Common Elements in Winemaking and Maturation Flashcards
what happens during alcoholic fermentation?
yeast converts sugar in the grape juice to alcohol
What are wines that have very little human intervention?
natural wines
what is the process of oxygen reacting with grape juice called?
oxidation
If you want more fruit flavors in the wine, what is one way to obtain this?
decrease oxygen by using more sulfuric dioxide
why are grapes picked when its cooler?
it reduces the effects of oxygen because the chemical interactions are slowed in cooler temperatures
what is protective or anaerobic winemaking?
the process of filling an airtight vessel with either carbon dioxide or nitrogen before they are used for grape processing or wine making
How do you mature wines that have had no oxygen during the winemaking process?
oxygen should not be used during maturation process. either inert steel or cement vats should be used and kept airtight
what kind of vessels are wines that matured in contact with oxygen in?
typically oak - may be watertight but is not airtight.
what can oxygen do to wines during maturation process?
soften tannins, and give more complexity to the flavors, eventually giving tertiary flavors (leather and earth)
how long are wines typically kept in barriques?
no longer than 2 years
the technique of not filling the oak barrel completely to leave room for oxidation is done with what types of wines?
fortified wines Olorosso Sherry, Tawny Port, and Rutherglen Muscat - gives smells of toffee, nuts and caramel
how is sulfur dioxide used in a wine?
acts as an antioxident and antisepti. It protects newly harvested grapes. wines can become harsh if too much used
what happens when SO2 protects the grape juice and wine from oxidation?
it becomes “bound” and can no longer have a protective effect
what kind of flavors does oak give to wine?
toast, vanilla, smoke and cloves
what are the four specific factors winemakers need to consider when looking at oak
- species and origin of oak
- size
- production of oak barrels
- age
why do smaller barrels have more impact on wine?
more of the wine is in contact with the surface of the barrel
what is one of the most important parts of the production of an oak barrel?
toasting it
what are some effects of heating an oak barrel?
the staves bend into shape, transforms the flavors and tannins (notes of toast and spice) and the amount of heat will (level of toasting) affects the flavors contributed to the wine.
What happens to a barrel after it is toasted?
the time each barrel can be used is diminished (the younger the barrel the more the flavor)
What are some alternative to oak barrels that can be used to still get oak flavors?
small planks of oak (staves), oak chips, or even adding small quantities of oxygen to the barrel
what is an inert vessel?
one that is not made of wood. Can be stainless steel or concrete. they do not add any flavors on the wine or allow oxidation.
why are stainless steel vessels used?
not to allow any new flavors in the wine and also easy temperature control
Why are concrete vessels used?
they are lined with epoxy resin which provides a waterproof barrier. not used frequently any more and most have been replaced by stainless steel
when do grapes receive their first dose of SO2
when they arrive at the winery
what happens if seeds are crushed during the crushing process?
they can release bitter oils and tannin and make the wine become more unpleasant, astringent, and bitter
when does pressing occur for white grapes?
before fermentation
when does pressing happen for red grapes?
after fermentation
what is a pneumatic press?
a press with a inflatable rubber tube within a perforated, horizontal, stainless steel cylinder, which makes it possible to apply pressure over a large area in a controlled way
when can adjustments to the wine be made?
before, during or after fermentation
what is grape juice commonly referred to as?
must
what will a winemaker do in a region where there is a cooler climate and there is not enough natural sugar to give it a satisfactory level of alcohol?
carry out a process called enrichment where they increase sugar levels in the juice by adding RCGM (Rectified Concentrated Grape Must) which is a colorless, ordorless, syrupy liquid. Can be added before or during fermentation
what is chaptalisation?
where sugar from sources other than grapes are added to juice (ex sugar beet)
what is a way to make wine higher in alcohol besides adding sugar?
removing water from the juice which concentrates the sugars, but also concentrates everything else (tannins, acids, flavor compounds, and faults).
What is acidification?
addition of tartaric acid in powder form to grape juice
Where is acidification permitted in Europe?
only in warmer regions
What is deacidification?
reducing of acid levels in grape juice - typically done by adding alkali (the chemical opposite of acid)
what is alcoholic fermentation
the conversion of sugar into alcohol and CO2 utilizing yeast.
what is the yeast species that is responsible for the most wine fermentation
Saccharomyces cerevisiae - it can tolerate high levels of alcohol and SO2
at what temperature will alcoholic fermentation start?
