White and Sweet Winemaking Flashcards
Where would it be common to blend different vintages to achieve a house style?
Champagne
What size barrel is best for oxidation? Why?
- 225 liter barriques because there is more contact between the wine and the surface area of the barrel.
- Wines are rarely kept in barrique for more than 2 years
- wines matured in larger vessels can mature longer
What is acidification and where does it happen most often?
The addition of tartaric acid in powder form. Occurs mostly in warm and hot regions.
What is must weight?
The level of sugar in the un-fermented grape juice
What is RCGM
Rectified Concentrated Grape Must - colorless, odorless syrupy liquid
Name 3 wines that are deliberately made in an oxidative style.
- oloroso sherry/PX
- Tawny Port
- Rutherglen Muscat
-tertiary characters of carmel, toffee and nut
What are natural wines?
wines made with minimal human intervention
What is passerillage?
Drying grapes on the vine. Sometimes referred to as late harvest. A great alternative to Noble Rot.
How can a winemaker can stop fermentation? Describe.
By killing or removing the yeast.
2 ways to kill yeast:
1) adding SO2
2) adding grape spirit
Removing yeast by filtration typically after fermentation has been temporarily halted by chilling the wine to below 5 degrees C
What is enrichment?
increasing sugar levels by adding RCGM in order to produce a higher level of alcohol.
What is chaptalisation?
using sugars from sources other than grapes, such as sugar beets to elevate alcohol during fermentation.
What can happen to the wine if enrichment is not carried out with care?
It can produce a wine that is hard and thin because there are insufficient flavours to balance the artificially elevated alcohol.
What are 3 forms of stabilisation? Briefly describe.
Tartrate - remove crystals by chilling the wine below 0 C and filtering
Microbiological - wines that have low to medium alcohol, low acidity and a little residual sugar are particularly at risk from yeast or bacterial storage. Careful handling and and addition of SO2 can protect these wines.
Oxygen - risk of oxidation can me minimized by avoiding exposure and topping off SO2
What is sulfur dioxide used for in winemaking?
- It acts as an antioxidant and antiseptic
- grapes receive their 1st dose of sulfur dioxide as they arrive at the winery
What is protective/anaerobic winemaking? List some methods
Avoiding as much oxygen as possible during winemaking.
- picking at night to keep the grapes cool
- keeping grapes cool during transportation using nitrogen and carbon dioxide
- Using airtight equipment and pumping CO2 and nitrogen
What is the yeast species that is responsible for the majority of alcoholic fermentations? Why?
Saccharomyces Cerevisiae
It is tolerant of high alcohol and SO2
List 7 important options in white winemaking:
- Skin contact
- Clarity of the juice
- fermentation temperature
- fermentation vessel
- use of lees
- MLF
- maturation options
What are the 3 main techniques used for clarification?
- Sedimentation
- Fining
- Filtration
What is sedimentation?
Once the gross lees have settled in a deposit (gravity process that is slow), the wine can then be slowly and gently pumped into a different vessel leaving the sediment behind, a process known as racking. The wine will continue to throw a deposit of fine lees during maturation and the clarity of wine can be improved by repeated rackings.
What is fining?
This involves adding a fining agent to the wine - a substance that forms bonds with certain wine constituents and causes visible clumps that can be removed by filtering.
Name and describe the two forms of filtration.
Depth filtration - filters are made from a thick layer of material. As wine passes through the filter it traps the gross lees.
Surface filtration - filters resemble very fine sieves. The filters are very expensive and clog up very easily, so they are generally used for wines that have already passed through depth filtration. Where the pore size is small enough to remove yeast and bacteria that might still be present, this can be referred to as sterile filtration.
What processes do some winemakers feel can negatively affect a wine’s character, particularly it’s texture?
Fining and Filtration
What temperature does alcoholic fermentation happen?
5-35 degrees C
What are lees? What are the 2 types and their differences?
Dead yeast cells and grape fragments
Gross - larger particles that fall to the bottom of the fermentation tank and can cause unpleasant aromas if not removed
Fine - smaller particles that are sometimes removed during the fermentation process, but may be left in contact during pre bottling maturation in order to add extra flavour and textures to the wine.
What is the optimum temperature for white wine fermentation?
between 12-22 degrees C
What are the 4 important factors when choosing oak?
- Species and origin of oak
- size (225L barrique - 228L piece - vessels upward of 2000L)
- Age
- Production (level of toasting)
What is an inert vessel? Name and describe the 2 kinds most used.
vessels that do not add flavor to wines or allow oxidation.
a) stainless steel - easy to clean and regulate temperature
b) concrete - regulates temperature without the use of expensive equipment
What are the 2 important ways which a winemaker can control the fermentation?
-yeast: ambient yeast (bloom) or cultured yeast
-Temperature:
>lower temps encourage fruity flavours and avoids loss of floral notes
>higher temps are necessary for the extraction of colur and tannin
What is used to carry out MLF? How can a winemaker avoid MLF (3)?
- Lactic acid bacteria
- storage at cool temps, use of SO2, or filtering out bacteria
