Maturation Flashcards
What is maturation (élevage) in winemaking?
The post-fermentation period used to bring wine closer to the desired style by modifying organoleptic, microbial, chemical, and physical properties.
What are some outcomes of wine maturation?
Changes in clarity, colour, aroma/flavour intensity and type, acidity, astringency, sweetness, carbonation, and mouthfeel.
What are the key mechanisms of maturation?
Autolysis, barrel interactions, fining, anaerobic and aerobic reactions.
What is yeast autolysis and what does it release?
Breakdown of yeast cells releasing glucans, mannoproteins, peptides, amino acids, and glutathione.
What factors influence autolysis?
Yeast strain, biomass, ethanol, temperature, sulphite, oxygen, and physical activity.
How do yeast lees affect wine?
They can absorb sulphur compounds, phenols, fatty acids, and toxins; affect oxygen levels.
How do viable vs. non-viable yeast lees consume oxygen?
Viable yeast consume oxygen directly; non-viable yeast self-oxidise lipids or release glutathione.
What are the impacts of autolysis on wine?
Changes in ester and alcohol content, reduction in thiols, and modification of mouthfeel.
What roles do oak barrels play in maturation?
They allow lees contact, oxygenation, evaporation, and dissolve oak compounds into the wine.
What types of oak compounds influence wine?
Gallotannins, ellagitannins, coumarins, oak lactones, phenols (e.g., guaiacol), aldehydes (e.g., vanillin, furfural).
Name three oak species commonly used in cooperage.
Quercus alba (American), Quercus robur (French/English), Quercus petraea (Sessile/Irish).
Name three alternative woods used in wine maturation.
Cherry (Prunus avium), Sweet Chestnut (Castanea sativa), Ash (Fraxinus excelsior).
List alternative oak formats for wine maturation.
Oak powders, chips, nuggets, spirals, small/large staves.
What are hydrolysable tannins and their effects?
Non-flavonoid tannins (ellagitannins/gallotannins) affecting oxidation, astringency, and colour stability.
Name aromatic compounds from oak and their aromas.
Octalactone (coconut), vanillin (vanilla), eugenol (clove), guaiacol (smoke), furans (caramel/toast).
What vessel properties influence maturation?
Time, temperature, humidity, sealing, microbial presence, wood species, grain, seasoning, toasting.
List some non-traditional vessels and their oxygen characteristics.
Stainless steel (low ingress), concrete (slow ingress), terracotta/ceramic (porous), plastic (moderate ingress).
What are the purposes of fining agents?
Clarification, stability, organoleptic modification, reduction of phenols and reductive compounds.
What types of wine reactions occur during maturation?
Aerobic and anaerobic reactions; polyphenol condensation, polymerisation, co-pigmentation, browning.
What aroma reactions occur during maturation?
Esterification, ethanal formation, sulphur compound changes, acetic acid and maturation aroma formation.
