L2 Barrels Cork White Wine Making

Question 1

Who invented barrels?

Answer 1

The Gauls

(read the French who were as indisciplined at the time. Think Astérix)

Question 2

Why did the use of barrels start to decline in the 1950s?

Answer 2

. High cost

. Introduction of other vessels (concrete, coated steel, stainless steel)

. 50s - 80s in France: Cognac only

Question 3

Since when in the XXth century did the barrels make a comeback to mainstream usage?

Answer 3

1990s

Question 4

How old do oak trees need to be on average to be used in barrel making?

Answer 4

150 years old

(the right wood structure is needed to be worked into staves)

Question 5

What are the four species of oak relevant to barrel making?

Answer 5

1. Quercus robur (pedunculate oak)
2. Quercus petraea /sessiflora
3. Quercus alba
4. Quercus suber

Question 6

Tell me about Quercus robur?

Answer 6

. Found in Europe

. Can grow 20-30 meters with a circumference of 5-6 meters.

. Grows in fertile soils including clay

. Requires lots of sunshine

. Best woods are from 180-250 year old trees.

Question 7

Tell me about Quercus petraea/sessiflora

Answer 7

. Found in Europe too

. Grows in infertile, sandy, acidic soils on well-drained slopes

. Drought resistant

. Aroma compounds 4 x > Quercus robur

Question 8

Tell me about Quercus alba

Answer 8

It’s the white species used as American oak.

Question 9

Tell me about Quercus suber

Answer 9

Used for corks (Portugal and Mediterranean basin)

Question 10

In the Middle Ages what was used as a seal of authenticity guaranteeing origin?

Answer 10

Shape and size of the barrels, as each region had its own style.

Question 11

Name 5 oak tree growing regions in France

Answer 11

. Limousin

. Allier

. Nevers (close to Dijon)

. Bertranges (close to Dijon too)

. Vosges

Question 12

Are oak forests managed in France?

Answer 12

Yes, well managed according to traditions and sustainable standards by l’Office National des Forêts (dates back 8 centuries)

Question 13

How many seedlings per hectare do you need to plant on average to get 1000 mature trees?

Answer 13

50 000

Question 14

Why using oak?

Answer 14

1. Strong yet easy to work with (bends)
2. Makes containers that are air tight
3. Watertight (rich in tyloses blocking the xylem)
4. Flavors marry well with wine

Question 15

Can tasters tell the difference between oak ageing and oak chips addition?

Answer 15

Not really

Question 16

What oak barrel properties make a difference in the wine?

Answer 16

. Forests and growing conditions (origin)

. Grain (comes from oak species)

. Seasoning (leaving raw stave woods outside)

. Toasting

. Barrel size

Question 17

What are foudres?

Answer 17

Larger closed wood vessels for white fermentation and aging of both reds and whites. Little wood interaction with the wine due to size and tartrate deposit over time.

Question 18

Name benefits and characteristics of Diam cork closures?

Answer 18

. Guaranteed 5-10 years

. Guaranteed TCA free

. Micro-agglomerate closures: made of cork (cleaned with supercritical CO2) with beeswax and a plant-based binding agent.

. Different versions are available with varying oxygen transmission levels

. More expensive than natural corks, but more appealing to consumers than screw caps

Question 19

Name issues with natural corks and remedies

Answer 19

. Cork taint (caused by 2, 4, 6 trichloroanisole (TCA)

. Corks were treated with chlorine but this was worse than TCA.

. Corks are coated with silicon or paraffin (or both). White Burgundy suffered badly from paraffin coated cork where the paraffin was too slippery leading to oxidation (1998-2002).

Question 20

Name the predecessor of Diam which showed unfortunate levels of TCA?

Answer 20

Altec

Question 21

Describe Vino-Lok

Answer 21

Glass topper with a plastic o-ring that clips onto a specially designed bottle and is covered by an aluminium cap.

Long term cellaring is ok but oxygen transfer is unknown.

Question 22

Which markets is Vino-lok popular in?

Answer 22

Germany, Austria but also Provence rosé

Question 23

What are the two types of screw caps?

Answer 23

. Tin/Saran (Aussie, NZ)

. Saranex

Question 24

What do you possibly need for fruit transportation and selection?

Answer 24

Cases bins tractors machine harvesters

Vibrating and/or sorting table

Question 25

Tell me about whole bunches and de-stemming

Answer 25

Grapes can come into the winery as whole bunches (ie., no machine harvester was used as it shakes the berries off). Winemakers then have a choice: de-stem them or leave the grape bunch intact for fermentation. What they decide impacts how the wine will eventually taste.

