1
Q
What three factors encourage MLC?
A
- 18-22 C
- Moderate pH (3.3-3.5)
- Low total SO2
2
Q
What are the requirements for organic winemaking?
A
- Made with organically-grown grapes
- Can only use additives and processes on a list set by associations, a country, or the EU
- SO2 rules vary (allowed in EU, banned in US)
3
Q
What six factors prevent MLC?
A
- Temp below 15 C
- Low pH
- Moderate SO2
- The enzyme lysozyme (which kills lactic acid bacteria)
- Moving any batch of wine undergoing MLC to another part of the winery
- Filtering out lactic acid bacteria
4
Q
What are the four outcomes of MLC?
A
- Reduction in acidity and rise in pH (softer, smoother style of wine)
- Some color loss in red wines (only a problem for very pale reds)
- Greater microbial stability (no MLC in bottle, BUT higher pH could cause problems)
- Modification of flavor (loss of fruit, addition of buttery notices, increase in VA)
5
Q
What are two advantages of conducting MLC in barrels rather than larger batches in tanks? A disadvantage?
A
Advantages:
* Ability to stir lees at the same time
* Better integration of aromas
Disadvantage:
* More work because it needs monitoring
6
Q
What are advantages of encouraging MLC at the same time as fermentation?
A
- Increase fruity characteristics (or decrease loss of fruit)
- Shortens production time (saving money)
7
Q
What is the aim of conventional winemaking?
A
To produce stable wines which reliably show their fruit character and have no faults
8
Q
Who sets the requirements of biodynamic winemaking, and what are they?
A
- Detemeter certifiers in each country (different rules)
- For example, in the UK, organic yeasts (or, if those are unavailable, conventional yeasts) can be used
- In the US, natural yeasts must be used, but certain classes of conventional yeasts can be used for stuck ferm on a case-by-case basis
9
Q
What is the overall aim of natural winemaking?
A
“nothing added, nothing removed”
10
Q
What are typical practices of natural winemaking?
A
- Ferm by ambient yeasts
- Absolute minimum SO2 (only at bottling) or none added at all
- Use of organic or biodynamic grapes, whether certified or not
11
Q
What is the first nationally recognized natural wine certification body?
A
- France’s Vin méthode nature
12
Q
Immediately after harvest, what are grapes vulnerable to?
A
- Oxidation
- Microbial spoilage (ambient yeasts and acetic acid bacteria)
13
Q
What five measures can be taken to reduce the risk of oxidation and microbial spoilage of grapes between harvest and processing?
A
- Harvest and transport at night when cooler
- Addition of SO2 at time of harvest
- Put grapes in cold storage once received at winery
- Sanitize harvesting equipment/bins
- Use small crates to minimize crushing (only possible with hand-harvested grapes)
14
Q
What four processes are common during grape reception?
A
- Chilling
- Sorting
- Destemming
- Crushing
15
Q
The level of sorting (or whether it takes place) depends on what four factors?
A
- Ripeness and health of fruit arriving at winery
- the intended final wine quality and price
- whether any sorting has happened in the vineyard (e.g., by pickers)
- the physical state of the grapes (with large containers, the bottom grapes have already been crushed, so can’t be sorted)
16
Q
Why is it that the more sorting the higher the cost?
A
- Labor and time needed
- Yield inevitably less due to excluded grapes
17
Q
For quality wines, what are three methods of sorting?
A
- Before picking or during hand harvesting
- By hand on a table or vibrating belt before or after destemming
- Optical sorting
18
Q
What impact does using a combined destemmer-crusher machine have on sorting?
A
It can only be done at the level of whole bunches
19
Q
What are the four ways to “enrich” must via additions?
A
- Dry sugar (chaptalization)
- Grape must
- Grape concentrate
- Rectified concentrated grape must (RCGM)
20
Q
What are three ways to “enrich” must via concentration?
A
Remove water via:
* Reverse osmosis
* Vacuum evaporation
* cryoextraction (freezing, and removing ice) – cheap and therefore used widely
21
Q
When is sugar usually added?
A
When ferm is already underway, as the yeast is better able to cope with the additional sugar
22
Q
When is a must or wine usually acidified?
A
Can happen before, during, or after ferm, but usually happens before.
Reasons:
* Benefit of lower pH
* Acidity may be better integrated into the wine
23
Q
Besides tartaric acid, what are three other acids that can be used for acidification?
A
- citric (not permitted in EU)
- malic (but can be subject to MLC)
- lactic (after MLC; can taste less harsh)
24
Q
What are two general methods of deacidification?
