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Flashcards in Vinification Deck (24)
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1

What does malolactic conversion do to a wine?

Decreases acidity, increases PH

softer acid, can give buttery/creamy texture

2

What does lees ageing do to red wines, and what is a possible disadvantage (of lees ageing for red wines)

Can help soften tannins in red wines

Poss disadvantage is reduced colour intensity

Not typical to keep gross lees or stir the lees when making red wines

3

What are the 3 key ways of making rose wines?

Direct pressing

Short maceration

Blending

4

Why is malolactic conversion usually avoided in the production of rose wines?

Buttery flavours are not wanted, would mask the fresh fruit aromas that are appealing to these wines

Designed to be refreshing to drink and therefore winemakers looking to retain acidity

5

When does blending most often occur

Can be carried out at any time during winemaking process, most often prior to finishing and packaging

6

Blending may involve combining wines .... (5)

-From different grape varieties
-Different locations (from different vineyards, regions or countries)
-Different vintages
-that have been treated differently in winery (i.e. press juice/free-run juice, matured in oak/stainless steel or concrete
-treated equally in winery but different vessels for logistical reasons (fermented or matured in barrels need to blend together to make up quantities)

7

What does PDO stand for and what does it mean for the grapes

Protected Designation of Origin
100% of the grapes must come from the defined geographical area

8

What are the 7 key reasons for Blending a wine

-Balance
-Consistency
-Style
-Complexity
-Minimise Faults
-Volume
-Price

9

Why might a winemaker blend with price in mind

especially inexpensive or mid-priced wines will be made to be sold profitable at a certain price point.
Blending different parcels can help to create a certain style/quality
e.g. Chardonnay is sometimes blended with varieties such as trebbiano or semicolon - grapes that are generally cheaper to buy.
Inclusion of Chardonnay - one of the most recognised varieties internationally - helps wine to sell

10

Conventional winemaking includes... (3)

Temperature Control

Use of additives and/or processing aids of many types

Manipulations

11

What is the main certifying association for biodynamic?

Demeter International

12

What affect does low levels of nitrogen have on yeast, and what can be added as a yeast nutrient?

Can stress the yeasts - causing them to produce undesirable sulphur compounds (rotten eggs) or stop fermenting

DAP or B1 can be added

13

Explain Fining

Fining agents can be of protein or mineral content

Fining agent must have opposite charge to the colloid to be removed - they bond to form a solid large enough to be removed by racking or filtration.

14

What are the 3 types of fining agent

Those that remove -

-unstable proteins
-phenolics that contribute undesirable colour and bitterness
-Colour and off-odours

15

Name and describe a fining agent used to remove unstable proteins

BENTONITE - form of clay, adsorbs unstable proteins and colloidal colouring matter - can have some colour loss in red wines
Causes a large amount of sediment so wine can be lost when racked off

16

Name and describe 6 fining agents used to remove phenolics that contribute undesirable colour and bitterness

EGG WHITE- not vegan. Removes harsh tannins and clarifies. Gentle

GELATINE - Not veg, not vegan. It is a protein collagen extracted from pork. Removes bitterness and astringency in red, browing in white
Easy to overfine - stripping flavour and character. Can be used on MUST or WINE. Risk of protein haze later

CASEIN - not vegan. Milk-derived protein. Removes browning from white wines. Can be used on MUST or WINE

VEG. PROTEIN PRODUCTS - potato/legume derived

ISINGLASS - not veggie not veg. Clarifies white wines - bright appearance. Derived from fish bladders.
Too much used = Risk of protein haze later, and possibility of fishy smell

PVPP - Insoluble plastic powder form - removes browning, astringency from oxidised white wine. Gentler than charcoal

17

Name and describe a fining agent used to remove colour and off-odours

CHARCOAL - Removes brown, off-odours
Over fines easily removing desirable aromas/flavours
One option is to treat only one batch of wine and blend with others to reduce the effect of the "fault"

18

Describe Depth filtration

Not an absolute filter. Like a sponge. If too much pressure is applied, it can allow some particles through

Most popular = Kieselguhr (Diamotaceous Earth)
Silica, intert - wetted and used as filter medium

Wine is sucked from outside rotary drum - it is an oxidative process, can be flushed with inert gas, High initial investment - can get in a range of particle sizes

Other are sheet filters. The more sheets, the quicker - any portion of wine only goes through one sheet
Initial investment, trained personnel

19

Describe Surface filtration

Membrane Filters - Wine must be pre-filtered. Used as final precaution before bottling
Can easily get blocked

Cross Flow filters - Continuous, cleans surface filter as it works. Expensive machines, for large and/or well-funded wineries

20

Describe Cold stabilisation, and what it is used for

Used for tartrate stability

Chill down to -4°C, 8 days, crystals form and can be filtered out. Colloids must be removed by fining prior, otherwise could prevent crystals forming.
Removes Potassium bitartrate, NOT calcium bitartrate. Equipment, energy costs

21

Describe contact process and what it is used for

Used for tartrate stability

Quicker, continuous, more reliable, cheaper form of cold stabilisation. Potassium bitartrate is added to the wine - speeds up crystallisation process. Wine is chilled to around 0°C. Takes 1-2 hours - then filter crystals out

22

Describe CMC and what it is used for

Tartrate stability

Cellulose extracted from wood, prevents tartrates developing to visible size. Used for inexpensive white/rose.
Not suitable for red as it reacts with tannins - becomes ineffective and causes a haze
Cheaper than chilling
Stability for a few years

23

Describe what metatartaric acid is used for and why

Prevents growth of potassium bitartrate and calcium bitartrate crystals , reducing need for cold stabilisation

Unstable compound - positive effect lost over time especially at storage of 25-30°C

Only suitable for early consumption wines

More for red (white or rose - cmc is the better option)

24

What do you do for protein stability?

Fine with bentonite