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VINIFICATION > STABILIZATION > Flashcards

STABILIZATION Flashcards

1
Q

What types of stabilisation do we have? (3)

A

Tartaric
Colloïdal
Proteic

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2
Q

What do we mean with sursaturation?

A

Concentration of potassium bitartrate (KTH) higher than the solubility in wine.

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3
Q

What is nucleation?

A

Formation of nuclei allowing the growth of subsequent crystalline

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4
Q

What do we mean by ‘growth’ when we talk about precipitation?

A

The deposit if bitartrate on ‘germs-nuclei’ already formed.

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5
Q

What is the difference between the saturation zone and the solubility zone?

A

Saturation zone: wine is unstable
Solubility zone: wine is stable

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6
Q

What do we mean by ‘meta-stable’?

A

Stable as long as it does not undergo anymore disturbances

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7
Q

Name 3 general ways to obtain tartaric stabilization

A

Inhibition
Subtraction
Cold subtraction

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8
Q

Name 5 parameters that influence tartaric precipitation

A

Concentration of KTH and salts
Temperature
Alcohol
pH
Colloïds

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9
Q

Explain how KTH and salts influence precipitation

A

The more KTH/salts, the greater the precipitation

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10
Q

Explain how temperature influences precipitation (2)

A
  1. Temperature below stabilisation temperature (0C?) will cause precipitation.
  2. An increase in temperature can increase re-dissolve tartaric acids
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11
Q

How does alcohol influence precipitation

A

The higher the alcohol the higher precipitation due to decrease of polarity.
At pH 3.6 the tartrates are the less insoluble

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12
Q

How does pH influence preciptiation?

A

pH 3.6 is the most high formation of KTH which is the most insoluble.

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13
Q

How does colloïds influence precipitation?

A

Colloids can temporarily oppose tartaric precipitation.
The evaluation of tannin can make wines unstable

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14
Q

How can you determine wine stability?

A

With a predictive test. Based on the fall of conductivity for 4 hours at 4C.

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15
Q

How does stabilizion with mannoproteins work?

A

The mannoproteins are the colloidal protector (polysaccharides) that creates a cover which prevents the K+ from binding with tartaric (which will otherwise form crystals)

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16
Q

What is CMC?

A

Carboxymethylcelluloses. Can only be added when protein stable (heat stable otherwise will throw a haze). Colloidal protection

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17
Q

How does polyaspartate work?

A

Colloidal protection. Same as CMC only has less protein conflict.

18
Q

Describe the steps in the fining process

A

Flocculation
Sedimentation
Clarification
Stabilization
Refining

19
Q

Explain the principle of fining

A

Interaction between the charged particles of the fining agent and the particles of the wine

20
Q

What is the aim of fining? (3)

A

Clarification
Stabilization
Valorisation

21
Q

What are the reasons to do fining for red in comparison to white?

A

Red: clarification, stabilisation color, refining
White: clarification refining and treatment of oxidation, discolouration or bentonite.

22
Q

Name 3 types of fining agents

A

Organic (milk/eggs/fish/collagen/plants)
Minerals (silica/clay)
Synthetic (PVPP)

23
Q

What is the role of tannin in white wine?

A

Antioxidant
Elimination of proteins (clarification)
Antisceptic
Iron complexation (?)

24
Q

What is the role of tannin in red wine?

A

Antioxidant
Participation of structure
Stabilisation of anthocyanin
Antisceptic

25
Q

Name 3 types of enological tannin

A

Gallics
Ellagics
Proanthocyanidics

26
Q

When incorporating fining agents. What are the golden (5) rules before collage (adding agent)

A

Adequate fining agent
Make collage test
Temperature low and stable
Racking with aeration
Watch out for glucans and pectins

27
Q

When incorporating fining agents. What are the golden (5) rules during collage (fining agent to flocculation)

A

Respect hydration time and instructions
Respect the order of incorpration
Homogeneous incorporation
Rack on time and gently
Watch out for wind/aircurrents

28
Q

Name 4 ways to inhibit formation of tartrates

A

Polyaspartate K+
CMC
Mannoproteins
Metatartaric acid

29
Q

Name 2 ways to subtract tartrates from wine

A

Resins exchange
Electrodialysis

30
Q

Name 4 ways to cold subtract tartrates from wine

A

Bottle precipitation (no temp. manipulation)
Natural cold (cellaring)
Product cold (manipulate temp.)
Catalytic (Tartaric cream to speed up the formation of tartaric, low temp. Quicker)

31
Q

What are the temperatures for cold stabilisation?

A

-5C-5C

32
Q

What does tartaric cream do?

A

Excellarates precipitation of crystals

33
Q

What is the maximum dose of meta tartaric acid?

A

10g/hl during bottling

34
Q

What is the aimed esterification index?

A

40

35
Q

What is esterification?

A

Polymerisation of tartaric acid, through ester bonds

36
Q

Is meta tartaric acid a stable protection?

A

No, when the wine heats up the ‘cover’ gets broken

37
Q

Name the 4 protective colloids

A

Metatartaric acid
CMC
Mannoproteins
Polyaspartate

38
Q

Which fining agents can you use for red wines?

A

Egg whites and gelatine

39
Q

What is the only fining agent you cannot use for white wines?

A

Egg whites

40
Q

Which stabilisation method will decrease in effectiveness over time?

A

Metatartaric acid
Cold stabilisation (if the tartrates are not racked off)

VINIFICATION (13 decks)

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