Finishing, packaging, faults, quality control Flashcards
What are the four components of total package oxygen?
- oxygen in head space (usually this is greatest contributor)
- dissolved oxygen in wine
- oxygen in cork or other closure
- OTR of cork or closure
What are five advantages of glass bottles?
- Inert, conveys no taint to wine
- Bottles can be delivered near-sterile (shrink-wrapped when hot)
- Inexpensive and in a range of colors
- In principle 100% recyclable (though ease differs on color)
- Best for ageing wine as it is impermeable to oxygen
What are five disadvantages to glass bottles?
- High carbon footprint to manufacture, given high heat
- Heavy to transport, adding to carbon footprint
- Fragile
- Rigid, so oxygen fills space created by wine removed from bottle
- Clear bottles can lead to light strike from flourescent or natural light, creating sulfurous off aromas
What are 6 packaging options for wine?
- glass bottle
- plastic bottle
- bag-in-box
- bricks
- pouches
- cans
What are 5 options for closures?
- natural cork
- technical cork
- synthetic cork
- screwcap
- glass stopper
What are four ideal attributes of closures?
- protect from rapid oxidation
- inert so does not affect quality of wine adversely
- easy to remove and re-insert
- cheap, recyclable, free of faults
What are two issues with natural corks?
- TCA, estimated at 3-5% of cork-closed bottles
- Natural corks have variable OTRs
What four steps have been taken by the cork industry to eliminate cork taint?
- Cleaning with steam extraction
- Cork particles cleaned and reconstituted with plastic (Diam–a form of technical cork)
- More rigorous quality control, including high tech solutions (e.g., gas chromatography
- Inexpensive polymer barrier between cork and wine
What are three types of technical corks?
- Agglomerated cork granules glued together
- 1-plus-1 cork (ends are natural cork, middle is cheap agglomerated)
- Cork particles cleaned and reconstituted with plastic (Diam)
What are synthetic closures and the two primary types?
Made with food-grade plastic with a silicone coating
* Molded
* Extruded (plastic covering plastic foam)
What are the advantages and disadvantages of molded and extruded closures?
Molded: Very rigid, not good at blocking oxygen (so only suitable for a few months)
Extruded:
* More flexible
* Come in a range of OTRs
Both may flavor scalp (plastic absorbs some flavors)
What is an issue with screwcaps and how is it addressed?
They can allow almost no oxygen ingress (esp the tin type) and can become reduction. To avoid use slightly lower SO2.
What are glass stoppers and what are their advantages and disadvantages?
Glass, with plastic ring forming seal
Advantages:
* Look nice
* Can store for similar time as natural cork
Disadvantages:
* Must use special bottles
* A expensive as top-quality cork
What are 9 wine faults?
i. Cloudiness and hazes
ii. Tartrates
iii. refermentation in bottle
iv. cork taint
v. oxidation
vi. volatile acidity
vii. reduction
viii. [light strike]
ix. brettanomyces
What are three causes of cloudiness and hazes, and how are they each remedied?
- Growth of yeast or bacteria: better hygiene, pre-bottling analysis, and possibly sterile filtering
- Poor filtering of wine (e.g., pumping wine at too high pressure through depth filter)
- Protein haze due to ineffective fining (wrong fining agent or over-fining): fine correctly and analyze thereafter
What are three signs of premature oxidation?
- Prematurely brown, loss of primary fruit
- Then a vinegary smell
What does reduction manifest as?
- Odors from onion to rotten eggs (caused by reductive sulfur compounds)
- Can be positive and give complexity in small amounts (struck match and smoke)
What three ways are reductive sulfur compounds created?
- Produced by yeast due to low nitrogen levels
- Near complete exclusion of oxygen during ageing in closed vessels (esp with lees ageing)
- Sometimes evolves in bottle with impermeable screw caps
How to avoid reductive sulfur compounds?
- Ensure yeast has sufficient nutrients and oxygen and must is at adequate temp
- Lower SO2 levels, esp in packaging with very low OTR
What does volatile acidity manifest as?
Pungent smell of nail varnish and/or vinegar
What causes volatile acidity?
- Presence of acetic acid bacteria
- Inadequate SO2 levels
- Excess exposure to O2
What is the impact of excessive Brett?
- Off-flavors dominate
- Fruity flavors reduced
- Acidity and tannins more prominent
What are the four key ways to avoid Brett?
- excellent hygiene
- maintaining effective SO2 levels
- keeping pH levels low
- keeping the period between alc ferm and MLC as short as possible, so SO2 can be added
What is light strike and what does it cause?
