WSET diploma intro Flashcards
Components of the grape
Describe PHOTOSYNTHESIS
A biochemical process by which green plants are synthesizing sugars (sucrose) from carbon dioxide and water with the aid of chlorophyll and energy from sun and warmth.
6 CO2 + 6 H2O + light –> C6H12O6 + 6 O2.
Describe the difference between SUCROSE, GLUCOSE and FRUCTOSE
Sucrose is produced in the leaves to be transported to grapes, which are the storehouses. Due to presence of acids in the grape it is broken down into glucose and fructose.
Fructose is the sweetest, followed by sucrose, and glucose being the least sweet.
Yeast prefer glucose and eat it first; fructose is the main sugar in sweet wines.
Name 2 tools used to measure sugar content
Refractometer and hydrometer.
Name 2 main acids found in grapes
Malic and Tartaric
Describe malic acid
Principal acid of apples (latin for apple is “malus”);
Sharp taste;
Present mostly in very young, green grapes;
Consumed by the grape as an energy source;
Converts into glucose in gluconeogenesis process - proportion of malic acid in the grape goes down as maturity approaches.
-released in 1st pressing
Describe tartaric acid
Unique to grapes;
Found in most finished wines;
Formed as a by-product of the synthesis of sugar;
Latin for deposit is “tartarus”: forms deposit in containers;
Quantity of tartaric acid in grape rises in proportion to the creation of sugars.
-released in 2nd pressing
Describe what happens to tartaric and malic acid in the maturation of the grapes
Malic acid is destroyed biochemically;
Tartaric acid becomes diluted in raising sugar levels.
How do you measure acid levels
Simple TITRATION - Titratable acidity
How the grape vine picks the mineral salts?
By the roots, as they delve deep in the subsoil in search of the moisture
Which minerals and why are the most abundand
Salts of potassium (K), they are associated with the production and translocation of the sugars; its concentration rises with the accumulation of the sugars in the grape.
What is negative influence of the minerals to the final bottling product?
Formation of potassium bi-tartare and other crystal formations.
List 5 most important minerals in grapes
- Salts of potassium (K)
- Calcium (Ca)
- Magnesium (Mg)
- Iron (Fe)
- Copper (Cu)
Describe relation between mineral salts, acids and pH.
Actual taste of wine is determined by pH of the juice, not the acidity. pH is controlled by the interaction between the acids and the salts.
Presence of certain salts can change the degree of acidity of the acids - “buffering”.
List 2 main classes of phenolic compounds
Flavonoids (polyphenols) and non-flavonoids (small, little influence on the finished wine)
What is the most important role of polyphenols (flavonoids)?
Antioxdiation: preservance of the wine and the winedrinker.
How can we sub-divide polyphenols
Into tannins and anthocyanins.
Where do we find tannins in grapes?
In skins (tough outer layer), stems and pips.
What are anthocyanins responsible for?
Colour in red and rose wines.
Where are anthocyanins found in grapes?
In the softer sells towards the inner layers of the skin grape.
How is the colour of red and rose achieved?
By extraction anthocyanins from the skins during the fermentation: alcohol extract anthocyanins from the skins;
The thicker skins, the more colouring matter.
Extraction can be done also by the heat, breaking down the cells walls.
Describe the colour changes connected with maturation of wine.
There are also other pigmented compounds –> during aging ratio of them changes: bluer one diminishes, so wine change from purple to orange.
Anthocyanins are not chemically stable;
With age anthocyanins link with tannins forming more stable pigmented polymers.
+ further reactions between anthocyanins and other phenolic compounds and aldehydes
Where are contained the flavour compounds?
In the inner surface of the skin, hence skin contact.
List flavour and aroma compounds (5).
Esters Higher alcohols Aldehydes Trepenols Hydrocarbides
Describe GLYCEROL and what it gives finished wine
(Glycerine): slighty sweet, syrupy substance, present in original juice and in finished wine (formed during fermentation), where it confers smoothness and body.
Proteins and amino acid function and danger?
- provides nutritions (nitrogen) for growing yeast and for consumer;
- can cause haze or cloudiness
- unstable colloids are removed in fining
List vine needs (5).
- sun
- warmth
- carbon dioxide
- nutrients
- water
Factors affecting SUNLIGHT (3)
- Latitude
- Bodies of water - have more cloud cover, but can reflect sunlight
- Aspect - facing the Equator = warmest and most sunlight
Sunlight hazards
- no sun = no photosynthesis
- low sun at flowering and fruitset can result in smaller crop of grapes
- low sun at ripening can stop ripening
Specify good vine growing temperature
–>10° - 25°C
Factors affecting WARMTH (6)
- Latitude
- Altitude
- Aspect
- Ocean currents
- Fog (like in California and Casablanca Valley in Chile)
- Soil
List 3 ocean currents influencing temperature in wine regions.
-Humbolt Current (Chile), Benguela Current (SA) - cooling down
+Gulf Stream (NW Europe) - heating up
Describe soil influence on heat.
