CH 15 : Finishing and Packaging Flashcards
describe sedimentation?
clarifying the wine by allowing particles to settle and racking the wine off this sediment. Takes time so often used for premium/super premium wines
What is centrifugation?
a clarification technique that uses centrifugal force to separate liquids and solids. It can replace depth filtration and hasten bottling. Primarily used in high-volume wineries.
What is fining?
the removal on unstable colloids in the wine to clarify and stabilised it against hazes forming
what is over-fining?
the desirable compounds are removed from the wine due to too much fining agents being added.
how do fining agents work against colloids?
the agent has the opposite charge to the colloid and binds with it forming a filterable solid.
What are the three kinds of fining agents
- removal of unstable proteins
- removal of phenolics that add unwanted colour and bitterness
- removal of colour and off odoursw
what is an example of a fining agents that removes unstable proteins?
bentonite clay
can lead to colour loss in red and significant sediment means some wine is lost
what fining agents remove undesirable phenolics
egg white
gelatine
casein
isinglass
vegetable protein products
PVPP
describe filtration
the removal of unwanted solids from a wine through a physical barrier that traps these particles
describe depth filtration
wine passes through different layers of a filter, catching different sized particles on the way.
can cope with many different particle sizes. Does not block easily. Too much pressure can push sediment through.
what is sheet filtration?
pannels or sheet are stacked and the wine passes through, with sheets catching particles on the way. Costs to operate are low but the upfront cost is high.
Describe how diatomaceous earth filtering works
DE is a form of depth filtration. The wet earth is used as a filter medium, as wine inside a rotary drum is sucked through it. Used to filter very cloudy wines.
Can expose the wine to oxygen. enclosed filters flushed with innert gas fix this problem
what is surface filtration?two kinds of surface filtration systems?
membrane filters
cross flow filters
what is stabilisation?
several winemaking interventions which mitigate unwanted effects in the finished wine post-bottling
how would a winemaker ensure protein stability?
fining with bentonite
what are the methods for creating tartrate stability in the wine?
cold stabilisation
contact ppress
electrodialysis
ion exchange
CMC
metatartaric acid
what temperatures are required for cold stabilisation?
-4C for 8 days
why would a winemaker use contact press over cold stabilisation for tartaric stability?
contact pressing is quicker, continuous, and more reliable than cold stabilisation.
It uses potassium bitartrate to speed up the crystallisation process. Takes 1-2 hours to form cristals that are filterable
what tartaric stabilisation techniques would an early drinking wine employ?
metatartaric acid
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what is a good tartaric stabilisation method for cheap white wine?
CMC
what is electrodialysis?
a charged membrane removes select ions to prevent the formation of tartrate cristals
how does ion exchange work?
it develops tartaric stability by replacing potassium and calcium ions with hydrogen or sodium ions which will not drop out of solution
how would a winemaker mitigate the risk of a secondary bottle ferment in sweet wines?
removing yeasts through sterile filtration
what microbes can live in wines low pH and high alcohol levels?
lactic acid bacteria
brett
acetic acid bacteria
how would a winemaker prevent Malo happening in-bottle?
ensuring it has already fully completed or filtering the wine to remove the bacteria
how would a winemaker eliminate brettanomyces?
treatment with filtering or DMDC (dimethyl dicarbonate)
what is measured in a chemical analysis?
alcohol
RS
free SO2
dissolved oxygen and CO2
what are the broad amounts of free SO2 in white, red, and sweet wines?
white - 25-45 mg/L
red - 30-55 mg/L
sweet - 30-60 mg/L
why will white wines require less free SO2 for stability?
because of the lower pH which promotes the efficacy of the free SO2w
what is sparging?
the process of removing dissolved oxygen from wine using innert gas
how will high levels of dissolved oxygen affect the wine?
it will accelerate the ageing process and reduce shelf life
how would a winemaker fix cloudiness and hazes in the wine?
winery hygiene
chemical analysis and filtering
fining with bentonite
what causes reduction?
yeast under stress due to low nitrogen levels or the absence of oxygen
what is lightstrike?
caused by UV and certain wavelengths of visible light that reacts with the wine to form volatile sulphur compounds that give off an unpleasant smell
how does one avoid brettanomyces?
good winery hygiene
SO2 level management
low pH
shortening vulnerable time between end of alcoholic conversion and start of MLC
what are the ideal properties of a wine closure
-protects from rapid oxidation
-inert
- easy to remove and re-insert
- cheap, recyclable, fault-free
what is HPLC and FTIR
high tech options for chemical analysis
High Performance Liquid Chromatography
Fourier Transform Infared Spectroscopy
what is the OTR
oxygen transmission rate
what is HACCP?
hazard Analysis of Critical Control Points
What are ISO standards?
International Organisation for Standardisation