A
- Adding calcium carbonate (chalk) or potassium carbonate, which forms a precipitate of tartrates
- Ion exchange
25
What are two general ways to macerate red wines before ferm?
* Cold soaking
* Macerations using heat (flash
détente and thermovinification)
26
* What is cold soaking for red wines?
* How long does it last?
* Why is it done?
* What are its cost components?
* Red wine must cooled to 4-10 C
* Usually lasts 3-7 days, with some punching down and/or pumping over
* Very common with Pinot Noir, or other varieties to extract color without tannins
* Cost in energy for chilling and time spent
27
What is thermovinification?
Heating the must to around 50–60°C and sometimes higher. The time spent macerating at this heat can range from a number of minutes to several hours; generally, the higher the temperature, the shorter the maceration.
28
What is flash détente?
Destemmed grapes are quickly heated to 85–90°C and then rapidly cooled under a vacuum. This takes place in as little as two minutes. The process bursts the cells in the grape skins, allowing a very rapid extraction of anthocyanins and flavours. The short time at high temperatures limits the risk of ‘cooked’ flavours developing
29
Why is flash détente only used at high-volume wineries?
Equipment is expensive
30
What are other reasons to use heated macerations?
* Both flash détente and thermovinification can be used for botrytis-affected grapes, as they denature an oxidative enzyme (laccase)
* Flash détente can be used for smoke taint
31
Why would heated maceration and then pressing off skins before fermentation be used, and what drawbacks are there?
* Used to create fruity, low-tannin style
* Issues with color stability because of lack of anthocyanins, so best suited to inexpensive or mid-price wines for early consumption
32
What are the three ways of making rose wines?
* Direct pressing
* Short maceration
* Blending
33
Describe direct pressing to make rose wines and what is a name for wines made in this way?
Description:
* Grapes of a black variety are either whole bunch pressed or destemmed (possibly crushed) and immediately pressed to minimize maceration
* Pneumatic presses typically used and flushed with inert gas
* Ferm like white wine
Also called *vin gris*
34
What four factors influence the intensity of color of rose wines made from direct pressing?
* Pressure used when pressing
* Duration of pressing time
* How much press juice is used
* Whether white grapes are co-pressed (if permitted by local law)
35
Describe making rose wine via short maceration
* Black grapes crushed, left to macerate for a couple hours to a few days (protected by inert gas)
* Juice drained and grape skins may be gently pressed
* Ferm like white wine
36
What is "saignée" and how does it relate to rose wines?
* Some juice from a red wine maceration bled off
* Produces (i) a short maceration rose wine and (ii) a more concentrated red wine
37
What is the advantage and potential disadvantage of making rose wine via the saignée method?
Advantage: Cheap
Disadvantage: Grapes typically grown to suit red wine, not rose
38
How do rose wines made via direct pressing typically compare with those made via short maceration?
Direct pressing wines are typically (though not always) lighter in color because there is less skin contact
39
What happens to the color of rose wines during ferm?
It decreases, so the color of the must has to be darker than the intended color of the wine
40
What are five ways of limiting effect of oxygen on must or wine?
* Avoid ullage (headspace of air), e.g., by topping off wine in wood vessels
* Flush with inert gas (like nitrogen, CO2, argon)
* SO2 use
* Impermeable containers
* Cool, constant temps
41
What are five ways of increasing oxygen exposure?
* Cap management techniques that spray or splash must or wine
* Small wooden barrels
* Increase rackings or lees stirring during ageing (requires opening bung or lid)
* Allow ullage without use of inert gases
* Use methods of pumping O2 (e.g., hyperoxidation in must or micro-oxygenation in wine)
42
What do wines exposed to O2 need to be monitored for, and why?
Microbes, because Brett, acetic acid bacteria, and others love oxygen
43
What are the seven components of wine?
* Water
* Alcohol
* Acids
* Wine aromatics
* Residual sugar
* Glycerol
* Phenolics
44
* What is the effect of alcohol at and above 14.5%?
* What must be true about these wines to be in balance?
* Reduces volatility of wine aromas and increase sense of bitterness
* Wines with high alc must have sufficient fruit concentration to balance
45
How much do tartaric and malic acids make up of the total acidity of a wine?
About two-thirds
46
What is the most common measure of acidity in wines and how is it measured?
* Total acidity: Sum of all acids
* Usually equivalent g/L of tartaric acid (in France, sulfuric acid)
47
What is the typical total acidity and pH of wine?
* TA: 5.5-8.5 g/L tartaric acid equivalent
* pH: 3-4
48
What are four impacts of a low pH in wine?
* Increases microbiological stability
* Increases effectiveness of SO2
* Gives red wines a brighter red color
* Enhances ageability
49
What are four categories of wine aromatics?
