Winemaking

Question 1

describe the influence of oxygen in wine making

Answer 1

a winemaker wanting to make a wine dominated by primary fruit, oxygen contact is kept to a minimum
grapes are harvested at night
when in winery juice is kept away from oxygen by filling airtight equipment with carbon dioxide or nitrogen - this is anerobic/protective winemaking

a question of winemaking style could be to keep oxygen contact for complexity and character

Question 2

Describe influence of oxygen in maturation

Answer 2

wines matured aerobically - intact with oxygen are stored in oak

small amounts can interact with wine, softening tannins and giving more complexity of flavours, tertiary and secondary aromas develop

small vessels (225l barriques) have more contact with oxygen - smaller barrels rarely age for more than 2 years

oxygen effects can also occur if container is not completely full (olorosso, port, rutherglen muscat) - pronounced caramel, toffee, nut

Question 3

what can extreme contact with oxygen do?

Answer 3

wine will lose fruit flavour become stale and oxidized being unfit for sale

can turn to vinegar

Question 4

what acts as an antiseptic and anti oxidant

Answer 4

so2

strictly controlled by law

if too high wine can harsh and lack fruit

Question 5

how does so2 act as an antiseptic vs antioxidant

Answer 5

anti septic - toxic to yeast and bacteria that is unwanted

anti oxidident - protects grapes and juice from oxygen effect - once doing this it becomes bound, losing effect so it needs monitoring and replenishing

Question 6

oak tannins give?

Answer 6

structure and textural complexity

Question 7

what is a con of oak?

Answer 7

hygiene - difficult to keep free from yeast, bacteria, mould

Question 8

what does the heating of oak barrels do

Answer 8

transforms tannins and flavour compounds in the oak giving sweet spice and toast

the temperature and length of heat exposure affects this

Question 9

how can you get a oxidized effect in wine with oak chips or staves

Answer 9

adding a small amount of controlled oxygen to the vessel

Question 10

how can you regulate temperature in stainless steel vats?

Answer 10

sleeves on the outside or internal coils that cold or hot liquid can be circulated

Question 11

pros and cons of concrete vats?

Answer 11

harder to clean and maintain

cheaper to regulate temperature

Question 12

briefly describe the grape processing process

Answer 12

1) grapes arive at winery, receive first dose of so2 and are sorted and checked (for premium)
2) optional destemming and crushing, crushing releases free run juice but should be careful not to crush the seed releasing oil and tannin causing unpleasant and astringent tastes

3) pressing, separating liquids and solids
white wine happens before ferment
red wine happens after ferment

Question 13

what is a pneumatic press?

Answer 13

inflatable rubber tube tube with a preferred horizontal stainless steel cylinder

this applies pressure to a large area in a controlled way, closed tank to keep away from oxygen

Question 14

how can juice be seperated during pressing?

Answer 14

the juice at the beginning vs end of pressing is different in flavour and texture, it is seperated into different pressings called fractions and can be blended in different proportions to create a certain style

Question 15

what 3 things may need adjustments in winemaking?

Answer 15

sugar, alcohol, acid

Question 16

why may there be insufficient sugar in grapes?

Answer 16

cooler climates

Question 17

what is RCGM

Answer 17

Rectified concentrated grape must

a colourless, odourless syrup that raises alcohol because there is more sugar to ferment

Question 18

what is chaptilisation

Answer 18

adding sugar from sources other than grapes (eg: beet)

Question 19

besides enrichment and chaptilisation, how can a winemaker raise sugar levels?

Answer 19

remove water from the juice

this concentrates sugar but also tannin acid and flavour compound and any faults, also reduces volume of juice

Question 20

can you remove alcohol from wine?

Answer 20

yes with modern machinery

Question 21

how is acidification carried out?

Answer 21

addition of tartaric acid in powder form - permitted in warm regions of europe and common in warmer regions around the world

Question 22

how is deacidification carried out?

Answer 22

common in cooler regions, it is neutralized by addition of alkali (chemical oppisite of acid)

Question 23

the yeast species that is responsible for majority of wine fermentation’s is?

Answer 23

saccharomyces cerevisiae

Question 24

why is SC (yeast) the majority yeast used?

Answer 24

tolerance to high alc and so2 levels

Question 25

what is the temperature fermentation starts at

Answer 25

it will not start if it’s below 5 celcius

Question 26

why could fermentation stop early or struggle to start?

Answer 26

if yeast run out of nutrients they need (other than sugar) or if temp goes over 35 celcius when the sugar level is very high the combination of high sugar and high alcohol may cause yeast to struggle to start fermentation

Question 27

if a winemaker wants to stop fermentation before all the sugar has been converted to alcohol it can be achieved by?

Answer 27

killing or removing yeast this can be done by adding so2 or grape spirit

Question 28

how can yeast be removed?

Answer 28

filtration, after the fermentation is haunted by chilling wine to below 5 celcius

Question 29

what are the choices a winemaker makes regarding yeast?

Answer 29

whether to use ambient yeast found on grape bloom and in winery or by adding a cultured yeast ambient yeast can produce complex flavours but the winemaker cannot control what yeast is present - also causes variations between batches cultured yeast consistently preform and produce attractive flavours - some argue it limits complexity

Question 30

what does controlling the temp of fermentation help?

Answer 30

if it becomes to hot yeast will die fermenting at lower temps avoids loss of most volitile aromas which often have a floral character and can encourage fruit flavour higher temps are necessary for extraction of colour and tannins

Question 31

when and how is MLF carried out

Answer 31

after fermentation by lactic acid bacteria, concertina tart malic grape acid into soft lactic acids it softens acidity and creates buttery flavours producing co2 it may be encouraged by raising temperature and not adding so2 after fermentation and can be avoided by storing at cool temperatures adding so2 and filtering bacteria

Question 32

what are gross lee’s

Answer 32

the sediment of dead yeast cells and grape fragments this is heavy and falls to the bottom of vessel within hours causing unpleasant aromas if not removed

Question 33

what are fine lee’s

Answer 33

finer particles, they are often removed gradually however a winemaker may chose to keep a white in contact with them for extra flavour and texture

Question 34

if a winemaker wants to retain as many of the primary fruit aromas as possible the wine is likely to be bottled?

Answer 34

after only a few months of being stored in an inert vessel

Question 35

to survive medium or long term aging wines need?

Answer 35

sufficient tannin, acidity and/or alcohol and flavours that will be worth wile

Question 36

what can blending achieve?

Answer 36

balance - eg free run blended with press to increase tannin consistency - different barrels or vessels need blending together in a large bay to smooth inconsistencies or from variations in fruit/harvesting time style - could include seperating press fractions, fermenting in different vessels or only allowing a portion of wine to go through MLF

Question 37

what are 3 methods of clarification?

Answer 37

sedimentation, fining, filtration

Question 38

what is the process of racking?

Answer 38

wine slowly pumped into a different vessel leaving sediment of lee’s behind - clarity can be improved through repeated racking this process can be accelerated by putting wine in a centrifuge- very expensive

Question 39

what is the process of fining?

Answer 39

wine constituents slowly clump together, fining speeds this process up so they can be removed before bottling adding a fining agent bonds with constituents and and are removed by filtering some wine makers do not because they find it effects flavour and texture

Question 40

what is the process of filtration?

Answer 40

physically removes particles from wine as it is passed through a filter after fermentation and during maturation to remove gross and fine lee’s quickly

Question 41

what are the 2 methods of filtration?

Answer 41

depth filtration - used for gross lees and can handle very cloudy wines surface filtration - removes fine sieves- expensive and clog up easily so used after a depth filter - referred to as sterile filtration some winemakers believe filtration effects texture

Question 42

3 stabilization methods are?

Answer 42

tartrate microbiological oxygen

Question 43

explain tartaric stability

Answer 43

tartaric acid is less soluble than grape juice and it can form crystals - harmless and flavourless cool temps accelerate the formation of them - so if matured a long time in cool cellar prior to bottling - they will develop or they can be forced to form by chilling wine to 0 for a short time and then removed by filtration

Question 44

which wine may be subject to microbiological stability easier?

Answer 44

a dry high acid wine that has gone through MLF or a wine with low to medium alcohol low acidity and little RS

Question 45

how can you prevent microbiological instability

Answer 45

so2

Question 46

how can a winemaker avoid oxygen at bottling

Answer 46

flushed with carbon dioxide or nitrogen prior

Question 47

what are cheaper alternatives to the pricy transport and cost of bottles

Answer 47

lighter weight bottles or transporting in bulk to be bottled where the wine will be sold

Question 48

why do plastic and bag in box wines need to be consumed quickly from bottling?

Answer 48

oxygen contact can lose freshness and fruitiness

Question 49

what causes corn taint?

Answer 49

TCA - mouldy and carboard like aroma

Question 50

what is the premium conditions for bottle maturation

Answer 50

10-15 celcius, humidity, lying on side to keep cork moist and optimum seal is retained