- direct sunlight fluorescent light through bottles
- volatile sulfur compounds, smalling like dirty drains
What are seven reasons to blend?
- balance
- consistency
- style
- complexity
- minimize faults
- volume
- price
What are six categories of wine that can be blended?
- different varieties
- different locations
- different grape growers or businesses that sell grapes, must, or wine
- from different vintages
- batches treated differently in the winery
- treated the same in the winery, but in different vessels for logistical reasons (e.g., in different barrels)
What are the three categories of fining agents?
- Those that remove unstable proteins
- Those that remove phenolics that contribute to undesirable color and bitterness
- Those that remove color and off-odors
What is the only fining agent that removes unstable proteins? What wines is this typically used with?
- Bentonite
- White and rose (not red, where these proteins bind to tannins and precipitate, removed when racking)
What is bentonite? What does it do? Can it fine must?
- Form of clay
- Minimal effect on flavor and texture
- Loss of color in red wine
- Large amounts of sediment (so loss wine)
- Can fine must as well as wine
What are six fining agents that remove phenolics that contribute to undesirable color and bitterness?
- Egg whites
- Gelatine
- Casein
- Isinglass
- Vegetable protein products
- PVPP
What is the only fining agent that removes color and off-odors?
Charcoal
- What does charcoal do?
- Why does it need to be used with care?
- What can be done to reduce bad effects?
- Removes brown colors and some off-odors
- Can over-fine easily by removing desirable aromas and flavors
- Can treat only part of wine and blend with the rest
What does fining do, how, and what is the danger?
- Fining removes a small proportion of unstable colloids
- Fining agent has opposite charge to the colloid, and so attaches to it, creating heavier particles that precipitate
- Danger: Over-fining, so add only the minimum effective amount of fining agent
What are the two forms of depth filtration?
a. Diatomaceous earth
b. Sheet filters (also: “plate and frame” or “pad” filters)
Describe use of Diatomaceous earth
- Pure silica and inert
- DE is wetted and used as filter medium
- Wine is sucked by vacuum from outside of a rotary drum, through the DE, to the inside of the drum
How can DE be used in a non-oxidative manner?
Enclosed DE filters can be flushed with an inert gas (e.g. nitrogen) to avoid oxidation
How expensive is DE?
- Initial investment in machinery important consideration, but DE per unit cost is low
What are sheet filters? What are their cost?
- The wine is passed through a sheet of the filtering material. More sheets speeds it up.
- Sheet filter systems require investment initially (the frame must be very robust to withstand the pressures involved)
- Cost of filter sheets is low
- Trained personnel must operate them to work properly.
What are two types of surface filtration?
- Membrane filters
- Cross-flow filters
What are membrane filters and when are they used?
- Surface filter, uses cartridges
- Wine must be pre-filtered first, as blocks easily
- Often final precaution before bottling (for microbiological stability)
- Initial investment is small, but cartridges are expensive
- What are cross-flow filters?
- When are they used?
- How expensive are they?
- Wines flows parallel to filter, cleaning surface while it works
- Very quick and can handle high loads of particles
- No replacement sheets, cartridges, or earth
- Machines are expensive, so only for large or well-funded wineries
- What is the traditional way to clarify wine?
- What are the three ways to speed up this process?
Traditional: Sedimentation
Three ways to speed it up:
* Centrifugation
* Fining
* Filtering (most common)
For what styles of wine is sedimentation appropriate? Inappropriate?
- Appropriate: premium and super-premium
- Inappropriate: high volume (where speed is important)
What factors does the speed of sedimentation of wines depend on?
- Temperature (typically cool temps take longer)
- Shape of container (larger, taller containers take longer, and also require more rackings)
What does centrifugation of wine replace, and what wineries use it?
- Replaces depth filtration
- Used by high-volume wineries given cost of machine
What are three major types of stability in a wine that winemakers seek?
- Protein
- Tartrate
- Microbiological
How is protein stability achieved in a wine?
Bentonite
What are six methods of achieving tartrate stability in wines?
- Cold stabilization
- Contact process
- Electrodialysis
- Ion exchange
- Carboxymethylcellulose (CMC)
- Metatartaric acid
Describe cold stabilization and what does it do?
Process:
* First remove colloids via fining
* Wine held at -4 C for 8 days
* Crystals removed via filtration
It removes the more common potassium bitartrate, not calcium tartrate.
Describe contact process, and why does one want to do it?
