Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

FPH-31306-Advanced mol. gastronomy > Astringency > Flashcards

Astringency Flashcards

1
Q

T or F : there is a receptor associated with astringency

A

False, it is a mouth feeling that results from the interaction between saliary proteins and polyphenols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is tea less astringent when you add milk?

A

Because of the interaction between the milk proteins and the tannins of tea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What at the two types of tannins seen in class and what is the difference between them?

A
  1. Hydrolysable - ester linkage
  2. Condensed - no esther linkage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Is this a condensed hydrolysable tannin ?

A

condensed because there is a c-c covalent linkage between the multiring phenols and because there is no esther linkage in the structure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Is this a condensed or a hydrolysable tannin ?

A

Hyrolysable because there are some esther linkage in the strucutre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the structure of galllic acid

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do you get after the hydrolysis of this condensed tannin

A

1 glucose molecule, a dimer of gallic acid and a tetramer of gallic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the major difference between the bitterness and the astringency

A

bitterness is receptor mediated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the molecular weight of epi-catechin and catechin

A

290

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the building blocks of flavan-3-ol

A

Catechin and epi-catechin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Catechin and epicatechin are part of the ____ family

A

Flavan-3-ols (sometimes referred to as flavanols)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the difference between flavanols and flavonols

A

flavonol contains a ketone group.
In the picture we can see the major classes of flavonoids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the different classes of proanthocyanidins ?

A

Propelargonidins: R1=R2=H

Procyanidins: R1=H, R2=OH

Prodelphinidins: R1=R2=OH

They depends on the R1 and R2 groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When cathecins polymerise, they can form _____

A

proanthocyanidins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is this molecule ?

A

Proanthocyanidins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The hydrolysable tannins can be hydrolysed by ___ enzyme or a ___ environment

A

tannase
alkali

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the two types of proanthocyanidins seen in class and what is the difference between them?

A
  1. A-type : two links between the cathecins subunits
  2. B-type : one links between the cathecin subunits
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what information can you get in the normal phase chromatography?

A

info on the molecular weight (time eluted) and on the concentration (height of peak)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

in normal phase chromatography, ___ molecules elutes first

A

small

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In normal phase chromatography, the ____ (polar/apolar) compounds elutes first because the column solvent gradient goes from ___ to ____

A

apolar ellutes first
apolar to polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In the reversed-phase chromatography, the first compounds to ellute are ____ (polar/apola)

A

polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In reverse phase chromatography, the column goes from ___ to ___

A

polar to apolar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

in the case of reverse phase chromatography your column is ___ while in normal phase the column is ____

A

reversed phase : apolar
normal phase: polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

When there is a peak at 575 on your MS spectrum, you have a ___ in your mixture

A

dimeric proanthocyanidins with A type linkage

25
Q

If you have a peak at 577 on your MS spectrum you have a type ___ proanthocyanidins

A

B

26
Q

What are the two types of complexation we saw in class

A
  1. Monodentate
  2. Multidentate
27
Q

in the case of monomeric polyphenol, you will have a ___ complexation

A

monodentate

28
Q

How does proteins aggregate in the case of monodentate complexation

A

they aggregate when a lot of monomeric polyphenols are present and increases the hydrophobicity of proteins which will then precipitate

29
Q

How does multidentate complexation precipitate the proteins?

A

large polyphenol can cross-link between them and the other proteins and so they will form complex that will precipitate

30
Q

Which a.a does the polyphenol need in order to bind the salivary proteins

A

proline

31
Q

What are the two hypothesis of the interaction between polyphenols and proline residues

A
  1. Stalking interaction (hydrophobic) between the A-ring of the polyphenol and the pyrrolidine ring of the proline
  2. Hydrogen bonding between the B ring of the polyphenol and the hydrogens of the pyrrolidine ring
32
Q

Why are proline good at binding the polyphenols?

