PRO concentrate
51
whey concentrate has more ____ than whey isolate
impurities
52
what causes whey PROs to denature?
heat ONLY
53
what are the 2 major parts of an egg?
egg white
egg yolk
54
older the egg is, the ____ the egg white
thinner
55
what decreases an eggs foaming capacity?
age
56
what part of the egg is nutritious?
yolk
57
how is the quality of eggs determined?
candling
haugh unit
58
candling
a light enables seeing in the egg where they look for cracks & air cell size
59
haugh unit
higher the unit better the quality egg
test buoyancy --> older the egg is, the larger its air cell & the more buoyant the egg
60
what is the major PRO of the egg called? & what characteristic does it have?
ovalbumin
high foaming capacity
61
what PROs are found in egg yolk?
HDL
LDL
62
what are the functional characteristics of an egg?
emulsification
foaming
coagulation
63
emulsification in eggs & when is this used?
lipoproteins & phospholipids present in the egg yolk help to keep fat dispersed in water
mayonnaise
64
foaming in eggs
PROs in the egg white have a high capacity to form strong PRO films that surrounds air bubbles to produce stable foams
65
coagulation in eggs
egg white PROs can set & form a gel during heating
denature easily at high temps
66
red meat eaten in Canada mainly comes from:
cattle
pigs
chicken
67
animal flesh consists of:
muscle tissue or fibres
connective tissue
fatty (adipose) tissue
68
muscle cells are comprised of:
water
PROs
minerals
Vitamins (especially B12)
myoglobin
fat
69
connective tissue PROs:
collagen
elastin
70
collagen & what does it form? & what effect does it have when cooked?
major PRO in the connective tissue in & around the muscle fibres & tendons is mostly collagen
forms a gel
becomes soft & soluble when cooked
71
collagen solubility
water soluble
72
elastin & what effect does it have when cooked?
the ligaments which join 2 bones together are mostly made up of elastin (present in tendons & ligaments)
remains tough even when cooked
(yellow colour)
73
muscle fibers are composed of what PROs:
actin & myosin
74
muscle fiber length varies due to:
Length of fibres varies
Depending on location of muscles in body
Some muscles will be used more than others (ex: legs vs. ribs on cows)
Type of animal
Ex: fish have smaller muscle fibers
Age of animal (more collagen will be deposited)
75
fine muscle fibres & what happens when cooked?
tend to come from the muscles of young animals or in older animals from the muscles which do the least work
contain little collagen & are tender even when cooking
76
thick muscle fibres & how does it need to be cooked?
tend to be from older animals & also muscles which do the most ‘work’ (ex: neck & skin)
Meat is tougher & needs long, slow cooking with moisture to make it tender (ex: casserole)
77
what are 2 methods of lowering the pH of meat? & why do you want to do this?
make the meat more tender
add acid = increase water holding capacity (marinate)
mechanical pounding, break down starch --> tenderization
78
visible fat
found in meat underneath the skin, cover fat (subcutaneous fat) & b/w the muscles (intermuscular fat)
seen with the eyes
creamy white colour
79
invisible fat
small amount of fat is found in connective tissue surrounding the bundles of muscle fibres
not obvious to the eye
80
removal of what type of fat affects the tenderness of meat? & what is the result?
invisible fat
causes it to be dry
81
what causes the colour of meat?
myoglobin & hemoglobin (varries with the types of muscle)
82
colour diffs in meat are due to:
mainly the metabolism of the species & function of the muscle
(also age & exercise)
83
darker meat comes from what kind of muslces?
muscles that have been used a lot more & are older
84
oxymyoglobin
myoglobin bound with oxygen
85
metmyoglobin
oxymyoglobin oxidized
86
how does oxidation affect the colour of meat?
darker = more oxidized
87
why are nitrides (antioxidants) added to meat?
prevent browning & growth of microbes
88
why is salt added to meat?
prevents growth of microbes & increases water holding capacity
89
what are the principle PROs in wheat?
gliadin & glutelin
90
gluten
complex formed form gliands & glutelins following hydration (water) & mixing of wheat flour
gliadin + glutelin = gluten
91
why are water & mixing important in the formation of gluten?.
triggers the formation of disulfide bonds b/w glutelin
mixing increases the rate of disulfide bond formation
92
hydrated gluten provides what type of structure? & what characteristics does it provide to the wheat flour?
3-D viscoelastic network
valued dough & bread making characteristics
93
what does gluten prevent from escaping?
CO2
94
gliadin ___b/w ___ molecules
floats
glutelin
95
what property does gliadin provide?
viscosity
96
what property does glutelin provide?
elastic property
97
pulse & oilseed storage PROs contain very little of what PROS & what is their main PROs?
gliadin & glutelin
majority of PROs are albumin & globulins
98
single celled PROS come from:
yeasts, bacteria & fungi
99
mycoPRO
PRO from a fungus
consumption from F. venenatum has been approved
100
mycoPRO supplies:
50% PRO
13% lipids
25% fibre
(no cholesterol)
101
what is the trade name of myco PRO?
Quorn
102
food use of mycoPROs:
Muscle fiber replacer in the manufacture of simulated meats like vegetarian burgers
Fat replacer
Cereal replacer in the manufacture of breakfast cereals