To de-stem means to take the berries off the bunch with a machine that separates the fruit from their stalks, or stems. Modern destemming machines do this very gently, so that whole, uncrushed berries come out at the other end. Other machines crush and de-stem simultaneously. But some winemakers forgo this process and ferment with the entire grape bunch intact, stems and all (ex: semi-carbonic or carbonic macérations).

Insight from Mathew: whole bunch is not limited to semi-carbonic and carbonic fementation; Dujac famously use whole fermentation in their classic ferments. The pluses, it can help fix colour, and reduce alcohol by 0,5% and the intercellular fermetation that takes place in whole berries gives the wines a little lift and florality (and logically if unfermented a little extra sweetness). The risk - adding too much (green) tannic astringency if the rachis (not the bunches) is not perfectly lignified. Another good example is Mark Haisma an Australian colleague of Jane. Here de-stemmed then added the rachis in a kind of muslin bag, like a teabag, to add an appropriate level of structure.

Question 26

Name types of presses

Answer 26

. Pneumatic (ex. Europress)
. Hydraulic
. Screw
. Basket

Question 27

What is settling (débourbage)?

Answer 27

After pressing, the juice is cloudy due to solid matters being present. Settling allows the larger particules to settle at the bottom of the tank. Factors: pressing duration, temperature, clarity or health of the juice.

Question 28

What types of presses were the original ones?

Answer 28

Basket presses

Then came hydraulic/screw systems (vertical press with a moveable end on a screw; great maceration)

Question 29

Describe a pneumatic press

Answer 29

Canvas membrane in a horizontal metal stainless cage. There are small slits on half the surface area to allow juice removal. There are drainage channels inside the press.

Variation to the theme and sizes.

Question 30

What variations in press programs are there?

Answer 30

. Duration
. Pressure
. Separation of pressings

Question 31

What is a drawback of over-protecting the juice during pressing?

Answer 31

Can lead to oxidation problems later on. Often better to remove oxydable compounds before.

Question 32

Explain lees stirring and what it adds to the wine when used?

Answer 32

After alcoholic fermentation the yeast dies. The decomposition is referred to as yeast autolysis. Lees = dead yeast cells.

Lees steering (batonnage) adds complexity to the wine as well as antioxidants properties.

Flavor characters = bread, toast, creaminess (autolytic)

Question 33

White wine typical ageing duration?

Answer 33

From several months after harvest, for unpacked earlier drinking styles, to 24 months for barrel aged Chardonnays.

Question 34

What is the basic transformation happening during malolactic conversion?

Answer 34

Converts malic acid to lactic acid (softens and reduces acidity)

Common in Burgundy. Less common is warmer regions.

Question 35

When does racking potentially occur in the winemaking process? What does it do to the wine?

Answer 35

. Often performed after completion of MLF
. Clarifies wine by removing lees
. Homogenize wine stored in different tanks/barrels
. Helps remove reductive characters
. Unifies wine
. Change oak regime

Question 36

What is fining?

Answer 36

Process for clarifying and purifying wine using natural or synthetic materials. It improves color or flavor of wine by removing unwanted phenols that could contribute to browning or haze in whites.

Mix it with wine, allow it to settle and then you rack your wine off the deposit.

Insoluble, colloidal, or soluble

Question 37

Name types of fining agents and their actions (7)

Answer 37

. Gelatin (derived from collagen, soluble, red wine mostly, removes astringent tannins)

. Isinglass (made from bladder of certain fish to remove phenolics and bitter tannins)

. Milk and casein (removes phenolic bitterness, focus on palate and color more than clarification.)

. PVPP (large molecular weight polymer absorbing low molecular weight phenolic compounds. Can lead to browning or pinking in whites, affects color of reds too. May improve aroma).

. Bentonite (clay, hydrates aluminium silicate, négatives charges to attract and bind with unstable proteins. May cause haze in white wine)

. Albumin (egg whites, often used in reds, doesn’t affect color as much)

. Copper (copper ions added as copper sulfate used to remove hydrogen sulfide).

Question 38

What are the filtration options (3)?

Answer 38

. Membrane
. Earth
. Sterile

Question 39

How does flash pasteurization occur? What does it do to the wine?

Answer 39

Must is lightly clarified then passed through a heat exchanger where it is rapidly heated to 87C and then cooled to 15C.

Kills microbial organisms that may lead to spoilage in the bottle. Helps stabilize wines for export.

Question 40

What final adjustments might you use before bottling your wine?

Answer 40

. Levels of sulphur
. Carbon dioxide
. Turbidity (visual clarity)