- Like cold stabilization, but potassium bitratrate is added to speed up start of crystallization
- Cooled to around 0 C for 1-2 hours (much quicker)
Describe electrodialysis for tartrate stability, and why one would want to use it
- Uses charged membrane to remove selected ions
- After high initial investment, (i) cheaper (less energy and quicker) and (ii) removes calcium ions and also some tartrate ions.
Describe ion exchange for tartrate stability
- Replaces potassium and calcium with hydrogen and sodium
- Not allowed in some areas because sodium is not conducive to health
Describe use of carboxymethylcellulose (CMC) for tartrate stability, and when it would be used
- CMC is wood cellulose, and prevents tartrates from forming visible size
- Good for inexpensive whites (lasts a few years)
- Not for reds (reacts with tannins and causes a haze)
Describe use of metatartaric acid for tartrate stability and when it would be used
- Prevents growth of tartrate crystals
- Effect lost over time when stored at high temps (25-30 C), so best for wines for early consumption
- Used more for cheap reds than whites, as CMC is better for them
How is microbiological stability in wine with residual sugar achieved?
- Sterile filtration
- Alternatively, add sorbic acid and SO2 (but some people can smell sorbic acid at very low levels)
How specifically to avoid Brett developing in bottle?
- Filter to remove bacteria
- Alternatively, add DMDC (dimethyl dicarbonate)
How specifically to avoid MLC in bottle?
- Ensure MLC has already taken place
- Filter to remove bacteria
What are four advantages to storing in bulk, and bottling when needed?
- Flexibility in selling wine, as it can be packaged with different labels/containers or blended as needed
- More efficient use of space
- Wine labels less likely be damaged
- Can use bulk shipping
What are two types of consistency are reasons to blend?
- Consistency across bottles of a single wine in a single vintage: usually necessary
- Consistency across different years: important in some products, like Sherry, NV sparkling, or inexpensive wines
What is an example of blending to minimize faults?
If one barrel is showing a lot of VA, the wine can be sterile filtered and blended with other barrels to lower the concentration below the sensory perception threshold
Why would one blend for volume?
If a winemaker doesn’t have sufficient grapes (because of small holdings or a poor vintage)–buy grapes and blend
What is an example of blending for price?
Blending cheaper varieties, like Trebbiano or Semillon, with a well-known variety like Chardonnay.
What are two reasons not to blend?
- To maintain the character from a single vineyard (or to market as from a single vineyard)
- To preserve distinctive varietal aromas (like Sauv Blanc or Riesling)
Describe the blending process
- Starts with blending trials using measuring cylinders and small volumes to find the best proportions
- For wines meant for ageing, have to estimate how blend will develop in the future
- Best done before stabilization (because changes can de-stabilize wines, like tartrate stability depending on pH)
- Requires considerable skill and experience
When it comes to finishing a wine, what is the aim for the overwhelming majority of winemakers?
To create a clear, stable wine
Describe the process of fining
- First conduct lab trials using fining agents with wine samples, to ensure minimum effective amount is used
- Then compare the fined wine with the original
- Finally, fine the wine
What problems can fining solve?
- Clarifies wine and stabilizes it against hazes forming later in bottle
- Can remove harsh tannins in reds
- Can remove browning in whites
What wines are egg whites used to fine, and why?
- High-quality red wines because it (i) removes harsh tannins and (ii) clarifies wine
- It is gentle on wine
What does gelatine do as a fining agent?
Can it be used to fine must?
- aids clarification
- removes bitterness and astringency in reds
- removes browning in whites
Yes, can be used to fine must
What is the danger of over-fining with gelatine?
- it can strip flavor and character
- It can create the risk of a protein haze forming later
What is gelatine made from?
Extracted from pork
What is casein and what does it do as a fining agent?
Can it fine must?
- A milk-derived protein
- Removes browning from whites and clarifies to some extent
- Can fine must
What is isinglass and what does it do as a fining agent?
What happens if too much is used?
- From fish bladders
- Clarifies whites, giving bright appearance
Too much:
* Formation of protein haze later
* Fishy smell
What does PVPP do as a fining agent? When is it used?
- Insoluble plastic in powder form
- Removes browning and astringency from oxidized whites
- Rarely used on red, but can reduce astringency and brighten color
- Gentler than charcoal
In what two circumstances can particles make their way through a depth filter?
- Too much pressure
- Used for too long
What are surface filters, and what is another name for them?
- Stops particles bigger than the pore size from going through
- Also called “absolute filters”
- What are two arguments against filtration?
- What are two arguments for filtration?
Arguments against:
* Negatively impacts wine’s character
* Strips wine of texture
Arguments for:
* Wines recover after some months
* Much lower fault rate, which actually helps optimal character expressions
What two checks happen before bottling?