* Aromas from the grapes
* Aromas created by ferm due to presence of aroma precursors in grape must
* Aromas originating from ferm and its by-products
* Aromas from other sources
50
What are two examples of aromas from grapes and wines in which they are present?
* Methoxypyrazines (Sauvignon Blanc: grassy, green bell pepper)
* Rotundone (Syrah and Grüner Veltliner: pepper)
51
What are two categories of aroma precursors, what are examples, and in what wine are they found?
* Thiols, like 4MMP (Sauvignon Blanc: box tree)
* Terpenes, like linalool and geraniol (Muscat: grapey)
52
How do aroma precursors often become aromatic?
Often bound to sugars and become aromatic during fermentation (e.g., due to hydrolysis)
53
What are four examples of aromas from ferm and by-products?
* Esters
* Acetaldehyde
* Diacetyl
* Reductive sulfur compounds
54
How are esters formed, what aromas do they give, and in what wines are they important?
* Formed by reaction of certain acids and alcohols, most created as part of fermentation process. Most break down a few months after fermentation.
* Fresh, fruity aromas
* Especially important in young white wines
55
What are two examples of esters?
* Isoamyl acetate (when high, banana in Beaujolais Nouveau) -- most common
* Ethyl acetate (nail varnish remover), from acetic acid and alcohol
56
How is acetaldehyde formed? What does it do and smell like?
* oxidation of ethanol
* masks fresh fruit aromas and has a stale smell
57
What are two examples of aromas from other sources, and where do they come from?
* Vanillin (from new oak)
* Eucalyptol (from neighboring trees)
58
In the EU, what level of RS is "dry" and what are two other names that can be used?
* 4 g/L RS, or no more than 9 g/L as long as TA is no more than 2 g below RS
* Sec, Trocken
59
In the EU, what level of RS is "medium dry" and what are two other names that can be used?
* more than 4 g/L and no more than 12 g/L, or up to 18 g/L if TA is no more than 10 g below RS
* Demi-sec, Halbtrocken
60
In the EU, what level of RS is "medium or medium sweet" and what are two other names that can be used?
* more than 12 g/L and not exceeding 45 g/L
* Moelleux, Lieblich
61
In the EU, what level of RS is "sweet" and what are two other names that can be used?
* at least 45 g/L
* Doux, Süss
62
What does glycerol contribute to a wine?
* Contributes smooth texture and fullness of body.
* Slightly sweet.
63
In what styles of wine is glycerol higher?
In order of higher glycerol:
* Wines from botrytis-affected grapes
* Wines made from carb mac
64
What are two major categories of phenolics in wine?
* Anthocyanins
* Tannins
65
What do anthocyanins do in a wine?
color pigment that gives red and sometimes blue
66
What are two examples where other wine components can change the sensation of tannins?
* A little RS: softer
* Dry wine with high acid: more astringent
67
What must acid in a wine be in balance with?
* Fruit concentration
* If present, residual sugar
68
What taste does malic acid give to wine?
A firm acidity
69
What are three primary types of practices of conventional winemaking?
* **Temperature control**: (i) cold soaking, (ii) ferm temp, (iii) temp control in maturation
* **Use of additives and/or processing aids**: (i) adding sugar to must or wine, (ii) adding SO2, (iii) cultured yeasts, (iv) fining agents
* **Manipulations**: pressing, reverse osmosis, etc.
70
What is the general cost impact of using organic, biodynamic, or natural winemaking?
Small costs, due to certification and possibly small scale of production (in biodynamic and natural)
71
What are two examples of how oxidation threatens fresh, fruity wines?
* Many aromas, like thiols in Sauvignon Blanc, break down
* Acetaldehyde (from oxidation of ethanol
72
Why are red wines more protected against oxidation?
Phenolic compounds in red wines have anti-oxidative effect
73
What are two ways in which oxygen is required for winemaking?
* Oxygen is required at the start of ferm of all wines to promote growth of healthy yeast population
* Lack of oxygen in winemaking or storage can lead to reductive off-flavors
74
In what three ways is SO2 an anti-oxidant?
* It reacts with oxygen itself very slowly
* It reduces the effects of oxidation by reacting with the products of oxidation reactions so they can't oxidize further compounds in the wine
* it inhibits oxidative enzymes
75
When does a wine need to state that it contains sulfites?
When it contains over 10 mg/L of SO2
76
What species does SO2 form when following hydration under acqueous conditions, and what are their effects on wine?
