General Winemaking Flashcards by Laura Zver

How can the effect of oxygen on must/wine be limited?

Avoid ullage in vessels
Use inert gases
Add SO2
Cool, constant temps

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How can you increase oxygen exposure in wine/must

Cap mgmt - spray or splash must/wine
Use small wooden barrels - oxygen enters through bung hole and staves
Increase number of rackings
Increase amount of lees stirring during aging
Allow ullage in wine containers
Hyperoxidation, micro-oxygenation

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Describe the protective properties of SO2

Anti-oxidant - reduces effects of oxidation - inhibits oxidative enzymes
Anti-microbial - inhibits development of microbes (yeast & bacteria)

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What is the most effective timing to add SO2 throughout the winemaking process

Add larger amounts:
When grapes are crushed
At end of MLC
At bottling
More effective than adding smaller amounts throughout winemaking process

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In General Winemaking, what is the order of high level categories for winemaking processes

Oxygen and SO2
Transportation to Winery
Grape Reception
Pressing
Must Adjustments
Alcoholic Fermentation
MLC
Post-Fermentation Adjustments

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While grapes are being transported to the winery, how can you minimize the threat of oxidation and microbial infection

Harvest at night when temps are lower
Adding SO2 at time of harvesting
Reduce grapes’ temps - put in cold storage
Sanitize harvesting equipment/bins
Collect grapes in small crates to minimize crushing

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During the Grape Reception stage, what processes can the winemaker use

Chilling - lower temp before crush/pressing begins
Sorting - (french word triage)
Destemming
Crushing

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List the sorting options for winemakers

Remove unwanted grapes/bunches before picking or during hand harvesting
Sort by hand on a table
Sort on a moving or vibrating belt - before or after destemming
Optical sorting - 100-grape sample - costly

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Describe how destemmers work

Destemmers work by a series of blades within a rotating drum that remove grapes from stems

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Give examples when grapes are not destemmed

Red wine fermentations use some whole bunches - Pinot Noir, Burgundy
Carbonic maceration - Gamay, Beaujolais
Whole bunch pressing for white wines - high-quality sparkling wine

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List the types of presses

Pneumatic Press - most popular
Basket Press
Horizontal screw press
Continuous press

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How does a pneumatic press work?

Press is made of a cylindrical cage with a bladder that runs down the side or middle
Grapes loaded into tank
Other side filled with air. As bladder inflates, grapes are pushed against grates on the side of the cage, separating juice of wine from skins

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What are the advantages of using pneumatic presses

Can be programmed to exert different amounts of pressure
Can be flushed with inert gas to protect must/wine from oxidation

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How does a basket press work?

Basket filled with grapes and pressure applied from above
Must/wine runs through gapes/holes in the side of basket and collected at bottom of the press
Pipe transfers must/wine to another vessel

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What is the advantage of using basket presses

Gentler than pneumatic presses

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What are the disadvantages of using basket presses

Hold smaller press load
More labour intensive
Suited to small wineries making premium wine
Not sealed vessels - cannot be flushed with inert gas to avoid oxygen exposure

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List the types of must adjustments that can be made before alcoholic fermentation

Enrichment
Reducing Alcohol
Acidification
Deacidification
Adding Tannins

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What is the aim of enrichment

Common practice for winemakers in cooler climates to enrich the must before or during fermentation to increase the alcoholic content of final wine

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What can be added to must to enrich it

Dry sugar (beet or cane sugar)
Grape must
Grape concentrate
Rectified Concentrated Grape Must (RCGM) - manufactured flavourless syrup from grapes

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What processes of concentration can be used to enrich must

Reverse osmosis
Vacuum extraction
Chilling

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How is potential alcohol reduced in wine

Adding water - dilutes grapes

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What types of acid can be added in the acidification process

Tartaric acid - most commonly used
Citric acid (not permitted in EU)
Malic acid - less used
Lactic acid - may be used if needed after MLC

When is the best time for winemakers to acidify

Can be done before, during or after fermentation
Preferred to do before fermentation - benefit from lower pH; integrates better within profile of wine

How is deacidification carried out? How does it lower acidity?

Adding calcium carbonate (chalk)
Or adding potassium carbonate
Lowers acidity by formation and precipitation of tartrates

What is a high tech option for deacidifcation?

