Element three - Maturation, Treatments and Bottling, Part Two, Blending, Clarification, Stabilisation

Question 1

What is Colloids and what does it consist of (5)?

Answer 1

Large organic molecules, consisting of polysaccharides, tannins, other phenolic, pigmented tannins and heat un-stable proteins

Question 2

Wine must be clarified because? (2)

Answer 2

1. Customers do not accept cloudy wines

2. Particles may cause taints in the wine at a later satge

Question 3

Why is winemakers speeding up sedimentation and how?

Answer 3

colloid are difficult to remove, takes time. By fining, filtering or centrifuging and or using the flotation technique.

Question 4

What are the main methods of clarification? (5)

Answer 4

1. Sedimentation and racking
2. Fining
3. Filtration
4. Centrifugation
5. Flotation

Question 5

The speed of sedimentation is affected by? (4)

Answer 5

1. relative density of the particles
2. the viscosity of the wine
3. temperature
4. the convection currents caused by the differences in temperature between the top and the bottom of the storage vessel

Question 6

what type of vessel is best for sedimentation?

Answer 6

Small, Shallow containers whit poor heat-conducting walls. (like a barrel)

Question 7

What are two main advantages of sedimentation?

Answer 7

1. it is a gentil, natural process

2. it requires minimal equipment, often only a hose and pump

Question 8

What are the three main disadvantages of sedimentation?

Answer 8

1. Can be slow, particularly for large volumes of wine.
2. Often needs to be done in several stages
3. A big volume of lees is produced.

Question 9

When is the racking of gross lees normally carried out?

Answer 9

after the alcoholic fermentation

Question 10

Why is racking preformed every two months on white wine stored on stainless steel tanks?

Answer 10

To prevent reduction, by removing grape matter and dead yeast cells.

Question 11

Why is racking preformed every 3-4 months on red wine stored on stainless steel tanks?

Answer 11

removal of lees consisting mainly of deposited colour material and tannins. Aeration occurs and this is important for further clarification and stabilisation reactions.

Question 12

What is assessed during the racking process?

Answer 12

the free sulfur dioxide levels.

Question 13

Why is not carbon dioxide used after racking is performed?

Answer 13

it readily dissolves in the wine.

Question 14

Name some applications for centrifuges! (6)

Answer 14

1. rapid clarification of musts after pressing
2. removal of yeasts during fermentation, slowing down the alcoholic fermentation
3. Clarification of new white wines at the end of fermentation
4. Clarifying new red wines just before they are run into barrels
5. Clarifying wines after fining
6. Facilitating tartrate precipitation - helps stabilisation

Question 15

Name two advantages of centrifugation!

Answer 15

1. removal of dense particals, (but will never remove every part)
2. relatively quick process

Question 16

Name two disadvantages of centrifugation!

Answer 16

1. Expensive and noisy

2. need to take good care to prevent contamination - oxidation.

Question 17

Fining does what to the wine? (3)

Answer 17

1. Clarifies 2. Stabilises and 3. may modify a wine´s organoleptic properties

Question 18

A fining agent is always, what and what happens?

Answer 18

electro-statically charged, enable them to attract oppositely charge colloid molecules. 
Clumping together (flocculating) and when to big falling down to the bottom.

Question 19

Colloids are to small to be removed by filtration alone, need fining. But why not leave them?

Answer 19

Then can cause a wine to become cloudy and or deposit to form. No good says wset.

Question 20

Tannins, pectins, dextrans and glucans whereas coloured pigments are ____ charged.

Answer 20

Negatively charged

Question 21

Proteins are ____ charged

Answer 21

Positively charged

Question 22

What three tings can fining do for the wine?

Answer 22

1. Remove colloids and make the wine mor stable
2. Remove other small particles, improving clarity
3. change the organoleptic properties of the wine, appearance, aroma and flavour.

Question 23

Give an other name for montmorillonite clay.

Answer 23

Bentonite

Question 24

Bentonite is a strong negative charge stuff, it attracts positively charged proteins such as…. (3)

Answer 24

1. Enzymes (oxidases)
2. Vitamins
3. Amino acids

Question 25

Bentonite is non-selective, meaning what?

Answer 25

some flavour reduction is possible as some positively charge molecules may also be removed.

Question 26

Name one good and bad thing about using Bentonite.