* Bound SO2: ineffective against oxidation and microbes
* Free SO2 (not bound)
* Molecular SO2: a small proportion of free SO2, and most effective against oxidation and microbes
77
What effect does pH have on SO2 efficacy, and what does this mean?
* More free SO2 is in molecular form at lower pH
* Thus, more SO2 is required to protect wines with higher pH
78
When three times is SO2 addition most effective?
* When grapes are crushed
* At end of MLC
* At bottling
79
Why do quality-conscious winemakers limit additions of SO2?
* Legal restrictions
* High levels can dull aromas/flavors and sometimes cause wine to taste harsh
80
What can be done to limit SO2 required?
* Limit microbes through winery hygiene and grape sorting
* Limit oxygen exposure
* Keeping grapes, must, or wine cool (protecting against both oxidation and microbes)
81
What three things are grapes vulnerable to in transportation?
* oxidation
* microbes (including ambient yeast and acetic acid bacteria)
82
What are the options for transportation when hand-harvested grapes are in small crates?
* Transport the small crates to the winery (because plots are small, or to **avoid crushing** and consequent oxidation and spoilage)
* Tip small crates into large hoppers for transport to winery (some add SO2 as potassium metabisulfite to minimize oxidation and spoilage due to inevitable crushing)
83
When large volumes of grapes are to be moved on reception, what are the two options?
How are smaller volumes often moved?
Large:
* Conveyor belt (gentler)
* Screw conveyor
Small:
* Manually, with pallet truck or forklift
84
What are the two ways of chilling grapes, and why?
* Whole bunches: refrigeration unit
* Grapes in more fluid form (e.g., machine harvested): heat exchanger
85
What is the advantage of using a vibrating belt for sorting?
It also removes MOG
86
What wine price points is optical sorting used for, and why?
* Premium and super-premium
* High cost of machinery and high level of selection
87
How does a destemmer usually work?
A series of blades within a rotating drum that remove the grapes from the stems
88
What are three examples of ways that wines are made in which grapes are not destemmed?
* red wine ferms using some whole bunches (e.g., Pinot Noir)
* carb mac (e.g., Beaujolais)
* whole bunch pressing for white wines (e.g., high-quality sparkling)
89
What is crushing?
Application of sufficient pressure to grapes to break the skins and release the juice, making it available for ferm
90
What is pressing?
Separation of juice or wine from skins and seeds
91
Why is soft pressing important for white wines?
* Avoid extracting tannins from skins and seeds
* Avoid excessive solids
92
Why is soft pressing important for red wines?
Avoid extracting excessive tannins and bitterness from skins and seeds softened in the must (for between 5 days and 3 weeks)
93
What are the four primary types of presses, and what are they known for?
* Pneumatic press (most popular)
* Basket press (traditional)
* Horizontal screw press (less gentle)
* Continuous press (continuous processing)
94
How does a pneumatic press work?
* cylindrical cage with a bladder that runs down the side or middle of it.
* Grapes are loaded into the tank (on one side of the bladder).
* The other side of the cage is filled with air and, as the bladder inflates, the grapes are gradually pushed against grates on the side of the cage, separating the juice or wine from the skins
95
What are the advantages of a pneumatic press?
* it can be programmed to exert different amounts of pressure (possibly for different press fractions)
* it can be flushed with inert gas
96
How does a basket press work?
* A ‘basket’ is filled with grapes and pressure is applied from above.
* The juice or wine runs through gaps or holes in the side of the basket and is collected by a tray at the bottom of the press.
* A pipe transfers the juice or wine to another vessel.
97
What is one advantage and three disadvantages to basket presses?
Advantage: Some winemakers believe they are gentler than pneumatic
Disadvantages:
* Not sealed, so can't be flushed with inert gas to avoid oxygen
* Hold smaller loads than pneumatic presses
* Much more labor intensive
98
What kinds of wineries are best suited to basket presses?
Small wineries making premium wines
99
How do horizontal presses work?
Similar to a basket press mounted horizontally above a rectangular draining tray.
100
How does a continuous press work?
Allows grapes to be continually loaded into the press as it works by using a screw mechanism; this allows for quicker pressing of large volumes of grapes
101
What types of wineries are best suited to using continuous presses and why?
* High volume, inexpensive wines
* Not as gentle, but can do continuous, quick processing of large amounts of grapes
102
* What is the impact of pressing with more pressure?
* What is the impact of pressing for a longer time?
* More tannin and color
* More tannin and aroma/flavor
103
What is the name of the remains left after pressing?
pomace
104
What is the goal in must adjustments?
Create a more balanced wine, especially if there has been a compromise in achieving optimum ripeness of sugars, acids, tannins, aromas
105
What are the five general types of must adjustments?
