STABILIZATION Flashcards
What types of stabilisation do we have? (3)
Tartaric
Colloïdal
Proteic
What do we mean with sursaturation?
Concentration of potassium bitartrate (KTH) higher than the solubility in wine.
What is nucleation?
Formation of nuclei allowing the growth of subsequent crystalline
What do we mean by ‘growth’ when we talk about precipitation?
The deposit if bitartrate on ‘germs-nuclei’ already formed.
What is the difference between the saturation zone and the solubility zone?
Saturation zone: wine is unstable
Solubility zone: wine is stable
What do we mean by ‘meta-stable’?
Stable as long as it does not undergo anymore disturbances
Name 3 general ways to obtain tartaric stabilization
Inhibition
Subtraction
Cold subtraction
Name 5 parameters that influence tartaric precipitation
Concentration of KTH and salts
Temperature
Alcohol
pH
Colloïds
Explain how KTH and salts influence precipitation
The more KTH/salts, the greater the precipitation
Explain how temperature influences precipitation (2)
- Temperature below stabilisation temperature (0C?) will cause precipitation.
- An increase in temperature can increase re-dissolve tartaric acids
How does alcohol influence precipitation
The higher the alcohol the higher precipitation due to decrease of polarity.
At pH 3.6 the tartrates are the less insoluble
How does pH influence preciptiation?
pH 3.6 is the most high formation of KTH which is the most insoluble.
How does colloïds influence precipitation?
Colloids can temporarily oppose tartaric precipitation.
The evaluation of tannin can make wines unstable
How can you determine wine stability?
With a predictive test. Based on the fall of conductivity for 4 hours at 4C.
How does stabilizion with mannoproteins work?
The mannoproteins are the colloidal protector (polysaccharides) that creates a cover which prevents the K+ from binding with tartaric (which will otherwise form crystals)
What is CMC?
Carboxymethylcelluloses. Can only be added when protein stable (heat stable otherwise will throw a haze). Colloidal protection
How does polyaspartate work?
Colloidal protection. Same as CMC only has less protein conflict.
Describe the steps in the fining process
Flocculation
Sedimentation
Clarification
Stabilization
Refining
Explain the principle of fining
Interaction between the charged particles of the fining agent and the particles of the wine
What is the aim of fining? (3)
Clarification
Stabilization
Valorisation
What are the reasons to do fining for red in comparison to white?
Red: clarification, stabilisation color, refining
White: clarification refining and treatment of oxidation, discolouration or bentonite.
Name 3 types of fining agents
Organic (milk/eggs/fish/collagen/plants)
Minerals (silica/clay)
Synthetic (PVPP)
What is the role of tannin in white wine?
Antioxidant
Elimination of proteins (clarification)
Antisceptic
Iron complexation (?)
What is the role of tannin in red wine?
Antioxidant
Participation of structure
Stabilisation of anthocyanin
Antisceptic
Name 3 types of enological tannin
Gallics
Ellagics
Proanthocyanidics
When incorporating fining agents. What are the golden (5) rules before collage (adding agent)
Adequate fining agent
Make collage test
Temperature low and stable
Racking with aeration
Watch out for glucans and pectins
When incorporating fining agents. What are the golden (5) rules during collage (fining agent to flocculation)
Respect hydration time and instructions
Respect the order of incorpration
Homogeneous incorporation
Rack on time and gently
Watch out for wind/aircurrents
Name 4 ways to inhibit formation of tartrates
Polyaspartate K+
CMC
Mannoproteins
Metatartaric acid
Name 2 ways to subtract tartrates from wine
Resins exchange
Electrodialysis
Name 4 ways to cold subtract tartrates from wine
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)
What are the temperatures for cold stabilisation?
-5C-5C
What does tartaric cream do?
Excellarates precipitation of crystals
What is the maximum dose of meta tartaric acid?
10g/hl during bottling
What is the aimed esterification index?
40
What is esterification?
Polymerisation of tartaric acid, through ester bonds
Is meta tartaric acid a stable protection?
No, when the wine heats up the ‘cover’ gets broken
Name the 4 protective colloids
Metatartaric acid
CMC
Mannoproteins
Polyaspartate
Which fining agents can you use for red wines?
Egg whites and gelatine
What is the only fining agent you cannot use for white wines?
Egg whites
Which stabilisation method will decrease in effectiveness over time?
Metatartaric acid
Cold stabilisation (if the tartrates are not racked off)
