Class 1 - Intermediate Wine Oenology Flashcards
What is the first step in the red wine process?
Harvest
The process includes multiple steps: Harvest, Crush, Ferment, Press, Barrel Age, Rack/Fine, Bottle, Bottle Age.
What is the typical yield of grapes to a barrel of wine?
600-700 pounds of grapes
This quantity typically yields a barrel of wine.
How many cases does a barrel of wine yield?
23 cases
Each case contains 12 bottles.
What Brix level should grapes be picked at for good reviews?
Approximately 24 Brix
Aiming for 25 Brix is preferred.
What does the Brix unit measure?
10 grams of sugar per liter
It is about the same as percent sugar.
What factors influence the quantity and quality of grapes produced?
- Level of soil fertility
- Weather-related advances and delays
- Ratio of exposed leaf area to fruit
These factors are critical for vineyard management.
What is the purpose of adding sugar during winemaking?
To increase final alcohol concentration
This is often necessary if grapes come in at low Brix levels.
What is Chaptalization?
Adding sugar to grape must before fermentation
This is done if initial sugar levels are low.
What is the role of sulfites in winemaking?
Sanitizes surfaces that contact grapes or juice
Sulfites are essential for cleanliness but restrict the wine from being labeled organic in the US.
What percentage of asthmatics have a severe sensitivity to sulfites?
5-10%
This sensitivity can trigger asthma attacks.
When does fermentation start in winemaking?
The moment the grapes are crushed
Wild yeasts colonize the grapes during growth.
Who invented the microscope, allowing for the discovery of yeast?
Antonie van Leeuwenhoek
This innovation occurred between 1632-1723.
What are the end products of fermentation according to Lavoisier?
Ethanol and CO2
This was established in 1789.
What is Assmannshausen known for?
A German yeast strain best suited for red wines
It intensifies color and adds a spicy aroma.
What is the fermentation characteristic of Epernay yeast?
Slow fermentation, tolerant to cold temperatures
Used in champagne production.
What is the primary use of Montrachet yeast?
Producing Chardonnay in barrel and stainless steel
It is popular for both red and white wine fermentations.
What is Chardonnay’s tolerance level for sulfur dioxide?
Chardonnay tolerates sulfur dioxide well.
This characteristic makes it suitable for various winemaking processes.
What is the maximum sugar level Chardonnay can effectively work with?
More than 23.5 percent.
High sugar levels can lead to stuck fermentations.
What is the second most common yeast strain used in winemaking?
Champagne yeast. Note that Saccharomyces cerevisiae (S. cerevisiae) is the most common yeast associated w/wine making
This yeast is preferred for its fermentation speed and effectiveness in low temperatures.
Where was Champagne yeast isolated?
Champagne, France.
It is a mixed-population culture used in sparkling wine production.
What types of wines is Pasteur Red yeast typically used for?
Red wines such as Cabernet Sauvignon, Merlot, and Zinfandel.
This strain is tolerant to heat and sulfur dioxide.
What is a characteristic of Pasteur White yeast?
It ferments slowly and tolerates cold temperatures.
It also imparts a noticeable yeasty aroma.
What is Premier Curvee yeast also known as?
Prise de Mousse.
This yeast is strong acting and low foaming, qualified for barrel fermentations.
What strain is used for white wine fermentation and tolerates cold better than Pasteur White yeast?
Steinberg.
It yields a lengthy fermentation process and is best used in stainless steel.
What are Saccharomyces cerevisiae generally referred to as?
Wine yeasts.
They are essential for the fermentation process in winemaking.
What are some examples of spoilage yeasts?
- Metschnikowia
- Kloeckera
- Hanseniaspora
- Hansenula
- Pichia
- Schizosaccharomyces
- Zygosaccharomyces
- Brettanomyces
- Dekker
These yeasts can become spoilage organisms under certain conditions.
Is Brettanomyces considered a wine fault?
True.
Brettanomyces is a kind of yeast (Brettanomyces literally means “British fungus,” but not because the Brits invented it; the stuff was discovered when a scientist was looking into spoilage of some English ales).
It is often debated whether it adds character or detracts from wine quality.
What is the primary aroma compound associated with Brettanomyces?
4-Ethyl guaiacol (4-EG).
This compound contributes to the earthy aroma often found in wines with Brett.
What is the vineyard microbiome responsible for?