* Enrichment
* Reducing alcohol
* Acidification
* Deacidification
* Adding tannins
106
Is chaptalization permitted in warmer areas?
No, but it is possible to add RCGM (within limits)
107
What are EU rules regarding enrichment?
* Regions divided into zones based on climate
* For each zone:
(i) min natural potential alcohol
(ii) max enrichment
(iii) max alcohol in final wine (if enriched)
* In general, less enrichment and higher max alc level permitted in warmer climates
108
What wines are commonly acidified?
It is routine in most warmer parts of the world for inexpensive and mid-priced wines, and many premium wines
109
What must the winemaker take into account when deciding how much to acidify?
TA and pH can change during some processes, like MLC and tartrate stabilization, and this needs to be taken into account.
110
What are EU regulations regarding acidification?
* In coolest zone, only deacidification is allowed (up to a limit)
* In moderate zone, deacidication or acidification is permitted
* In warmest zone, only acidification is permitted
111
In the EU, can winemakers both chaptalize and acidify?
No
112
What is the cost of ion exchange for deacidification?
Considerable cost in buying or renting machinery
113
What are two reasons that powdered tannins would be added to musts?
* to help clarify musts
* for red wine: to stablize color and improve mouthfeel
114
When might tannins be added?
* To the must before ferm
* To the wine before maturation
115
Does yeast need oxygen to start ferm?
Yes, but as soon as it is used up (via aerobic respiration), yeast switches to anaerobic ferm.
116
What three things need to be true for yeast to produce alcohol from sugars?
* Viable temp range
* Yeast nutrients
* Absence of oxygen
117
What are 7 things produced by ferm?
* alcohol
* CO2
* heat
* volatile acidity
* very small amounts of SO2
* wine aromatics, (i) from precursors and (ii) created by yeast
* glycerol
118
What happens when must is allowed to ferm using ambient yeast?
* A range of species of yeast (including *Kloeckera* and *Candida*) start the ferm
* Typically, *Saccharomyces cerevisiae* quickly becomes to dominant yeast, as others die out once alc passes 5%
119
What are four advantages of ferm using ambient yeast?
* Can add complexity due to diversity of species
* Costs nothing
* Yeast population may be unique to place or region, adding typicity
* Can be referenced in marketing
120
What are four disadvantages of ferm using ambient yeast?
* Ferm can start slowly, which can be dangerous for buildup of unwanted VA and growth of Brett
* Increased risk of stuck ferms (which leaves wine vulnerable for spoilage)
* Ferm to dryness can take longer
* Consistent product can't be guaranteed
121
Describe the use of cultured yeast
Purchased from supplier
Then either:
* Must cooled to prevent ferm by ambient yeast; or
*SO2 added to must to suppress ambient yeast
Then starter batch created by adding cultured yeast to buckets of must, which are then poured into the main vat when activated
122
What are four advantages of using cultured yeast?
* Fast, reliable ferm
* Low levels of VA, and less danger from spoilage
* Consistent product
* Many choices of strains available, allowing winemaker more control over style
123
What is another species of cultured yeast used, and when is it used?
*Saccharomyces bayanus*, sometimes used for must with high potential alc or for re-ferm sparkling wines
124
What are two disadvantages of using cultured yeast?
* Some believe it leads to similarity of fruit expression ("industrial wine")
* Adds cost
125
What are three typical considerations for during ferm for white wines?
* Yeast (cultured vs. ambient)
* Temp
* Vessel
126
What are four typical considerations for during ferm for red wines?
* Yeast (cultured vs. ambient)
* Temp
* Maceration techniques (e.g., cap management)
* Vessel
127
What are three typical temp ranges for ferm?
* 12 - 16 C: fresher, fruitier whites and roses
* 17 - 25 C: Easy drinking fruity reds, less fruity whites, barrel-ferm whites (top of range)
* 26 - 32 C: Reds with pronounced flavor and high tannins (some loss of fruity)
128
What is one of the primary goals of cool ferms for fresher, fruitier whites and roses?
Production and retention of esters
129
What temp does ferm slow down and stop?
Above 35 C
130
What are three methods of temp control during ferm?
* Move to a warmer/cooler room
* Temp control in the vessel (jackets around vessel, or insets in vessel)
* Pumping over
131
What are three primary types of vessels available for ferm?
* Stainless steel
* Concrete
* Wood
132
What are two lesser-used alternatives for ferm vessels, and what is notable about them?
* Plastic: But permeable to O2 and difficult to control temp
* Terracotta: Traditional use
133
What are 7 reasons why stainless steel is the modern standard for ferm vessels?
