Flashcards in Winemaking Deck (132)
What are Anti-oxidative Phenolic Compounds
Compounds found in red wine that slow oxidation
(Phenolic compounds in red wines have an anti-oxidative effect, which means that they can absorb more oxygen before oxidation effects are perceptible)
How long does wine generally spend in pre bottling maturation (red and white)
White wine - 6-12 months
Red wine - 12-24 monthss
What is Ullage
Headspace within a container that allows the wine to come in contact with oxygen.
Can be filled with inert gas (nitrogen, carbon dioxide, argon) to prevent/slow oxidation.
How does wine get oxygen exposure during maturation
Whenever the bung is removed.
What are the effects of Micro-oxygenation
- Colour stability and intensity
- Soften tannins
- Improve texture
- Herbaceous flavours (lessen)
- Oxygen exposure. Gentle controlled, quick and cheaper than barrel aging.
Integrate any oak alternatives used (chips, staves).
Compounds that give American oak the aromas of coconut.
What and how - Reduction (fault)
Rotten egg smell that comes from high levels of hydrogen sulphide.
Fault from uncontrolled/unmonitored ageing on gross lees.
Bottling without sufficient oxygen or ingress via closure.
What might differ about wines that are blended together
- grape varieties
- locations (from different vineyards, different regions or even different countries)
- grape growers or businesses that sell grapes, must or wine
- treated differently in the winery (e.g. wine made from free run juice and wine made from press juice, or wine matured in oak with wine that has been stored in stainless steel or concrete)
- equally in the winery but are in different vessels for logistical reasons (e.g. unless a wine is made in very small quantities, wine fermented or matured in barrels will need to be blended together to make up the required volume).
Key reasons for blending wines
Balance – Blending may help to increase or moderate the levels of certain characteristics of the wine to produce a wine that is better balanced, and in this way enhance quality. (Merlot in Bordeaux provides body and ripe, plummy fruit to a blend with Cabernet Sauvignon, which can be too astringently tannic if not fully ripe)
Consistency – Across vintage or many years depending on wine style (Sherry and non-vintage sparkling wine, inexpensive wines).
Style – 'house style' or required style (rose)
Complexity – The blending of two or more parcels of wine may lead to a greater range of flavours.
Minimise faults – If wine in one barrel is showing significant volatile acidity (see Faults), that wine may be sterile-filtered to remove acetic acid bacteria and then blended into a larger volume of un-faulty wine. Lower concentration and sensory perception of Acetic Acid.
Volume – Blend the wines from different small vineyards to produce viable volumes of certain wines, or in poor vintages where yields are low.
Price – Include cheaper grapes along with more well recognised expensive grapes - eg Chardonnay and Trebbiano.
Bottling day checklist
4 months to 8 weeks ahead - Assemble final blend
Full chemical analysis – alcohol, residual sugar, free SO2, etc.
8 weeks ahead - Final adjustments: alcohol, acidity, tannins if desired
6 weeks ahead - Protein stability trial and if necessary fine with bentonite
4–6 weeks ahead - Test for tartrate stability and, if necessary, treat - 4 weeks ahead
Check protein stability and tartrate stability again, treat as necessary
1–2 weeks ahead - Add sweetening agents e.g. grape concentrate, if using (for mouth feel and finish)
72–48 hour ahead - Test filterability of wine
24 hours ahead - Adjust free SO2
Bottling day - Adjust dissolved oxygen and CO2
During bottling - Check dissolved oxygen (to ensure no pickup) and SO2 levels regularly and keep sample of bottle wines for quality assurance purposes
Three categories of fining agents
- Remove unstable proteins
- Remove phenolics that contribute undesirable colour and bitterness
-Remove colour and off-odours.
What are tartrates
Harmless deposits of crystals that can form in the finished wine
calcium tartrate (less common)
How to treat Brettanomyces in wine
Brettanomyces is a problem, wine can be treated with DMDC (dimethyl dicarbonate, commercial name: Velcorin)
What are the generally allowed amounts of SO2 before bottling
White wine: 25–45 mg/l (lower than for red wines due to lower pH)
Red wine: 30–55 mg/l
Sweet wine: 30–60 mg/l
What is sparging
Flushing wine with an inert gas to remove oxygen (done before bottling).
What causes cork taint and how does it affect the aroma/flavour of the wine
- Unpleasant smell of mould or wet cardboard
- Suppresses the fruit character.
What is OTR
Oxygen transmission rate. Refers to how permeable wine bottle closure is.
What aromas do volatile reductive sulphur compounds give in wine
Low levels - aromas that may be perceived as positive, such as struck match and smoke.
High levels they give rotten egg (always a fault) and other unpleasant aromas.
What does HACCP stand for and mean
HACCP (Hazard Analysis of Critical Control Points):
Identify each hazard and what can go wrong. The state how serious the hazard is, how it can be prevented and how it can be corrected.
What is a Flexitank
A single-use, recyclable polyethylene bag that fills a standard container for bulk shipping of wine.
Purpose of skin contact in white wine production
- Extraction of aroma and flavour compounds and precursors.
- Improve texture of the wine by extracting a small amount of tannin.
Why would winemakers choose to press whole bunch, uncrushed grapes.
- Limit skin contact
- Reduce risk of oxidation
Typical for wines requiring:
- Early drinking
- Delicate fruity flavours
- Minimal colour
- Smooth mouthfeel.
How are Orange Wines made and what is their flavour profile
Amber (orange) coloured wines that are fermented on their skins without temperature control or SO2 added. The colour develops due to the oxidation of compounds extracted from the grape skins.
- Notable levels of tannins
- Mainly tertiary characteristics (nuts and dried fruit).
Define Free Run Juice and describe it's characteristics
The juice that can be drained off the press as soon as the grapes are crushed.
(whole bunches, destemmed)
Lowest levels of solids, tannin and colour of the
Highest acidity and sugar.
What are Press Fractions
Juice from different stages of pressing (free run is the first)
Different press fractions may be blended later in the winemaking and maturation process.
The last press fractions too generally astringent or bitter (due to phenolic compounds from the skins, seeds or stems) to use.
What esther gives a banana like smell
What is the French term for lees stirring
What are the conditions for Noble Rot and how does it affect the grape.
- The grapes must be fully ripe.
- Humid, misty mornings followed by sunny, dry afternoons.
- Damp conditions in the morning allow rot to develop on the grapes.
- The fungus punctures the grape skin with microscopic filaments, leaving tiny holes in the skin.
- Warm sunny afternoons slow the rot and cause water to evaporate from the grape.
- Modifies aroma compounds in the grape adds flavours. Honey, apricot, citrus zest, ginger and dried fruit.
Define cryoextraction in terms of ice wine and advantages/disadvantages
Picking grapes as usual and then freezing them at a winery.
- Does not entail the risks of leaving the grapes on the vine into late autumn or winter.
- Lessens risk of yield loss to disease or pests.
- Much cheaper than traditional production.
- The terms Eiswein and Icewine cannot be used on the label.
- Energy to freeze the grapes.