Winemaking Decisions Flashcards
Why do winemakers usually try to avoid crushing seeds during the winemaking process?
Seeds contain tannins and high levels of bitter oils.
Which part of a grape contains the highest concentration of flavor compounds?
The grape’s skin and the area immediately beneath it.
What are the first and second largest components in a grape by percentage?
(1) Water
(2) Sugar
What are the three important components found in grape skins?
(1) Tannin (2) Flavor Compounds (3) Color
What are the two functions played by SO2 in winemaking?
(1) Antiseptic (SO2 is toxic to many of the yeast and bacteria strains that cause unwanted flavors and aromas in wine)
(2) Antioxidant (SO2 protects the must and wine from the effects of oxidation until it becomes “bound” and needs replenishing)
What are three functions played by oak vessels?
(1) Oak is not airtight and so allows a small level of oxidation while the wine is maturing, allowing tertiary aromas to develop
(2) Oak gives tannin to the wine, increasing structure and textural complexity
(3) Oak tannins give aromas and flavors like toast, vanilla and cloves
What are the four factors which affect the influence of an oak vessel on wine?
(1) Origin: European or American oak
(2) Size: 225l barrique or 228l piece, vs large foudre or botti
(3) Production: Level of barrel toasting is the main factor here, as heating of staves transforms tannins and flavor compounds of the oak
(4) Age: The effect and flavors imparted by toasting diminish each time the vessel is used and by the fourth use, little flavor and tannin remains
What are three advantages associated with stainless steel vessels?
(1) Easy to keep clean
(2) Can be made in any shape and size
(3) Can incorporate temperature control mechanisms (either sleeves on the outside of the vessels or internal heating/cooling coils)
Two advantages of using cultured yeast?
(1) Produces uniform and predictable flavors and (2) fast
Why and how is acidification performed as a must adjustment?
Acidification is done in warmer climates or vintages to: (1) balance the wines, which may have too high a pH by the time the grapes reach physiological ripeness; and (2) add ageing potential, usually by adding tartaric acid.
What is one advantage and one disadvantage associated with concrete vessels?
(1) Advantage—cheaper as thick concrete shells help to regulate temperature during fermentation and maturation without expensive temperature control equipment
(2) Disadvantage—more difficult to clean and maintain
Why and how is de-acidification performed as a must adjustment?
De-acidification is done in cooler climates or vintages to balance what might otherwise be excessive acidity in the wines, by adding alkalines.
What is the difference between crushing and pressing of grapes? Why is pressing done post-fermentation for red wines?
The purpose of crushing is to liberate some of the grape juice from the fruit, whereas the purpose of pressing is to separate the liquid and solid components of the fruit—hence for red wine, pressing is done only after fermentation, to ensure color and tannin is extracted from the skins.
What are the fermentation temperatures for white / red wine. Account for the differences between them?
12-22 deg for white wines, as cooler temperatures help to retain fruit aromas.
20-32 deg for red wines as higher heat and alcohol help to extract tannin and color.
Why and how is enrichment performed as a must adjustment? What is the main risk with enrichment? Name one alternative method and its two disadvantages
Enrichment is done to increase the sugar levels of the must and therefore, the potential alcohol levels. This is important in cooler climates or vintages where the grapes may not have ripened sufficiently to produce the desired sugar and potential alcohol levels. Enrichment or chaptalization is done by adding RCGM or sugar respectively.
The main risk is that if the grapes did not attain physiological ripeness, there may be insufficient flavors to balance out the additional alcohol.
An alternative is to remove water from the juice to concentrate the sugars and increase potential abv, but the disadvantage is that this also concentrates tannins, acids, flavor compounds and most importantly faults; and also reduces the volume of the wine available for sale.
Describe the process of malolactic conversion. How and why might a winemaker block MLC?
MLC is process whereby lactic acid bacteria convert malic acid (with its tart green apple flavors) to dairy and hazelnut flavors. Since MLC tends to suppress the purity of primary fruit flavors, a winemaker looking to highlight such flavors may block MLC in addition to minimizing the use of oak—especially for aromatic whites like Riesling—by storing at cool temperatures, using SO2 or filtering out the bacteria.
3 methods of blocking MLC?
(1) storing at cool temperatures
(2) using SO2
(3) filtering out the bacteria.
What is the main consideration for a premium winemaker in determining the length and type of pre-bottling maturation?
The main consideration is aromatic and flavor profile: whether to retain and emphasize primary fruit aromas (which favors a shorter pre-bottling maturation in an inert vessel) or to develop complexity and secondary / tertiary aromas (which favors a longer pre-bottling maturation in a non-inert vessel like oak ).
What are gross lees? How and why are they usually removed?
Gross lees are sediment consisting of dead yeast cells and grape fragments.
They are removed because they give the wine a cloudy appearance and may develop unpleasant aromas.
Gross lees are usually heavy enough to settle to the bottom of the vessel within a few hours.
What are three stylistic reasons why a winemaker might choose to blend wine? Give an example for each reason.
(1) Improve** balance** (e.g. blending free-run wine with more tannic press wine);
(2) Attain consistency (e.g. by evening out subtle differences / inconsistencies in the maturation process from one barrel to another)
(3) Achieve a certain **house style **(e.g. GM champagnes).