* Easy to clean (enable high level of hygiene)
* Range of sizes
* Enables high degree of control over temp
* Inert
* Can isolate from O2
* Low cost overall
* High level of mechanization possible
134
What are the cost components of stainless steel vessels in ferm?
* High initial cost of purchasing tanks and computerized temp-control systems
* Can be low overall due to automation
135
What are the two advantages of concrete vessels for ferm?
* High thermal inertia
* Egg-shaped vessels are said to set up convention currents that mix must during ferm and lees during maturation
136
What is the disadvantage of concrete egg-shaped vessels for ferm?
Very expensive
137
What are three advantages of wood ferm vessels?
* Retains heat well
* Some winemakers value small O2 that wood provides to fermenting reds
* Cost over the long term is low because can be reused many times
138
What is the disadvantage of using wood vessels in ferm?
Hygiene: Pores in wood can harbor bacteria and spoilage organisms
139
What two types of wooden vessels can be used for ferm whites?
* Open-top vats
* Barrels (not for reds, given cap management)
140
Why should the winemaker aim to make only small adjustments post-ferm?
To not upset balance of wine
141
What are three key factors that influence the wine during maturation?
* Oxygen
* New wood
* Yeast lees
142
What styles of wine are not matured, but finished and packaged shortly after ferm?
Young, fruity, or aromatic styles
143
When can blending happen, and when does it usually happen?
Can happen anytime in the winemaking process, but usually happens at end of maturation
144
What is the effect of exposure of young red wine to oxygen on color, and why?
Greater color stability and intensity
Why:
* anthocyanins to bind with tannins, which protect them from being bleached by SO2 or adsorbed by yeast lees
* Esp important for pale reds, like Pinot Noir
145
What three things does the speed of oxidation primarily depend on?
* amount of O2 exposure
* compounds in wine
* temp
146
When wood is matured in small wooden vessels, what factors play a role in O2 exposure? In order of importance
* Removal of bung and/or transfer: Racking, lees stirring, topping up
* O2 released from pores of vessel in first month
* Very small O2 through gaps in staves and bung hold
147
Why is wine lost during maturation in wood vessels, and what needs to be done because of this?
* Water and alc impregnate wood, which diffuses to air outside
* Barrels need to be topped up to avoid ullage
148
What factors increase the amount of wine lost during maturation in oak?
* Size of barrel
* Temp
* Humidity
149
What happens to wine stored in oak barrel at under 70% humidity?
Water lost at a greater rate than alc, leading to higher alc (usually not desirable)
150
Describe micro-oxidation
* Oxygen bubbled through wine held in stainless steel tanks
* O2 measured in mg/L
* Carried out for a number of months post-ferm
* Used to be only inexpensive and mid-priced; now used on prem and super-prem
* This is new, so research needed on when it is best and how it compares with barrel maturation
151
What 5 benefits does micro-ox provide?
* increase color stability and intensity
* soften tannins
* improve texture
* reduce unripe, herbaceous flavors
* can also integrate oak if used with chips or staves
152
What are three reasons why micro-ox is better than oxidation in barrels?
* quicker than barrel ageing
* cheaper than barrels
* rate of oxidation can be controlled
153
What temps are whites and reds matured?
* Whites: 8-12 C
* Reds: 12-16 C
154
What 4 features of wood barrels impact the compounds extracted from them in maturation?
* age
* size
* type of wood
* production of vessel
155
How much new oak flavors does a barrel lose in its first year of use?
About 50%
156
Is it typical to use solely new oak barrels?
No. When used, typically some is matured in new oak and some in old.
157
What are two factors related to the type of oak that have an impact on the compounds imparted to wine?
* species of oak (American vs. European)
* tightness of grain
158
What impact does the species of oak (American vs. European) have on the compounds imparted to wine?
* American oak has much higher levels of lactones (coconut)
* American oak imparts greater intensity of aromas (European is subtler)
* European oak imparts more tannins
159
Why are oak grains more or less tight, and what impact does it have on compounds imparted?
* Slow growing (e.g., in continental climates, like Russia and Hungary) leads to tighter grains
* Tighter grains leads to slower extraction of aromas and tannins
160
What are two reasons why French oak barrels are twice as expensive as American oak barrels?
* European oak has to be split, whereas American can be sawn (so more barrels can be made from American oak)
* American oak grows much more quickly
161
What are the two basic steps of constructing oak barrels?
* Seasoning: Oak staves outside for 2-3 years
* Heating staves so they can be bent into shape
162
What three things does seasoning of oak staves do?
