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Food Chemistry - FDSC251 > U9 > Flashcards

U9 Flashcards

(78 cards)

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1
Q

true or false: egg white is high in carb and lipid content

A

false! 1%

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2
Q

main 4 protein constituents in albumin

A
  1. ovalbumin
  2. ovotransferrin
  3. ovomucoid
    lysozyme
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3
Q

what kind of protein is ovalbumin

A

phosphoglycoprotein

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4
Q

what is special about ovalbumin that the other egg white proteins dont have

A

free sulfhydryl group

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5
Q

how stable is ovalbumin

A

not very stable - easily coagulated in heat and easily denatures when exposed to new surfaces

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6
Q

what are 2 important functions of ovalbumin

A

stabilizes foam

gelling agent

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7
Q

what kind of gel does ovalbumin create (in heat)

A

transparent, turbid gel

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8
Q

what process is used to purify ovalbumin

A
  1. half-saturate with ammonium sulfate
  2. filter
  3. sulfuric acid lowers the pH to pL 4.6-4.8
  4. recrystallizations
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9
Q

what kind of protein is ovotransferrin

A

iron-binding transferrin

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10
Q

what kind of prosthetic group does ovotransferrin have

A

carbohydrate

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11
Q

what allows ovotransferrin to have bacteriostatic and bactericidal avticities

A

iron-sequestering properties

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12
Q

how to purify ovotransferrin

A
  1. half-saturate with ammonium sulfate
  2. precipitate with more ammonium sulfate or alcohol fractionation
    or ion exchange chromotography
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13
Q

what is the most easily heat-denatured egg protein

A

ovotransferrin

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14
Q

wht kind of protein is ovomucoid

A

glycoprotein

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15
Q

what is the quaternary structure of ovomucoid like

A

3 homogenous domains crosslinked

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16
Q

where are the polysacchridees of the ovomucoid

A

attached to Asp

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17
Q

how are ocomucoids purified

A

complete saturation with ammonium sulfate or adding excess alcohol

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18
Q

what kind of protein is lysozyme

A

bacteriolytic enzyme

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19
Q

what is the function of lysozme

A

Catalyzes hydrolysis of glycosidic links between NAM and NAG in bacterial cell walls

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20
Q

optimal ph activity for lysozyme

A

5.3-6.4

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21
Q

what funcitonal characterisitc is special about lysozyme

A

heat stable and stable during drying

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22
Q

what is avidin

A

basic protein

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23
Q

what is ovoglobulin

A

foaming protein

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24
Q

what is ovoinhibitor

A

inhibits trypsin, chymotrypsin, elastase

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25
what is flavoprotein
binds riboflavin
26
what does yolk act like in food and why
lipid - it has high proportions of phosphoplipids and lipoproteins
27
what function does yolk have
emulsifier
28
4 classes of yolk proteins
Lipoproteins - LDL and HDL lipid-free globular proteins phosphoproteins minor proteins
29
what is heat coagulation
thermal denaturation and aggregation of proteins in albumen and yolk
30
what is denaturation
breaking of h-bonds, uncoiling of peptide chains, exposure of reactive groups
31
what do proteins form when denatured and with what bonds
aggregate to form a 3D gel network via h-binds, electrostatic links, disulfide links
32
what effect does heating albumin have
increased viscosity and opacity
33
what effect does heating have on yolk
viscosity increases (65C) and solidifies (70C)
34
how does increasing temperature and heating time affect gel
strengthens it
35
what does the oH of the gel depend on
net charge of the protein
36
describe the gel at its isoelectric point
protein aggregates into a curd, forming an opaque gel
37
describe the gel at basic pH
protein denatures, forming a translucent, rubbery gel
38
describe the gel at acidic pH
poor winding capacity, forming a coarse, open gel structure
39
describe the gel at pH 9
lots of crosslinking, forming a firm gel with high WBC
40
how does dry heating affect the egg protein's propertie
improves foaming, gelling, and emulsifying properties
41
how is dry heating performed
storing the dried egg white at 80C with controlled humidity for 7-10 days, forming a partially denatured structure
42
how does conjugating a protein with a polysaccharide effect the proteins properties
favors protein-protein interactions, so it protects the protein from thermal denaturaion and increases amphiphilic properties
43
how do enzymes work
they bind with high specificity and lower the activation, speeding up chemical reactions
44
what are oxidoreductases
catalyze oxidations or reductions of substrates
45
what does lipoxygenase do
lipid oxidation - adding O to a fatty acid
46
what does polyphenol oxidase do
enzymatic browning - oxidizes phenols in food
47
what do hydrolases do
catalyzes hydrolysis of substrates using water
48
what do proteases do
cleave the peptide bonds in proteins, affecting texture and protein modification
49
what do amylases do
cleave glycosidic bonds in carbohydrates, affecting texture and carbohydrate modification
50
wht do lipases do
cleave ester bonds, affecting hydrolytic rancidity and fat crystallization modification
51
what do isomerases do
catalyze intramolecular rearrangements
52
what does glucose isomerase do
convert aldose to ketose (glucose to fructose)
53
what do glycoside hydrolases do
hydrolyze glycosidic bonds in stach
54
a-amylase
hydrolyze alpha 1-4 link within starch. Releasing dextrins, maltose, and maltotriose
55
b-amylase
hydrolyze beta 1-4 links from the non-reducing end of starch. Releasing maltose
56
glucoamylase
hydrolyzes alpha 1-4 and alpha 1-6 links in starch. Can go all the way to glucose
57
pullulunase
hydrolyzes alpha 1-6
58
where are glycoside hydrolases supplied from
microbes or food systems
59
what 3 processes are glycosde hydrolysases used in
production of corn syrup, baking, and brewing
60
what occurs in corn syrup production
1. a-amylase breaks down amylose into amylopectin 2. glycoamylase breaks it down into glucose OR b-amylase / pullulanase break down into maltose - depending on what is desired
61
what occurs in baking
1. a-amylases dextrinize dirsupted starch granules 2. b-amylase hydrolyze dextrins into maltose 3. the fermentable sugar maltose is used by yeast amd causes produciton of CO2 4. the bread rises
62
what occurs in brewing
amylases in barley malt hydrolyze starch to form maltose during mashing which is then used by yeast o produce CO2 and ethanol
63
what kind of enzyme is invertase
glycoside hydrolase
64
what does invertase do
hydrolyzes glycosidic bond in sucrose, resulting in an invert sugar - fructose and glucse
65
what kind of enzyme is lactase
glycoside hydrolase
66
what does lactase do
hydrolyzes glycosidic bond in lactose
67
what effect does lactase have on products
less crystallization , sweeter, and lactose-free
68
what kind of enzyme are pectinases
hydrolase
69
what do pectinases do
hydrolyze the methyl ester link in pectin
70
what effect do pectinases have on products
less cloudy juices
71
what kind of enzyme are proteases
hydrolases
72
what do proteases do
hydrolye peptide bonds in proteins
73
what is papain
protease found in papaya used as a meat tenderizer to break down collagen
74
what are papains used in
meat tenderizers, make beer more clear (proteins aggregate to make it cloudy)
75
what are examples of digestive proteases
trypsin, chymotrrypsin, pepsin, chymosin, microbial proteases,
76
what kind of enzyme are lipases
hydrolases
77
what do lipases do
hydrolyze ester bond between FA and glycerol
78
1,3-lipases v 2-lipases
1,3: cleaves sn1 and sn2 ester | 2: cleaves sn2 ester

Food Chemistry - FDSC251 (10 decks)

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