- dark soil or soil with high stone and rock content absorbs and reradiate heat; lighter colour soil do this less;
- soil with higher water content requires more energy to warm up; can delay budburst.
Describe CONTINENTALITY
- -> temperature difference between the coldest and the warmest months
- high continentality = large difference
- low continentality = smaller difference
-as water retains heat, regions located closer to water will have lower continentality; region far inland will have higher concinentality
Describe DIURNAL RANGE
–> the amplitude between day and night temperatures.
- cool nights preserve the aromas
- where climate is hot, cold nights (large diurnal range) can preserve the aromas and freshness
- close proximity to seas and lakes can reduce diurnal range
- level of cloud cover influences diurnal range
Describe TEMPERATURE HAZARDS in winter
- growth stops when it’s too cold
- at -20°C sap freezes in vine, exploding and destroying internal structure (plant rots) - can be protected by burning (earthing up), most delicate is the graft
- warm winter = no dormancy, resulting in lowe crop, bad quality, etc.
- warm winter = more pests
Forms of protecting against SPRING FROST
- heaters
- sprinklers
- wind machines
- thoughtful vineyard design
Describe TEMPERATURE HAZARDS in summer
-above 28°C water content evaporates and leaves wither
3 main irrigation techniques
- Sprinklers
- Drip irrigation
- Flooding
Water hazards (3)
- drought: stopped transpiration and photosynthesis, failed ripening, death
- too much water: excess leaves (less sugar for grapes to ripen, too much sunshade, waterlogged soil
- heavy rainfall
- hail
- fungal diseases
Name 3 most important vine nutrients
- nitrogen
- phosphorus
- potassium
Most common symptom for lack of nutrients is…
Chlorosis.
List all stages in the growth cycle (8+1)
- Dormancy
- Budburst (March-April)
- Shoot and leaf growth
- Flowering (May-June)
- Fruit set (early summer)
- Grape berry formation (slow in first 20 days > fast > slow)
- Veraison (August)
- Ripening
- Extra - ripening
List pests and diseases (8)
- Phylloxera
- Nematodes
- Grape moths
- Spider mites
- Birds
- Mammals
- Fungal diseases
- Viruses & bacteria
Describe PHYLLOXERA
- an insect, native to North America;
- V.vinifera is defenceless || American vines clog insects mouth with sticky sap (!!!), and form protective layers behind the wounds, preventing secondary infections
- eats the roots, infections enter through the wounds, vine is weakened and dies ;(
- safe zones: some parts of Chile, Argentina, South Australia, Santorini
- grafting
- quarantine
- hybrids
Describe NEMATODES
- microscopes worms, attacking roots > interfering with water and nutrient intake
- can transmit vine viruses
- sanitising soils
- using resistan rootstocks
- THEY KILL SNAILS
List 5 approaches to grape growing
- Conventional
- Biodynamic
- Organic
- Precision viticulture - Viticulture Raisonee
- Sustainable
Describe conventional viticulture
- controling the life in the vineyard using toxic sprays, killing everything that may be harmful for vines
- can give large yields with low risk
- kills also the beneficial and necessary organisms, natural pests predators, and microbes around the roots, making vine unable to feed itself (further sprays)
- makes vine weaker and dependable
- roots don’t grow far
- kills the soil
- pests grow tolerance, hence more or different spray is needed
- expensive
- sprays reside in grapes and soil
Describe organic viticulture
- growing healthy vine in complex ecosystem, by prevention and only natural treatments (nothing chemical)
- SOIL: plouging and composting (organic), avoiding compacting the soil by tractors
- allowed: sulphur and copper for diseases, seaweed for borytris damage, sexual confusion of the pests
- encouraging biodiversity
- cover crops: secondary crops planted between thevines
- different organisations keeping varying rules
- period of conversion
Describe biodynamic viticulture
- 1924, Rudolf Stainer, Austrian esoteric philosopher and scientist, guidelines for connecting universe, farming with nature
- whole farm as a single living organism in a cosmic rythym
- branch of organic
- uses “fundamental” products
- uses principle of homeophaty, incl. special mixing techniques,
- special preparations nettles, cedar, horsetail, valerian, cow manure fermented in cow horn, flower heads of yarrow fermented in stag’s bladder
- Nicolas Joly of Coulee de Serrant, Domaine de la Romanee Conti, Domaine Leflaive, Zind Humbrecht, Chapoutier
- enhances terroir
Describe viticulture raisonee (precision viticulture)
- treatment only when necessary, maintaining fight against pests and diseases
- monitoring is the key, with keeping records
- not certified
- semi-organic without commintment
Describe sustainable viticulture
- “good practises that are objectively environmentally friendly”
- man-made chemicals allowed, but minimal use only
- monitoring weather and pests life cycles
- preventing diseases
- encouraging contr-pests
- developing range of flora, rather than monoculture
List 8 faults
- cloudiness and hazes
- tartrates
- refermentation in bottle
- cork taint
- oxidation
- volatile acidity
- reduction
- brettanomyces
Describe VOLATILE ACIDITY
- acetic acid separated from the other acids
- volatile = lotny