5 C
what might cause alcoholic fermentation to stop before all the sugar is consumed?
if the yeast runs out of nutrients they need other than sugar or the temperature is above 35 C. sometimes the sugar level can be so high the yeast can struggle to start in the first place
if a winemaker wanted to, how would they stop the fermentation before all the sugar has been converted to alcohol?
either killing or removing the yeast by adding S02 or grape spirit. yeast can then be removed using filtration after the fermentation has been temporarily halted by chilling the wine below 5 C
what are the two important ways a winemaker can control fermentation?
yeast and temperature management
what are the two types of yeast that the winemaker can add to the grape juice?
the various ambient yeast strains found on the grape bloom or in the winery; or adding a cultured yeast.
what does fermenting at lower temperatures do?
avoids the loss of the most volatile aromas which often have floral characteristics. it can also develop more fruity flavors in white wines.
what does fermenting at higher temperatures do?
extracts color and tannins from black grape skins
how can excess heat be released?
pumping over
when does malolactic fermentation take place?
after alcoholic fermentation
how is malolactic fermentation carried out?
lactic acid bacteria - converting the tart malic grape acid into softer lactic acids which reduce acidity and create a buttery flavor and produces CO2
what are gross lees?
the suspended particles that are left in wine directly after fermentation which will fall to the bottom of the storage vessel within a matter of hours. they can cause unpleasant aromas in the wine if not removed.
what are fine lees
smaller particles that settle to the bottom of the vessel after fermentation more slowly than gross lees. often removed gradually through maturation process.
when would a winemaker do if they want to retain as many primary fruit aromas as possible?
bottle the wine only after a few months of maturation in an inert vessel
when can blending take place?
at any stage, but mainly carried out after fermentation or during maturation
what is blending used for?
improve balance, attain consistency, or achieve a certain style.
why is consistency important?
significant variation among bottles can be seen as a fault.
what are three main techniques a winemaker can use to ensure the wine is perfectly clear?
- sedimentation
- fining
- filteration
when does sedimentation occur?
after fermentation has finished
what is sedimentation?
after the gross lees have settled in a deposit, the wine is slowly and gently pumped into a different vessel leaving the sediment behind (racking). Fine lees will continue to form during maturation causing repeated rackings to be needed
why is sedimentation a slow process and what can speed it up?
it relies on gravity to pull the suspended particles to the bottom and gravity is a weak and slow force. it can be sped up by putting the wine into a centrifuge.
what is fining?
a process that speeds up the process of wine constitutes slowly clumping together over time in wine. It involves adding a fining agent to the wine which is a substance that forms a bond with certain wine constituents and causes the clumping to form.
how are clumps removed after fining occurs?
filteration
what is filteration?
a process that physically removes particles from wine as it passes through a filter.
when can wines be filtered?
after fermentation and during maturation, usually prior to bottling
what are the two methods of filteration?
- depth filtration
2. surface filtration
what is depth filtration?
uses filters made from a thick layer of material. the wine passes through and the solid parts become trapped inside the material. used to handle very cloudy wines and gross lees.
what is surface filtration
resembling a fine sleve, particles are trapped on the surface are wine flows through. filters are expensive and clog easily. often used for sterile filtration which is small enough to remove the yeast and bacteria. final treatment before bottling
what are two examples of surface filtration?
rotary drum filter and plate and frame filter
how does a winemaker consider a wine stable?
if over a specific time frame it changes in a slow predictable manner
what are three areas that require stabilization?
- tartrate stability
- microbiological stability
- oxygen stability
what is tartrate stability.
when tartaric acid forms crystals in wine after being in cool temperatures. winemakers can force the crystals to form prior to bottling by chilling the wine down below 0 C for a short period of time and then remove the crystals through filtration
what is microbiology stability
yeast and bacteria can make a wine undrinkable. these thrive in grape residues meaning all equipment need to be thoroughly cleaned
what types of wines are at risk of bacteria or yeast
wines with low to med alcohol, low acidity, little residual sugar, or have not gone through MLF
what is oxygen stability?
letting oygen into the wine can cause it to oxidize. it can be prevented by keeping oxygen out of vessels and keeping SO2 levels topped off.
