Chapter 13 - General Winemaking Options Flashcards
(46 cards)
1
Q
Bad effects of O2
A
- Breaks down aroma compounds
- Turns white wines darker –> brown (phenolics in red wine have anti-oxidative effect)
- Creates unwanted products (acetaldehyde is the oxidation of ethanol that causes nutty apple aromas)
- Growth of spoilage organisms (brett, acetic acid bacteria)
2
Q
How to avoid O2
A
- Ullage
- Cool constant temp
- Adding SO2
- Using impermeable vessels
- Using inert gases to flush O2 out of equipment
3
Q
Good effects of O2 (6 things)
A
- Adds complexity
- Changes aromas and flavors for greater range and diversity
- Exposure to some O2 for white wine must increases oxidation stability
- Prevents reduction faults
- Needed to grow initial yeast population
- Required for reaction between anthocyanins and tannins for color stability
4
Q
How to increase O2 exposure
A
- Racking
- Pump overs (cap management)
- Limiting SO2
- Using permeable vessels (barrels)
- Allowing ullage
- Using techniques that pump oxygen into the must (ie micro-oxygenation)
5
Q
When are the best times to add SO2?
A
- Right after grapes are harvest
- Right when they arrive at the winery
- When grapes are crushed
- After malo
- Right before bottling
6
Q
2 main purposes of SO2
A
Anti-microbial
anti-oxidant
7
Q
Bound SO2 vs Free SO2
A
Bound SO2 - the portion that reacts with compounds in the liquid and are ineffective against oxidation and microbes
Free SO2 - unbound portion. Most exist in an inactive form. Some exist as molecular SO2 that is the most effective against oxidation and microbes
8
Q
Why is adding too much sulfur bad?
A
- Reductive faults can occur (rotten eggs)
2. Can dull aromas and cause the wine to taste harsh
9
Q
Threats to grapes when they first get to the winery
A
- Ambient yeast
- Oxidation
- Bacteria (ie acetic acid bacteria)
- Warm temp
10
Q
How to minimize threat of oxidation & microbial infection during transport to winery?
A
- Pick at night or at cool temps
- Put grapes in smaller crates so they dont get crushed
- Spray crates w/ So2 or upon arrival
- Storing grapes in cool storage upon arrival
- Sanitizing all equipment used
11
Q
Order of processes once grapes arrive at the winery:
A
- Chill
- Sort
- Destem (optional)
- Crush (optional)
12
Q
Ways to sort grapes
A
- Hand harvest
- Sorting by hand on a table or vibrating belt
- Optical sorting (only for premium/super premium wines)
13
Q
When would you not destem your grapes?
A
- Whole Cluster/Bunch Fermentation (some whites like for high quality sparkling will also be whole cluster)
- Carbonic Maceration
14
Q
Whata is Must?
A
The mixture of grape juice, pulp, skins, and seeds. AKA substance being fermented
15
Q
Types of Batch Presses
A
- Pneumatic Press
- Basket Press
- Horizontal Screw Press
16
Q
Pros of Pneumatic Presses
A
- Can adjust pressure depending on desired extraction
2. Can be flushed with inert gas to prevent oxidation
17
Q
Pros of Basket Press
A
- Most gentle press method
18
Q
Cheapest Press Method
A
Continuous Press - quicker, less gentle than pneumatic and basket, used for high volume inexpensive wines
19
Q
Pomace
A
The solid remains of the grapes after pressing
20
Q
Reducing Alcohol Methods
A
- Adding water (will dilute the flavors though)
2. Removing alcohol post fermentation
21
Q
Enrichment Methods
A
- Chaptalization (in EU, only allowed in cooler regions) via cane sugar or beet sugar
- Adding RCGM (rectified concentrated grape must)
- Adding Grape Must
- Reverse Osmosis
- Vacuum Evaporation
- Cryoextraction (freezing and then removing ice)
Con of 4-6 - decreases overall volume
22
Q
Acidification Methods
When is the best time to add acid?
A
Most common: adding tartaric acid
Others:
citric acid (not allowed in EU)
Malic acid (can be turned into lalic acid via malo)
Lactic acid (used if adjustments are after malo. Tends to taste less harsh)
Best time to acidify: before ferm bc it lowers the pH (helps prevent microbial spoilage) and integrates better with the rest of the wine
23
Q
Deacidification Methods:
A
- Adding calcium carbonate to precipitate the acid out as tartrates
- Ion exchange (expensive and not always allowed)
24
Q
Adding Tannins method and why would you do it?