- Before finishing options, full chemical analysis: at least alc, RS, free SO2
- Within hours of bottling, dissolved O2 and CO2
What are typical ranges of free SO2 in finished wines?
- white: 25-45 mg/L (lower than red due to lower pH)
- red: 30-55 mg/L
- sweet: 30-60 mg/L
If dissolved O2 is too high, how can it be removed?
Sparging: flushing wine with inert gas to remove it
What wines have CO2 added just before bottling?
Inexpensive youthful whites and roses, to give it a tiny bit of spritz for added freshness
What are three typical causes of oxidation as a fault?
- Faulty bottling
- Poor quality corks or plastic closures
- Keeping wine too long if it is not ageable
What 5 things can be done to reduce the threat of volatile acidity?
- Sorting to exclude damaged grapes
- Hygiene in winery
- Keeping vessels topped up (avoid ullage)
- Careful racking (to avoid O2 exposure)
- Maintaining adequate SO2 levels
If a wine has been infected by Brett, what should be done prior to bottling?
- Sterile filtration or
- Add DMDC (inactivates Brett)
What are two major exceptions to the use of glass bottles as preferred packaging?
- Producer markets (e.g., France) where inexpensive plastic (PVC) containers used to collect wine for short-term storage and early drinking
- Dominance of bag-in-box in some markets, like Sweden (nearly 60%)
What are the four advantages of plastic (PET) bottles?
- Light (1/8th of glass)
- Tough
- Inexpensive
- In principle, recyclable
In what 3 circumstances do plastic bottles work well?
- Wines with limited shelf life and for quick consumption
- For informal settings (e.g., outdoor eating, travel)
- On planes, where breakage is a problem
What are two requirements for using plastic bottles?
- Must be lined with a barrier to O2
- Special filing equipment required (as bottle is inflated during filling)
What are two ways to make bag-in-box?
- Usually: very thin AL foil covered on both sides by plastic
- Also: a plastic that gives some protection from O2 and is resistant to cracking (unlike AL)
What are five advantages of bag-in-box?
- Flexible pour size
- Good protection from O2 after wine has been poured (given collapse of bag)
- Available in range of sizes
- Easy to store (not fragile, and can be stacked)
- Low environmental impact (light and can be recycled)
What is the shelf life of bag-in-box?
Range of 6-9 months, though the best may protect up to 1 year
What are factors to keep in mind when using bag-in-box?
- Wine must have slightly higher SO2, no headspace, and low CO2
- Must use high-quality tap, as most O2 ingress is there
How is “brick” or Tetra Pak made?
Paper card with plastic layers and an AL layer that excludes light and O2
What is the cost of using of Tetra Paks?
Filling equipment is a big investment; can be outsourced
What are 5 advantages of cans?
- Light
- Robust
- Easy to open
- Impermeable to O2
- Recyclable
How are cans made?
AL must be lined with plastic to avoid acidity attacking AL
At what price points are cans used?
- inexpensive
- mid-priced
What is the cost with use of cans?
Filling equipment is a big investment; most outsource
What is the range of market acceptance of screwcaps?
- All but the finest wines: Australia, NZ, UK
- Inexpensive wines: USA (though changing), China
What are the three things confirmed in a pre-filling analysis?
The wine is:
* stable
* meets technical specifications, if any, set by winemaker or the client
* conforms to legal standards, like limits on SO2 and trace metals (e.g., Cu and Fe)
What is included in a technical specification?
- free and total SO2
- volatile acidity
- alcohol content
- residual sugars
- total acidity and pH
- malic acid and lactic acid
- total dry extract
- tartrates and proteins (stability analysis)
- turbidity
- various minor acids: sorbic, ascorbic, metatartaric, citric
- trace metals such as copper, iron, potassium, calcium, sodium
- dissolved oxygen
- CO2
- microbial populations (various strains of yeast, bacteria)
- taints, e.g. TCA
What is checked and corrected in the last hours before filling?
dissolved O2 and CO2
Where would pre-filling analysis be done?
- In the winery if they have the lab equipment (large producers)
- Samples can be sent to an external lab
Describe traditional bottling
- Wine matured for 6-12 months in a cool cellar (so naturally become clear)
- Producers siphon wine into bottle and seal it with a cork
What are the two major steps in modern bottling?
- Bottles cleaned ((i) rinsed with sterile water and (ii) steam cleaned at 82 C for 20 mins)
- Potentially harmful yeast and bacteria eliminated from wine
What are the two primary ways to eliminate harmful microbes from wine?