what are the disadvantages of using glass bottles for packaging?
they are heavy and rigid which increases transportation costs and can’t be packed to save space
what are disadvantages of plastic bottles?
allow a small amount of oxygen to pass through the bottle
what is cork taint?
cause by a chemical called TCA, found in some corks that gives the wine a moldy and cardboard like aroma.
what is the downside of a screw top?
does not allow any oxygen in and therefore the aging in the bottle does not develop tertiary flavors
When is it best to consume MOST wines?
within a year of bottling
what is one method winemakers use to limit the contact between the grapes and the skins in white wine making?
load full full bunches of grapes to the press, uncrushed. this reduces the chance of oxidation and can lead to wines with more purity and delicacy
how long do winemakers typically leave wine grapes on the skins to increase flavor intensity?
only a few hours
what is the next step after crushing that needs to happen in the white wine process?
the juice needs to be clarified by using settling, filtration, fining, or centrifugation before moving to fermentation
what is the optimal temperature for white wine fermentation?
12-22 C
what happens is the temperature is too low while fermenting a white wine?
can develop pear drop aromas
what happens if the temperature is too high while fermenting a white wine/
the varietal fruit characteristics can be lost
what are the three main choices a winemaker needs to make post fermentation of white wine
- age in oak, or inert vessels (with or without oak chips or staves)
- use the fine lees to add texture and flavor
- allow or block MLF
how are white wines that are blended labeled?
“dry white”, “fruity wine” - not with the variety
describe an oaked vs unoaked chardonnay?
unoaked - peach and melon, more fruit flavors
oaked - toast and vanilla - more secondary flavors
describe how a pinot grigio is typically made
unoaked, light pear drop aromas, light body, med acidity
where are most high volume inexpensive white wines made?
warm or hot regions
what is a common adjustment that is needed for high vol inexpensive white wines?
acidification
what fermentation vessel is the choice for high vol inexpensive white wines?
stainless steel tanks
what will a winemaker do if he wants to prevent MLF and retain acidity and fruit aromas?
chill the wine and add SO2. the wine will also be racked off its lees as soon as fermentation is finished and stored temporarily in another inert vessel
what varietals of white grapes are high in pronounced aromas and flavors?
sauvignon blanc, reisling, Muscat, Gewurztraminer and torrontes
what are the two most famous regions for premium Sauvignon Blanc
Loire Valley, France
Marlborough, New Zealand
What is Sauvignon Blanc called in Loire VAlley?
Sancerre or Pouilly Fume
What are characteristics of Loire Valley Sauvignon Blanc?
green apple and asparagus with a hint of wet pebbles
What are characteristics of Marlborough Sauvignon Blanc
despite being a cool climate teh long sunlight hours give flavors of gooseberry, elderberry, grapefruit and passionfruit. Some may have herbaceous notes as well.
What are some regions which produce high quality Sauvignon Blanc with fresh fruity flavors.
South Africa and Chile
What are some regions where Sauvignon is blended with Semillion?
Margaret Valley, Western Australia
What is done with Sauvignon Blanc in Pessac-Leognon in Bordeaux?
the wine is fermented and matured in at least a proportion of oak giving a rounded body and spicy toasty notes. It is also blended with Semillion which further adds to the richness and fullness of body.
Which varietal is very tolerant of cold winters and buds late so it avoids spring frosts?
Reisling
What notes are common in Rieslings from cooler climates?
green fruit flavors and often floral notes
What notes are common in Rieslings from warmer climates?
richer in flavor, more predominant citrus and stone fruit flavors. loses some of the delicacy.
Why are Rieslings ideal for making a wide range of sweetness styles?
if left on the vine it can accumulate sugar without losing its naturally high acidity
When Rieslings mature what flavors are apaprent?
honey and toast, while still maintaining acidity. Some have petrol like aromas
What kind of Riesling is Germany known for
a wide range from dry to sweet including noble rot grapes.
Describe a Riesling from Austria?
either very dry or very sweet. very little in between
Describe a Riesling from Alsace?
mostly they are very dry. Sweet ones will only be made when vintage conditions permit
Describe Rieslings from Austrailia?
mostly from Clare or Eden Valley they are often Bone dry with refreshing acidity and aromas of lime.
