STABILIZATION

Question 1

What types of stabilisation do we have? (3)

Answer 1

Tartaric
Colloïdal
Proteic

Question 2

What do we mean with sursaturation?

Answer 2

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

Question 3

What is nucleation?

Answer 3

Formation of nuclei allowing the growth of subsequent crystalline

Question 4

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

Answer 4

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

Question 5

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

Answer 5

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

Question 6

What do we mean by ‘meta-stable’?

Answer 6

Stable as long as it does not undergo anymore disturbances

Question 7

Name 3 general ways to obtain tartaric stabilization

Answer 7

Inhibition
Subtraction
Cold subtraction

Question 8

Name 5 parameters that influence tartaric precipitation

Answer 8

Concentration of KTH and salts
Temperature
Alcohol
pH
Colloïds

Question 9

Explain how KTH and salts influence precipitation

Answer 9

The more KTH/salts, the greater the precipitation

Question 10

Explain how temperature influences precipitation (2)

Answer 10

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

Question 11

How does alcohol influence precipitation

Answer 11

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

Question 12

How does pH influence preciptiation?

Answer 12

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

Question 13

How does colloïds influence precipitation?

Answer 13

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

Question 14

How can you determine wine stability?

Answer 14

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

Question 15

How does stabilizion with mannoproteins work?

Answer 15

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

Question 16

What is CMC?

Answer 16

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

Question 17

How does polyaspartate work?

Answer 17

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

Question 18

Describe the steps in the fining process

Answer 18

Flocculation
Sedimentation
Clarification
Stabilization
Refining

Question 19

Explain the principle of fining

Answer 19

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

Question 20

What is the aim of fining? (3)

Answer 20

Clarification
Stabilization
Valorisation

Question 21

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

Answer 21

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

Question 22

Name 3 types of fining agents

Answer 22

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

Question 23

What is the role of tannin in white wine?

Answer 23

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

Question 24

What is the role of tannin in red wine?

Answer 24

Antioxidant
Participation of structure
Stabilisation of anthocyanin
Antisceptic

Question 25

Name 3 types of enological tannin

Answer 25

Gallics Ellagics Proanthocyanidics

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

Name 4 ways to inhibit formation of tartrates

Answer 28

Polyaspartate K+ CMC Mannoproteins Metatartaric acid

Question 29

Name 2 ways to subtract tartrates from wine

Answer 29

Resins exchange Electrodialysis

Question 30

Name 4 ways to cold subtract tartrates from wine

Answer 30

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)

Question 31

What are the temperatures for cold stabilisation?

Answer 31

-5C-5C

Question 32

What does tartaric cream do?

Answer 32

Excellarates precipitation of crystals

Question 33

What is the maximum dose of meta tartaric acid?

Answer 33

10g/hl during bottling

Question 34

What is the aimed esterification index?

Answer 34

40

Question 35

What is esterification?

Answer 35

Polymerisation of tartaric acid, through ester bonds

Question 36

Is meta tartaric acid a stable protection?

Answer 36

No, when the wine heats up the 'cover' gets broken

Question 37

Name the 4 protective colloids

Answer 37

Metatartaric acid CMC Mannoproteins Polyaspartate

Question 38

Which fining agents can you use for red wines?

Answer 38

Egg whites and gelatine

Question 39

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

Answer 39

Egg whites

Question 40

Which stabilisation method will decrease in effectiveness over time?

Answer 40

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