Answer 26

Good: Lees are argued to settle better and faster in wines which use Bentonite.
Bad: Produce a large quantity of lees, wine loss can be up to 10%.

Question 27

Why is Bentonite used in White/Rose wine and Why is bentonite used in red wine?

Answer 27

White/Rosé: protein stability

Red: eliminate any colloidal colouring matter

Question 28

Bentonite is avaliable in either powder or granule form, how should you prepare it?

Answer 28

You need 10 times its own weight in hot water, allow to swell for 24h before addition. Let it settle for two to three weeks and then racked. the after, use coarse plates or diatomaceous earth also give good results.

Question 29

Gelatin is a protein extracted from ….

Answer 29

Pig skins and animal bones by boiling.

Question 30

Gelatin is sold as a powder or liquid form and should be prepared how for powder?

Answer 30

Dissolved in warm water (30°) in an 8-10% solution before use

Question 31

Name one good and one bad thing about using Gelatin!

Answer 31

Good: good clarifier and can remove off-tastes.
Bad: Reduce the “body” of the wine.

Question 32

What is the ideal temperature in which to use Gelatin?

Answer 32

16-25°

Question 33

Why is Gelatin used in White and why is it used in red wines?

Answer 33

White: if rotten grapes are used, remove astringency and off-flavours. To much will make the wine protein-unstable and will need to add tannin or silica sol.
Red: Remove harsh tannins and will increase suppleness in the wine. However, can remove colouring matter so use with care.

Question 34

Cassein is the principal protein in milk and it is an excellent fining agent for white wine with what problem?

Answer 34

Excess colour or oxidised characters but can also help with reducing the iron content of wine.

Question 35

Cassein is used in powder form as either sodium or potassium caseinate but can be difficult to use, why?

Answer 35

coagulates immediately with contact with a acidic medium, so need to be mixed thoroughly and fast in wine.

Question 36

Why the use of skimmed milk in fining?

Answer 36

EU do not permit the use of whole milk, skimmed milk has a lower adsorption capacity then whole milk but better clarifying abilities.

Question 37

Isinglass is what?

Answer 37

a raw unprocessed product from the swim bladder of a type of fish.

Question 38

Isinglass works how?

Answer 38

Consists of collagen, forms clumps on contact with wines tannin content, all will take the negatively charged molecules to the bottom.

Question 39

Isinglass is used for white wines, what works good and what works bad?

Answer 39

Good: improve colour vibrancy and clarity.
Bad: To much can give a fishy nose and palate and produces small amounts of light fluffy lees which will clog filters, expensive and difficult to prepare.

Question 40

PVPP Or Polyvinylpolypyrrolidone is used for white and red wine, what is it doing?

Answer 40

White: used to reduce bitterness or browning in white that has had skin contact.
Red: Reduces stringency and soften excessivley tannic red wine.

Question 41

Carbon (charcoal) from burnt animal or plant is used why and best used with?

Answer 41

as a last resort to remove off-odours and colour, best used with ascorbic acid as it otherwise may provoke oxidation. Non-selective and will remove wanted aromas and flavours.

Question 42

Silica sol is used with a protein-based fining agent and help with what?

Answer 42

Silica particales are negatively charged, help accelerate the clarification and reduce compact lees (minimises the wine loss), help remove gelatin from solution (minimises the risk of over-fining) and help improve filterability of teh wine.

Question 43

Tannin helps with what?

Answer 43

Facilitate the stabilisation of new wines, may also be added to white wine with gelatin to aid the fining process.

Question 44

What did the EU stop allowing in wine 1987?

Answer 44

Blood products

Question 45

What is the white if the chickens egg called?

Answer 45

Egg albumen

Question 46

When a fresh egg white is used for fining how many for 225L?

Answer 46

3-8 eggs, one egg white corresponds to about 4g of dry matter

Question 47

Egg whites need to be mixed and dissolved, how?

Answer 47

Mixed and dissolved in a quarter of a liter of wine, to get as little foam as possible. Add little sodium chloride (salt) help dissolving.

Question 48

Egg whites is used in red wine, how does it work?

Answer 48

adsorbs the harshest, greenest tannins. (egg whites (+) and tannin (-), ) and give a softer tannin structure.
Only little of colour or aromas are removed, popular for premium red

Question 49

The biggest advantages of fining is what?

Answer 49

it saves the winemaker time and money as it speeds upp the clarification process.