What are 3 ways to make wine sweet?
- stopping fermentation
- Adding a sweetening component
- Concentrating grape sugars
How do you stop fermentation?
traditional way is fortification (addition of grape spirit, which kills the yeast, making no other fermentation possible, can also be stopped by chilling the wine or adding SO2.
What is Sussreserve?
unfermented grape juice
What are two ways to add sweetening component to wine?
Sussreserve or RCGM is added to the wine when ready to be bottled
What are four ways to Concentrate grape sugars?
- noble rot
- drying grapes on the vine
- drying grapes after picking
- freezing grapes on the vine
what types of wines are noble rot used with?
Sauternes, Tokaji, Beerenauslesen and Trockenbeerenauslesen
What conditions help grey rot become noble rot?
the grapes must be fully ripe before the rot begins. the grapes must be grown in a region with misty mornings and sunny dry afternoons.
what kind of aromas do wines with noble rot have?
honey, apricot, citrus zest, and dried fruit aromas.
what is something that is typically seen on a very sweet wine label?
botrytised
what is passerillage?
drying grapes on the vine - they are left on the vine until they dehydrate and turn into raisins
What is needed for grapes to dry on the vine?
warm dry autumns otherwise grey rot will form instead
what characteristics do wines that have been dried on the vine have?
ripe fruit (dried fruit, tropical fruit) and a richly textured mouthfeel.
What are wines labeled Late Harvest?
grapes that have been dried on the vine
what happens when drying grapes after picking them?
causes healthy harvested grapes to dehydrate which concentrates the sugar in the juice.
what wines use drying after picking commonly?
the passito wines of Italy - Recioto della Valpolicella DOCG
what is the process of freezing grapes on the vine?
the grapes are left on the vine into the winter months. when freezing temps arrive, the the water in the grape pulp turns to ice. later when the grapes are picked and pressed that ice remains in the press increasing sugar content.
What type of wine use freezing grapes on the vine?
Eiswein from Germany and Icewine from Canada
what are foudres?
large old oak vessels
How long is Sauvignon typically fermented until?
until dry
How long is Riesling typically fermented until?
it can be made from dry to lusciously sweet
name two less aromatic white grape varieties?
pinot gris/grigio and Chardonnay
what white variety can suffer where spring frosts are common
chardonnay
what are some characteristics of Chardonnay in cool climates?
green fruit and citrus
what are some characteristics of Chardonnay in moderate climates?
fleshy fruits such as melon and white peach
what are some characteristics of Chardonnay in warm to hot climates?
ripe tropical fruits - bananas, and pineapple. it can lose its acidity quickly in these regions.
explain a Burgandy, French Chablis (north region)
high acidity, green apple and citrus notes, sometimes a hint of wet stones or slate.
explain a Cote D’Or Chardonnay
best wines have stone fruit and creamy oak notes
explain a Macconnais Chardonnay
more ripe and rounded and have a toasty oak flavor. most are aged using MLF and lees aging giving nut and mushroom flavors
Besides France which regions are known for premium Chardonnay?
Russian River Valley and Carneros, CA; Adelaide Hills, Geelong, and Mornington Peninsula Australia; Gisborne and Marlborough New Zealand; and Casablanca Valley Chile.
When does PInot Gris ripen in warm climates?
early budding, early ripening, accumulating high sugar levels and losing acidity
Describe a typical Alsace Pinot Gris
dry to off dry, oily texture, ripe tropical fruit with a hint of honey and ginger. often golden in appearance
Explain a New Zealand Pinot Gris
very similar to French style but normally show more pure fruit flavors and have slightly more residual sugar.
Besides France and New Zealand what other regions make a Pinot Gris in a rich and dry style?
Tasmania, Australia; Oregon, USA
what regions in Italy make a high quality Pinot Grigio?
Alto Adige, Trentino, Friuli-Venezia Giulia (NE Italy)
what characteristics do a high quality PInot Grigio wines in Italy disiplay?
greater depth in flavor, dry style.
describe pinot grigio wines from northern italy
typically amde from pinot gris/grigio clones from France or Germany
When white grapes are crushed and pressed what is the difference between high aromatic and low aromatic grapes?
low aromatic grapes benefit from controlled oxygen, where oxygen would only harm highly aromatic grapes.