Ion exchange - expensive

When are tannins added to musts

Tannins added to must before fermentation or to wine before maturation

Why are tannins added to musts

Helps clarify musts Red wines - helps stabilize colour of musts and improve mouthfeel

Describe alcoholic fermentation

Alcoholic fermentation is the conversion of sugar into ethanol and carbon dioxide carried out by yeast in the absence of oxygen (anaerobically) Conversion also produces heat, which has to be managed

What does the process of fermentation produce

Alcohol CO2 Heat Volatile acidity (vinegar, nail polish remover smell) Very small amounts of naturally produced SO2 Aroma precursors and compounds Aromas created by yeasts Glycerol

Give examples of aroma precursors and compounds that are produced during alcoholic fermentation

Thiols - MMP - boxwood/gooseberry in Sauvignon Blanc Terpenes - linalool and geranoil - gives Muscat its floral, grapey aroma

Give examples of aromas created by yeast during alcoholic fermentation

Esters - fruity flavours - banana from carbonic maceration - Beaujolais Nouveau Undesirable reductive sulfur compounds - rotten eggs, rotten cabbage Acetaldehyde - bruised apple, paint thinner

What effect does Glycerol have on wine

Increases the body of wine

Name some ambient yeast strains

Kloeckera Candida Saccharomyces cerevisiae - quickly becomes dominant yeast

Advantages of using ambient yeast

Adds complexity Costs nothing to use Yeast population unique to place/region Can be used as part of marketing of wine

Disadvantages of using ambient yeast

Fermentation starts slowly - can build up unwanted volatile acidity and growth of spoilage organisms (Brett) - lead to off-flavours Fermentation to dryness takes longer Risk of stuck fermentation Consistent product cannot be guaranteed

What is the main yeast strain used in commercially cultured yeasts

Saccharomyces cerevisiae

Advantages of using cultured yeast

Reliable, fast fermentation to dryness Produces low levels of volatile acidity Less danger of spoilage organisms and bacteria Produces consistent product from one vintage to another Large selection of yeast strains

Disadvantages of using cultured yeast

Leads to certain similarity of fruit expression - industrial wine Adds cost of using a commercial product

What are the cool fermentation temps used for fresher, fruitier white wines and rose?

12-16C

Mid-range fermentation temps used for easy-drinking fruity red wines to retain fruit aromas and for low tannin extraction

17-25C

Warm fermentation temps used for red wines with pronounced flavour concentration and high tannins

26-32C

Above what temperature does fermentation slow down and yeast struggles to survive

35C

What are options for temperature control during fermentation

Sluggish ferments can be moved to warmer room Overheating ferments can be moved to cooler room Water or glycol jackets that surround vessels (typically SS) Inserts that can be put into vessels Monitor/control systems by computer

List fermentation vessel options

Stainless Steel Concrete Large wooden fermentation casks Small wooden barrels Plastic vessels - small-batch fermentations Terracotta

Advantages of using stainless steel as a fermentation vessel

Easy to clean Large range of sizes High degree of control over temp of must/wine Neutral vessels - protect wine from oxygen Do not add flavours

List various names for terracotta fermentation vessels

Amphora Qvevri (Georgia) Tinaja (Spain)

Describe malolactic fermentation

Lactic acid bacteria converts malic acid into lactic acid and carbon dioxide, and it produces heat.

What conditions encourage MLC

Temperature 18-22C Moderate pH (3.3-3.5) Low total SO2

What conditions inhibit MLC

Temperature below 15C Low pH Moderate SO2 levels Add enzyme lysozyme - kills lactic acid bacteria Move batch of wine going through MLC to another part of winery to avoid spread of lactic acid bacteria Filter out lactic acid bacteria

What are the outcomes/effects of MLC

Reduction in acidity and rise in pH Some colour loss for red wines Greater microbial stability Modification of flavour - buttery notes, slight loss of fruit character

List the general winemaking post-fermentation adjustments

Removal of Alcohol Colour

How is alcohol removed after fermentation

Marginal adjustment - add water to must - reduces intensity of flavour

How do winemakers reduce unwanted colour tints

Fine wines

How do winemakers enhance the colour of red wine

Adding small amounts of grape-derived colouring agent, MegaPurple