Some of the ‘terroir’ associated with that place.
The collection of microorganisms varies from vineyard to vineyard.
What significant historical contribution did Buchner make in 1897?
Extract of yeast retains ability to ferment glucose to ethanol.
This finding was pivotal in understanding fermentation.
What does the Embden-Meyerhof pathway describe?
The conversion of glucose to pyruvate.
This pathway is essential in glycolysis and energy production.
What is ATP in the context of chemistry?
In wine chemistry, ATP (adenosine triphosphate) is an energy molecule that’s produced during fermentation. ATP is a chemical compound that’s found in all living cells.
Reactions that release energy produce ATP, while reactions that consume energy use ATP.
What molecule is produced when pyruvate is converted in glycolysis?
CH3CH2OH (ethanol).
This reaction also regenerates NAD, allowing glycolysis to continue.
What temperature range favors the growth of Saccharomyces cerevisiae yeast during fermentation?
16-20 degrees C
This temperature range helps suppress non-Saccharomyces yeast.
What is the function of sulfur dioxide (SO2) in winemaking?
Limits the growth of non-Saccharomyces yeast
SO2 is added to fresh pressed must to favor desired yeast.
What happens during cold stabilization in winemaking?
Reduces tartrate crystals in wine.
Cold stabilization is a winemaking process that removes unstable potassium bitartrate, or cream of tartar, from wine. This process involves chilling wine to near freezing temperatures for a period of time.
Tartrate crystals can appear as sediment but are not harmful.
What are the primary benefits of using selected strains of Saccharomyces cerevisiae?
Initiate fermentation and suppress non-Saccharomyces yeast
They ensure a controlled fermentation process.
What is battonage?
Stirring the lees to extract more flavors.
Note. Lees are the dead yeast cells and other particles that settle to the bottom of a winemaking tank after fermentation.
This technique enhances the flavor profile of wine.
What is the primary type of yeast used in winemaking?
Saccharomyces cerevisiae
This yeast is favored for its fermentation properties.
Fill in the blank: Cold stabilization is used to reduce ______ in wine.
tartrate crystals
True or False: Most whites need to be cold stabilized.
True
Cold stabilization prevents tartrate formation in refrigerated wines.
What percentage of sugar is typically converted into ethanol during fermentation?
Approximately 95%
This indicates high efficiency in sugar conversion.
What is the main purpose of adding yeast nutrients during fermentation?
Improve nutrition available to yeasts
Nutrients support healthy yeast growth and fermentation.
What is one common defect that winemakers try to avoid during fermentation?
Wine aroma defects
Proper fermentation techniques help maintain desirable aromas.
What acid can be reduced to improve the taste of wine?
Malic acid
Reducing malic acid to lactic acid makes the wine softer and smoother.
What is the suitable pH for malo-lactic cultures?
2.9 or greater
This pH level allows for effective fermentation.
What is the typical barrel aging duration for red wines?
18 months
This aging process helps develop complex flavors.
What is the typical barrel aging duration for white wines?
9 months
White wines generally have a shorter aging period than reds.
What does the term ‘Reserve’ indicate about a wine?
An additional year in oak barrels
Reserve wines are typically aged longer for enhanced flavor.
What must be done before filling a barrel with wine?
Swelling the barrel with water
This prevents leakage and ensures proper sealing.
What is the impact of Virginia oak on Chardonnay? [American Oak Choices]
Very light, almost sweet character
It provides soft vanilla notes in the flavor profile.
Which type of oak is primarily used with red wines? [American Oak Choices]
Missouri oak
It generates a good mouth-feel and noticeable oak aromas.
What is a common practice for barrel management in wineries?
Replace 1/3 of the barrels each year
This ensures that a portion of the wine sees new oak.
What is the purpose of racking in winemaking?
To separate wine from sediment
Racking helps clarify the wine and improve its taste.
What is the role of copper sulfate in winemaking?
To remove hydrogen sulfide
It helps improve the aroma and flavor of the wine.
What does ‘Assemblage’ refer to in winemaking?
Blending of wines from different lots or varieties
It is a crucial step to create a balanced final product.
What components are involved in wine balance?
Sugar, acid, tannin, alcohol, flavor intensity
Balance is essential for a harmonious tasting experience.
True or False: High acid makes tannins more apparent.
True
The interaction between acid and tannins influences wine perception.
What is cold stabilization used for in winemaking?
To cause the precipitation of potassium bitartrate
This process helps clarify the wine before bottling.
What causes cork taint in wine?
Presence of TCA (2,4,6-trichloroanisole)
TCA leads to undesirable smells and tastes in wine.
What are some sources of cork taint?
- Wooden barrels
- Rubber hoses
- Wood beams in wine cellars
- Storage conditions
- Transport of corks and wine
These factors can introduce TCA into wine.
What is the primary cause of cork taint?
Presence of TCA (trichloroanisole) and/or TBA (tribromoanisole)
These compounds produce unpleasant aromas similar to moldy newspaper.
What can happen if TCA persists in a winery?
It can affect the entire winemaking plant
This may necessitate a complete revamping of equipment.
What does TCA stand for?
TCA stands for trichloroanisole
TCA is a compound responsible for cork taint in wine.
What is the primary consequence of unchecked TCA?
It can affect an entire winemaking plant
This can lead to the need for a total revamping with clean, uninfected wood.
What materials have modern winemakers switched to in order to prevent TCA?
Stainless steel barrels, pipes, and other fixtures
These materials help prevent TCA from roosting in winemaking facilities.
Who was the first recorded user of cork as a stopper?
The Egyptians
Cork has been used for thousands of years.
What were some of the uses of cork by the ancient Greeks?
Fishing buoys, sandals, and stoppers for vessels
They used cork oak bark for these purposes.
Since when have traditional cork bottle stoppers been used in the wine industry?
Since the 1600s
This long history highlights the significance of cork in winemaking.
What year did the world’s first cork stopper factory open?
1750
The factory opened in Spain due to the rapidly growing wine industry.
What country is currently the world’s leading cork producer?
Portugal
Portugal dominates the cork production market.
What are alternative wine closures?
Substitute closures used for sealing wine bottles instead of traditional cork closures
These closures emerged to protect against cork taint.
What is the taint rate cited by the cork-industry group APCOR?
0.7-1.2%
This indicates the prevalence of cork taint in wines.
What are artificial corks designed to do?
Match real cork in size and shape
They are used in the same sort of bottles as real corks.
What is a significant advantage of screw caps over natural cork?
Screw caps seal considerably better and let in far less oxygen
This reduces the risk of cork taint.
What is ‘Vino-Seal’?
A glass stopper product that fits in the bottle’s neck and over the lip
It is a relatively new product in the market.
What are crown caps commonly used for?
Sparkling wine production
They are the same metal caps found on beer bottles.
What are the pros of synthetic corks?
Immune to cork taint and cheap to make
They can be made in any color or mold and do not dry out.
What is a con of synthetic corks?
They can pose a harmful effect to the environment if not recycled
Greater reliance on synthetic corks may lead to the end of cork tree forests.
What is one advantage of screw caps (Stelvin closure)?
They provide a better seal for wine
They eliminate oxidation problems that can occur with corking.
What is a disadvantage of screw caps?
Absence of the dramatic ‘popping’ sound when opening
Many people have become accustomed to this sound with corked wine.
What does Oenoseal technology aim to provide?
Maximum impermeability suited to delicate wines.
OenoSeal is a wine liner that’s used with screwcaps instead of corks. It’s designed to prevent wine taint and preserve the wine’s quality.
It offers options for different wine types, including nano-oxygenation.
What is a pro of glass stoppers (Vino-Seal)?
Made from recyclable glass and reusable
They reduce oxidation and have no cork taint.
What is a con of glass stoppers?
The cost of the product and bottling equipment
This can be a limiting factor for wineries.
What is a pro of crown caps?
Effective, inexpensive, and recyclable
They look more visually appealing than synthetic corks or screw caps.
What is a con of crown caps?
They require a bottle opener to open
The cap is no longer useful for closure once opened.
How can one determine if a wine has cork taint?
By smelling and/or tasting it
A foul taste will linger longer than a rancid smell.
What was the TCA contamination rate found by the French Wine Society in a test of 500 bottles?
0.8 percent
This was found even in older vintages.
What significant change has occurred regarding TCA levels since 2001?
TCA levels are now 81% lower
This is according to testing of more than 10 million corks.
For wines intended to be drunk young, what is recommended instead of natural cork?
Screw caps or synthetic corks
This helps to avoid cork taint.