A
Add powedered tannins Why? Better mouthfeel Help clarify the must in red wine Help stabilize the color
25
Fermentation equation/products:
Sugar ----(yeast)----> ethanol + CO2 + heat
Anaerobic reaction
Side reactions:
1. VA (mainly acetic acid. EtOH ---- (acetic acid bacteria) ---> Acetic Acid) gives a vinegar/nail polish remover smell (not detectable in small amts)
2. Wine aromatics from aroma precursors (ie thiols like 4MMP that give SB boxwood aroma, tarpenes like linalool and geraniol that give Muscat grapey, floral aroma)
3. Wine aromatics from yeast activity (esters give banana like flavors during carbonic maceration, reductive sulfur compounds like rotten eggs, acetaldehyde during the oxidation of EtOH that masks fresh fruit and gives a stale smell, diacetyl give a buttery aroma but mostly during malo)
4. Glycerol (fermentation by product derived from grape sugars esp botrytised grapes and gives smoothness, fullness, and a slightly sweet taste)
26
Most common yeast strain and why
Saccharomyces cerevisiae
Can withstand low pH, SO2, increasing levels of alcohol (imp so the wine can ferment to dryness), high acidity
27
Pros of Ambient Yeast
1. Adds complexity bc different yeast species adds different aromas
2. No cost
3. Unique to region/vineyard
4. Good for marketing
28
Cons of Ambient Yeast
1. Not as reliable to ferment must to dryness (most strains die off once alcohol gets to 5%) - stuck fermentation risk that then leads to oxidation and microbial spoilage risk
2. Fermentation may start slowly - causes unwanted VA buildup, growth of spoilage organisms
3. Consistent product is not guaranteed
29
How do you add in cultured yeast for fermentation?
1. Cool down grapes so ambient yeast is not active and then overwhelm ambient yeast with addition of cultured yeast
2. Add So2 to suppress ambient yeast. Create a starter batch of fermenting grape must and cultured yeast and then add to the rest of the must
30
Pros of Cultured Yeast
1. Reliable fermentation to dryness - much less risk of stuck or slow fermentation
2. Consistent end products (know what you're going to get)
3. Low levels of VA, microbial spoilage
4. Wine maker can choose the strain based on the style of wine he wants to make and what yeast flavors he wants imparted in his wine
31
Cons of Cultured Yeast
1. No uniqueness - wines all end up with a universal fruity flavor
2. Costly
32
Yeast needs what to grow and ferment wine?
1. Oxygen before fermentation to grow the yeast population
2. Nutrients, esp Nitrogen, to prevent yeast stress (causes undesirable sulfur compounds) or stuck fermentation
Nutrient can be added in the form of DAP
33
Yeast specie for high potential alcohol or refermenting sparkling wine
Saccharomyces bayanus
34
Does higher or lower temp induce a faster fermentation?
Faster
35
Cool Fermentation temp & style
12-16C
Fresher, fruitier whites and rosés
Esters are produced and retained better
36
Mid-range Fermentation temp & style
17-25C
Easy-drinking fruity reds for fruit aroma and low tannins
Less fruity whites --> barrel aged whites
37
Warm Fermentation temp & Style
26-32C
Red wines with pronounced flavor and high tannins
Maximum color and tannin extraction but also loss of fruity flavors
38
Pros/Cons of Stainless Steel Ferment
1. Easy to clean
2. Comes in many sizes
3. Temp control
4. Neutral
5. Impermeable
6. Highly mechanized (auto pump over, temp control, auto emptying, etc)
7. Costly
39
Pros/Cons of Concrete
1. Have high thermal inertia - naturally maintain an even temp
2. Historically inexpensive
3. Small egg-shaped vessels are expensive but creates natural convection currents that mix the mermenting must and lees during maturation)
40
Pros/Cons of Wood
1. Imparts flavor (if new oak is used)
2. Slight oxidation for complexity
3. Retains heat well
4. If not cleaned properly, pores are hiding spots for spoilage microbes
5. Comes in all sizes and types of wood
41
Malo equation
Malic acid ----(lactic acid bacteria ----> lactic acid + CO2 + heat
42
Conditions to cause Malo:
1. Temp between 18-22C
2. Moderate pH (3.3-3.5)
3. low total SO2
43
How do you prevent malo?
1. Lower temp to below 15C
2. Adding SO2
3. Having a low pH
4. Add lysozyme enzyme, which kills lactic acid bacteria
5. Filtering out lactic acid bacteria
6. Moving wine to a different space to avoid spread of lactic acid bacteria
44
Results of Malo:
1. Reduction of acidity and rise in pH (lactic acid is weaker than malic acid)
2. Some color loss in reds
3. Greater microbial stability - prevents spontaneous malo in bottle
4. Addition of flavor - slight loss in fruit aromas but creation of diacetyl - gives buttery notes. Also increases VA
45
Removing alcohol post fermentation methods:
1. Adding water
2. Reverse Osmosis
3. Spinning Cone
46
Adjusting Color Post Fermentation
1. Fining
| 2. Enhance color intensity by adding MegaPurple (grade-derived coloring agent)