A

Because the oxygen in proline are next to a tertiary amide and so they re partially positive and so they are good H-bond acceptors

33
Q

What are the three functions of saliva

A
  1. protective: tissue coating, lubri-cation, remineralizationof teeth
  2. host-defense: immunological activity, anti-viral, anti-microbial
  3. digestion: digestive enzymes, bolus
34
Q

T or F : the composition of the saliva depends on the gland it originate from

A

true

35
Q

Why is saliva good for binding polyphenols although it has less proteins per /l than serum?

A

Because there are more random coil proteins and protein rich in proline in the saliva than in the serum

36
Q

What are the three types of proteins in the saliva

A
  1. Mucins
  2. PRP (proline rich proteins)
  3. Histadins
37
Q

____ is a family of proline-rich proteins, with MUC7 as most important representative in saliva

A

mucins

38
Q

Which protein family are we talking about here :
-most abundant salivary proteins

  • at least 6 family members, in 3 subclasses
  • between 6 and 66 kDa
A

The proline rich proteins

39
Q

____ is a family of proteins that are rich in histidine

A

Histatins

40
Q

What do the three classes of salivary proteins have in common?

A

They are rich in proline and histadine and also flexible (random coils).

41
Q

Which family is the most abundant in salivary proteins?

A

The proline rich proteins

42
Q

What are the three types of PRP ?

A
  1. acidic
  2. basic
  3. Glycosylated
43
Q

___ and ____ PRPs are related and have a higher proline content than the acidic PRPs

A

Basic and glycosylated

44
Q

Why is gelatin used in fining of wine

A

gelatin is used to reduce the astringency because it is rich in proline and can interact with the tannins.

45
Q

What are the way used to reduce the astringency in wine processing?

A
  1. Adding gelatins (rich in proteins)
  2. Adding laccase that convert the B type (1 link) into the A type (2+ links)
46
Q

T or F : A type bonds are more common in peanut skins

A

true

47
Q

____ is cleaved into ___ to study the salivary-polyphenol interactions because it is a flexible C-terminal part of the pro-protein

A

PRB4S is cleaved into IB-5 (the C terminal part of the protein)

48
Q

Which of these molecules would have the highest affinity to the salivary proteins?

A

It would be the pentagalloyl glucose and the proanthocyanidin because they are more flexible because there is free rotation around the ester bond and between the phenolic rings

49
Q

T or F : the affinity of a tannins to proteins measured by the BSA precipitation test can predict its astringency in senosry analysis

A

false because grandinin has the less afinity for the salivary proteins but it is the one that is perceived as the most astringent

50
Q

what are the physical properties of B-type proanthocyanidins

A
  1. linkage are easier to break
  2. Less compact
  3. higher astringency
51
Q

What are the physical properties of A-type proanthocyanidins?

A
  1. compact structure that doesn’t faciliate the interaction with proteins
  2. lower astringency
  3. can be converted by laccase to reduce the astringency
52
Q

What are the three important factor for the affinity of the polyphenol for salivary proteins?

A
  1. size
  2. flexibility
  3. Conformation
53
Q

The presence of ___ residue in proteins and the ____ of these residues will promote binding with tannis

A

proline residues
repeats

54
Q

In the case of tannins, the presence of ___ in the molecule will promote the binding to the protein

A

presence of gallic acid because they are not connected by c-c bonds and so they give some flexibility to the tannins

55
Q

What is the primary interaction responsible for the binding of the polyphenol ?

A

The primary interaction is the stalking interaction

56
Q

T or F : the most astringent compounds are the one that are the most efficient precipitating proteins

A
57
Q

T or F : the glycosylation pattern of the molecule will determine if the molecule is perceived very astringent of moderatly astringent.

A

true

58
Q

T or F : Compounds with high affinity for salivary proteins show relatively low astringency scores

A

true

59
Q
A

FPH-31306-Advanced mol. gastronomy (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions