13. General Winemaking Options

Question 1

What is reductive/protective winemaking?

Answer 1

Minimizing oxygen exposure during winemaking process

Question 2

What are some examples of reductive winemaking?

Answer 2

1) avoiding ullage by topping up vessels
2) use of “inert” gases (nitrogen, CO2, argon) to flush out oxygen from machinery/fill ullage
3) addition of SO2
4) use of impermeable containers
5) cool, constant temperatures

Question 3

How can oxygen exposure be increased? (5)

Answer 3

1) use of cap management techniques that spray/splash
2) use of small wooden barrels
3) increasing number of rackings/lees stirring during aging
4) allowing ullage
5) use of techniques that involve pumping oxygen through must/wine

Question 4

What is sulphur dioxide’s two main properties?

Answer 4

1) anti-oxidant – reacts with oxygen very slowly and inhibits oxidative enzymes
2) anti-microbial – inhibits development of microbes such as yeast and bacteria

Question 5

When is SO2 usually added?

Answer 5

Soon after grapes are picked/reach the winery, then at various points, then at bottling

Question 6

What are some things that can be done to minimize the threats of oxidation in transportation to the winery?

Answer 6

1) harvesting at night
2) addition of SO2
3) putting grapes in cold storage once received at winery
4) sanitizing equipment/bins

Question 7

What are the 4 things that happen once grapes are received?

Answer 7

1) chilling
2) sorting
3) destemming (only for hand-harvested)
4) crushing

Question 8

What are 3 examples of when grapes would not be de-stemmed?

Answer 8

1) red wine fermentations using whole bunches (ex. PN in Burgundy)
2) carbonic maceration
3) whole bunch pressing for some whites (high quality sparkling)

Question 9

What is the difference between crushing and pressing?

Answer 9

• crushing = breaking grape’s skins and releasing juice, making it available for fermentation
• pressing = separation of juice/wine from skin/seeds

Question 10

How does a pneumatic press work?

Answer 10

Cylindrical cage with bladder that runs down middle -> bladder inflates and grapes are pushed against grates on side of cage

Question 11

How does a basket press work?

Answer 11

A “basket” is filled with grapes and pressure is applied from above -> juice runs through gaps/holes in side of basket and collected by a tray

Question 12

What are 4 examples of must adjustment?

Answer 12

1) enrichment
2) reducing alcohol
3) acidification
4) de-acidification

Question 13

What are 3 ways to “enrich” wine?

Answer 13

1) adding dry sugar (called “chaptalisation”)
2) adding grape must, grape concentrate or RCGM
3) the processes of concentration by removing water

Question 14

Why is acidification done and what type of acid is typically used to acidify wines?

Answer 14

• done to bring back freshness in warm-climate grapes where malic acid drops dramatically as grapes ripen
• tartaric acid

Question 15

Why is de-acidification done and what is added?

Answer 15

• done in cool climates where grapes may have to be picked before they’re ripe
• calcium carbonate (chalk) or potassium carbonate

Question 16

What is alcoholic fermentation?

Answer 16

The conversion of sugar into ethanol and CO2 carried out by yeast in the absence of oxygen (anaerobically)

Question 17

What is a definition of yeast?

Answer 17

A collective term given to a group of microscopic fungi that convert sugar into alcohol and affect the aroma/flavour characteristics of a wine

Question 18

What are the right conditions for yeast to convert sugars in must into alcohol? (3)

Answer 18

1) viable temperaturen range
2) access to yeast nutrients (nitrogen)
3) absence of oxygen

Question 19

What does the fermentation process also produce aside from alcohol, CO2 and heat?

Answer 19

1) volatile acidity (not enough to be detected)
2) very small amounts of naturally produced SO2
3) wine aromatics
4) glycerol (increases body of wine)

Question 20

What is the most common species of yeast used? Why?

Answer 20

• saccharomyces cerevisiae
• it can withstand high acidity/alcohol
• it is resistant to SO2
• there are different strains – winemakers can choose

Question 21

What is ambient yeast?

Answer 21

Yeast that is present in the vineyard/winery

Question 22

What are advantages of ambient yeast? (4)

Answer 22

1) can add complexity
2) costs nothing
3) adds to “terroir”
4) can be used in marketing of wine

Question 23

What are disadvantages of ambient yeast? (3)

Answer 23

1) fermentation may start slowly – results in build cup of VA and off flavours
2) fermentation to dryness may take longer
3) consistent product can’t be guaranteed

Question 24

What is cultured yeast?

Answer 24

• strains that are selected in a lab and then grown in volumes suitable for sale
• to use cultured yeast, must may be cooled down to prevent fermentation by ambient yeast

Question 25

What are advantages of cultured yeast? (3)

Answer 25

1) produces reliable, fast fermentation to dryness
2) produces low levels of VA and less risk of spoilage
3) consistent product from one year to another

Question 26

What are disadvantages of cultured yeast? (2)

Answer 26

1) can lead to a similarity of fruit expression

2) adds the cost of using a commercial product

Question 27

What are cool, mid-range and warm temperatures during fermentation and what do they favour? .

Answer 27

• cool (12-16) favours fresher, fruiter whites and roses
• mid-range (17-25) favours easy drinking fruity reds
• warm (26-32) favours powerful reds

Question 28

What are options for temperature control during fermentation?

Answer 28

1) temperature of cellar
2) use of water or glycol in jackets that surround vessels
3) temperatures can be reduced by pumping over (releases heat)

Question 29

What are benefits of stainless steel fermentation vessels?

Answer 29

• easy to clean, various sizes available, enables temperature control, neutral vessels

Question 30

What are benefits of concrete fermentation vessels?

Answer 30

• high thermal inertia (maintain an even temperature), natural lees stirring occurs in smaller ones through convection currents

Question 31

What are benefits of wood fermentation vessels?

Answer 31

• retains heat well, allows a small amount of oxygen, can be re-used

Question 32

What is malolactic conversion? When does it happen?

Answer 32

• result of lactic acid converting malic acid into lactic acid and CO2 (and heat)
• happens after alcoholic fermentation and during it occasionally

Question 33

What conditions encourage and discourage it?

Answer 33

• encourage = 18-22 degrees, moderate pH (3.3-3.5) and low total SO2
• discourage = temperature below 15, low pH and moderate levels of SO2

Question 34

What are the outcomes of malo? (4)

Answer 34

1) reduction in acidity and rise in pH - results in softer, smoother wines
2) some colour loss in reds
3) greater microbial stability (less likely that it’ll happen later at inconvenient time)
4) modification of flavour (addition of buttery notes)

Question 35

What are 3 options for removal of alcohol after fermentation?

Answer 35

1) adding water (but this dilutes flavour)
2) reverse osmosis (most common high-tech option)
3) spinning cone (extracts VA compounds from wine then removes alcohol – flavour components added back in)

Question 36

What are some options for removing unwanted colour tints post-fermentation?

Answer 36

• fining wine, adding MegaPurple