* lower humidity in wood
* reduces bitter flavors
* increases some aroma compounds (like those that give cloves)
163
What are two basic variables that cooperages can change to adjust the effect their barrels have on wine?
* Length of seasoning
* Length of heating staves and how intensely or gently they heat staves (light, medium, heavy toast)
164
What aromas do toasting of staves add, and what type of toasting makes them more
* Spice, caramel, roasted nuts, char, smoke
* Heavy toast
165
What are the two general impacts of wine spending longer maturing in oak barrels?
* More extraction of compounds from oak (and O2 exposure)
* More diversity of wood-derived aromas (given that different compounds are extracted at different speeds)
166
What are 4 reasons barrel maturation is costly, and thus used for at least mid-priced wines?
* barrels are expensive, and winemakers need a lot of them (as they are small)
* labor for monitoring and performing winemaking operations (e.g., lees stirring or racking)
* lots of cleaning due to Brett and other spoilage organisms
* barrel maturation is slow, tying up capital
167
What are three reasons oak alternatives (like chips and staves) are cheaper than barrels?
* much cheaper to purchase
* can be added to a large tank of wine (so less labor)
* large surface area means they have a quick effect
168
What are two oak alternatives, and how are they used?
* Oak staves: (i) attached inside of vessel or (ii) float in wine
* Oak chips: placed in permeable sack, soaked in wine
169
How can oak alternatives be better than barrel maturation?
Can finely tune the effect
170
What are the five components of lees?
* dead and dying yeast and bacteria
* grape fragments
* precipitated tannins
* nutrients
* other insoluble compounds
171
How quickly do the gross lees form?
Within the first 24 hours after the end of ferm
172
What 5 positive effects on the wine do lees/autolysis have?
* release of compounds contributing flavors, body, and texture
* compounds bind to phenolic compounds, reducing color and softening tannins
* compounds bind to wood tannins and flavors, reducing astringency and modifying flavors from wood
* stabilize white wines against unstable proteins that can cause hazes
* protect wine from O2, reducing need for SO2
173
What four aroma descriptors are used for the effect of lees in white wines?
* yogurt
* dough
* biscuit
* toasted bread
174
What are two possible negative impacts of lees ageing?
* volatile, reductive sulfur compounds (a reductive fault at high concentrations)
* provide nutrients for microbes (lactic acid bacteria (may be positive), but also Brett)
175
What are the cost components of lees ageing?
* Increase storage time of wine (BUT this is not a factor if already barrel ageing)
* Increase labor (monitoring, stirring, etc.)
176
What yeast nutrients can be added prior to ferm, especially if N2 is low?
* Diammonium phosphate (known as DAP)
* Thiamine (vitamin B1)
177
What are the two primary purposes for skin contact for whites, and what is the danger if it is used too excessively?
Purposes:
* to enhance the extraction of aroma and flavor compounds and precursors
* to enhance the texture by extracting a small amount of tannin
Danger:
* It can make whites taste bitter and feel course in the mouth
178
In white wines, what are three reasons a winemaker might want to load the press with whole bunches of uncrushed grapes?
* one of the gentlest forms of pressing, providing juice low in solids (skin, stem, seeds), tannin and color
* reduce risk of oxidation (esp if press is flushed with inert gas)
* helps break up mass of grape skins, providing channels for juice to drain
179
What four types of wine is minimal skin contact typical for?
* wines where delicate fruity flavors, minimal color, and smooth mouthfeel are desired
* wines designed to be drunk early (because tannins wouldn't have time to soften)
* if the fruit is at all underripe (given extraction of bitter flavors and astringent tannins)
* on inexpensive wines (because it takes time and labor)
180
What are typical steps in white winemaking after pressing and before newly made wine?
Non-optional in **bold**.
* hyperoxidation
* clarification
* must adjustments
* **alc ferm**
* post-ferm adjustments
* MLC
181
What are typical steps in white winemaking after newly made wine and before wine for sale?
Non-optional in **bold**.
* blending
* maturation in oak (or oak alternatives)?
* lees ageing
* blending
* stabilization
* clarification
* **packaging**
182
* In what varieties is skin contact used most effectively?
* Two reasons why?
Aromatic, like:
* Riesling
* Gewurztraminer
* Viognier
* Muscat
* Sauvignon Blanc
Reasons:
* lots of aromas to extract
* seldom matured in oak, so this improves texture
183
What temp is cold soaking for whites generally done at, and for how long?
* below 15 C
* 1 - 24 hours and more
184
Why is cold soaking for white wines done at temps below 15 C?
* slower extraction, so easier to control
* reduces oxidation
* reduces threat of spoilage
185
How are orange wines made, and what are their characteristics?