- Sterile filtration (“cold bottling”)
- Heat treatments (e.g., flash pasteurization at 80-90 C for a few seconds)
What is one advantage and two disadvantages to cold bottling?
Advantage: No heat applied, so no deterioration of quality or premature ageing of wine
Disadvantages:
* considerable investment compared with flash pasteurization
* need to employ highly trained staff
In modern bottling, what needs to be done in addition to elimination of harmful microbes from wine?
- Sterilization of bottling line (pipes, fillers, etc.)
- Ensure no oxidation takes place during filling
What are the considerations with filling bag-in-boxes and pouches?
Greater focus on avoiding oxidation, given permeability of these containers. This means:
* Slightly higher SO2
* Low dissolved O2
* No ullage
* Low CO2 (to avoid bag bulging)
How are bricks filled?
- First sterilized with UV radiation
- Then fill in sterile container
What are 4 positives of small amounts of O2 during bottle maturation?
- primary aromas become tertiary
- tannins soften
- oak aromas become better integrated
- color moves towards brown and becomes paler in reds and darker in whites
What is a consequence of too little O2 during bottle maturation?
Reductive sulfur compounds:
* Pleasant at low levels (struck match, smoke)
* A fault at high levels (rotten egg)
What are three things that new wineries have to facilitate cleaning?
- use of easy-to-clean stainless steel
- hard non-porous floors that slope to aid drainage
- equipment located so it can be reached to be cleaned (including underneath equipment and dead-ends of pipes)
What are the three procedures for hygiene?
- Cleaning
- Sanitation
- Sterilization
What is cleaning?
removal of surface dirt
What is sanitation?
the reduction of unwanted organisms to acceptably low levels, typically with water and a detergent or other sanitizing agent and/or steam
What is sterilization?
the elimination of unwanted organisms; for example, from high risk areas such as the filler heads of bottling lines
What is quality control?
the set of practices by which the company ensures a consistently good quality product
What is quality assurance? What are three attributes of it?
the complete way a business organizes itself to deliver a good product consistently and to protect itself from legal challenge, including:
* planning
* management systems
* monitoring and recording of key standards from vineyard to bottling
What is HACCP (Hazard Analysis of Critical Control Points)?
A document in which:
* Every hazard (i.e., everything that can go wrong) is identified
* Each hazard is assessed by (i) seriousness, (ii) how it can be prevented, and (iii) how it can be corrected
What two third parties are involved with ISO certifications?
- ISO sets the standards
- Certification bodies carry out audits
What 4 things do external auditors from certification bodies look for in their audits?
- the company’s quality management system
- management structure
- physical and human resources
- and how the company measures, analyses and improves its performance
Why is a traceability system important for a winemaker?
- respond to and investigate complaints about its wine
- improve its practice so that similar problems do not occur in the future
How does a traceability system work?
- each bottle has a lot number (required in EU and other markets)
- winery keeps records at every point, starting at the vineyard, to identify what happened to every lot
- larger producers (and those most concerned) will keep samples of every batch in a library (so they can compare returned bottles with their samples)
What are 3 common problems reported about wines?
- cork taint
- tartrate crystals
- faulty or missing labels
What are the two primary options for transportation of wine, and how much does each account for volume?
- In glass bottles
- In bulk (40% of volume, but far less in value)
What are two types of containers for shipping wine in bulk?
- flexitank (more common)
- ISO tank
What is a flexitank?
- single-use, recyclable polyethylene bag that fits into a standard container
- coated with a barrier to prevent taint and reduce O2 ingress
What is an ISO tank?
a stainless steel vessel built to the ISO standard that can be reused many times and may have additional insulation
What is the advantage of shipping wine in bottle?
the entire product – the wine, the bottling, the labeling and any external packaging – is controlled by the producer
What are 5 disadvantages to shipping wine in bottle?
- higher cost due to smaller amount of wine that can be shipped in one container
- financial and environmental cost of shipping heavy glass
- potential damage to wine due to high and fluctuating temps in transit
- potential damage to labels and packaging in transit
- shorter shelf life of inexpensive wine because bottled earlier
What are 5 advantages to shipping wine in bulk?
- cheaper and more environmentally friendly than shipping in bottles
- greater thermal inertia of contain means less fluctuation of temps
- strict quality control (tech specs can be checked at filling and then on emptying)
- wine can be adjusted (e.g., SO2) at point of bottling close to consumer
- shelf life of inexpensive wines is extended (especially important for bag-in-box shipped over long distances)
What are two disadvantages of shipping in bulk?
- loss of the direct relationship with the producer
- transfer of business and employment opportunities from producer countries to the countries close to the final market