Ferm white grapes on skins, as with reds.
Characteristics:
* notable tannin
* dried fruit, dried herbs, hay, or nuts
* often by natural winemakers, so ambient yeast, no temp control or SO2
186
Why is whole bunch pressing for whites only used for smaller batches of premium wines?
* can only be done when grapes are hand-harvested
* bunches take up a lot of room in the press, reducing throughput
187
What is free run juice and what are its characteristics?
The juice that drains off as soon as destemmed grapes are crushed.
Characteristics:
* lowest in solids, tannin, and color
* lower in pH and higher in acidity
188
What are press fractions?
* Juice that flows from pressed grapes, separated as pressure is increased
* Increases in solids, tannin, and color as the pressure increases
189
Describe hyperoxidation in whites
* must is deliberately exposed to large amounts of O2
* compounds that oxidize easily are turned brown
* during ferm, these compounds precipitate, returning wine to normal color
190
What are two benefits from hyperoxidation?
* create wine more stable against oxidation after ferm
* helps remove bitter compounds that can come from unripe grape skins, seeds and stems
191
What are the cost components of hyperoxidation?
overall, a small impact on cost:
* inexpensive equipment
* requires labor to set up and monitor
192
What wines is hyperoxidation most appropriate for?
Less aromatic, like Chard (as it reduces thiols and methoxypyrazines--i.e., not appropriate for fruity or herbaceous styles)
193
What is the goal of clarification of white wine must, and what do they aim for?
* The aim is to reduce suspended solids (particulars of skin, stem and seeds)
* Winemakers generally aim for solids to be 0.5 - 2%
194
What needs to be used to achieve white wine must levels of solids below 1%?
Pectolytic enzymes or centrifugation
195
* Why would a winemaker want to retain 1-2% of solids or marginally higher?
* Why not?
Why:
* Add to texture (tannins from skins/seeds add subtle astrigency)
* Greater range of aromas from ferm, giving greater complexity
Why not:
* Lower solids are better for fruity aromas
196
* What is a disadvantage of high levels of solids?
* What is a disadvantage of low levels of solids?
High levels:
* Require careful monitoring and management (hence costlier--better for smaller, premium)
* Can give reductive sulfur compounds (good at low levels, bad at high)
Low levels:
* Can lead to stuck ferm, because solids provide nutrients for yeast
* Yeast nutrients (like DAP) may need to be added
197
What are three methods of clarification of white wine must?
* Sedimentation
* Flotation
* Centrifugation
198
Describe sedimentation of white wine must
* Chilled to 4 C
* Takes 12-24 hours
* Solids left at the bottom often filter by cross flow or depth filter to extract extra juice
199
Why is sedimentation of white wine must most commonly used for small production premium?
* Most traditional
* Takes time
* Energy cost in chilling
* Batch process, so takes labor and time
200
Describe flotation for clarification of white wine must
* Fining agents added (to bind particles together)
* Bubble gas through must
* Bubbles bring solid particles to top, which are then skimmed off
201
What are the advantages and disadvantages of flotation for clarification of white wine must over sedimentation?
Advantages:
* If O2 is used, can also be hyperoxidation
* Effective and quick
* Can be continuous or batch
* No need to chill, saving energy costs
Disadvantages:
* A little more expensive in terms of equipment, gases, fining agents, and bubbling equipment
202
What are the advantages and disadvantages of centrifugation for clarifying white wine must, when compared with sedimentation?
Advantages:
* Quick
* Continuous (rather than batch)
Disadvantages:
* Equipment is expensive
* Increases O2 exposure (unless flushed with inert gas, which adds to cost)
203
What are four examples of clarifying agents that can be used to speed up rate of sedimentation of white wine must?
* Pectolytic enzymes
* Bentonite
* Gelatine
* Casein
204
What are the five characteristics of white wines fermented in small oak barrels?
* deeper color
* fuller body
* more integrated oak aromas (due to action of yeast during ferm)
* more texture
* more blending options because each barrel is slightly different (leading to more complexity)
205
What are three reasons why ferm of white wines in small oak barrels is costly?
* need to buy barrels
* a lot of them because they are small
* monitoring is more labor-intensive than in larger vessels
206
In what four ways does lees stirring change wine above simply lees ageing?
* Increase in O2 exposure
* Increase in the effects from dead yeast
* Decrease in fruity flavors
* Decrease of reductive sulfur compounds
207
What is a new alternative to mix lees? What is their advantage?
* Barrel racks, which permit rolling of barrels
* Gives winemaker control over the different impact of lees and oxidation
208
What is the cost component of lees stirring?
Labor, which can be expensive
